Bacteriology: necrotising fasciitis: 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: necrotising fasciitis

Sample item

A diabetic man has a rapidly spreading painful leg infection with bullae and severe systemic toxicity. Gram stain shows Gram-positive cocci in chains, and surgical debridement has been done. Why is clindamycin added to penicillin?

AIt increases penicillin binding protein levelsBIt is bactericidal against the cell wallCIt suppresses synthesis of bacterial toxinsDIt neutralises circulating superantigen

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

The answer and the reasoning

C. It suppresses synthesis of bacterial toxins

In severe group A streptococcal infection, large bacterial numbers make penicillin less effective, and clindamycin acts at the ribosome to stop production of toxins and M protein even in stationary-phase organisms. It does not act on the cell wall and cannot neutralise toxin already made.

Option by option

A. It increases penicillin binding protein levels
It does not raise penicillin binding protein levels.
B. It is bactericidal against the cell wall
Clindamycin acts at the ribosome, not the cell wall.
C. It suppresses synthesis of bacterial toxins (correct)
Correct. Clindamycin inhibits protein synthesis including toxin production.
D. It neutralises circulating superantigen
It cannot neutralise toxins already formed; immunoglobulin may do that.

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 C, It suppresses synthesis of bacterial toxins. In severe group A streptococcal infection, large bacterial numbers make penicillin less effective, and clindamycin acts at the ribosome to stop production of toxins and M protein even in stationary-phase organisms.

Why is "It increases penicillin binding protein levels" not the answer?

It does not raise penicillin binding protein levels.

Why is "It is bactericidal against the cell wall" not the answer?

Clindamycin acts at the ribosome, not the cell wall.

Why is "It neutralises circulating superantigen" not the answer?

It cannot neutralise toxins already formed; immunoglobulin may do that.

What concept does this question test?

It tests Bacteriology: necrotising fasciitis in Microbiology. It does not act on the cell wall and cannot neutralise toxin already made.

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: necrotising fasciitis?

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.