Bacteriology: Treponema pallidum: 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 pallidum

Sample item

Which feature distinguishes a non-treponemal test such as RPR from a treponemal test in syphilis follow-up?

ARPR remains positive for life in nearly every patientBRPR titres usually fall with successful treatmentCRPR directly identifies spirochaetes by microscopyDRPR is specific for congenital syphilis only

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

The answer and the reasoning

B. RPR titres usually fall with successful treatment

Non-treponemal titres help monitor treatment response because they generally decline after adequate therapy. Treponemal tests are more specific but may remain positive long-term.

Option by option

A. RPR remains positive for life in nearly every patient
Persistent lifelong positivity is more typical of treponemal assays.
B. RPR titres usually fall with successful treatment (correct)
Correct. Serial non-treponemal titres are used to assess response.
C. RPR directly identifies spirochaetes by microscopy
Dark-field microscopy can visualise organisms in suitable lesions; RPR is a serologic test.
D. RPR is specific for congenital syphilis only
RPR is used across syphilis stages, not only congenital infection.

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.

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is B, RPR titres usually fall with successful treatment. Non-treponemal titres help monitor treatment response because they generally decline after adequate therapy.

Why is "RPR remains positive for life in nearly every patient" not the answer?

Persistent lifelong positivity is more typical of treponemal assays.

Why is "RPR directly identifies spirochaetes by microscopy" not the answer?

Dark-field microscopy can visualise organisms in suitable lesions; RPR is a serologic test.

Why is "RPR is specific for congenital syphilis only" not the answer?

RPR is used across syphilis stages, not only congenital infection.

What concept does this question test?

It tests Bacteriology: Treponema pallidum in Microbiology. Treponemal tests are more specific but may remain positive long-term.

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 pallidum?

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.