Leprosy: rifampicin: practice question

A Dermatology 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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Dermatology · Leprosy: rifampicin

Sample item

What is the mechanism of action of rifampicin against M. leprae?

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

The answer and the reasoning

B. Inhibition of the beta subunit of DNA-dependent RNA polymerase

Rifampicin binds the beta subunit of bacterial DNA-dependent RNA polymerase, blocking transcription, and is rapidly bactericidal against M. leprae. A single dose kills over 99 percent of viable bacilli.

Option by option

  • A. Inhibition of folate synthesis

    Dapsone inhibits folate synthesis by acting as a sulphone.

  • B. Inhibition of the beta subunit of DNA-dependent RNA polymerase (correct)

    Correct. RNA polymerase inhibition is the action of rifampicin.

  • C. Inhibition of arabinosyl transferase

    Ethambutol inhibits arabinosyl transferase.

  • D. Inhibition of mycolic acid synthesis

    Isoniazid inhibits mycolic acid synthesis.

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 Dermatology questions

Questions about this Dermatology question

What is the answer to this Dermatology question?

The best answer is B, Inhibition of the beta subunit of DNA-dependent RNA polymerase. Rifampicin binds the beta subunit of bacterial DNA-dependent RNA polymerase, blocking transcription, and is rapidly bactericidal against M.

Why is "Inhibition of folate synthesis" not the answer?

Dapsone inhibits folate synthesis by acting as a sulphone.

Why is "Inhibition of arabinosyl transferase" not the answer?

Ethambutol inhibits arabinosyl transferase.

Why is "Inhibition of mycolic acid synthesis" not the answer?

Isoniazid inhibits mycolic acid synthesis.

What concept does this question test?

It tests Leprosy: rifampicin in Dermatology. leprae. A single dose kills over 99 percent of viable bacilli.

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 Leprosy: rifampicin?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.