Parasitology: Cryptosporidium: practice question

A Microbiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

Try it

Microbiology · Parasitology: Cryptosporidium

Sample item

A 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?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Modified acid-fast stain showing 4 to 6 micrometre oocysts

Cryptosporidium is a coccidian parasite that causes severe prolonged watery diarrhoea in advanced HIV. Its small oocysts stain with modified Ziehl-Neelsen (modified Kinyoun) stain and can also be detected by antigen assays. Restoring immunity with antiretroviral therapy is the key treatment, with nitazoxanide as an adjunct.

Option by option

  • A. Gram stain showing curved Gram-negative rods

    Curved Gram-negative rods suggest Vibrio cholerae, a bacterium that is not identified by acid-fast staining.

  • B. Modified acid-fast stain showing 4 to 6 micrometre oocysts (correct)

    Correct. Acid-fast small oocysts identify Cryptosporidium.

  • C. Saline mount showing operculate eggs

    Operculate eggs indicate flukes such as Fasciola or Clonorchis.

  • D. Iodine wet mount showing large cysts with chromatoidal bars

    Large cysts with chromatoidal bars describe Entamoeba histolytica, which causes dysentery.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is B, Modified acid-fast stain showing 4 to 6 micrometre oocysts. Cryptosporidium is a coccidian parasite that causes severe prolonged watery diarrhoea in advanced HIV.

Why is "Gram stain showing curved Gram-negative rods" not the answer?

Curved Gram-negative rods suggest Vibrio cholerae, a bacterium that is not identified by acid-fast staining.

Why is "Saline mount showing operculate eggs" not the answer?

Operculate eggs indicate flukes such as Fasciola or Clonorchis.

Why is "Iodine wet mount showing large cysts with chromatoidal bars" not the answer?

Large cysts with chromatoidal bars describe Entamoeba histolytica, which causes dysentery.

What concept does this question test?

It tests Parasitology: Cryptosporidium in Microbiology. Its small oocysts stain with modified Ziehl-Neelsen (modified Kinyoun) stain and can also be detected by antigen assays. Restoring immunity with antiretroviral therapy is the key treatment, with nitazoxanide as an adjunct.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Parasitology: Cryptosporidium?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.