Bacteriology: Mycobacterium tuberculosis: 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 tuberculosis

Sample item

A patient with active pulmonary tuberculosis begins standard therapy. Which drug is most associated with optic neuritis and impaired red-green colour discrimination?

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

The answer and the reasoning

C. Ethambutol

Ethambutol can cause dose-related optic neuritis, so visual acuity and colour vision should be assessed. Isoniazid causes neuropathy and hepatitis; pyrazinamide causes hyperuricaemia; rifampicin causes enzyme induction and orange secretions.

Option by option

  • A. Rifampicin

    Rifampicin can discolor body fluids orange.

  • B. Isoniazid

    Isoniazid is prevented from causing neuropathy with pyridoxine.

  • C. Ethambutol (correct)

    Correct. Optic toxicity with red-green dyschromatopsia is ethambutol's hallmark.

  • D. Pyrazinamide

    Pyrazinamide commonly raises uric acid.

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 C, Ethambutol. Ethambutol can cause dose-related optic neuritis, so visual acuity and colour vision should be assessed.

Why is "Rifampicin" not the answer?

Rifampicin can discolor body fluids orange.

Why is "Isoniazid" not the answer?

Isoniazid is prevented from causing neuropathy with pyridoxine.

Why is "Pyrazinamide" not the answer?

Pyrazinamide commonly raises uric acid.

What concept does this question test?

It tests Bacteriology: Mycobacterium tuberculosis in Microbiology. Isoniazid causes neuropathy and hepatitis; pyrazinamide causes hyperuricaemia; rifampicin causes enzyme induction and orange secretions.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 tuberculosis?

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.