Bacteriology: Bordetella pertussis: 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: Bordetella pertussis

Sample item

A child has paroxysmal coughing followed by an inspiratory whoop. Which organism causes lymphocytosis by ADP-ribosylating Gi protein?

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

The answer and the reasoning

A. Bordetella pertussis

Pertussis toxin inactivates Gi, increasing cAMP and causing prominent lymphocytosis. The catarrhal phase is the period of greatest transmissibility.

Option by option

  • A. Bordetella pertussis (correct)

    Correct. Pertussis toxin is the Gi-inactivating toxin.

  • B. Corynebacterium diphtheriae

    Diphtheria toxin inhibits elongation factor 2.

  • C. Legionella pneumophila

    Legionella grows intracellularly and causes hyponatraemia, not this toxin effect.

  • D. Haemophilus influenzae

    H. influenzae does not produce pertussis toxin.

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 A, Bordetella pertussis. Pertussis toxin inactivates Gi, increasing cAMP and causing prominent lymphocytosis.

Why is "Corynebacterium diphtheriae" not the answer?

Diphtheria toxin inhibits elongation factor 2.

Why is "Legionella pneumophila" not the answer?

Legionella grows intracellularly and causes hyponatraemia, not this toxin effect.

Why is "Haemophilus influenzae" not the answer?

H. influenzae does not produce pertussis toxin.

What concept does this question test?

It tests Bacteriology: Bordetella pertussis in Microbiology. The catarrhal phase is the period of greatest transmissibility.

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: Bordetella pertussis?

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.