Antimicrobials: neurosyphilis treatment: practice question

A Pharmacology 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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Pharmacology · Antimicrobials: neurosyphilis treatment

Sample item

A 40-year-old man has Argyll Robertson pupils, a positive CSF VDRL and a lymphocytic pleocytosis. Which treatment is recommended?

AIV aqueous benzylpenicillin for 10 to 14 daysBOral doxycycline for 28 days at standard doseCA single intramuscular dose of benzathine penicillinDOral azithromycin as a single large dose

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

The answer and the reasoning

A. IV aqueous benzylpenicillin for 10 to 14 days

Benzathine penicillin gives low and prolonged levels that do not reliably reach the cerebrospinal fluid, so neurosyphilis is treated with high-dose intravenous aqueous penicillin G for 10 to 14 days.

Option by option

A. IV aqueous benzylpenicillin for 10 to 14 days (correct)
Correct. High-dose intravenous penicillin achieves treponemicidal CSF levels.
B. Oral doxycycline for 28 days at standard dose
Doxycycline is an alternative for penicillin-allergic early syphilis, not preferred for neurosyphilis.
C. A single intramuscular dose of benzathine penicillin
Benzathine penicillin does not reach adequate CSF concentrations.
D. Oral azithromycin as a single large dose
Azithromycin is unreliable because of macrolide resistance in Treponema pallidum.

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 Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, IV aqueous benzylpenicillin for 10 to 14 days. Benzathine penicillin gives low and prolonged levels that do not reliably reach the cerebrospinal fluid, so neurosyphilis is treated with high-dose intravenous aqueous penicillin G for 10 to 14 days.

Why is "Oral doxycycline for 28 days at standard dose" not the answer?

Doxycycline is an alternative for penicillin-allergic early syphilis, not preferred for neurosyphilis.

Why is "A single intramuscular dose of benzathine penicillin" not the answer?

Benzathine penicillin does not reach adequate CSF concentrations.

Why is "Oral azithromycin as a single large dose" not the answer?

Azithromycin is unreliable because of macrolide resistance in Treponema pallidum.

What concept does this question test?

It tests Antimicrobials: neurosyphilis treatment in Pharmacology. The correct option holds because: Correct. High-dose intravenous penicillin achieves treponemicidal CSF levels.

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 Antimicrobials: neurosyphilis treatment?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology 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.