Bacteriology: Treponema pertenue: 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: Treponema pertenue

Sample item

A child from a tribal hamlet has a painless raspberry-like papilloma on the leg that is later followed by bone pain and painful soles. VDRL and TPHA are reactive. Which organism and mode of spread fit best?

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

The answer and the reasoning

B. Treponema pallidum subspecies pertenue, by skin contact

Yaws is caused by Treponema pallidum subspecies pertenue and spreads by skin-to-skin contact among children in warm, humid rural areas. It causes papillomatous skin lesions and later bone involvement, and responds to single-dose azithromycin or benzathine penicillin.

Option by option

  • A. Treponema carateum, by skin contact

    T. carateum causes pinta, which is a pigmentary skin disease in the Americas without bone disease.

  • B. Treponema pallidum subspecies pertenue, by skin contact (correct)

    Correct. Yaws is caused by T. pallidum pertenue and spread by skin contact.

  • C. Borrelia recurrentis, by body louse

    Borrelia recurrentis causes louse-borne relapsing fever and does not give a papilloma.

  • D. Treponema pallidum subspecies pallidum, by sexual contact

    T. pallidum pallidum causes venereal syphilis, spread sexually or congenitally.

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 B, Treponema pallidum subspecies pertenue, by skin contact. Yaws is caused by Treponema pallidum subspecies pertenue and spreads by skin-to-skin contact among children in warm, humid rural areas.

Why is "Treponema carateum, by skin contact" not the answer?

T. carateum causes pinta, which is a pigmentary skin disease in the Americas without bone disease.

Why is "Borrelia recurrentis, by body louse" not the answer?

Borrelia recurrentis causes louse-borne relapsing fever and does not give a papilloma.

Why is "Treponema pallidum subspecies pallidum, by sexual contact" not the answer?

T. pallidum pallidum causes venereal syphilis, spread sexually or congenitally.

What concept does this question test?

It tests Bacteriology: Treponema pertenue in Microbiology. It causes papillomatous skin lesions and later bone involvement, and responds to single-dose azithromycin or benzathine penicillin.

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: Treponema pertenue?

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.