Bacteriology: enterococcal combination therapy: 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: enterococcal combination therapy

Sample item

A 68-year-old man with Enterococcus faecalis endocarditis is given ampicillin with low-dose gentamicin instead of either drug alone. What is the basis of this combination?

AAmpicillin boosts aminoglycoside entry, giving synergyBBoth drugs inhibit protein synthesis, so effects are additiveCGentamicin inhibits the beta-lactamase of Enterococcus faecalisDAmpicillin blocks aminoglycoside-modifying enzymes in the cell

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

The answer and the reasoning

A. Ampicillin boosts aminoglycoside entry, giving synergy

Enterococci are inherently tolerant to cell wall agents alone and have poor aminoglycoside uptake. Ampicillin damages the cell wall, allowing gentamicin to enter and act on the ribosome, so the combination is bactericidal.

Option by option

A. Ampicillin boosts aminoglycoside entry, giving synergy (correct)
Correct. Cell wall damage increases aminoglycoside uptake, converting static activity into bactericidal synergy.
B. Both drugs inhibit protein synthesis, so effects are additive
Ampicillin acts on the cell wall, not on protein synthesis.
C. Gentamicin inhibits the beta-lactamase of Enterococcus faecalis
Gentamicin is not a beta-lactamase inhibitor, and the mechanism is not enzymatic.
D. Ampicillin blocks aminoglycoside-modifying enzymes in the cell
Ampicillin does not inhibit aminoglycoside-modifying enzymes.

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 A, Ampicillin boosts aminoglycoside entry, giving synergy. Enterococci are inherently tolerant to cell wall agents alone and have poor aminoglycoside uptake.

Why is "Both drugs inhibit protein synthesis, so effects are additive" not the answer?

Ampicillin acts on the cell wall, not on protein synthesis.

Why is "Gentamicin inhibits the beta-lactamase of Enterococcus faecalis" not the answer?

Gentamicin is not a beta-lactamase inhibitor, and the mechanism is not enzymatic.

Why is "Ampicillin blocks aminoglycoside-modifying enzymes in the cell" not the answer?

Ampicillin does not inhibit aminoglycoside-modifying enzymes.

What concept does this question test?

It tests Bacteriology: enterococcal combination therapy in Microbiology. Ampicillin damages the cell wall, allowing gentamicin to enter and act on the ribosome, so the combination is bactericidal.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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: enterococcal combination therapy?

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.