Antimicrobials: ampicillin for Listeria: 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: ampicillin for Listeria

Sample item

A 70-year-old man has meningitis, and CSF Gram stain shows Gram-positive rods. Empirical ceftriaxone and vancomycin are running. Which drug should be added to cover Listeria monocytogenes?

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

The answer and the reasoning

A. Ampicillin

Listeria is intrinsically resistant to cephalosporins, so empirical meningitis therapy in the elderly, neonates and immunocompromised adds ampicillin. Co-trimoxazole is the alternative in penicillin allergy.

Option by option

  • A. Ampicillin (correct)

    Correct. Ampicillin is active against Listeria, which cephalosporins do not cover.

  • B. Azithromycin

    Azithromycin has poor penetration into the cerebrospinal fluid.

  • C. Ciprofloxacin

    Ciprofloxacin is not a standard drug for Listeria meningitis.

  • D. Cefotaxime

    Cefotaxime is a cephalosporin and Listeria is intrinsically resistant to this class.

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 Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, Ampicillin. Listeria is intrinsically resistant to cephalosporins, so empirical meningitis therapy in the elderly, neonates and immunocompromised adds ampicillin.

Why is "Azithromycin" not the answer?

Azithromycin has poor penetration into the cerebrospinal fluid.

Why is "Ciprofloxacin" not the answer?

Ciprofloxacin is not a standard drug for Listeria meningitis.

Why is "Cefotaxime" not the answer?

Cefotaxime is a cephalosporin and Listeria is intrinsically resistant to this class.

What concept does this question test?

It tests Antimicrobials: ampicillin for Listeria in Pharmacology. Co-trimoxazole is the alternative in penicillin allergy.

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: ampicillin for Listeria?

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.