Bacteriology: Vibrio cholerae: 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: Vibrio cholerae

Sample item

A patient with profuse 'rice-water' diarrhoea is infected with Vibrio cholerae. What is the principal action of cholera toxin?

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

The answer and the reasoning

A. ADP-ribosylates Gs alpha, raising intracellular cAMP

Cholera toxin locks Gs alpha in its active state, increasing adenylate cyclase activity and cAMP. Chloride and water secretion then produce severe watery diarrhoea.

Option by option

  • A. ADP-ribosylates Gs alpha, raising intracellular cAMP (correct)

    Correct. Persistent Gs activation drives cAMP-mediated secretion.

  • B. Inactivates Gi alpha, lowering cAMP

    Pertussis toxin inactivates Gi, which also raises cAMP.

  • C. Blocks 60S ribosomal subunits

    Shiga toxin blocks the 60S subunit.

  • D. Cleaves SNARE proteins

    Botulinum toxin cleaves SNARE proteins.

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.

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Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is A, ADP-ribosylates Gs alpha, raising intracellular cAMP. Cholera toxin locks Gs alpha in its active state, increasing adenylate cyclase activity and cAMP.

Why is "Inactivates Gi alpha, lowering cAMP" not the answer?

Pertussis toxin inactivates Gi, which also raises cAMP.

Why is "Blocks 60S ribosomal subunits" not the answer?

Shiga toxin blocks the 60S subunit.

Why is "Cleaves SNARE proteins" not the answer?

Botulinum toxin cleaves SNARE proteins.

What concept does this question test?

It tests Bacteriology: Vibrio cholerae in Microbiology. Chloride and water secretion then produce severe watery diarrhoea.

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: Vibrio cholerae?

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.