Microbiology MCQs for NEET PG
840 worked Microbiology questions across 64 areas. Each one has its own page with the reasoning for every option.
What this set is
Microbiology rewards organised recall: organism, key feature, test, and disease. Immunology and clinical scenarios carry as much weight as lists of organisms.
This page lists the 840 Microbiology questions that have a full worked page: 617 application questions that put a fact to use on a patient or a finding, and 223 multi-step questions that combine two or more ideas. Plain one-fact recall items are left out here on purpose. The Microbiology practice bank in the app is larger, with 4,004 questions in all, and is where timed tests and daily practice draw from.
How to use it
- Pick an area you are weak in, below.
- Answer first, then read why each wrong option fails.
- Write a three-line note for every miss, and revisit it in a week.
- Move to a timed Microbiology test once an area feels steady.
These are original practice items, not recalled exam questions, and they are not yet reviewed by independent faculty. Confirm important facts in a standard textbook.
What Microbiology covers in the exam
- General microbiology and sterilisation
- Immunology
- Bacteriology
- Virology
- Mycology
- Parasitology
- Clinical microbiology and hospital infection control
A study map from the standard curriculum; the NBEMS bulletin is the authority. See the Microbiology study guide.
Worked questions by area
64 areas, largest first. Open an area to see its questions.
Bacteriology204
- Bacteriology · ApplicationA patient has profuse painless watery 'rice-water' stools and rapid dehydration. The causative organism is a:
- Bacteriology · ApplicationAlbert's stain is used to demonstrate which of the following?
- Bacteriology · ApplicationWhich organism classically causes 'currant jelly' sputum?
- Bacteriology · ApplicationA chronic alcoholic has rusty sputum and lobar consolidation. Sputum Gram stain shows lancet-shaped Gram-positive diplococci with alpha-haemolytic colonies. Which test…
- Bacteriology · ApplicationA pregnant woman develops fever and diarrhoea after eating unpasteurised soft cheese. Her newborn develops meningitis. Gram stain of CSF shows small Gram-positive rods…
- Bacteriology · ApplicationA man develops pneumonia with diarrhoea and hyponatraemia after staying in a hotel with a contaminated air-conditioning cooling tower. Which investigation is the most p…
- Bacteriology · ApplicationA man develops profuse watery diarrhoea with fever and abdominal pain, and colonoscopy shows yellow-white plaques on the mucosa, after a course of clindamycin. Which in…
- Bacteriology · ApplicationA sewage worker develops fever, jaundice, renal failure and conjunctival suffusion. Which organism is likely, and what is the typical microscopic method for demonstrati…
- Bacteriology: streptococci · ApplicationA throat swab culture grows Gram-positive cocci in chains with a wide zone of clear (beta) haemolysis on blood agar. The organism is sensitive to bacitracin and PYR pos…
- Bacteriology: anaerobes · ApplicationA farmer has a deep contaminated leg wound with severe pain, crepitus and a brownish discharge. Gram stain shows large Gram-positive bacilli without spores. On egg-yolk…
- Bacteriology: Bacillus · ApplicationA wool sorter has a painless black eschar on the forearm with surrounding oedema. Gram stain shows large Gram-positive bacilli in chains. On culture the colonies look l…
- Bacteriology: mycobacteria · ApplicationA man with advanced HIV and a CD4 count of 30 cells/mm3 has fever, night sweats, weight loss and anaemia. Blood culture grows acid-fast bacilli after several weeks. Whi…
- Bacteriology: enteric pathogens · Multi-stepA 4-year-old child develops bloody diarrhoea after eating undercooked beef. Five days later he has pallor, reduced urine output, a raised creatinine and schistocytes wi…
- Bacteriology: Brucella · Multi-stepA 34-year-old dairy farmer from Punjab who drinks raw milk has undulating fever, night sweats, arthralgia and mild splenomegaly for 6 weeks. The serum agglutination tit…
- Bacteriology: Salmonella Typhi · Multi-stepA 24-year-old man has had fever for 12 days and took oral amoxicillin and ofloxacin for the last 5 days from a local practitioner without relief. Enteric fever is suspe…
- Bacteriology: Shigella · ApplicationA 5-year-old child has fever, tenesmus and blood-and-mucus stools. Stool culture on MacConkey agar grows pale non-lactose-fermenting colonies. The isolate is non-motile…
- Bacteriology: Campylobacter · ApplicationA 28-year-old man has bloody diarrhoea and cramps after eating undercooked chicken. Ten days later he develops ascending symmetrical limb weakness with areflexia. Which…
- Bacteriology: Vibrio vulnificus · ApplicationA 58-year-old man with alcoholic cirrhosis develops fever, hypotension and haemorrhagic bullae on the leg 24 hours after eating raw oysters. Blood cultures grow a halop…
- Bacteriology: Haemophilus influenzae · ApplicationA CSF isolate from an unimmunised child with meningitis grows poorly on sheep blood agar but forms tiny satellite colonies around a streak of Staphylococcus aureus. Whi…
- Bacteriology: Bordetella pertussis · Multi-stepA 4-month-old unimmunised infant has paroxysms of cough ending in an inspiratory whoop with post-tussive vomiting. Total leucocyte count is 38,000 per microlitre with 7…
- Bacteriology: Acinetobacter · ApplicationA patient on mechanical ventilation in an ICU for 10 days develops ventilator-associated pneumonia. The endotracheal aspirate grows Gram-negative coccobacilli that are…
- Bacteriology: Burkholderia pseudomallei · Multi-stepA 52-year-old diabetic rice farmer from coastal Karnataka presents in the monsoon with fever, pneumonia and multiple liver and subcutaneous abscesses. Culture shows oxi…
- Bacteriology: leprosy and lepromin test · ApplicationA 30-year-old man has a single hypoaesthetic, hypopigmented plaque with a raised, well-defined edge and a thickened adjacent nerve; slit-skin smear is negative. A lepro…
- Bacteriology: Mycobacterium marinum · ApplicationA 35-year-old aquarium hobbyist develops violaceous nodules in a linear pattern up the forearm several weeks after cleaning a fish tank with an abraded finger. Acid-fas…
- Bacteriology: syphilis serology and prozone · Multi-stepA 25-year-old woman has a diffuse maculopapular rash involving the palms and soles with condylomata lata. VDRL on undiluted serum is reported non-reactive. Clinical sus…
- Bacteriology: Borrelia recurrentis · ApplicationA homeless man in a crowded shelter has abrupt high fever, headache and myalgia for 4 days that resolves by crisis and recurs after a week. A smear taken during fever s…
- Bacteriology: scrub typhus and Weil-Felix test · ApplicationA 38-year-old farmer from a hill district of Himachal Pradesh has fever for 8 days, headache, and a painless black eschar in the axilla with regional lymphadenopathy. W…
- Bacteriology: Mycoplasma pneumoniae · ApplicationA 19-year-old college student has a 10-day dry cough, low-grade fever and headache. The chest radiograph shows patchy infiltrates out of proportion to the clinical find…
- Bacteriology: Nocardia · Multi-stepA 60-year-old man on long-term prednisolone has cough, and CT shows cavitating lung nodules; MRI shows a brain abscess. Sputum shows thin, branching, beaded Gram-positi…
- Bacteriology: Actinomyces · ApplicationA 32-year-old woman with an intrauterine device in place for 7 years has chronic pelvic pain and a tubo-ovarian mass. Pus shows yellow sulphur granules containing Gram-…
- Bacteriology: infant botulism · ApplicationA 5-month-old breastfed infant has had constipation for 4 days and now has a weak cry, poor suck, drooping eyelids and generalised hypotonia. The parents had been givin…
- Bacteriology: vancomycin-resistant enterococci · Multi-stepAn ICU patient has bacteraemia with Enterococcus faecium that is resistant to ampicillin and to vancomycin at high level, with the vanA gene detected. By which mechanis…
- Bacteriology: Streptococcus gallolyticus endocarditis · Multi-stepA 65-year-old man has fever for 3 weeks and a new murmur. Two of three blood culture sets grow Gram-positive cocci that are bile-esculin positive but do not grow in 6.5…
- Bacteriology: Staphylococcus saprophyticus · ApplicationA 23-year-old sexually active woman has dysuria and frequency a few days after her honeymoon. Urine culture grows Gram-positive cocci in clusters that are catalase-posi…
- Bacteriology: toxic shock syndrome toxin · ApplicationA 22-year-old woman using a high-absorbency tampon develops fever of 39.5 degrees C, hypotension, diffuse macular erythroderma and, a week later, desquamation of the pa…
- Bacteriology: meningococcal chemoprophylaxis · ApplicationA 20-year-old hostel resident has meningococcal meningitis. His roommate, who is 21 years old and not pregnant, needs chemoprophylaxis to eliminate nasopharyngeal carri…
- Bacteriology: Proteus and struvite stones · ApplicationA 45-year-old woman with recurrent urinary infections has flank pain, urine pH 8.5 and a staghorn calculus on imaging. Urine culture shows swarming growth on blood agar…
- Bacteriology: Bartonella henselae · Multi-stepA man with HIV and a CD4 count of 40 cells per cubic mm has multiple red-purple, friable, bleeding papules on the skin. He keeps kittens at home. Biopsy shows lobular p…
- Bacteriology: brucellosis treatment · ApplicationA 35-year-old dairy farmer in Punjab has a three-week undulating fever, sweating, backache with sacroiliac tenderness and splenomegaly. Blood culture grows small Gram-n…
- Bacteriology: scrub typhus · ApplicationA farmer who cleared bushland two weeks ago has high fever, headache and lymphadenopathy. There is a painless black eschar in the axilla. The Weil-Felix test is perform…
- Bacteriology: Coxiella burnetii · Multi-stepA 45-year-old shepherd has fever for six weeks and a new aortic regurgitation murmur. Several blood cultures on routine media are negative and the Weil-Felix test is ne…
- Bacteriology: infant botulism · Multi-stepA 5-month-old breastfed infant has had constipation for four days, followed by a weak cry, poor suck, ptosis and symmetrical descending hypotonia. His mother had applie…
- Bacteriology: Mycobacterium marinum · ApplicationA man who cleans a home fish aquarium has a purple nodule on the hand that has spread as a line of nodules up the forearm over four weeks. Smears show acid-fast bacilli…
- Bacteriology: Campylobacter jejuni · Multi-stepA 28-year-old man develops ascending symmetrical weakness with areflexia two weeks after an episode of bloody diarrhoea. Stool culture, if it were still positive, would…
- Bacteriology: Nocardia versus Actinomyces · Multi-stepA renal transplant recipient has a lung cavity and a brain abscess. Pus shows thin, beaded, branching Gram-positive filaments that stain with modified Ziehl-Neelsen (1%…
- Bacteriology: rapid-growing mycobacteria · Multi-stepSix weeks after a cosmetic abdominal liposuction at a small clinic, a 34-year-old woman has multiple discharging subcutaneous abscesses that do not respond to cephalexi…
- Bacteriology: Pasteurella multocida · ApplicationA 40-year-old woman is bitten on the hand by a cat. Within 12 hours the hand is swollen, red and very painful with purulent discharge. Gram stain shows small Gram-negat…
- Bacteriology: anthrax toxin · ApplicationA tannery worker has a painless black eschar on the forearm with marked surrounding oedema. In the pathogenesis of this disease, which component of the toxin binds the…
- Bacteriology: staphylococcal exfoliative toxin · Multi-stepA 10-day-old neonate has fever, perioral erythema and flaccid blisters that rupture to leave moist red skin. Gentle rubbing produces skin separation, the mouth is spare…
- Bacteriology: post-streptococcal sequelae · Multi-stepA 6-year-old develops cola-coloured urine, periorbital oedema and hypertension 3 weeks after impetigo on the legs. The parents ask if rheumatic fever may also follow. W…
- Bacteriology: Mycobacterium leprae cultivation · ApplicationMycobacterium leprae does not grow on artificial media but multiplies in the footpads of mice and in the nine-banded armadillo. Which property of these hosts explains t…
- Bacteriology: Escherichia coli pathotypes · ApplicationSeveral infants in a nursery develop prolonged watery diarrhoea without blood. Stool microscopy shows no leucocytes. Electron microscopy of the intestinal biopsy shows…
- Bacteriology: Escherichia coli pathotypes · Multi-stepA 20-year-old man has fever, tenesmus and stools containing blood, mucus and many pus cells. Culture yields a non-motile, late lactose-fermenting Gram-negative bacillus…
- Bacteriology: typhoid complications · Multi-stepA 24-year-old whose blood culture on day 5 of fever grew Salmonella Typhi, and who was not treated, suddenly has severe abdominal pain, a rigid abdomen, tachycardia and…
- Bacteriology: Lyme disease · ApplicationA hiker in New England develops an expanding annular erythematous rash with central clearing on the thigh 7 days after a tick bite, with mild fever and fatigue. What is…
- Bacteriology: CSF interpretation · Multi-stepA 35-year-old has a 3-week history of headache and vomiting, and now has a sixth cranial nerve palsy. CSF shows 150 cells per microlitre (90% lymphocytes), glucose 25 m…
- Bacteriology: staphylococcal food poisoning · ApplicationFour guests develop severe vomiting 3 hours after eating a custard dessert that was left unrefrigerated and then reheated before serving. Fever is absent and they recov…
- Bacteriology: group B streptococcus · Multi-stepA woman at 36 weeks of gestation has a rectovaginal swab culture positive for Streptococcus agalactiae. She goes into labour at term with no allergies. What is the best…
- Bacteriology: Bacillus cereus · ApplicationWithin 2 hours of eating fried rice from a roadside stall, three students develop nausea and repeated vomiting without fever. The rice had been boiled in the morning an…
- Bacteriology: Mycobacterium ulcerans · ApplicationA child from a swampy region of West Africa has a painless, large skin ulcer with undermined edges and little fever. Acid-fast bacilli are seen in the smear. Which fact…
- Bacteriology: uropathogenic E. coli · ApplicationA 22-year-old woman with acute pyelonephritis has no vesicoureteric reflux or obstruction. The causative Escherichia coli carries a pap gene cluster. Which virulence fa…
- Bacteriology: psittacosis · ApplicationA pigeon breeder presents with fever, headache, dry cough and splenomegaly. Chest radiograph shows patchy consolidation. Gram stain of sputum shows no bacteria. Which d…
- Bacteriology: toxin mechanisms · Multi-stepA traveller develops watery diarrhoea from enterotoxigenic Escherichia coli that produces only the heat-stable toxin (ST). What is the intracellular mechanism responsib…
- Bacteriology: ecthyma gangrenosum · ApplicationA neutropenic patient on chemotherapy develops painless dark necrotic skin lesions with a surrounding erythematous rim. Blood cultures grow an oxidase-positive Gram-neg…
- Bacteriology: neurosyphilis · Multi-stepA man with untreated syphilis for years develops dementia and ataxia, and has small pupils that constrict to accommodation but not to light. Which test on cerebrospinal…
- Bacteriology: Mycobacterium bovis · ApplicationA child from a dairy farm has cervical lymphadenitis due to Mycobacterium bovis. This species is intrinsically resistant to which first-line antitubercular drug?
- Bacteriology: post-splenectomy sepsis · ApplicationA splenectomised adult presents with fulminant sepsis, and blood culture shows Gram-positive lancet-shaped diplococci. Which preventive measure was most likely omitted?
- Bacteriology: leptospirosis sampling · Multi-stepA paddy farmer has high fever, conjunctival suffusion, jaundice and renal failure. On which week of illness is culture or PCR of blood most likely to be positive?
- Bacteriology: necrotising fasciitis · Multi-stepA diabetic man has a rapidly spreading painful leg infection with bullae and severe systemic toxicity. Gram stain shows Gram-positive cocci in chains, and surgical debr…
- Bacteriology: Brill-Zinsser disease · Multi-stepA 68-year-old man who survived epidemic typhus in a refugee camp decades ago now has a mild fever and rash, though there is no louse exposure. What explains this?
- Bacteriology: nalidixic acid resistance in typhoid · Multi-stepA patient with culture-confirmed typhoid shows no fever response after 5 days of ciprofloxacin. The isolate is resistant to nalidixic acid with ciprofloxacin MIC in the…
- Bacteriology: Burkholderia mallei · ApplicationA horse handler has a nodular suppurative skin lesion with lymphangitis and nasal discharge. The organism is a non-motile Gram-negative bacillus. Which disease is this?
- Bacteriology: Clostridioides difficile · Multi-stepA patient develops watery diarrhoea 5 days after starting clindamycin. Stool is positive for glutamate dehydrogenase and toxin B gene PCR, and colonoscopy shows yellow…
- Bacteriology: Salmonella · Multi-stepA child with sickle cell disease has fever and bone pain, and bone aspirate grows a motile Gram-negative bacillus that is non-lactose fermenting and produces H2S. Which…
- Bacteriology: Haemophilus ducreyi · Multi-stepA man has multiple painful genital ulcers with ragged undermined edges and a tender suppurative inguinal bubo. Smear shows Gram-negative coccobacilli in parallel chains…
- Bacteriology: Treponema · Multi-stepA newborn has snuffles, hepatosplenomegaly and a rash on the palms and soles. The mother was untreated for syphilis. Which later finding is part of late congenital syph…
- Bacteriology: Borrelia · ApplicationA trekker in a temperate region develops an expanding annular rash with central clearing after a tick bite. Which organism is responsible?
- Bacteriology: anaerobes · ApplicationA patient after colorectal surgery develops a pelvic abscess. Culture yields a bile-resistant, Gram-negative anaerobic bacillus. Which drug gives best anaerobic cover?
- Bacteriology: donovanosis · ApplicationA man has a painless, beefy-red, easily bleeding genital ulcer with no lymph node suppuration. Smear stained with Giemsa shows intracellular bipolar organisms in macrop…
- Bacteriology: erythema nodosum leprosum · Multi-stepA 30-year-old man with lepromatous leprosy has taken multidrug therapy for three months. He develops fever, tender red nodules on the limbs, arthralgia and iritis. Biop…
- Bacteriology: type 1 lepra reaction · Multi-stepA patient with borderline tuberculoid leprosy starts multidrug therapy. Two months later his existing skin patches become red, swollen and tender, and he develops acute…
- Bacteriology: Rickettsia rickettsii · ApplicationA child returns from a camping trip with fever, severe headache and a rash that began at the wrists and ankles, then spread centrally and onto the palms and soles. A ti…
- Bacteriology: Ehrlichia chaffeensis · ApplicationA hunter from the central United States has fever, leukopenia, thrombocytopenia and raised transaminases a week after a tick bite. A peripheral smear shows mulberry-lik…
- Bacteriology: Panton-Valentine leukocidin · ApplicationA healthy 20-year-old has recurrent painful skin boils. His cousin from the same household develops rapidly progressive necrotising pneumonia with leukopenia after an i…
- Bacteriology: Streptococcus anginosus group · Multi-stepA man with chronic sinusitis develops a frontal lobe abscess. Aspirated pus grows catalase-negative Gram-positive cocci in chains with a butterscotch odour, and they ar…
- Bacteriology: HACEK endocarditis · Multi-stepA 28-year-old with a bicuspid aortic valve and poor dentition has six weeks of low-grade fever and a new regurgitant murmur. Blood cultures show no growth at 2 days, bu…
- Bacteriology: Vi polysaccharide vaccine · ApplicationA paediatrician considers typhoid vaccination for a 12-month-old child. Why is the unconjugated Vi capsular polysaccharide vaccine unsuitable at this age?
- Bacteriology: biological false-positive VDRL · ApplicationA 28-year-old woman with systemic lupus erythematosus and recurrent miscarriages has a reactive VDRL at a titre of 1 in 8. TPHA and FTA-ABS are both non-reactive and sh…
- Bacteriology: Treponema pertenue · ApplicationA child from a tribal hamlet has a painless raspberry-like papilloma on the leg that is later followed by bone pain and painful soles. VDRL and TPHA are reactive. Which…
- Bacteriology: rat-bite fever · Multi-stepA laboratory worker bitten by a rat develops fever, a rash on the hands and feet and migratory polyarthritis five days after the healed bite. Blood grows, on serum-enri…
- Bacteriology: Moraxella catarrhalis · Multi-stepA 65-year-old with COPD has an acute exacerbation. Sputum Gram stain shows kidney-bean shaped Gram-negative diplococci. The isolate is oxidase positive, produces beta-l…
- Bacteriology: Capnocytophaga canimorsus · Multi-stepA 58-year-old splenectomised man with alcohol use disorder develops fulminant sepsis with purpura and DIC one day after a dog bite. Blood culture eventually grows slow-…
- Bacteriology: Rhodococcus equi · Multi-stepA man with AIDS (CD4 count 25 per microlitre) who works on a horse farm has fever and a cavitating upper lobe pneumonia. Sputum shows pleomorphic Gram-positive coccobac…
- Bacteriology: Erysipelothrix rhusiopathiae · Multi-stepA fishmonger has a well-demarcated violaceous, painful swelling of the finger after a fish bone puncture, with little suppuration and no fever. Culture grows a thin Gra…
- Bacteriology: Tropheryma whipplei · ApplicationA 45-year-old farmer has chronic diarrhoea with steatorrhoea, weight loss and migratory arthralgia for a year. Small bowel biopsy shows foamy macrophages in the lamina…
- Bacteriology: wound botulism management · ApplicationA 32-year-old man who injects black-tar heroin under the skin develops diplopia, ptosis, dysarthria and dysphagia, followed by symmetrical descending weakness. He is af…
- Bacteriology: gonococcal ophthalmia neonatorum · ApplicationA full-term neonate delivered vaginally without ocular prophylaxis develops bilateral severe purulent conjunctivitis with marked eyelid oedema on day 3 of life. Which o…
- Bacteriology: Stenotrophomonas maltophilia treatment · ApplicationA ventilated ICU patient treated with meropenem for 10 days develops new pneumonia. Sputum grows an oxidase-negative, non-fermenting Gram-negative bacillus that is resi…
- Bacteriology: Aeromonas after leech therapy · ApplicationThree days after leech therapy for venous congestion of a replanted finger, a patient develops cellulitis with a discharging wound. Culture grows a beta-haemolytic, oxi…
- Bacteriology: Kingella kingae in children · Multi-stepA 15-month-old fully immunised child has a limp and a warm swollen knee with low-grade fever and a mildly raised CRP. Synovial fluid culture on routine agar is sterile…
- Bacteriology: yaws treatment · Multi-stepA child in a remote tribal hamlet has a painless raspberry-like papillomatous lesion on the leg, and later bone pains. VDRL and TPHA are both reactive, genital examinat…
- Bacteriology: spontaneous gas gangrene · Multi-stepA 66-year-old man with no history of trauma has sudden severe thigh pain, crepitus and rapidly spreading myonecrosis. Blood culture grows an aerotolerant Gram-positive…
- Bacteriology: Cutibacterium prosthetic joint infection · Multi-stepEight months after total shoulder arthroplasty, a 60-year-old man has persistent low-grade pain and prosthesis loosening without fever. Intra-operative cultures are neg…
- Bacteriology: Mycobacterium kansasii · ApplicationA 48-year-old man with chronic obstructive lung disease has chronic cough and an upper-lobe cavity resembling tuberculosis. Sputum smear shows acid-fast bacilli. On Low…
- Bacteriology: Listeria meningitis therapy · ApplicationA 72-year-old renal transplant recipient on tacrolimus has fever, neck stiffness and confusion. CSF Gram stain shows Gram-positive bacilli. He has been started on ceftr…
- Bacteriology: tetanus prophylaxis in a dirty wound · ApplicationA 45-year-old farmer has a deep, soil-contaminated puncture wound from a rusty tool. He cannot recall ever being immunised against tetanus. Which tetanus prevention is…
- Bacteriology: Jarisch-Herxheimer reaction · ApplicationFour hours after the first injection of benzathine penicillin for secondary syphilis, a man develops fever with chills, headache, myalgia and intensification of his ras…
- Bacteriology: Pontiac fever · Multi-stepWithin two days of cleaning a hotel's air-conditioning cooling system, six maintenance workers develop fever, chills, headache and myalgia. None has cough or pneumonia,…
- Bacteriology: trench fever · Multi-stepA homeless man with body lice has recurrent fever lasting about five days, with headache and severe bilateral shin pain. A blood smear shows no spirochaetes and there i…
- Bacteriology: erythrasma · ApplicationA diabetic man has well-demarcated, dry, red-brown patches in both groins and axillae. Under Wood's lamp they fluoresce coral red, and a KOH mount shows no fungal eleme…
- Bacteriology: scarlet fever exotoxin · ApplicationA 7-year-old has sore throat, fever, a fine sandpaper rash sparing the area around the mouth, and a strawberry tongue. A throat swab grows beta-haemolytic, bacitracin-s…
- Bacteriology: enterococcal combination therapy · Multi-stepA 68-year-old man with Enterococcus faecalis endocarditis is given ampicillin with low-dose gentamicin instead of either drug alone. What is the basis of this combinati…
- Bacteriology: Eikenella in human bite wounds · ApplicationA man punches another in the mouth and develops a swollen, tender, infected knuckle wound two days later. Gram stain of the pus shows Gram-negative bacilli, and the col…
- Bacteriology: katG isoniazid resistance · ApplicationA Mycobacterium tuberculosis isolate shows high-level isoniazid resistance. Sequencing finds a mutation in the katG gene. How does this mutation cause resistance?
- Bacteriology · ApplicationWhich organism is catalase positive staphylococcus?
- Bacteriology · ApplicationWhich organism causes diphtheria?
- Bacteriology · ApplicationWhich organism causes whooping cough?
- Bacteriology · ApplicationWhich organism commonly causes neonatal meningitis?
- Bacteriology · ApplicationWhich organism is urease positive and linked to struvite stones?
- Bacteriology · ApplicationWhich organism causes cholera?
- Bacteriology · ApplicationWhich organism causes dysentery with low infectious dose?
- Bacteriology · ApplicationWhich organism produces pseudomembranous colitis after antibiotics?
- Bacteriology · ApplicationWhat organism causes tetanus?
- Bacteriology · ApplicationWhat organism causes gas gangrene?
- Bacteriology · ApplicationWhat organism commonly causes peptic ulcer?
- Bacteriology · ApplicationWhat organism causes typhoid?
- Bacteriology · ApplicationWhat organism causes plague?
- Bacteriology · ApplicationWhat organism can cause neonatal listeriosis?
- Bacteriology · ApplicationWhat organism causes anthrax?
- Bacteriology · ApplicationWhat organism is associated with rust-colored sputum?
- Bacteriology · ApplicationWhat stain differentiates bacteria by cell-wall characteristics?
- Bacteriology · ApplicationGram-positive bacteria retain which color after Gram staining?
- Bacteriology · ApplicationWhich organism is a gram-positive coccus in clusters?
- Bacteriology · ApplicationWhich organism is a gram-positive coccus in chains?
- Bacteriology · ApplicationWhich organism is classically acid-fast?
- Bacteriology · ApplicationWhat is the usual mode of transmission of cholera?
- Bacteriology · ApplicationWhat feature helps Staphylococcus aureus evade phagocytosis?
- Bacteriology · ApplicationWhat is a common virulence factor of Streptococcus pyogenes?
- Bacteriology · ApplicationWhich organism is a common cause of uncomplicated urinary tract infection?
- Bacteriology · ApplicationWhat laboratory test detects catalase production?
- Bacteriology · ApplicationWhat bacterial structure helps some organisms resist phagocytosis?
- Bacteriology · ApplicationWhat structure enables motility in many bacteria?
- Bacteriology · ApplicationWhat process transfers plasmid DNA between bacteria through cell contact?
- Bacteriology · ApplicationWhat enzyme produced by Staphylococcus aureus helps form clots in laboratory testing?
- Bacteriology · ApplicationWhich organism is a common cause of community-acquired lobar pneumonia?
- Bacteriology · ApplicationWhat morphology is typical of Vibrio cholerae?
- Bacteriology · ApplicationWhat organism commonly causes tetanus?
- Bacteriology · ApplicationWhat toxin-mediated disease is caused by Corynebacterium diphtheriae?
- Bacteriology · ApplicationWhat is the primary mode of transmission of tuberculosis?
- Bacteriology · ApplicationWhat test is used to detect mycobacterial acid-fast bacilli in sputum?
- Bacteriology · ApplicationWhat bacterial structure is targeted by beta-lactam antibiotics?
- Bacteriology · ApplicationWhat is an endotoxin component of gram-negative bacteria?
- Bacteriology · ApplicationWhat bacteria commonly cause pseudomembranous colitis after antibiotics?
- Bacteriology · ApplicationWhat is a common cause of meningitis in young adults?
- Bacteriology · ApplicationWhat is the shape of Neisseria gonorrhoeae on microscopy?
- Bacteriology · ApplicationWhat organism is associated with bloody diarrhea and hemolytic uremic syndrome?
- Bacteriology · ApplicationWhat organism causes typhoid fever?
- Bacteriology · ApplicationWhat is a common route of transmission for Salmonella Typhi?
- Bacteriology · ApplicationWhat feature helps Bacillus anthracis persist in harsh conditions?
- Bacteriology · ApplicationWhat is the usual cause of whooping cough?
- Bacteriology · ApplicationWhat stain differentiates bacteria by cell-wall structure?
- Bacteriology · ApplicationWhat morphology describes Staphylococcus aureus?
- Bacteriology · ApplicationWhat morphology describes Streptococcus pyogenes?
- Bacteriology · ApplicationWhat organism is classically acid-fast?
- Bacteriology · ApplicationWhat is the usual transmission route of cholera?
- Bacteriology · ApplicationWhat virulence factor allows Staphylococcus aureus to bind immunoglobulin Fc portions?
- Bacteriology · ApplicationWhat is a major virulence factor of Streptococcus pyogenes?
- Bacteriology · ApplicationWhat organism is most commonly implicated in uncomplicated urinary tract infection?
- Bacteriology · ApplicationWhat test identifies catalase production by bacteria?
- Bacteriology · ApplicationWhat is the main mechanism of tetanus toxin?
- Bacteriology · ApplicationWhat does catalase testing distinguish?
- Bacteriology · ApplicationWhat is the usual reservoir of Clostridioides difficile infection?
- Bacteriology · ApplicationWhat does a blood culture primarily help determine?
- Bacteriology · ApplicationWhat structure helps bacteria adhere to host surfaces?
- Bacteriology: Vibrio cholerae · ApplicationA patient with profuse 'rice-water' diarrhoea is infected with Vibrio cholerae. What is the principal action of cholera toxin?
- Bacteriology: Clostridioides difficile · ApplicationWatery diarrhoea and pseudomembranes develop after clindamycin treatment. Which test best supports infection by toxigenic Clostridioides difficile?
- Bacteriology: Listeria monocytogenes · Multi-stepWhich empiric addition is appropriate for suspected bacterial meningitis in an older adult to cover Listeria monocytogenes?
- Bacteriology: Bordetella pertussis · ApplicationA child has paroxysmal coughing followed by an inspiratory whoop. Which organism causes lymphocytosis by ADP-ribosylating Gi protein?
- Bacteriology: Pseudomonas aeruginosa · ApplicationA burn-wound culture has a fruity odour and blue-green pigment. Which pathogen is most likely?
- Bacteriology: Helicobacter pylori · ApplicationHelicobacter pylori survives in gastric mucus chiefly because it produces which enzyme?
- Bacteriology: Mycobacterium tuberculosis · Multi-stepA patient with active pulmonary tuberculosis begins standard therapy. Which drug is most associated with optic neuritis and impaired red-green colour discrimination?
- Bacteriology: Treponema pallidum · ApplicationWhich feature distinguishes a non-treponemal test such as RPR from a treponemal test in syphilis follow-up?
- Bacteriology: Neisseria gonorrhoeae · ApplicationA man has urethritis, and microscopy shows intracellular kidney-shaped Gram-negative diplococci within neutrophils. Which organism is most likely?
- Bacteriology · ApplicationWhich feature enables encapsulated bacteria to resist phagocytosis?
- Bacteriology · ApplicationWhat virulence factor allows Staphylococcus aureus to bind fibrinogen?
- Bacteriology · ApplicationWhich organism is classically associated with pseudomembranous colitis after antibiotics?
- Bacteriology · ApplicationWhich organism is oxidase positive and commonly causes pneumonia in cystic fibrosis?
- Bacteriology · ApplicationWhat is the usual source of Legionella infection?
- Bacteriology · ApplicationWhich test helps identify Streptococcus pneumoniae in the laboratory?
- Bacteriology · ApplicationWhich infection is linked to Neisseria gonorrhoeae dissemination?
- Bacteriology · ApplicationWhat is the significance of beta-haemolysis on blood agar?
- Bacteriology · ApplicationWhich organism is strongly associated with bacillary angiomatosis in immunosuppression?
- Bacteriology · ApplicationWhich bacterium causes erysipelas with a sharply demarcated raised edge?
- Bacteriology · ApplicationWhat toxin-mediated illness follows ingestion of preformed Staphylococcus aureus toxin?
- Bacteriology · ApplicationWhich organism is associated with neonatal meningitis and foodborne infection in pregnancy?
- Bacteriology · ApplicationWhich bacterial feature allows Helicobacter pylori to survive gastric acidity?
- Bacteriology · ApplicationWhich disease is caused by Corynebacterium diphtheriae toxin?
- Bacteriology · ApplicationWhat bacterial structure contains lipopolysaccharide?
- Bacteriology · ApplicationWhich organism is associated with gas gangrene after traumatic wound contamination?
- Bacteriology · ApplicationWhat feature is characteristic of Bordetella pertussis infection?
- Bacteriology · ApplicationWhich organism is classically associated with painless genital chancre?
- Bacteriology · ApplicationWhat is the vector of Lyme disease?
- Bacteriology · ApplicationWhich organism causes relapsing fever through antigenic variation?
- Bacteriology · ApplicationWhat is the main virulence mechanism of tetanus toxin?
Virology126
- Virology · ApplicationA teenager has fever, exudative pharyngitis, posterior cervical lymphadenopathy and splenomegaly. Which serological test supports the diagnosis of the likely causative…
- Virology · ApplicationA new influenza A strain with a novel haemagglutinin subtype causes a pandemic. Which process best explains the abrupt appearance of this strain?
- Virology: herpesviruses · ApplicationA 35-year-old man has fever, headache, altered behaviour and a focal seizure. MRI shows hyperintensity in the left temporal lobe. CSF shows lymphocytes and red cells. W…
- Virology: poliovirus surveillance · ApplicationA 3-year-old child develops acute flaccid paralysis of the left leg with fever two days earlier and no sensory loss. Under the national polio surveillance programme, wh…
- Virology: measles complications · ApplicationA 9-year-old boy who had measles at 1 year of age develops progressive intellectual deterioration, school failure and myoclonic jerks over 6 months. EEG shows periodic…
- Virology: congenital rubella · Multi-stepA term newborn has bilateral cataracts, a continuous machinery murmur, sensorineural hearing loss and a blueberry muffin rash. The mother had a mild rash with suboccipi…
- Virology: mumps · ApplicationA 22-year-old man has fever and painful parotid swelling. Five days later he develops fever with a painful, swollen, tender right testis. What is the usual course of th…
- Virology: norovirus outbreak control · ApplicationOn a cruise ship, many passengers develop sudden vomiting and watery diarrhoea 24 to 36 hours after a buffet, with recovery within 3 days. Which measure is most importa…
- Virology: hepatitis A · ApplicationSeveral students in a hostel develop fever, anorexia and jaundice after a common mess meal, and all recover within weeks. Which serological marker best confirms acute i…
- Virology: hepatitis E · ApplicationAfter floods contaminate the water supply of a village, many adults develop jaundice, and a pregnant woman in the third trimester develops fulminant hepatic failure. Wh…
- Virology: hepatitis D · ApplicationA chronic HBsAg carrier abruptly develops severe hepatitis. Testing shows anti-HDV IgM positive. Why can the delta agent cause infection in this patient?
- Virology: hepatitis B serology · Multi-stepA man with acute jaundice 10 weeks after a tattoo has these results: HBsAg negative, anti-HBs negative, IgM anti-HBc positive. How should this be interpreted?
- Virology: hepatitis B prevention · Multi-stepA woman who is HBsAg and HBeAg positive delivers a healthy full-term baby. What is the best management of the newborn?
- Virology: hepatitis C diagnosis · Multi-stepA health-care worker has a needle-stick injury from a patient with hepatitis C. Three weeks later he has fatigue and a raised ALT, but anti-HCV antibody is negative. Wh…
- Virology: HIV early infant diagnosis · Multi-stepA 6-week-old exclusively breast-fed infant is born to an HIV-positive mother. Which test is most appropriate to find out whether the infant is infected?
- Virology: HIV co-receptors · ApplicationA person who is homozygous for the CCR5-delta32 deletion remains HIV negative despite repeated high-risk exposure. What explains this resistance?
- Virology: cytomegalovirus retinitis · ApplicationA man with AIDS and a CD4 count of 30 cells/mm3 has progressive floaters and loss of vision. Fundoscopy shows perivascular yellow-white infiltrates with haemorrhages. H…
- Virology: JC virus · ApplicationA man with advanced HIV has progressive right hemiparesis and visual field loss over weeks. MRI shows multiple non-enhancing white matter lesions without mass effect. W…
- Virology: Epstein-Barr virus oncogenesis · ApplicationA 6-year-old child from a malaria-endemic region has a rapidly growing jaw mass. Biopsy shows a starry-sky pattern, and EBV is detected in the tumour cells. Which genet…
- Virology: perinatal varicella · Multi-stepA mother develops a varicella rash 2 days before delivering a term baby, who is currently asymptomatic. What is the most appropriate step for the newborn?
- Virology: congenital cytomegalovirus · Multi-stepA newborn has microcephaly, periventricular calcifications, petechiae, hepatosplenomegaly and sensorineural hearing loss. Which test best shows that the infection was c…
- Virology: human herpesvirus 6 · ApplicationAn 11-month-old infant has high fever up to 40 degrees C for 3 days with a febrile convulsion. As the fever settles, a pink maculopapular rash appears on the trunk. Whi…
- Virology: human herpesvirus 8 · ApplicationA man with HIV has several purple-red nodules on the legs and palate. Biopsy shows spindle-shaped cells and slit-like vascular spaces. Which virus is implicated?
- Virology: parvovirus B19 · ApplicationA 10-year-old with sickle cell disease has sudden pallor and fatigue. Haemoglobin has fallen to 4 g/dL and the reticulocyte count is nearly zero. What is the mechanism?
- Virology: adenovirus · ApplicationSeveral children at a summer camp develop fever, sore throat and unilateral conjunctivitis after swimming in a shared pool. Which virus is most likely?
- Virology: BK polyomavirus · Multi-stepFour months after kidney transplantation a patient has a rising serum creatinine. Urine cytology shows decoy cells, plasma BK virus PCR is high and biopsy shows tubular…
- Virology: molluscum contagiosum · ApplicationA 5-year-old has multiple pearly, dome-shaped papules with central umbilication on the trunk and axillae. A curetted lesion is stained and examined. What is the expecte…
- Virology: mpox · ApplicationA traveller has fever followed by a vesiculopustular rash that is at the same stage in all areas, with prominent tender cervical and inguinal lymphadenopathy. Which tes…
- Virology: rabies post-exposure prophylaxis · Multi-stepA 20-kg unvaccinated child has multiple deep bites on the face from a stray dog. Human rabies immunoglobulin is available. What is the correct dose and administration?
- Virology: rabies diagnosis · ApplicationA man with a dog bite 6 weeks ago has hydrophobia, aerophobia and agitation. Which ante-mortem specimen has the highest diagnostic yield?
- Virology: Japanese encephalitis · ApplicationAn outbreak of encephalitis in children occurs in a rice-growing district with extensive pig rearing after the monsoon. Which vector and amplifying host explain the tra…
- Virology: severe dengue pathogenesis · Multi-stepA 7-year-old who had dengue two years earlier now develops a second dengue illness and on day 4 shows plasma leakage with pleural effusion and shock. What best explains…
- Virology: chikungunya · ApplicationA 45-year-old woman has fever, rash and severe symmetric small-joint pain after a mosquito season. Joint pain persists for months despite resolution of fever. Which sta…
- Virology: Kyasanur forest disease · ApplicationA forest worker in the Western Ghats of Karnataka has high fever, severe myalgia and bleeding, after dead monkeys were found in the forest. What is the vector of this i…
- Virology: Crimean-Congo haemorrhagic fever · ApplicationA slaughterhouse worker in Gujarat has fever, petechiae and haematemesis. A nurse who looked after him develops a similar illness. Which agent is most likely?
- Virology: Nipah virus · ApplicationIn an endemic region of South Asia, several people develop fever, headache, drowsiness and respiratory distress after one patient drank raw palm sap. Which source is mo…
- Virology: prion disease · ApplicationA 62-year-old woman has rapidly progressive dementia and startle myoclonus over 3 months. EEG shows periodic sharp wave complexes, and brain pathology shows spongiform…
- Virology: viral genome and replication · Multi-stepPurified genomic RNA from poliovirus produces progeny virus when introduced into susceptible cells, but purified genomic RNA from rabies virus does not. What explains t…
- Virology: interferon · ApplicationWhich statement correctly describes the antiviral action of interferon?
- Virology: Tzanck smear · Multi-stepA scraping from the base of a vesicle stained by Giemsa shows multinucleated giant cells with intranuclear inclusions. How should this result be interpreted?
- Virology: antiviral resistance · Multi-stepA man with AIDS has chronic perianal herpes simplex ulcers that do not heal despite 2 weeks of intravenous acyclovir. The isolate lacks viral thymidine kinase activity.…
- Virology: hepatitis B reactivation · Multi-stepA 55-year-old man with diffuse large B-cell lymphoma is about to start rituximab-containing chemotherapy. Serology shows HBsAg negative, total anti-HBc positive and ant…
- Virology: acute HIV and fourth-generation assay · Multi-stepA 29-year-old man develops fever, rash and pharyngitis 10 days after unprotected sex. A fourth-generation HIV antigen and antibody test is reactive, but the HIV-1/HIV-2…
- Virology: immune reconstitution inflammatory syndrome · Multi-stepA man with HIV (CD4 count 25 cells/mm3) begins antitubercular therapy for pulmonary tuberculosis and starts antiretroviral therapy 3 weeks later. Four weeks after that,…
- Virology: human papillomavirus types · ApplicationA 2-year-old child has progressive hoarseness and stridor. Laryngoscopy shows multiple exophytic papillomatous lesions on the vocal cords. The mother had genital warts…
- Virology: herpes simplex keratitis · ApplicationA 30-year-old man has a painful red eye with photophobia and watering. Fluorescein staining shows a branching linear (dendritic) corneal ulcer. Which treatment should b…
- Virology: herpes zoster ophthalmicus · ApplicationA 70-year-old man has a painful vesicular rash on the left forehead. Several vesicles are also present on the tip of the nose. Why is this finding important?
- Virology: ganciclovir-resistant cytomegalovirus · Multi-stepA kidney transplant recipient has cytomegalovirus viraemia that rises despite 3 weeks of adequately dosed intravenous ganciclovir. Genotyping shows a mutation in the UL…
- Virology: Reye syndrome · ApplicationA 7-year-old child recovering from influenza B and treated with aspirin develops persistent vomiting, then confusion and seizures. Blood glucose is low, ammonia and tra…
- Virology: enterovirus A71 · Multi-stepA 3-year-old child has hand, foot and mouth disease. Three days later he develops myoclonic jerks, ataxia, tremor, tachycardia and pulmonary oedema. Which agent is most…
- Virology: Zika virus · ApplicationA pregnant woman has mild fever, maculopapular rash, non-purulent conjunctivitis and arthralgia after returning from an endemic area, and her partner has similar sympto…
- Virology: hepatitis B replication · ApplicationHepatitis B virus has a DNA genome, yet lamivudine, a nucleoside reverse transcriptase inhibitor, suppresses its replication. What is the explanation?
- Virology: HIV virological failure · Multi-stepA 38-year-old man has taken a tenofovir, lamivudine and dolutegravir regimen for 14 months. A routine viral load is 2300 copies/mL. He reports good adherence but admits…
- Virology: viral structure · ApplicationA laboratory finds that an unidentified virus loses its infectivity after treatment with diethyl ether. Which conclusion is most appropriate?
- Virology: cultivation of viruses · ApplicationA laboratory inoculates a clinical sample on the chorioallantoic membrane of 10-day-old embryonated hen eggs. After 3 days, discrete white pock lesions are seen on the…
- Virology: avian influenza · Multi-stepIn an outbreak of poultry deaths, a poultry farm worker develops fever, cough and rapidly progressive breathlessness with bilateral infiltrates. Avian influenza A(H5N1)…
- Virology: hepatitis B virus structure · ApplicationElectron microscopy of serum from a hepatitis B carrier shows 22 nm spheres, filamentous forms and 42 nm double-shelled particles. Which particle is the complete, infec…
- Virology: EBV and transplantation · Multi-stepA renal transplant recipient on tacrolimus, mycophenolate and prednisolone develops fever and cervical lymphadenopathy 8 months after transplantation. Biopsy shows a B-…
- Virology: hantavirus · ApplicationA young man cleans a long-closed, rodent-infested grain shed and 10 days later develops fever, myalgia and then rapidly progressive breathlessness with non-cardiogenic…
- Virology: herpes simplex latency · ApplicationA woman has had several episodes of genital herpes, always at the same site on the buttock, between which the lesions disappear completely. Where does the virus remain…
- Virology: cytopathic effect · ApplicationA nasopharyngeal aspirate from an infant with bronchiolitis is inoculated onto HEp-2 cells. After several days, the monolayer shows multinucleated giant cells and syncy…
- Virology: replication cycle · ApplicationIn a one-step growth experiment, cells are lysed 2 hours after infection with a virus, and no infectious virions can be recovered, although later samples show a rapid r…
- Virology: polio eradication · Multi-stepSince 2016 the trivalent oral polio vaccine was replaced by a bivalent vaccine containing types 1 and 3, with inactivated vaccine added to the routine schedule. What wa…
- Virology: subacute sclerosing panencephalitis · ApplicationA 10-year-old who had measles at the age of 1 year develops declining school performance, myoclonic jerks and periodic complexes on EEG. Which finding in cerebrospinal…
- Virology: Ramsay Hunt syndrome · ApplicationA 60-year-old has severe ear pain, vesicles in the external auditory canal, and facial weakness on the same side. Which virus has reactivated?
- Virology: hepatitis B window period · Multi-stepA patient recovering from acute hepatitis B has HBsAg negative, anti-HBs negative, and anti-HBc IgM positive. How is this pattern best interpreted?
- Virology: severe dengue and antibody-dependent enhancement · Multi-stepAn adolescent who had dengue 3 years ago develops shock and plasma leakage after a second dengue illness caused by a different serotype. Which mechanism best explains t…
- Virology: MERS coronavirus · ApplicationA returning pilgrim from the Arabian Peninsula has severe pneumonia, renal failure and a history of contact with camels. Which virus is suspected?
- Virology: rubella · ApplicationA newborn has cataract, sensorineural deafness and a continuous machinery murmur. Which maternal infection is most likely?
- Virology: varicella zoster · Multi-stepAn elderly man has vesicles in the external auditory canal with ipsilateral facial palsy and ear pain. Which latent virus has reactivated?
- Virology: Lassa fever · ApplicationA traveller from West Africa who lived in a rodent-infested hut has fever, sore throat, retrosternal pain and facial oedema. Sensorineural hearing loss appears during c…
- Virology: Chandipura virus · Multi-stepDuring the monsoon, children in central and western India present with high fever, vomiting and rapidly progressive encephalitis with high mortality. The virus is a bul…
- Virology: Merkel cell polyomavirus · ApplicationA 78-year-old man has a rapidly growing, painless, firm violaceous nodule on the sun-exposed cheek. Biopsy shows small round blue cells with perinuclear dot-like cytoke…
- Virology: CMV pp65 antigenaemia · ApplicationFive weeks after renal transplantation, a patient has fever and leucopenia. Which test detects active cytomegalovirus infection rapidly by demonstrating viral protein i…
- Virology: precore mutant hepatitis B · Multi-stepA man with chronic hepatitis B has persistently raised ALT. HBsAg is positive, HBeAg is negative, anti-HBe is positive and HBV DNA is markedly raised. Which explanation…
- Virology: yellow fever pathology · Multi-stepA forest worker has fever and jaundice followed by black vomit and bleeding, with a slow pulse relative to fever. At autopsy, the liver shows midzonal necrosis with eos…
- Virology: smallpox rash · ApplicationA medical student compares the rash of smallpox with that of chickenpox. Which description applies to smallpox?
- Virology: oral hairy leukoplakia · ApplicationA man with HIV infection (CD4 count 180 cells per cubic mm) has white corrugated plaques on the lateral borders of the tongue that cannot be scraped off. Biopsy shows e…
- Virology: IgG avidity in congenital infection · Multi-stepA woman at 14 weeks of gestation has positive CMV IgM and IgG on screening. Which additional test best helps decide whether the infection was acquired recently?
- Virology: haemagglutination inhibition test · ApplicationTo measure antibodies to influenza virus, a serum sample is incubated with a standard amount of virus, and red blood cells are then added. No haemagglutination occurs i…
- Virology: EBV and Burkitt lymphoma · ApplicationA 7-year-old boy from sub-Saharan Africa has a rapidly enlarging jaw mass. Biopsy shows sheets of medium-sized B cells with many macrophages giving a starry-sky pattern…
- Virology: selectivity of acyclovir · ApplicationAcyclovir is much less toxic to uninfected cells than to cells infected with herpes simplex virus. What is the main reason?
- Virology: HBV cccDNA persistence · Multi-stepA man with chronic hepatitis B has had undetectable serum HBV DNA on tenofovir for five years. After he stops the drug, viraemia returns within months. Which viral feat…
- Virology: chronic hepatitis E in transplant recipients · Multi-stepA kidney transplant recipient on tacrolimus has had raised transaminases for eight months. HEV RNA is repeatedly detected in serum, and hepatitis B and C tests are nega…
- Virology: rapid CMV culture · ApplicationA laboratory wants culture-based detection of cytomegalovirus in urine within 48 hours rather than waiting weeks for characteristic cytopathic effect. Which method is m…
- Virology: congenital varicella syndrome · ApplicationA newborn has limb hypoplasia, cicatricial skin scars in a dermatomal pattern, and chorioretinitis. The mother had a febrile vesicular rash at 14 weeks of gestation. Wh…
- Virology · ApplicationWhich virus causes chickenpox?
- Virology · ApplicationWhich virus causes hand-foot-mouth disease?
- Virology · ApplicationWhat virus causes cervical cancer risk?
- Virology · ApplicationWhat virus can cause hepatocellular carcinoma?
- Virology · ApplicationWhat virus causes parotitis?
- Virology · ApplicationWhat virus causes shingles?
- Virology · ApplicationWhat is required for viruses to replicate?
- Virology · ApplicationWhich virus is a common cause of infectious mononucleosis?
- Virology · ApplicationWhat is a common route of influenza transmission?
- Virology · ApplicationWhat type of organism causes COVID-19?
- Virology · ApplicationWhat type of genome does influenza virus contain?
- Virology · ApplicationWhich virus can cause acute gastroenteritis in young children?
- Virology · ApplicationWhat is a common route of hepatitis B transmission?
- Virology · ApplicationWhat vaccine-preventable virus causes parotid swelling?
- Virology · ApplicationWhat virus causes infectious mononucleosis?
- Virology · ApplicationWhat is a common clinical feature of mumps?
- Virology · ApplicationWhat infection is caused by human papillomavirus?
- Virology · ApplicationWhat is a major route for hepatitis C transmission?
- Virology · ApplicationWhat is required for viral replication?
- Virology · ApplicationWhat virus commonly causes infectious mononucleosis?
- Virology · ApplicationWhat route commonly spreads influenza?
- Virology · ApplicationWhat pathogen type causes COVID-19?
- Virology · ApplicationWhich virus is strongly linked to cervical cancer?
- Virology · ApplicationWhat is the purpose of an influenza vaccine?
- Virology: hepatitis B · Multi-stepA patient's hepatitis B serology is HBsAg negative, anti-HBs positive, and anti-HBc IgG positive. How should this be interpreted?
- Virology: influenza · ApplicationWhy does antigenic shift in influenza A have pandemic potential?
- Virology: rabies · ApplicationAfter a bite from a rabid animal, where does rabies virus typically travel before reaching the central nervous system?
- Virology: cytomegalovirus · ApplicationWhich histologic finding is characteristic of cytomegalovirus infection?
- Virology: human papillomavirus · ApplicationPersistent infection with which human papillomavirus types carries the greatest risk of cervical carcinoma?
- Virology · ApplicationWhich viral feature allows influenza to change antigenically by reassortment?
- Virology · ApplicationWhich infection is most strongly associated with Kaposi sarcoma?
- Virology · ApplicationWhat is the usual route of rabies virus spread to the central nervous system?
- Virology · ApplicationWhich virus establishes latency in dorsal-root ganglia after primary varicella infection?
- Virology · ApplicationWhat is the main route of hepatitis A transmission?
- Virology · ApplicationWhich virus causes congenital infection with periventricular calcification and hearing loss?
- Virology · ApplicationWhat is the defining cellular target of HIV?
- Virology · ApplicationWhich hepatitis virus requires hepatitis B surface antigen for replication?
- Virology · ApplicationWhat complication is associated with parvovirus B19 infection in pregnancy?
- Virology · ApplicationWhich virus causes hand-foot-and-mouth disease most commonly?
- Virology · ApplicationWhat is the usual reservoir for Nipah virus outbreaks?
Immunology119
- Immunology · ApplicationA young adult is admitted with his second episode of meningococcal meningitis. Which immune defect should be suspected?
- Immunology · Multi-stepA boy aged 18 months has recurrent otitis, sinusitis and pneumonia due to encapsulated bacteria. All immunoglobulin classes are very low and CD19-positive B cells are a…
- Immunology · Multi-stepWithin minutes of reperfusion of a transplanted kidney, the graft becomes cyanosed and mottled with fibrinoid necrosis of vessels. The recipient was sensitised by multi…
- Immunology · ApplicationA newborn has tetany from hypocalcaemia, a conotruncal cardiac defect and absent thymic shadow on chest film, with recurrent viral and fungal infections. Which deficien…
- Immunology: phagocyte disorders · ApplicationA 5-year-old boy has recurrent abscesses of the skin, lymph nodes and liver caused by Staphylococcus aureus and Aspergillus. The nitroblue tetrazolium test remains colo…
- Immunology: hypersensitivity type III · ApplicationA 30-year-old man bitten by a snake receives equine antivenom. Nine days later he develops fever, a generalised urticarial rash, joint pains and proteinuria, and serum…
- Immunology: hypersensitivity type II · ApplicationA 24-year-old smoker has haemoptysis and rapidly rising serum creatinine. Renal biopsy immunofluorescence is performed. Which finding is expected if anti-glomerular bas…
- Immunology: transplant rejection · Multi-stepSix weeks after a renal transplant, a patient's creatinine rises. Graft biopsy shows interstitial lymphocytic infiltrate with tubulitis and no C4d staining in peritubul…
- Immunology: chronic graft rejection · ApplicationWhich feature characterises chronic rejection of a kidney graft, appearing months to years after transplantation?
- Immunology: graft-versus-host disease · ApplicationThree weeks after allogeneic bone marrow transplantation for leukaemia, a patient develops a maculopapular rash, jaundice and watery diarrhoea. Which cells are the prin…
- Immunology: complement deficiency · ApplicationA 20-year-old man has recurrent episodes of non-itchy, non-pitting swelling of the lips and face and severe abdominal colic. Antihistamines and adrenaline give no relie…
- Immunology: selective IgA deficiency · Multi-stepA man with recurrent sinopulmonary infections and chronic giardiasis develops fever, bronchospasm and hypotension within minutes of a plasma transfusion. Which measure…
- Immunology: hyper IgM syndrome · ApplicationA 3-year-old boy has recurrent pyogenic infections and Pneumocystis pneumonia. Serum IgM is high, while IgG, IgA and IgE are very low, and B cell numbers are normal. Wh…
- Immunology: severe combined immunodeficiency · ApplicationA 4-month-old infant has persistent oral thrush, chronic diarrhoea, failure to thrive and profound lymphopenia, and developed disseminated disease after BCG vaccination…
- Immunology: Wiskott-Aldrich syndrome · ApplicationA 1-year-old boy has eczema, recurrent ear infections and bleeding with petechiae. His platelet count is low and the platelets are small. Which statement about the unde…
- Immunology: Chediak-Higashi syndrome · ApplicationA child with silvery hair and partial oculocutaneous albinism has recurrent pyogenic infections. A blood smear shows giant cytoplasmic granules in neutrophils. What is…
- Immunology: leukocyte adhesion deficiency · ApplicationA 2-month-old infant had delayed umbilical cord separation at 5 weeks and now has omphalitis and a skin infection without pus. The neutrophil count is 40,000 per microl…
- Immunology: complement regulation · ApplicationA 28-year-old woman has episodes of dark morning urine, unexplained abdominal vein thrombosis and pancytopenia. Which test best establishes the diagnosis?
- Immunology: immunoglobulin classes · ApplicationA newborn has a markedly raised IgM in cord blood, with no maternal infection recognised. What is the reasoning behind suspecting intrauterine infection?
- Immunology: natural killer cells · ApplicationA virus down-regulates MHC class I expression on infected cells to escape cytotoxic T cells. Which cell is best placed to kill such cells, and why?
- Immunology: antigen processing · Multi-stepA patient has an inherited deficiency of TAP1 transporter. Which immune function is most directly impaired?
- Immunology: HLA and drug hypersensitivity · ApplicationBefore prescribing abacavir to a patient with HIV, which test is advised to prevent a potentially fatal systemic hypersensitivity reaction?
- Immunology: cytokine pathways · Multi-stepA 6-year-old child develops disseminated disease with a non-tuberculous mycobacterium after BCG vaccination. Immunoglobulins, CD4 count and neutrophil function are norm…
- Immunology: antiglobulin test · ApplicationA newborn of an Rh-negative mother develops jaundice within 24 hours of birth. Which test confirms that the infant's red cells are coated with maternal antibody?
- Immunology: vaccine immunology · ApplicationA pure capsular polysaccharide vaccine gives a poor, short-lived response in infants under 2 years, but the same polysaccharide linked to a protein carrier is effective…
- Immunology: serological techniques · Multi-stepA man has a painless genital ulcer healing, a diffuse rash and generalised lymphadenopathy, and a neat-serum VDRL is non-reactive. When the serum is diluted 1 in 8, VDR…
- Immunology: anaphylaxis tryptase · ApplicationA 34-year-old woman collapses 20 minutes after a wasp sting with urticaria, wheeze and hypotension, and recovers after intramuscular adrenaline. The allergist wants lab…
- Immunology: common variable immunodeficiency · Multi-stepA 28-year-old man has had recurrent sinusitis and pneumonia since age 22 and now has chronic diarrhoea with Giardia in the stool. Serum IgG, IgA and IgM are all low, an…
- Immunology: ataxia-telangiectasia · ApplicationA 6-year-old girl has progressive gait ataxia, dilated conjunctival blood vessels and recurrent sinopulmonary infections. Which laboratory pair would be expected?
- Immunology: scleroderma antibodies · Multi-stepA 45-year-old woman has had Raynaud phenomenon for ten years, with subcutaneous calcinosis, facial telangiectasia and sclerodactyly. Skin thickening is limited to the f…
- Immunology: drug-induced lupus · ApplicationA 62-year-old man on long-term procainamide for ventricular arrhythmia develops fever, arthralgia and pleuritic chest pain. Antinuclear antibody is positive. Renal func…
- Immunology: ABO haemolytic disease of the newborn · Multi-stepA group O, Rh-positive mother delivers her first child, who is group A, Rh-positive. The baby becomes jaundiced on the second day, with spherocytes on the smear and a w…
- Immunology: central tolerance and AIRE · Multi-stepAn 8-year-old boy has chronic mucocutaneous candidiasis, then hypoparathyroidism and later adrenal insufficiency. Multiple endocrine organ antibodies are found. Which d…
- Immunology: IL-12 and interferon-gamma axis · Multi-stepA 7-year-old boy develops disseminated infection after BCG vaccination, followed by recurrent non-tuberculous mycobacterial infection and Salmonella bacteraemia. HIV is…
- Immunology: hyper IgE syndrome · ApplicationA 10-year-old boy has eczema, recurrent staphylococcal skin and lung abscesses with little warmth or inflammation, pneumatoceles, retained primary teeth and fractures a…
- Immunology: cytokine release syndrome · Multi-stepThree days after infusion of anti-CD19 CAR T cells for refractory lymphoma, a 52-year-old man develops fever of 39.5 degrees C and hypotension. Ferritin and C-reactive…
- Immunology: hybridoma selection · ApplicationIn producing monoclonal antibodies, mouse spleen B cells are fused with HGPRT-deficient myeloma cells and cultured in HAT medium. Why do only the hybridoma cells survive?
- Immunology: interferon-gamma release assay interpretation · Multi-stepA 35-year-old man with advanced HIV (CD4 count 40 cells/mm3) is screened for latent tuberculosis. The interferon-gamma release assay reports an indeterminate result bec…
- Immunology: rheumatoid arthritis serology · ApplicationA 45-year-old woman has symmetrical swelling of the small joints of both hands with 90 minutes of morning stiffness for 4 months. Which serological test is most specifi…
- Immunology: MHC class II deficiency · Multi-stepA 9-month-old infant has chronic diarrhoea with Cryptosporidium, recurrent pneumonia and failure to thrive. CD4 T cells are markedly low with a normal CD8 count, immuno…
- Immunology: regulatory T cells · ApplicationA 3-month-old boy has neonatal-onset type 1 diabetes, severe watery diarrhoea from autoimmune enteropathy and eczema. Which gene defect is most likely?
- Immunology: immunofluorescence · ApplicationIn the fluorescent treponemal antibody absorption test for syphilis, a patient's serum is layered on a slide containing Treponema pallidum. In this indirect immunofluor…
- Immunology: innate immunity · ApplicationIn Gram-negative sepsis, macrophages release large amounts of TNF-alpha and IL-1 after recognising bacterial lipopolysaccharide. Which receptor complex is chiefly respo…
- Immunology: antibody structure · ApplicationAn IgG molecule is digested with pepsin instead of papain. Which fragments are obtained?
- Immunology: cytokines · ApplicationA patient with a bacterial infection has a markedly raised C-reactive protein and fibrinogen within 24 hours. Which cytokine acts on hepatocytes to drive this acute pha…
- Immunology: primary immunodeficiency · Multi-stepA 4-month-old boy has persistent oral candidiasis, chronic diarrhoea and failure to thrive. Flow cytometry shows markedly reduced T cells and NK cells with normal numbe…
- Immunology: X-linked agammaglobulinaemia · Multi-stepA 9-month-old boy has recurrent pneumococcal pneumonia and otitis media. Tonsils are not visible, and flow cytometry shows absent CD19-positive cells with low levels of…
- Immunology: hereditary angioedema · Multi-stepA young woman has recurrent episodes of non-pitting facial swelling and severe abdominal pain after minor dental work. There is no urticaria and antihistamines and adre…
- Immunology: serum sickness · ApplicationNine days after receiving equine anti-snake venom, a farmer develops fever, urticaria, joint pains and proteinuria, with a low serum C3. What is the underlying mechanism?
- Immunology: rabies passive immunisation · Multi-stepA man is bitten on the hand and face by a stray dog. The wounds are deep and bleeding. After thorough washing, which step gives immediate protection before his own anti…
- Immunology: live vaccines in immunodeficiency · Multi-stepA 3-month-old with severe recurrent infections and absent T cells develops disseminated infection with regional lymphadenitis a few weeks after a birth dose. Which vacc…
- Immunology: anti-GBM disease · ApplicationA young smoker has haemoptysis and rapidly progressive glomerulonephritis. Renal biopsy immunofluorescence shows smooth, linear IgG deposits along the basement membrane…
- Immunology: secretory IgA · ApplicationWhich feature explains why secretory IgA remains intact in the protease-rich lumen of the gut?
- Immunology: complement · ApplicationAn immune complex of IgG bound to antigen activates complement. Which component first binds the Fc region to start this pathway?
- Immunology: serological tests · ApplicationA fourth-generation HIV ELISA can detect infection earlier than third-generation assays because it also detects which viral component?
- Immunology: C3 nephritic factor · Multi-stepA 12-year-old girl has haematuria, proteinuria and loss of subcutaneous fat from the face and upper trunk. Serum C3 is persistently very low with normal C4, and biopsy…
- Immunology: NK cell markers · ApplicationFlow cytometry of peripheral blood lymphocytes shows a population that is CD3 negative and positive for CD16 and CD56. Which cell is this, and what is its main function?
- Immunology: Ouchterlony double diffusion · ApplicationIn an Ouchterlony double diffusion plate, antiserum is placed in the central well and two antigen preparations in adjacent wells. The two precipitin lines meet and fuse…
- Immunology: late phase of type I hypersensitivity · Multi-stepA 25-year-old with allergic rhinitis develops an immediate wheal after a skin-prick test with grass pollen. Six hours later the site becomes swollen, firm and tender ag…
- Immunology: anti-TNF therapy and tuberculosis · Multi-stepA 45-year-old man with rheumatoid arthritis, who had a strongly positive tuberculin test years ago, starts infliximab. Four months later he has fever, weight loss and a…
- Immunology: secondary antibody response · ApplicationA child receives a first dose of tetanus toxoid and develops a slowly rising, mainly IgM antibody response. At a booster four weeks later, IgG antitoxin appears within…
- Immunology: neonatal lupus · ApplicationA newborn has a heart rate of 55 per minute with complete heart block on ECG and a transient annular rash. The mother has mild arthralgia and has never been diagnosed w…
- Immunology: T cell anergy and co-stimulation · Multi-stepA naive CD4 T cell binds peptide on MHC class II of an antigen-presenting cell that is not activated and expresses no B7 molecules. What is the most likely outcome for…
- Immunology: haptens · ApplicationA patient develops urticaria after penicillin, although penicillin is too small to be immunogenic by itself. How does it provoke an antibody response?
- Immunology: lectin complement pathway · ApplicationA serum protein that binds mannose residues on the surface of a bacterium triggers cleavage of C4 and C2 through associated serine proteases, even before any specific a…
- Immunology: C3 deficiency · Multi-stepA 2-year-old has had repeated pneumonias and a bacteraemia due to Streptococcus pneumoniae and Haemophilus influenzae, plus a proliferative glomerulonephritis. Immunogl…
- Immunology: IgG2 subclass deficiency · Multi-stepA 6-year-old has recurrent otitis media and pneumococcal pneumonia. Serum IgG, IgM and IgA levels are in the normal range, but there is no antibody rise after pneumococ…
- Immunology: eosinophil-mediated killing of helminths · ApplicationSchistosomula are far too large to be phagocytosed. Which mechanism allows the host to damage them?
- Immunology: anti-Smith antibody · ApplicationA 25-year-old woman has a malar rash, arthritis and proteinuria, and her antinuclear antibody test is strongly positive. Which of the following autoantibodies is highly…
- Immunology: anti-mitochondrial antibody · ApplicationA 48-year-old woman has generalised itching and fatigue for months. Her alkaline phosphatase is markedly raised with a mildly raised bilirubin, and ultrasound shows no…
- Immunology: c-ANCA and proteinase 3 · ApplicationA 42-year-old man has chronic sinusitis with nasal crusting, cough with haemoptysis and haematuria with red cell casts. Which autoantibody is most strongly associated w…
- Immunology: pemphigus vulgaris autoantigen · ApplicationA 45-year-old man has painful oral erosions and flaccid blisters on the trunk that rupture easily; pressure on normal skin next to a blister extends it. Biopsy shows su…
- Immunology: HLA association in coeliac disease · ApplicationA 28-year-old woman with iron-deficiency anaemia, chronic diarrhoea and positive IgA anti-tissue transglutaminase antibodies has villous atrophy on duodenal biopsy. Whi…
- Immunology: affinity maturation · Multi-stepOver successive tetanus toxoid boosters, a child's antibodies bind the toxin with progressively higher affinity, and sequencing of antibody genes from B cells shows man…
- Immunology: Omenn syndrome · Multi-stepA 2-month-old has generalised erythroderma, lymphadenopathy, hepatosplenomegaly, eosinophilia and a high serum IgE with chronic diarrhoea. B cells are absent, and a few…
- Immunology: adenosine deaminase deficiency · ApplicationAn infant has severe recurrent infections, very low lymphocyte counts and flaring at the costochondral junctions on chest radiograph. The diagnosis is adenosine deamina…
- Immunology: physiological hypogammaglobulinaemia of infancy · ApplicationA thriving 5-month-old breastfed infant with only two mild colds has a low serum IgG level on a screening test, with normal IgM. There is no history of serious infectio…
- Immunology: IgA1 protease · ApplicationNeisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae can all colonise the nasopharynx despite mucosal antibody. Which shared virulence factor hel…
- Immunology: skin prick test reading · ApplicationA 14-year-old with seasonal sneezing has a skin prick test performed with a drop of grass pollen extract, and a wheal with surrounding flare develops. When is this reac…
- Immunology: mechanism of allergen immunotherapy · Multi-stepA beekeeper with a history of systemic reactions to stings completes a course of venom immunotherapy and tolerates a sting without anaphylaxis. Which immunological chan…
- Immunology: patch test for contact dermatitis · ApplicationA woman has recurrent eczematous dermatitis under the clasp of her watch. Small amounts of suspected allergens are applied under occlusion on her back, and the sites ar…
- Immunology: mixed cryoglobulinaemia · Multi-stepA 55-year-old man with chronic hepatitis C has palpable purpura, arthralgia and glomerulonephritis. A blood sample kept at 4 degrees C develops a precipitate that redis…
- Immunology: complement levels in active lupus · ApplicationA patient with systemic lupus erythematosus develops a flare with nephritis, and serum C3 and C4 are both markedly low. What is the best explanation?
- Immunology: direct allorecognition · Multi-stepIn the first weeks after a kidney transplant, a large fraction of the recipient's T cells react to the graft by recognising intact donor MHC molecules on dendritic cell…
- Immunology: crossmatch before transplantation · ApplicationBefore a renal transplant, the laboratory mixes the potential recipient's serum with donor lymphocytes in the presence of complement. Which risk does a positive result…
- Immunology: mixed lymphocyte reaction · Multi-stepIn a one-way mixed lymphocyte reaction used for assessing donor and recipient compatibility, the donor cells are treated with mitomycin C or irradiated. Why?
- Immunology: immune checkpoint blockade · ApplicationA patient with metastatic melanoma treated with an antibody against PD-1 develops watery diarrhoea eight weeks later, and colonic biopsy shows lymphocytic colitis. What…
- Immunology: myeloperoxidase deficiency · ApplicationRoutine blood counts on an automated peroxidase-based analyser reveal neutrophils that lack peroxidase staining in an otherwise healthy adult. The cells generate supero…
- Immunology: single radial immunodiffusion · ApplicationA laboratory measures serum IgG by placing patient serum in wells cut into agar containing anti-human IgG. After 24 hours, circular precipitin rings form, and the squar…
- Immunology: Ascoli thermoprecipitation · ApplicationA suspect dried animal hide is boiled in saline and the clear extract is layered over a specific anthrax antiserum in a narrow tube. A white ring appears at the interfa…
- Immunology: complement fixation test interpretation · Multi-stepIn a complement fixation test, patient serum, antigen and a measured amount of guinea pig complement are incubated, and sheep red cells coated with anti-sheep antibody…
- Immunology: principle of the ASO titre · ApplicationIn the antistreptolysin O titration, serial dilutions of patient serum are incubated with a fixed amount of streptolysin O before indicator red cells are added. The hig…
- Immunology: chimeric monoclonal antibodies · ApplicationRituximab and infliximab are described as chimeric monoclonal antibodies. Which part of the molecule is of mouse origin?
- Immunology: positive selection in the thymus · ApplicationImmature CD4 and CD8 double-positive thymocytes must recognise self MHC molecules with at least weak affinity or they die by neglect. Where does this positive selection…
- Immunology: lymph node paracortex · ApplicationA lymph node biopsy from an infant with a 22q11.2 deletion and absent thymic tissue is examined. Which lymph node region is expected to be depleted of lymphocytes?
- Immunology: idiotype and allotype · ApplicationAn anti-idiotype antibody is raised against a particular monoclonal antibody. Which part of the antibody does it recognise?
- Immunology: avidity of IgM · ApplicationEarly in an infection, IgM antibodies with relatively low affinity at each binding site still agglutinate bacteria very efficiently. Which property explains this?
- Immunology: cross-presentation · Multi-stepA virus infects only airway epithelial cells and does not infect dendritic cells, yet naive CD8 T cells in the draining node are primed against viral peptides. Which me…
- Immunology: molecular mimicry · ApplicationA 30-year-old man develops ascending flaccid paralysis two weeks after an episode of Campylobacter jejuni gastroenteritis. Antibodies raised against bacterial lipo-olig…
- Immunology: Prausnitz-Kustner reaction · ApplicationIn the classical Prausnitz-Kustner experiment, serum from a fish-allergic person was injected into the skin of a non-allergic volunteer. A day later, fish extract injec…
- Immunology: aluminium adjuvant · ApplicationTetanus toxoid is adsorbed onto aluminium hydroxide before injection. What is the main benefit of the aluminium salt?
- Immunology: sandwich ELISA for antigen · ApplicationA blood bank screens donor serum for hepatitis B surface antigen by a sandwich ELISA. What is coated on the wells at the beginning of the assay?
- Immunology · ApplicationWhich cell presents antigen to naive T cells most effectively?
- Immunology · ApplicationWhich immunoglobulin mediates immediate allergy?
- Immunology · ApplicationWhich antibody appears first in primary immune response?
- Immunology · ApplicationWhich major-histocompatibility-complex class presents endogenous viral peptides to cytotoxic T cells?
- Immunology · ApplicationWhich cells kill virus-infected cells without prior sensitization?
- Immunology · ApplicationWhich complement component is key opsonin?
- Immunology · ApplicationWhat is the main function of antibodies?
- Immunology · ApplicationWhich cell type produces antibodies?
- Immunology · ApplicationWhat is the role of neutrophils in innate immunity?
- Immunology · ApplicationWhat cells are central to cellular immune responses?
- Immunology · ApplicationWhat immunoglobulin predominates in mucosal secretions?
- Immunology · ApplicationWhat immunoglobulin is produced first in a primary humoral response?
- Immunology · ApplicationWhat component of innate immunity can directly lyse some bacteria?
- Immunology · ApplicationWhat is the main role of antibodies?
- Immunology · ApplicationWhich innate lymphocytes can kill virus-infected cells without prior antigen sensitization?
- Immunology: complement deficiency · ApplicationRecurrent invasive infections with Neisseria species should prompt evaluation for deficiency of which complement components?
- Immunology: type IV hypersensitivity · ApplicationA positive tuberculin skin test 48 hours after injection is mediated primarily by which mechanism?
Parasitology101
- Parasitology · ApplicationA patient treated with chloroquine for Plasmodium vivax malaria recovers, but fever with parasitaemia recurs eight months later without any travel. What is the explanat…
- Parasitology · ApplicationA man presents with new-onset seizures and CT shows a ring-enhancing cystic lesion with an eccentric dot. How is neurocysticercosis acquired?
- Parasitology · ApplicationA patient on prolonged high-dose corticosteroids develops larvae in sputum and Gram-negative bacteraemia. Which nematode can multiply in the host through autoinfection…
- Parasitology · Multi-stepIn falciparum malaria, peripheral smears usually show only ring forms and gametocytes, although all asexual stages are produced. What is the reason?
- Parasitology · ApplicationA teenager who swam in a warm freshwater pond develops severe frontal headache, fever, neck stiffness and rapid deterioration within days. CSF shows motile trophozoites…
- Parasitology: filariasis · ApplicationA man from an endemic area has recurrent fever, painful lymphadenitis and later scrotal swelling. When should a blood sample be taken to detect microfilariae of Wuchere…
- Parasitology: cestodes · ApplicationA shepherd has a large cystic lesion in the liver on ultrasound, with daughter cysts inside. Which statement about management is correct?
- Parasitology: Trichomonas vaginalis · ApplicationA 27-year-old woman has frothy greenish malodorous vaginal discharge, vulval itching and a strawberry-appearing cervix. Vaginal pH is 5.5, and wet mount shows motile fl…
- Parasitology: Giardia lamblia · ApplicationA 6-year-old child has several weeks of foul-smelling greasy stools, bloating and weight loss, without fever or blood in stool. Stool microscopy shows pear-shaped binuc…
- Parasitology: Cryptosporidium · ApplicationA man with HIV and a CD4 count of 40 per microlitre has had profuse watery diarrhoea for 6 weeks. Which stool test identifies the likely pathogen?
- Parasitology: Toxoplasma gondii · Multi-stepA man with HIV and a CD4 count of 50 per microlitre has headache and left hemiparesis. MRI shows multiple ring-enhancing basal ganglia lesions, and Toxoplasma IgG is po…
- Parasitology: severe falciparum malaria · ApplicationA 35-year-old man with Plasmodium falciparum malaria is drowsy, with a Glasgow Coma Scale score of 10 and 8% parasitaemia. Which regimen is appropriate?
- Parasitology: antimalarial toxicity · ApplicationA man given primaquine for Plasmodium vivax develops dark urine, jaundice and pallor on day 3. His smear shows bite cells and Heinz bodies. What is the mechanism?
- Parasitology: Plasmodium malariae · ApplicationA 7-year-old boy has fever recurring at intervals of 72 hours, with paroxysms on days 1, 4 and 7. Months later he develops oedema and 4 g per day proteinuria that does…
- Parasitology: Trypanosoma cruzi · ApplicationA 45-year-old man from rural South America has dilated cardiomyopathy with conduction block, and dysphagia from a dilated oesophagus. Which organism is the most likely…
- Parasitology: post-kala-azar dermal leishmaniasis · ApplicationA 30-year-old man from Bihar was treated for kala-azar 3 years ago. He now has hypopigmented macules and nodules on the face with no fever. Which statement about this c…
- Parasitology: Ascaris lumbricoides · Multi-stepA 5-year-old rural child has cough, wheeze and transient pulmonary infiltrates with 12% eosinophils. Stool microscopy shows no eggs. What is the most likely explanation?
- Parasitology: hookworm · ApplicationA barefoot agricultural worker has fatigue and a haemoglobin of 7 g/dL with microcytic hypochromic red cells. Stool shows thin-shelled oval eggs containing a morula of…
- Parasitology: Schistosoma haematobium · ApplicationA 25-year-old student returns from a trip to Africa where he swam in freshwater lakes. He has terminal haematuria, and urine shows eggs with a terminal spine. Which lon…
- Parasitology: Fasciola hepatica · Multi-stepA shepherd who regularly eats raw watercress has fever, right upper quadrant pain and eosinophilia. Stool shows large operculated eggs, and praziquantel produced no cur…
- Parasitology: Taenia species · ApplicationA man passes motile segments in his stool. A gravid proglottid is examined and has about 17 lateral uterine branches on each side. What is the implication?
- Parasitology: Diphyllobothrium latum · ApplicationA man who regularly eats raw freshwater fish has macrocytic anaemia and paraesthesiae. Operculated eggs are seen in his stool. Which mechanism explains his anaemia?
- Parasitology: Dracunculus medinensis · ApplicationIn a village, several adults develop a painful blister on the lower leg from which a long thread-like worm emerges when the foot is immersed in a pond. Which measure in…
- Parasitology: Onchocerca volvulus · Multi-stepA farmer from West Africa living near a fast-flowing river has itchy dermatitis, subcutaneous nodules and visual loss. A skin snip shows microfilariae. Which drug is th…
- Parasitology: Acanthamoeba keratitis · ApplicationA soft contact lens wearer who rinsed lenses with tap water has severe eye pain out of proportion to signs, with a ring-shaped corneal infiltrate. Bacterial cultures ar…
- Parasitology: amoebic liver abscess · Multi-stepA man with a solitary right lobe liver abscess containing reddish-brown pus has improved after 10 days of metronidazole. What should be given next to prevent relapse?
- Parasitology: visceral leishmaniasis treatment · ApplicationA 28-year-old farmer from north Bihar has had fever for 3 months with massive splenomegaly and pancytopenia. The rK39 rapid test is positive. Which is the first-line tr…
- Parasitology: African trypanosomiasis · Multi-stepA 40-year-old man returns from a safari in Tanzania with a painful ulcerated skin chancre, high fever, and tender enlarged regional lymph nodes. Within three weeks he d…
- Parasitology: Babesia · ApplicationA 62-year-old splenectomised man from the north-eastern United States has fever, haemolytic anaemia and haemoglobinuria after a summer hiking trip. The blood smear show…
- Parasitology: Plasmodium knowlesi · Multi-stepA 35-year-old forest worker returns from Borneo with daily fever spikes. A smear shows band forms resembling Plasmodium malariae but with 12% parasitaemia, and the plat…
- Parasitology: malaria parasite density · Multi-stepOn a thick blood film from a febrile patient, 320 asexual malaria parasites are counted against 200 white blood cells. The patient's white cell count is 7500/µL. What i…
- Parasitology: Entamoeba histolytica identification · Multi-stepAn asymptomatic food handler has stool microscopy showing cysts with four nuclei and chromatoidal bars, consistent with the Entamoeba histolytica complex. Which investi…
- Parasitology: Loa loa · Multi-stepA man from Cameroon has transient painless subcutaneous swellings on the forearm and once saw a worm cross his conjunctiva. Blood films show 45,000 microfilariae/mL. Ma…
- Parasitology: Paragonimus lung fluke · ApplicationA man from Manipur who eats raw freshwater crabs has a chronic cough with rusty brown sputum, eosinophilia and a cavitating lesion on chest radiograph. Sputum is negati…
- Parasitology: Hymenolepis nana · ApplicationA 6-year-old child in a crowded hostel has recurrent abdominal pain and diarrhoea. Stool shows small round eggs with polar filaments and a hexacanth embryo, and the bur…
- Parasitology: crusted scabies · Multi-stepA 70-year-old nursing home resident on long-term oral corticosteroids has thick, scaly plaques on the hands and elbows with little itching. Several staff and residents…
- Parasitology: Schistosoma mansoni acute infection · Multi-stepA 24-year-old man returns from a trip to Africa with fever, urticaria, cough and hepatosplenomegaly 4 weeks after swimming in a freshwater lake. Eosinophilia is marked,…
- Parasitology: tropical pulmonary eosinophilia · Multi-stepA 30-year-old man from coastal Odisha has nocturnal cough and wheeze for 5 months with low-grade fever and weight loss. Absolute eosinophil count is 3500/µL, serum IgE…
- Parasitology: cerebral malaria pathogenesis · Multi-stepA 5-year-old with Plasmodium falciparum malaria has deep coma, and the peripheral smear shows only ring forms, while trophozoites and schizonts are absent. Which mechan…
- Parasitology: liver flukes · ApplicationA man from southern China who regularly eats raw freshwater fish has recurrent cholangitis, and 20 years later develops cholangiocarcinoma. Stool shows small, operculat…
- Parasitology: scabies management · ApplicationA 7-year-old has intense nocturnal itching with papules and burrows in the finger webs, and two family members have similar symptoms. Which management is correct?
- Parasitology: malaria diagnosis · Multi-stepA man treated for falciparum malaria 3 weeks ago is asymptomatic. A rapid test based on HRP-2 is positive, but two peripheral blood smears are negative. What is the mos…
- Parasitology: filariasis diagnosis · ApplicationA farmer from an endemic area has a hydrocele and swollen leg. A blood smear collected at noon shows no microfilariae. Which test can still demonstrate Wuchereria bancr…
- Parasitology: Casoni test · ApplicationAn old intradermal test in a patient with a cystic liver lesion produces an immediate wheal in response to fluid from a sheep parasite. Which infection did it support?
- Parasitology: Cystoisospora belli · Multi-stepA patient with advanced HIV has chronic watery diarrhoea, and a modified acid-fast stain of stool shows large oval oocysts, 20 to 30 micrometres, each with two sporocys…
- Parasitology: hydatid cyst surgery · Multi-stepDuring surgery for a hepatic hydatid cyst, the patient suddenly becomes hypotensive with wheeze and urticaria after cyst fluid spills. Which complication has occurred?
- Parasitology: chyluria in filariasis · ApplicationA man from a filariasis-endemic coastal area passes milky urine, and fat is demonstrated in it. What explains this?
- Parasitology: Schuffner dots · Multi-stepA thin film from a febrile patient shows enlarged red cells with fine red-pink stippling, amoeboid trophozoites and 12 to 24 merozoites in a schizont. Which species is…
- Parasitology: microsporidia · ApplicationA patient with AIDS has chronic diarrhoea. A stool smear stained with modified trichrome shows tiny oval spores of 1 to 3 micrometres, each with a belt-like stripe. The…
- Parasitology: Fasciolopsis buski · Multi-stepA child in Assam who regularly eats raw water chestnuts has abdominal pain, diarrhoea, and facial and abdominal oedema. Stool contains large operculated eggs and the ch…
- Parasitology: Angiostrongylus cantonensis · ApplicationA 30-year-old in Southeast Asia who ate raw snails develops severe headache, neck stiffness and paraesthesia. CSF shows more than 10 percent eosinophils. Which parasite…
- Parasitology: Tunga penetrans · ApplicationA barefoot child in a coastal village has a painful white nodule with a central black dot between the toes. Extraction reveals an enlarged gravid female arthropod burro…
- Parasitology: hookworm species identification · ApplicationAdult hookworms expelled after treatment are examined in the laboratory. The buccal capsule of the specimen carries two pairs of curved teeth on its ventral margin. Whi…
- Parasitology: cutaneous larva migrans · Multi-stepA traveller who lay on a tropical beach develops an intensely itchy, raised, winding red track on the sole that advances a few millimetres each day. Stool microscopy is…
- Parasitology: Gambian sleeping sickness · ApplicationA man from West Africa has intermittent fever, headache, pruritus and enlarged posterior cervical lymph nodes. Months later he develops sleep-wake reversal and tremors.…
- Parasitology: Romana sign in Chagas disease · ApplicationA 4-year-old child from a mud-walled house in rural Brazil has fever, unilateral painless periorbital oedema, conjunctivitis and a tender preauricular lymph node. The p…
- Parasitology: chronic Chagas disease pathogenesis · Multi-stepA 45-year-old man from rural Latin America has dysphagia with a dilated oesophagus, chronic constipation with megacolon and dilated cardiomyopathy. Which process underl…
- Parasitology: Plasmodium ovale morphology · Multi-stepA man returning from West Africa has tertian fever. A Giemsa smear shows slightly enlarged oval red cells with fimbriated edges, Schuffner's dots and compact trophozoit…
- Parasitology: artemisinin resistance marker · ApplicationIn Southeast Asia, falciparum malaria shows delayed parasite clearance after artesunate-based therapy. Mutations in which gene are the molecular marker of this partial…
- Parasitology: chloroquine resistance mechanism · Multi-stepChloroquine-resistant Plasmodium falciparum accumulates much less drug in its digestive vacuole than sensitive strains. Which change mainly explains this?
- Parasitology: hyperreactive malarial splenomegaly · Multi-stepA woman from a hyperendemic malaria area has massive splenomegaly, anaemia and very high serum IgM. Smears show no parasites, and the liver biopsy shows sinusoidal lymp…
- Parasitology: transfusion-transmitted malaria · Multi-stepA patient develops fever with chills nine days after receiving a unit of blood from a donor who had lived in an endemic area, and the smear shows Plasmodium vivax. Whic…
- Parasitology: congenital toxoplasmosis timing · Multi-stepA woman acquires primary Toxoplasma infection during pregnancy. Which statement about vertical transmission is correct?
- Parasitology: Toxoplasma IgG avidity · Multi-stepA pregnant woman at 12 weeks has positive Toxoplasma IgM and IgG. IgG avidity testing shows high avidity. What does this indicate?
- Parasitology: Brugia malayi microfilaria · Multi-stepA blood film taken at night in Kerala shows sheathed microfilariae about 220 micrometres long, with two discrete nuclei at the tail tip. Which species is it?
- Parasitology: unfertilised Ascaris egg · Multi-stepStool microscopy in a child shows elongated oval eggs with a thin shell, a scanty irregular outer coat and a mass of refractile granules inside. What is the correct int…
- Parasitology: furuncular myiasis · ApplicationA man back from the Amazon basin has a boil-like nodule on the scalp with a central punctum that exudes serosanguinous fluid, and he feels intermittent crawling movemen…
- Parasitology: Strongyloides screening before steroids · Multi-stepA 50-year-old man from rural Bangladesh has long-standing eosinophilia and intermittent itchy tracks over the buttocks. High-dose prednisolone is planned for vasculitis…
- Parasitology: Schistosoma japonicum intermediate host · ApplicationA rice farmer from the Philippines has hepatosplenic disease with periportal fibrosis. Stool shows oval eggs with a tiny lateral spine. Which snail genus is the interme…
- Parasitology: Dipylidium caninum · ApplicationA 2-year-old child with a pet dog passes motile, cucumber-seed-shaped segments, each with a genital pore on both sides. Which is the intermediate host of this tapeworm?
- Parasitology: anisakiasis · ApplicationA man develops sudden severe epigastric pain and vomiting four hours after eating raw marine fish. Endoscopy shows a thin white worm penetrating the gastric wall. Which…
- Parasitology: cryptosporidiosis treatment · ApplicationAn immunocompetent child has watery diarrhoea for a week after swimming in a pool. A modified acid-fast stain shows 4 to 6 micrometre oocysts in stool. Which drug is th…
- Parasitology: hypoglycaemia in severe malaria · Multi-stepA pregnant woman with severe falciparum malaria on intravenous quinine becomes sweaty, drowsy and convulses. Blood glucose is 28 mg/dL. Which mechanism contributes main…
- Parasitology: autoinfection in cysticercosis · ApplicationA man who has passed Taenia solium proglottids for years develops seizures from multiple brain cysts. He is a strict vegetarian. By which route could the cysts have ari…
- Parasitology: amoebic liver abscess pathology · Multi-stepAspiration of an amoebic liver abscess yields reddish-brown, odourless pus. In which part of the abscess are trophozoites most likely to be found on examination?
- Parasitology: ascariasis intestinal obstruction · ApplicationA 5-year-old in a rural area has colicky abdominal pain, bilious vomiting and a palpable ropy abdominal mass, and X-ray shows gas-fluid levels. Stool contains round mam…
- Parasitology: pinworm household treatment · ApplicationA child has pinworm infection confirmed by an adhesive tape test. Which approach best prevents repeated infection in the family?
- Parasitology: Entamoeba coli cyst · ApplicationA stool concentration smear shows a cyst with eight nuclei and splinter-shaped chromatoid bodies. What is the correct interpretation?
- Parasitology · ApplicationWhich protozoan causes malaria?
- Parasitology · ApplicationWhat vector transmits malaria?
- Parasitology · ApplicationWhat is a common manifestation of intestinal giardiasis?
- Parasitology · ApplicationWhat protozoan can cause dysentery with flask-shaped ulcers?
- Parasitology · ApplicationWhat is the intermediate host for many schistosome species?
- Parasitology · ApplicationWhat helminth infection can cause perianal itching at night?
- Parasitology · ApplicationWhat protozoan is transmitted by the tsetse fly?
- Parasitology · ApplicationWhat vector transmits leishmaniasis?
- Parasitology · ApplicationWhat helminth can cause intestinal obstruction when burden is heavy?
- Parasitology · ApplicationWhat protozoan causes malaria?
- Parasitology · ApplicationWhat symptom is common in giardiasis?
- Parasitology · ApplicationWhat parasite may cause dysentery with flask-shaped colonic ulcers?
- Parasitology: malaria · Multi-stepA returning traveller has fever every 48 hours, thrombocytopenia, and a blood film showing multiple delicate ring forms in single erythrocytes. Which species is most co…
- Parasitology: toxoplasmosis · ApplicationAn HIV-positive patient with low CD4 count has headache, seizures, and multiple ring-enhancing brain lesions. Which organism is most likely?
- Parasitology: Strongyloides stercoralis · Multi-stepWhy should a patient from an endemic region be evaluated for Strongyloides before prolonged high-dose corticosteroids?
- Parasitology · ApplicationWhich parasite causes hydatid cyst disease?
- Parasitology · ApplicationWhich feature is typical of strongyloidiasis in an immunosuppressed host?
- Parasitology · ApplicationWhich parasite causes nocturnal perianal itch in children?
- Parasitology · ApplicationWhich parasite is transmitted by the sandfly and can cause visceral leishmaniasis?
- Parasitology · ApplicationWhich helminth can cause iron-deficiency anaemia through chronic intestinal blood loss?
- Parasitology · ApplicationWhich parasite causes African trypanosomiasis?
- Parasitology · ApplicationWhat is a classic feature of Schistosoma haematobium infection?
- Parasitology · ApplicationWhich test is used to diagnose malaria promptly?
Mycology66
- Mycology · ApplicationA man with advanced HIV has headache and neck stiffness for two weeks. India ink preparation of CSF is performed. What is the expected finding?
- Mycology · ApplicationA patient in diabetic ketoacidosis develops facial pain and a black necrotic eschar on the nasal turbinate. Biopsy shows broad, ribbon-like hyphae with right-angle bran…
- Mycology · ApplicationA young adult has hypopigmented scaly patches on the trunk. KOH mount shows short curved hyphae with clusters of round yeasts. What is the causative organism?
- Mycology: subcutaneous mycoses · ApplicationA gardener has a nodular lesion on the finger that progressed up the forearm as a chain of firm nodules along lymphatics, after a rose thorn prick. Biopsy shows cigar-s…
- Mycology: tinea capitis · Multi-stepA 7-year-old boy has a round patch of scaly alopecia with broken lusterless hairs. Under a Wood's lamp the hairs show bright green fluorescence, and microscopy shows a…
- Mycology: antifungal mechanisms, terbinafine · ApplicationA diabetic man has Trichophyton rubrum toenail onychomycosis and is started on oral terbinafine. Which enzyme does this drug inhibit?
- Mycology: Candida auris · Multi-stepIn an ICU outbreak, several patients with central lines develop candidaemia. The yeast is identified as Candida haemulonii by a biochemical system, is resistant to fluc…
- Mycology: Candida krusei · ApplicationA neutropenic patient on fluconazole prophylaxis develops candidaemia. The blood isolate shows elongated yeast cells with branching pseudohyphae resembling crossed matc…
- Mycology: allergic bronchopulmonary aspergillosis · Multi-stepA 30-year-old man with long-standing asthma has recurrent wheeze, expectoration of brownish mucus plugs, peripheral eosinophilia and a total serum IgE of 2,500 IU/mL. C…
- Mycology: invasive aspergillosis · Multi-stepA 45-year-old man with acute myeloid leukaemia has been neutropenic for 14 days and remains febrile despite broad-spectrum antibiotics. He has pleuritic chest pain, and…
- Mycology: mycotoxins · ApplicationA rural community in a hot humid region stores groundnuts and maize badly, and the incidence of hepatocellular carcinoma is high. Which fungal toxin from Aspergillus fl…
- Mycology: mucormycosis and iron · ApplicationA patient on maintenance dialysis is treated with deferoxamine for iron overload and develops rhino-orbital mucormycosis. What explains the increased risk?
- Mycology: cryptococcal meningitis management · Multi-stepA man with HIV and a CD4 count of 40 cells/mm3 has cryptococcal meningitis, with a positive CSF cryptococcal antigen and an opening pressure of 38 cm of CSF. Which mana…
- Mycology: Histoplasma capsulatum · Multi-stepA man who explored a bat-inhabited cave has fever, weight loss, hepatosplenomegaly and pancytopenia. A Giemsa-stained bone marrow smear shows 2 to 4 micrometre oval yea…
- Mycology: Talaromyces marneffei · Multi-stepA man with advanced HIV from north-east India has fever, weight loss and umbilicated papules on the face. A smear shows yeast-like cells dividing by a central septum, a…
- Mycology: Pneumocystis pneumonia · Multi-stepA 34-year-old man with untreated HIV (CD4 count 70 cells/mm3) has three weeks of progressive dyspnoea and dry cough. SpO2 is 86% and PaO2 is 58 mmHg on room air. Chest…
- Mycology: mycetoma · ApplicationA farmer from Rajasthan has a painless swollen foot with multiple sinuses discharging black granules. Which diagnosis and treatment are most appropriate?
- Mycology: chromoblastomycosis · ApplicationA barefoot agricultural worker has a three-year history of a warty cauliflower-like plaque on the leg. A KOH mount of crusts shows thick-walled brown round cells that d…
- Mycology: rhinosporidiosis · ApplicationA 25-year-old man from coastal Odisha who bathes in a village pond has recurrent unilateral epistaxis and nasal obstruction. Examination shows a pink friable polyp with…
- Mycology: Malassezia and lipid dependence · Multi-stepA preterm neonate on intravenous lipid emulsion through a central line has fever, thrombocytopenia and pulmonary infiltrates. Routine blood cultures are negative, but t…
- Mycology: voriconazole interactions · Multi-stepA kidney transplant recipient on tacrolimus is started on voriconazole for invasive aspergillosis. Tacrolimus trough levels rise sharply and creatinine increases. What…
- Mycology: fungal keratitis · ApplicationA farmer scratched his eye with a sugarcane leaf. He has a corneal ulcer with feathery margins and satellite lesions, and a KOH mount of the scraping shows septate bran…
- Mycology: Epidermophyton floccosum · ApplicationA man has an erythematous scaly groin plaque with a raised active edge that spares the scrotum. Culture grows a fungus with smooth club-shaped macroconidia in clusters…
- Mycology: Basidiobolus ranarum · ApplicationA 6-year-old boy has a painless, firm, woody swelling over the thigh for four months, with skin that slides over it. Biopsy shows broad sparsely septate hyphae surround…
- Mycology: tinea incognito · ApplicationA 30-year-old man has extensive, itchy, ring-shaped lesions on the groin and trunk that have lost their raised scaly border after months of using an over-the-counter st…
- Mycology: Blastomyces dermatitidis · ApplicationA man who returned from an outdoor trip in the Ohio River valley has chronic pneumonia and a verrucous skin lesion. Biopsy shows thick-walled yeasts about 10 micrometre…
- Mycology: Coccidioides laboratory hazard · Multi-stepA laboratory receives a respiratory specimen from a traveller returning from Arizona. A white cottony mould grows on Sabouraud agar, and the technician considers openin…
- Mycology: serum beta-D-glucan · Multi-stepA neutropenic patient with persistent fever is being screened with serum (1,3)-beta-D-glucan. Which of the following invasive infections would typically not raise this…
- Mycology: candidaemia management · Multi-stepA 60-year-old ICU patient on total parenteral nutrition through a central venous catheter develops fever and hypotension. Blood cultures grow budding yeast after 36 hou…
- Mycology: aspergilloma · ApplicationA 55-year-old man treated for cavitary tuberculosis years ago has recurrent haemoptysis. Chest imaging shows a mobile rounded mass within an upper-lobe cavity with a cr…
- Mycology: Fusarium species · ApplicationA patient with acute myeloid leukaemia and prolonged neutropenia develops fever and multiple painful necrotic skin papules. Blood cultures grow a hyaline septate mould…
- Mycology: Pythium insidiosum · Multi-stepA farmer in a waterlogged rice-growing region has a chronic non-healing corneal ulcer after exposure to stagnant water. Scrapings show broad, sparsely septate, hyphae-l…
- Mycology: Trichosporon · Multi-stepA neutropenic patient receiving caspofungin develops breakthrough fungaemia. The isolate is a yeast that forms arthroconidia, true hyphae and pseudohyphae, is urease po…
- Mycology: dermatophyte identification · ApplicationA culture from a patient with tinea corporis grows a powdery colony with numerous round microconidia in grape-like clusters and spiral hyphae. Urease is positive and th…
- Mycology: cryptococcosis · ApplicationA lung biopsy from an HIV-positive patient shows round yeasts surrounded by clear halos. Which special stain colours the polysaccharide capsule of the yeast and helps c…
- Mycology: dimorphic fungi · ApplicationA farmer from Brazil has chronic painful oral ulcers and lymphadenopathy. A smear from the lesion shows a large yeast cell with multiple narrow-necked buds all around i…
- Mycology: tinea capitis treatment · ApplicationA 6-year-old has scaly, itchy patches of hair loss on the scalp, and scrapings grow Microsporum canis. Which oral drug is traditionally preferred for this organism?
- Mycology: cryptococcal antigen screening · Multi-stepA man with newly diagnosed HIV has a CD4 count of 40 per cubic millimetre and no neurological symptoms. A lateral flow serum cryptococcal antigen test is positive. What…
- Mycology: invasive fungal infection · Multi-stepA neutropenic leukaemia patient on broad-spectrum antibiotics has persistent fever and nodules with halo sign on CT chest. Which serum biomarker supports the diagnosis?
- Mycology: favus · ApplicationA child from a rural area has yellowish cup-shaped crusts centred on scalp hairs, with a mousy odour and scarring alopecia. Which dermatophyte is the usual cause?
- Mycology: Cryptococcus gattii · ApplicationAn immunocompetent farmer from an area with eucalyptus trees has a pulmonary mass and meningitis with a large cryptococcoma on MRI. Which species is most likely?
- Mycology: tinea nigra · ApplicationA 10-year-old returning from a tropical coastal holiday has a painless, non-scaly, brown-black macule on the palm that looks like a silver nitrate stain. KOH mount show…
- Mycology: Scedosporium apiospermum · Multi-stepA man develops a brain abscess and a lung lesion months after a near-drowning in a pond. Biopsy shows hyaline septate hyphae resembling Aspergillus, but the isolate is…
- Mycology: Candida parapsilosis in neonatal units · Multi-stepA cluster of candidaemia in a neonatal ICU is traced to colonised hands of staff and catheters used for parenteral nutrition. The yeast is germ-tube negative, forms pse…
- Mycology: oesophageal candidiasis in HIV · ApplicationA man with HIV (CD4 count 45 cells per cubic mm) has painful swallowing and white plaques on the tongue and palate that scrape off. What is the most appropriate initial…
- Mycology: allergic fungal rhinosinusitis · Multi-stepA 22-year-old atopic man has chronic nasal obstruction with polyps. At surgery, thick tenacious peanut-butter mucin is removed. Histology shows eosinophils and Charcot-…
- Mycology: actinomycetoma treatment · Multi-stepA 35-year-old farm worker has a swollen foot with multiple sinuses discharging red grains. Crushing a grain shows thin branching Gram-positive filaments less than 1 mic…
- Mycology: Histoplasma antigen detection · ApplicationA man with advanced HIV from eastern India has fever, weight loss, hepatosplenomegaly, pancytopenia and mucocutaneous ulcers. A Giemsa smear of the bone marrow shows sm…
- Mycology · ApplicationWhich organism is a common cause of oral thrush?
- Mycology · ApplicationWhat is a common microscopic feature of Candida species?
- Mycology · ApplicationWhat opportunistic fungus can cause pneumonia in severely immunocompromised patients?
- Mycology · ApplicationWhat is a common cause of tinea pedis?
- Mycology · ApplicationWhat fungus is associated with pigeon droppings and meningitis in immunocompromised hosts?
- Mycology · ApplicationWhat disease is commonly caused by Aspergillus fumigatus in immunocompromised patients?
- Mycology · ApplicationWhat organism commonly causes oral thrush?
- Mycology · ApplicationWhat microscopic feature supports Candida identification?
- Mycology · ApplicationWhich opportunistic fungus is especially associated with invasive lung disease and characteristic septate branching hyphae in profoundly neutropenic patients?
- Mycology: Cryptococcus neoformans · ApplicationIn a person with advanced HIV, which test rapidly demonstrates the capsule of Cryptococcus neoformans in cerebrospinal fluid?
- Mycology: Aspergillus · Multi-stepA neutropenic patient has pleuritic chest pain and a CT halo sign. Tissue shows septate hyphae branching at acute angles. Which infection is most likely?
- Mycology: Candida albicans · ApplicationWhich laboratory feature supports identification of Candida albicans from a bloodstream isolate?
- Mycology · ApplicationWhich fungus is associated with meningitis in advanced HIV infection?
- Mycology · ApplicationWhich microscopic appearance is typical of Candida albicans?
- Mycology · ApplicationWhich fungal infection is suggested by acute-angle branching septate hyphae?
- Mycology · ApplicationWhich risk factor strongly predisposes to mucormycosis?
- Mycology · ApplicationWhich fungus is associated with pigeon droppings and an encapsulated yeast appearance?
- Mycology · ApplicationWhich feature distinguishes mucormycosis from aspergillosis on microscopy?
Clinical microbiology and hospital infection control25
- Clinical microbiology and hospital infection control: IMViC · Multi-stepTwo lactose-fermenting Gram-negative bacilli grow from a urine culture. Isolate A is indole positive and methyl red positive, and isolate B is indole negative, methyl r…
- Clinical microbiology and hospital infection control: Legionella in water systems · Multi-stepTwo transplant patients develop hospital-acquired pneumonia, and Legionella is found in the hot water tanks. Which control measure is most appropriate?
- Clinical microbiology and hospital infection control: cefoxitin disc · ApplicationA laboratory wants to detect methicillin resistance in a Staphylococcus aureus isolate using disc diffusion. Which disc is used as the preferred surrogate marker?
- Clinical microbiology and hospital infection control: scabies outbreak · Multi-stepSeveral patients and two nurses in a long-term care ward develop intensely itchy rashes worse at night, with burrows between fingers. What is the best infection control…
- Clinical microbiology and hospital infection control: plasmid-mediated colistin resistance · Multi-stepA urinary Klebsiella pneumoniae isolate is resistant to colistin. Sequencing shows a plasmid-borne gene encoding a phosphoethanolamine transferase. How does this confer…
- Clinical microbiology and hospital infection control: biomedical waste glass · ApplicationA ward generates broken glass ampoules and discarded glass medicine vials. According to the Bio-Medical Waste Management Rules 2016 in India, in which container should…
- Clinical microbiology and hospital infection control: Serratia outbreak · ApplicationSeveral ICU patients develop urinary and respiratory infections with a Gram-negative bacillus that forms red-pigmented colonies at room temperature. Cultures trace the…
- Clinical microbiology and hospital infection control: AmpC beta-lactamase · Multi-stepEnterobacter cloacae from a patient treated with ceftriaxone for five days, initially susceptible, is now resistant to ceftriaxone and cefoxitin. Adding clavulanate doe…
- Clinical microbiology and hospital infection control: NDM treatment · Multi-stepA bloodstream Klebsiella pneumoniae isolate from an ICU patient is resistant to meropenem. The EDTA combined disc test is positive and PCR detects blaNDM. Which regimen…
- Clinical microbiology and hospital infection control: paired sera · ApplicationA patient has a febrile illness and a single serum drawn at presentation shows a moderately raised IgG titre to the suspected pathogen. What is the best way to confirm…
- Clinical microbiology and hospital infection control: asymptomatic bacteriuria · ApplicationA 70-year-old woman with a long-term indwelling urinary catheter has no fever or urinary symptoms. A routine urine culture grows more than 100,000 CFU/mL of Escherichia…
- Clinical microbiology and hospital infection control: blood culture yield · ApplicationWhich factor most strongly determines the yield of blood cultures in adults with bacteraemia?
- Clinical microbiology and hospital infection control: varicella exposure in staff · Multi-stepA nurse with no history of varicella or vaccination and negative serology is exposed to an inpatient with chickenpox. When should she be excluded from work?
- Clinical microbiology and hospital infection control: environmental sampling · ApplicationA hospital's infection control committee reviews its policy on culturing surfaces, air and water. When is environmental sampling justified?
- Clinical microbiology and hospital infection control: molecular typing in outbreaks · ApplicationFour MRSA isolates from different patients in one ward have identical antibiograms. Which method best shows whether they belong to a single clone?
- Clinical microbiology and hospital infection control: candiduria · Multi-stepAn afebrile, non-neutropenic ICU patient with an indwelling urinary catheter has Candida albicans at 100,000 CFU/mL in urine. No urologic procedure is planned. What is…
- Clinical microbiology and hospital infection control: quantitative BAL culture · ApplicationIn a ventilated patient with suspected pneumonia, quantitative culture of bronchoalveolar lavage fluid is performed. Growth above which threshold is conventionally take…
- Clinical microbiology and hospital infection control: antibiotic de-escalation · ApplicationA septic patient is started on piperacillin-tazobactam plus vancomycin. At 72 hours, blood cultures grow only a fully susceptible Escherichia coli, and the patient is i…
- Clinical microbiology and hospital infection control: Clostridioides difficile testing algorithm · Multi-stepA hospitalised patient on clindamycin has five loose stools a day. Stool glutamate dehydrogenase antigen is positive, but the toxin enzyme immunoassay is negative. What…
- Clinical microbiology and hospital infection control: CSF transport · ApplicationA CSF sample from a patient with suspected bacterial meningitis cannot reach the laboratory for three hours. How should it be handled?
- Clinical microbiology and hospital infection control: PCR contamination control · Multi-stepA molecular laboratory repeatedly obtains false-positive PCR results because of amplicon carry-over. Which measure is a recognised way to prevent this?
- Clinical microbiology and hospital infection control: hepatitis C needlestick · ApplicationA health care worker has a needlestick injury from an anti-HCV positive patient. Which statement about post-exposure management is correct?
- Clinical microbiology and hospital infection control: Acinetobacter persistence · ApplicationAn Acinetobacter baumannii outbreak in an ICU continues despite routine cleaning of bed rails and ventilators. Which property of the organism best explains its persiste…
- Clinical microbiology and hospital infection control: colistin susceptibility testing · Multi-stepA laboratory reports colistin susceptibility of a Klebsiella isolate using disc diffusion, and a reviewer objects. What is the correct reason?
- Clinical microbiology and hospital infection control: vancomycin testing in S. aureus · Multi-stepA laboratory tests the vancomycin susceptibility of Staphylococcus aureus by disc diffusion only. Why is this method not appropriate?
General microbiology and sterilisation23
- General microbiology and sterilisation: phage typing · ApplicationSeveral cases of typhoid appear in one hostel, and the public health laboratory wants to know whether all isolates come from a single source. Which typing method, class…
- General microbiology and sterilisation: cetrimide agar · ApplicationA swab from an infected burn wound grows a blue-green pigmented, oxidase-positive, non-lactose-fermenting bacillus. Which selective medium containing a quaternary ammon…
- General microbiology and sterilisation: oxygen requirements · ApplicationIn a tube of fluid thioglycollate medium, the organism grows as a narrow band a few millimetres below the surface, but neither at the very top nor at the bottom. What i…
- General microbiology and sterilisation: integrons · Multi-stepA hospital Klebsiella isolate carries several resistance genes arranged in cassettes next to a site-specific recombinase, all expressed from one promoter. What is this…
- General microbiology and sterilisation: Gram stain artefacts · ApplicationA Gram stain from a 72-hour culture of a known Gram-positive Bacillus shows many pink rods alongside a few purple ones. What is the most likely reason?
- General microbiology and sterilisation: mannitol salt agar · ApplicationA nasal swab from a surgeon is plated on a medium containing 7.5 percent sodium chloride, mannitol and phenol red. Small colonies surrounded by a yellow zone grow. Whic…
- General microbiology and sterilisation: Kauffmann-White scheme · Multi-stepA Salmonella isolate agglutinates with O group D (O9) antiserum, with H antiserum d, and with Vi antiserum. According to the Kauffmann-White scheme, which serovar is it?
- General microbiology and sterilisation: porin loss · Multi-stepDuring therapy of Pseudomonas aeruginosa pneumonia, the isolate becomes resistant to imipenem but stays susceptible to ceftazidime and piperacillin-tazobactam. No carba…
- General microbiology and sterilisation: operation theatre fumigation · ApplicationAfter a cluster of postoperative wound infections, a sealed operation theatre is fumigated overnight by adding potassium permanganate crystals to a liquid placed in ope…
- General microbiology and sterilisation: oxidation-fermentation test · ApplicationA Gram-negative bacillus is inoculated into two tubes of glucose semisolid medium, and one tube is sealed with liquid paraffin. After incubation, acid production turns…
- General microbiology and sterilisation: chemical indicator for autoclave · ApplicationA technician places a sealed glass tube containing a red liquid inside an autoclave load as a quick check of conditions. After a complete cycle at 121 degrees C the liq…
- General microbiology and sterilisation: decimal reduction time · Multi-stepA spore suspension contains 10^6 viable spores per mL, and its decimal reduction time at 121 degrees C is 1.5 minutes. Assuming log-linear killing, how long is needed t…
- General microbiology and sterilisation: anaerobic jar indicator · ApplicationA GasPak anaerobic jar for culturing Clostridium species contains a methylene blue indicator strip. After 48 hours the strip is still blue. What is the correct interpre…
- General microbiology and sterilisation: role of iodine in Gram stain · ApplicationIn the Gram staining sequence of crystal violet, Gram's iodine, alcohol and safranin, what is the specific function of the iodine step?
- General microbiology and sterilisation: infective dose · ApplicationWhich of the following enteric pathogens is known for the lowest infective dose by the oral route?
- General microbiology and sterilisation: Ames test · ApplicationA food laboratory screens a new additive by plating histidine-requiring mutant Salmonella on histidine-free agar, with a rat liver extract added to the additive. A mark…
- General microbiology and sterilisation: tellurite medium · ApplicationA throat swab from a child with a grey pharyngeal membrane is plated on blood agar containing potassium tellurite. After 48 hours, grey-black colonies of club-shaped Gr…
- General microbiology and sterilisation: alkaline peptone water · ApplicationA stool sample from a patient with suspected cholera is first inoculated into alkaline peptone water (pH about 8.6) and incubated for a few hours before subculture to a…
- General microbiology and sterilisation: viable count calculation · Multi-stepA broth culture is serially diluted, and 0.1 mL of the 10^-5 dilution is spread on an agar plate, giving 120 colonies after incubation. What is the viable count of the…
- General microbiology and sterilisation: 16S rRNA sequencing · ApplicationA patient with a prosthetic valve has culture-negative endocarditis after antibiotics were given. A resected vegetation is amplified with broad-range primers, and the p…
- General microbiology and sterilisation: aminoglycoside-modifying enzymes · ApplicationA plasmid in a Klebsiella isolate carries a gene that encodes an enzyme adding an acetyl group to gentamicin. How does this make the isolate resistant?
- General microbiology and sterilisation: why moist heat is more effective · ApplicationAt the same temperature, moist heat kills organisms in much less time than dry heat. Which statement best explains this?
- General microbiology and sterilisation: cationic disinfectants and soap · ApplicationA ward uses benzalkonium chloride to disinfect a trolley that was cleaned earlier with ordinary soap and not rinsed. The disinfection is poor. What is the most likely e…
Infection control18
- Infection control: Clostridioides difficile · ApplicationDuring an outbreak of Clostridioides difficile diarrhoea on a medical ward, which hand hygiene measure is best for staff after caring for an affected patient?
- Infection control: biofilm on prosthetic devices · ApplicationA patient with a prosthetic knee has persistent infection with Staphylococcus epidermidis despite antibiotics showing susceptibility in vitro. Cure requires removal or…
- Infection control: MRSA decolonisation · ApplicationA patient scheduled for elective cardiac surgery has a nasal screening swab positive for MRSA. Which pre-operative measure is most appropriate?
- Infection control: transmission-based precautions · ApplicationA 17-year-old is admitted with fever, headache and a petechial rash, and Gram-negative diplococci are seen in CSF. Which precautions should be applied until he has rece…
- Infection control: HIV post-exposure prophylaxis · ApplicationA staff nurse sustains a deep needlestick injury with a hollow-bore needle from a patient known to be HIV positive. She presents one hour later. Which approach is most…
- Infection control: surgical antibiotic prophylaxis · ApplicationA surgeon plans an elective inguinal hernia repair with a mesh in a patient with no allergies. What is the correct timing of cefazolin prophylaxis?
- Infection control: WHO five moments for hand hygiene · ApplicationA nurse adjusts the bed rails and IV pole of a patient without touching the patient, then moves to another bed. Which WHO moment for hand hygiene applies?
- Infection control · ApplicationWhy are standard precautions used?
- Infection control · ApplicationWhat breaks fecal-oral transmission?
- Infection control · ApplicationWhat is the most effective routine measure to reduce healthcare transmission?
- Infection control · ApplicationWhy are standard precautions used for all patients?
- Infection control: alcohol hand rub · ApplicationIn a ward caring for a patient with Clostridioides difficile diarrhoea, why is soap-and-water handwashing preferred after glove removal?
- Infection control · ApplicationWhy are alcohol hand rubs less effective against Clostridioides difficile spores?
- Infection control · ApplicationWhat is the main purpose of an antimicrobial susceptibility test?
- Infection control · ApplicationWhat is the purpose of negative-pressure isolation for airborne infection?
- Infection control · ApplicationWhy are central-line insertion bundles used?
- Infection control · ApplicationWhy are surgical instruments cleaned before sterilization?
- Infection control · ApplicationWhat is the purpose of standard precautions?
Clinical microbiology12
- Clinical microbiology: blood culture interpretation · Multi-stepA 60-year-old woman has fever and hypotension after a hospital stay. Two blood culture sets are drawn from separate venepuncture sites before antibiotics. One of four b…
- Clinical microbiology: quantitative urine culture · Multi-stepA 26-year-old woman has dysuria. A 0.001 mL calibrated loop of her midstream urine is plated on CLED agar, and 150 colonies of Escherichia coli grow overnight. What is…
- Clinical microbiology: ESBL treatment · Multi-stepA 70-year-old woman in a surgical ICU has Klebsiella pneumoniae bacteraemia. The isolate is resistant to ceftriaxone, ceftazidime and aztreonam, with zone enhancement t…
- Clinical microbiology: carbapenemase detection · Multi-stepAn ICU isolate of Klebsiella pneumoniae is resistant to meropenem. In a combined disc test, the imipenem disc with EDTA gives a clearly larger zone than the imipenem di…
- Clinical microbiology: D-test · Multi-stepStaphylococcus aureus from an abscess is resistant to erythromycin and appears susceptible to clindamycin. When the two discs are placed 15 to 20 mm apart, the clindamy…
- Clinical microbiology: disc diffusion standardisation · ApplicationIn a Kirby-Bauer disc diffusion test, a technician accidentally prepares a bacterial suspension far denser than the 0.5 McFarland standard and lawns it on Mueller-Hinto…
- Clinical microbiology: CBNAAT result · Multi-stepA 38-year-old man with cough for six weeks has sputum tested by CBNAAT (Xpert MTB/RIF), which reports MTB detected, rifampicin resistance detected. What is the most app…
- Clinical microbiology: catheter-related bloodstream infection · Multi-stepA patient has a central venous catheter and fever. Paired blood cultures are drawn at the same time from the catheter and from a peripheral vein. The catheter sample fl…
- Clinical microbiology: Truenat · ApplicationA primary health centre in a remote block has intermittent electricity and no cartridge-based laboratory. Under the national TB programme, which test can detect Mycobac…
- Clinical microbiology: real-time PCR · Multi-stepTwo plasma samples are tested by real-time PCR for a viral load using the same assay with 100% amplification efficiency. Sample A has a cycle threshold of 22 and sample…
- Clinical microbiology: MRSA detection · Multi-stepA Staphylococcus aureus isolate from a wound shows a 30 microgram cefoxitin disk zone of 18 mm on disk diffusion. How should the isolate be reported?
- Clinical microbiology: automated blood culture · ApplicationAn automated blood culture system flags a bottle as positive after 14 hours of incubation. Which principle underlies the detection, and what is the immediate next labor…
General microbiology12
- General microbiology: capsule demonstration · ApplicationAlpha-haemolytic Gram-positive diplococci are isolated from sputum. When a drop of the specimen is mixed with type-specific antiserum and methylene blue, the capsule ap…
- General microbiology: cell wall-deficient bacteria · ApplicationA 19-year-old student has a persistent dry cough and low-grade fever for two weeks. The chest radiograph shows patchy infiltrates, and Gram stain of sputum shows no org…
- General microbiology: special stains · ApplicationA man has a painless genital ulcer and the laboratory wants to visualise the causative spirochaete in a smear from the lesion. The organism is too thin to be seen with…
- General microbiology: selective media · ApplicationA stool culture from a suspected typhoid carrier among food handlers is plated on a bismuth sulphite-based selective medium. After 48 hours the laboratory sees jet-blac…
- General microbiology: biosafety levels · ApplicationA tertiary hospital laboratory plans to start liquid culture and drug susceptibility testing of Mycobacterium tuberculosis from sputum. Which minimum biosafety level an…
- General microbiology: normal flora · ApplicationA woman develops itching and a thick, white, curd-like vaginal discharge after a 10-day course of a broad-spectrum antibiotic. Which mechanism most directly explains th…
- General microbiology: sterilisation · ApplicationA hospital needs to sterilise a heat-labile, moisture-sensitive fibreoptic endoscope accessory between cases without leaving toxic residues. Which method is most suitab…
- General microbiology: disinfection · ApplicationA bottle of blood from a patient with hepatitis B breaks on the ward floor. After wearing gloves and covering the spill with absorbent material, which disinfectant is a…
- General microbiology: staining · ApplicationA laboratory technician leaves the decolouriser on a Gram-stained smear of Staphylococcus aureus for several minutes. Under the microscope the cocci appear pink-red. Wh…
- General microbiology: bacterial genetics · Multi-stepIn a patient's gut, a commensal Escherichia coli strain carrying a plasmid with several resistance genes transfers resistance to an incoming Shigella strain by direct c…
- General microbiology: transport media · ApplicationDuring a suspected cholera outbreak in a remote village, rectal swabs have to be sent to a district laboratory 8 hours away without refrigeration. Which transport mediu…
- General microbiology: laboratory safety · ApplicationA tuberculosis laboratory needs a cabinet that protects the worker, the culture sample and the surrounding environment while processing sputum specimens. Which equipmen…
Sterilisation9
- Sterilisation · ApplicationWhich item is best sterilised in a hot air oven rather than an autoclave?
- Sterilisation · ApplicationWhich method is appropriate for disinfecting a heat-sensitive flexible endoscope between patients?
- Sterilisation: prion decontamination · ApplicationNeurosurgical instruments were used on a patient later diagnosed with sporadic Creutzfeldt-Jakob disease. Which reprocessing method is appropriate for the reusable inst…
- Sterilisation: Tyndallisation · ApplicationA laboratory must sterilise a sugar-containing fermentation medium that caramelises and decomposes at 121 degrees C. Which method is most appropriate?
- Sterilisation: filtration · ApplicationHeat-labile foetal calf serum for cell culture is sterilised by passage through a 0.22 micrometre membrane filter. Which contaminant could still be present in the filtr…
- Sterilisation: Bowie-Dick test · ApplicationA central sterile supply department uses a pre-vacuum steam steriliser. Each morning a technician runs a folded-towel test pack with a chemical indicator sheet at 134 d…
- Sterilisation: Bowie-Dick test · ApplicationA central sterile services department runs a Bowie-Dick test pack in an empty pre-vacuum (porous load) autoclave. After the cycle, the indicator sheet shows a pale unch…
- Sterilisation: ionising radiation · ApplicationA manufacturer wants to sterilise sealed, pre-packed disposable plastic syringes and catheters, which would melt in heat. Which method is commonly used on an industrial…
- Sterilisation: biological indicator for dry heat · ApplicationA laboratory sterilises glass syringes and heat-stable powders in a hot air oven at 160 degrees C for 2 hours. Which spore preparation is placed in the load as the biol…
Sterilization9
- Sterilization · ApplicationWhich method sterilizes heat-sensitive liquids?
- Sterilization · ApplicationWhat does autoclaving use?
- Sterilization · ApplicationWhat process destroys all microbial life including spores?
- Sterilization · ApplicationWhat method uses pressurized steam to sterilize instruments?
- Sterilization · ApplicationWhat process destroys all microorganisms including spores?
- Sterilization · ApplicationWhat method sterilizes instruments using pressurized steam?
- Sterilization · ApplicationWhat does autoclaving use?
- Sterilization · ApplicationWhich process is suitable for heat-sensitive endoscopic equipment?
- Sterilization · ApplicationWhat is biological indicator testing used for in autoclave validation?
Antimicrobial resistance8
- Antimicrobial resistance: ESBL · Multi-stepA diabetic ICU patient has Escherichia coli bacteraemia. The isolate is resistant to ceftriaxone, ceftazidime and aztreonam, susceptible to cefoxitin and shows an enlar…
- Antimicrobial resistance: metallo-beta-lactamase · ApplicationA meropenem-resistant Klebsiella pneumoniae is isolated from an ICU patient. In a combined disc test, a meropenem disc with EDTA gives a zone at least 7 mm larger than…
- Antimicrobial resistance: vancomycin-resistant enterococci · Multi-stepEnterococcus faecium from a dialysis patient's blood shows a vancomycin MIC above 256 mg/L and is also resistant to teicoplanin. Which gene and mechanism explain this p…
- Antimicrobial resistance · ApplicationWhat is a major driver of antimicrobial resistance?
- Antimicrobial resistance: ESBL · Multi-stepAn Escherichia coli isolate is reported as an extended-spectrum beta-lactamase producer. What resistance mechanism is most characteristic?
- Antimicrobial resistance · ApplicationWhat is an extended-spectrum beta-lactamase?
- Antimicrobial resistance · ApplicationWhat does a biofilm contribute to in device-associated infection?
- Antimicrobial resistance · ApplicationWhat is antimicrobial de-escalation?
Hospital infection control8
- Hospital infection control: ventilator-associated pneumonia prevention · ApplicationA hospital infection control committee reviews measures to prevent ventilator-associated pneumonia in its ICU. Which measure is supported by evidence?
- Hospital infection control: hepatitis B exposure · Multi-stepA 24-year-old nurse who has never been vaccinated sustains a needle-stick injury from a patient who is HBsAg positive and HBeAg positive. Her baseline anti-HBs is negat…
- Hospital infection control: HIV post-exposure prophylaxis · ApplicationA resident doctor has a deep needle-stick injury from a patient with known HIV infection. Post-exposure prophylaxis is planned. What is the recommended timing and durat…
- Hospital infection control: transmission-based precautions · ApplicationA 7-year-old child admitted with fever and a vesicular rash is diagnosed with chickenpox. Which isolation arrangement is appropriate in the ward?
- Hospital infection control: spore-forming pathogen hygiene · ApplicationA surgical ward is managing an outbreak of Clostridioides difficile infection. Which hand hygiene practice is recommended for staff after caring for affected patients?
- Hospital infection control: surveillance calculation · Multi-stepAn ICU records 6 central line-associated bloodstream infections in a month during which central lines were in place for a total of 3,000 catheter-days. What is the CLAB…
- Hospital infection control: surgical prophylaxis · ApplicationA 62-year-old woman is scheduled for elective total hip replacement, and the team plans cefazolin prophylaxis. When should the dose be given for maximum benefit in prev…
- Hospital infection control: outbreak investigation · Multi-stepFour neonates in a neonatal ICU develop Klebsiella pneumoniae bacteraemia within one week, while the unit usually sees about one such case per month. What is the most a…
Laboratory diagnosis7
- Laboratory diagnosis: Limulus amebocyte lysate test · ApplicationSeveral patients develop rigors and fever during an infusion from one batch of intravenous fluid. Cultures of the sterile fluid are negative. Which in vitro test detect…
- Laboratory diagnosis: MALDI-TOF · ApplicationA laboratory identifies bacterial colonies within minutes using MALDI-TOF mass spectrometry. What does the instrument actually measure?
- Laboratory diagnosis: blood culture interpretation · Multi-stepA 62-year-old man with fever and a urinary source has two blood culture sets (four bottles) drawn from separate sites before antibiotics. At 36 hours, one aerobic bottl…
- Laboratory diagnosis · ApplicationWhat does culture of a clinical specimen allow?
- Laboratory diagnosis · ApplicationWhat is the purpose of a blood culture?
- Laboratory diagnosis · ApplicationWhat does PCR detect in an infectious-disease sample?
- Laboratory diagnosis · ApplicationWhat specimen issue can make sputum culture less useful?
Vaccines7
- Vaccines: live vaccines in pregnancy · ApplicationA primigravida at 14 weeks of gestation is found to be rubella IgG negative. What is the best advice?
- Vaccines · ApplicationWhat is a toxoid vaccine made from?
- Vaccines · ApplicationWhat is herd immunity?
- Vaccines · ApplicationWhy are live attenuated vaccines generally avoided in severe immunosuppression?
- Vaccines · ApplicationWhat is the main purpose of an adjuvant in some vaccines?
- Vaccines · ApplicationWhat is herd immunity threshold influenced by?
- Vaccines · ApplicationWhy are booster doses used for some vaccines?
Parasites6
- Parasites · ApplicationWhich parasite causes enterobiasis with perianal itch?
- Parasites · ApplicationWhich parasite can cause hydatid cysts?
- Parasites · ApplicationWhich parasite causes kala-azar?
- Parasites · ApplicationWhat parasite causes cerebral malaria?
- Parasites · ApplicationWhat parasite causes pork tapeworm infection?
- Parasites · ApplicationWhat parasite causes biliary ascariasis?
Culture media5
- Culture media · ApplicationThayer–Martin medium is used selectively to isolate which organism?
- Culture media · ApplicationWhich medium is used to grow Corynebacterium diphtheriae?
- Culture media: TCBS agar · ApplicationA man develops acute watery diarrhoea after eating raw shellfish. Stool plated on TCBS agar grows green colonies. Which organism is most likely?
- Culture media: Haemophilus growth factors · ApplicationGram-negative coccobacilli from sputum fail to grow on blood agar but grow on chocolate agar and form small colonies around a Staphylococcus aureus streak on blood agar…
- Culture media: enrichment broth · ApplicationA food handler is suspected to be a carrier of Salmonella, and a stool sample contains abundant coliforms. Which medium is used first to favour growth of Salmonella bef…
Infection prevention5
- Infection prevention · ApplicationWhat is the most effective routine measure to reduce healthcare-associated transmission?
- Infection prevention · ApplicationWhat type of precautions are used for pathogens spread by large respiratory droplets?
- Infection prevention · ApplicationWhy are standard precautions applied to all patients?
- Infection prevention · ApplicationWhat is an essential element of safe injection practice?
- Infection prevention · ApplicationWhat routine practice most reduces healthcare-associated transmission?
Disinfection4
- Disinfection: phenol coefficient tests · ApplicationA hospital wants to compare a new disinfectant with phenol under conditions that mimic soiled surfaces, with organic matter added to the test. Which test is designed fo…
- Disinfection: alcohols · ApplicationA student asks why 70% ethanol is used for skin preparation instead of absolute (100%) ethanol. What is the correct explanation?
- Disinfection: chlorhexidine · ApplicationA surgeon is choosing a skin antiseptic for an elective operation. Which property of chlorhexidine makes it attractive for pre-operative skin preparation?
- Disinfection: Spaulding classification · ApplicationA flexible bronchoscope, which contacts intact mucous membranes but does not enter sterile tissue, is heat-labile. According to the Spaulding classification, what is th…
Microbial genetics4
- Microbial genetics · ApplicationWhat is horizontal gene transfer?
- Microbial genetics · ApplicationWhat is bacterial conjugation?
- Microbial genetics · ApplicationWhat mechanism allows bacteria to acquire resistance genes from bacteriophages?
- Microbial genetics · ApplicationIn bacterial genetics, what is a plasmid molecule?
Antimicrobial susceptibility3
- Antimicrobial susceptibility: Etest · ApplicationOn an Etest plate, a lawn of an isolate shows an elliptical zone of inhibition whose edge meets the antibiotic gradient strip at the 0.5 mark on the scale. What does th…
- Antimicrobial susceptibility · ApplicationWhat does an antibiotic susceptibility test help determine?
- Antimicrobial susceptibility · ApplicationWhat does antimicrobial susceptibility testing determine?
Bacterial toxins3
- Bacterial toxins · ApplicationDiphtheria toxin acts by:
- Bacterial toxins · ApplicationA farmer with a deep soil-contaminated wound develops trismus, risus sardonicus and painful spasms. What is the mechanism of the toxin responsible?
- Bacterial toxins · ApplicationA patient has profuse painless watery diarrhoea resembling rice water. Which action of cholera toxin explains the fluid loss?
Fungi3
Gastrointestinal microbiology3
- Gastrointestinal microbiology · ApplicationWhich organism causes enteric fever and may persist in the gallbladder of a chronic carrier?
- Gastrointestinal microbiology · ApplicationWhich pathogen is associated with Guillain-Barré syndrome after gastroenteritis?
- Gastrointestinal microbiology · ApplicationWhich organism causes cholera through enterotoxin-mediated chloride secretion?
Laboratory microbiology3
Antimicrobial testing2
- Antimicrobial testing: MIC and MBC · Multi-stepA Staphylococcus aureus isolate from a patient with endocarditis has a vancomycin MIC of 1 mg/L, which is in the susceptible range, but the minimum bactericidal concent…
- Antimicrobial testing: fractional inhibitory concentration · Multi-stepIn a checkerboard assay, the MIC of drug A alone is 8 mg/L and of drug B alone is 16 mg/L. In the best combination well, the MICs are 2 mg/L of A and 4 mg/L of B. What…
Bacterial genetics2
- Bacterial genetics · Multi-stepA non-toxigenic strain of Corynebacterium diphtheriae isolated from a carrier starts producing diphtheria toxin after infection with a temperate bacteriophage. Which pr…
- Bacterial genetics: Hfr conjugation · Multi-stepIn a laboratory cross, an Hfr donor strain is mixed with an F-negative recipient. After mating, many recipients have received donor chromosomal genes, yet almost all of…
Bacterial growth2
- Bacterial growth: phases of the growth curve · ApplicationA culture of Escherichia coli is exposed to a beta-lactam antibiotic during different phases of growth. In which phase are the bacteria most susceptible?
- Bacterial growth: generation time calculation · Multi-stepEscherichia coli has a generation time of 20 minutes in log phase. If 2 x 10^3 cells in log phase are inoculated into broth and lag is ignored, what is the approximate…
Hospital infection2
Resistance2
Respiratory microbiology2
Serology2
- Serology · Multi-stepA healthy health-care worker tests negative for HBsAg, positive for anti-HBs and negative for total anti-HBc. How is this best interpreted?
- Serology · Multi-stepA traveller returns with high fever, retro-orbital pain and myalgia on the second day of illness. Which test is most useful at this stage to confirm dengue?
Virus detection2
- Virus detection: haemadsorption · ApplicationA parainfluenza virus is inoculated into monkey kidney cell monolayers, but no cytopathic effect develops after a week. Which simple test can show that the virus has re…
- Virus detection: interference · ApplicationRubella virus from a throat swab is inoculated into African green monkey kidney cells, and no cytopathic effect appears. When ECHO 11 virus is added, the cells are also…
Zoonoses2
Chlamydiae1
Corynebacterium diphtheriae1
Hepatitis B vaccination of healthcare workers1
Hospital infections1
Immunology and serology1
Sepsis biomarkers1
Tuberculosis diagnosis1
Varicella zoster virus1
Common questions
How many Microbiology questions are there?
840 original questions across 592 topics, and the bank grows over time.
Which Microbiology topics are covered?
Bacteriology, Culture media, Immunology and serology, Bacterial toxins, Serology, Parasitology, Mycology, Immunology, Sterilisation, Virology, Bacterial genetics, Chlamydiae, and more.
How difficult are these Microbiology questions?
0 are recall, 617 are application and 223 are multi-step. The tags are our own editorial judgement, not an official difficulty rating.
Are these Microbiology questions from past papers?
No. They are original practice items. NBEMS does not publish its paper or an official key, and we do not use recalled or leaked questions.
Can I practise Microbiology for free?
Yes. The free plan includes 20 practice questions a day across all subjects, and the free 20-question assessment covers every subject. A paid term removes the daily limit.
Is there a timed Microbiology test?
Yes. The Microbiology subject test is included with a paid term, with a countdown and a question palette.
How should I use these Microbiology questions?
Answer before you look, read the reason for every option, and write a three-line note for each mistake. A few questions you fully review are worth more than many you skim.
Have these Microbiology questions been reviewed by faculty?
Not yet. They are original and drafted with AI assistance, then edited by our team. Independent faculty review is planned, and each item shows its status. Confirm important facts in a standard textbook.