Bacteriology: Bacillus cereus: 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.

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Microbiology · Bacteriology: Bacillus cereus

Sample item

Within 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 and kept at room temperature. Which organism is the most likely cause?

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

The answer and the reasoning

B. Bacillus cereus

The emetic form of Bacillus cereus food poisoning follows ingestion of rice in which surviving spores germinated after cooking and produced heat-stable cereulide toxin; onset is 1 to 5 hours with vomiting. Clostridium perfringens causes diarrhoea after 8 to 16 hours, Salmonella needs a longer incubation with fever, and Vibrio parahaemolyticus is associated with seafood.

Option by option

  • A. Clostridium perfringens

    C. perfringens causes watery diarrhoea with a longer incubation.

  • B. Bacillus cereus (correct)

    Correct. Rice kept warm allows emetic toxin formation by B. cereus.

  • C. Vibrio parahaemolyticus

    V. parahaemolyticus is linked to raw or undercooked seafood.

  • D. Salmonella Typhimurium

    Salmonella gastroenteritis has a longer incubation and usually fever.

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, Bacillus cereus. The emetic form of Bacillus cereus food poisoning follows ingestion of rice in which surviving spores germinated after cooking and produced heat-stable cereulide toxin; onset is 1 to 5 hours with vomiting.

Why is "Clostridium perfringens" not the answer?

C. perfringens causes watery diarrhoea with a longer incubation.

Why is "Vibrio parahaemolyticus" not the answer?

V. parahaemolyticus is linked to raw or undercooked seafood.

Why is "Salmonella Typhimurium" not the answer?

Salmonella gastroenteritis has a longer incubation and usually fever.

What concept does this question test?

It tests Bacteriology: Bacillus cereus in Microbiology. Clostridium perfringens causes diarrhoea after 8 to 16 hours, Salmonella needs a longer incubation with fever, and Vibrio parahaemolyticus is associated with seafood.

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 Bacteriology: Bacillus cereus?

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.