Bacteriology: Mycobacterium bovis: 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: Mycobacterium bovis

Sample item

A child from a dairy farm has cervical lymphadenitis due to Mycobacterium bovis. This species is intrinsically resistant to which first-line antitubercular drug?

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

The answer and the reasoning

D. Pyrazinamide

M. bovis lacks a functional pyrazinamidase because of a pncA mutation and so is naturally resistant to pyrazinamide. Standard regimens are adjusted accordingly. It is acquired from unpasteurised milk.

Option by option

  • A. Rifampicin

    Rifampicin is active against M. bovis.

  • B. Ethambutol

    Ethambutol is active against M. bovis.

  • C. Isoniazid

    Isoniazid remains active against M. bovis.

  • D. Pyrazinamide (correct)

    Correct. M. bovis is intrinsically resistant to pyrazinamide.

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 D, Pyrazinamide. M.

Why is "Rifampicin" not the answer?

Rifampicin is active against M. bovis.

Why is "Ethambutol" not the answer?

Ethambutol is active against M. bovis.

Why is "Isoniazid" not the answer?

Isoniazid remains active against M. bovis.

What concept does this question test?

It tests Bacteriology: Mycobacterium bovis in Microbiology. bovis lacks a functional pyrazinamidase because of a pncA mutation and so is naturally resistant to pyrazinamide. Standard regimens are adjusted accordingly. It is acquired from unpasteurised milk.

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: Mycobacterium bovis?

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.