Infection control: surgical antibiotic prophylaxis: 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 · Infection control: surgical antibiotic prophylaxis

Sample item

A surgeon plans an elective inguinal hernia repair with a mesh in a patient with no allergies. What is the correct timing of cefazolin prophylaxis?

AA single dose within 60 minutes before skin incisionBA dose given the evening before surgeryCA dose started after the wound is closed and continued for 5 daysDA dose given 6 hours before surgery

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

The answer and the reasoning

A. A single dose within 60 minutes before skin incision

Prophylaxis should achieve adequate tissue levels when the incision is made, so a single dose is given within 60 minutes before incision, and within 120 minutes for vancomycin or fluoroquinolones. It is repeated for long operations or major blood loss and is generally stopped within 24 hours. Prolonged courses do not lower infection but promote resistance.

Option by option

A. A single dose within 60 minutes before skin incision (correct)
A dose within 60 minutes before incision gives peak tissue levels during surgery.
B. A dose given the evening before surgery
A dose the evening before is mostly cleared by the time of incision and gives no benefit.
C. A dose started after the wound is closed and continued for 5 days
Starting after closure misses the period of contamination and prolonged use promotes resistance.
D. A dose given 6 hours before surgery
A dose six hours earlier would be below effective tissue level for the operation.

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, A single dose within 60 minutes before skin incision. Prophylaxis should achieve adequate tissue levels when the incision is made, so a single dose is given within 60 minutes before incision, and within 120 minutes for vancomycin or fluoroquinolones.

Why is "A dose given the evening before surgery" not the answer?

A dose the evening before is mostly cleared by the time of incision and gives no benefit.

Why is "A dose started after the wound is closed and continued for 5 days" not the answer?

Starting after closure misses the period of contamination and prolonged use promotes resistance.

Why is "A dose given 6 hours before surgery" not the answer?

A dose six hours earlier would be below effective tissue level for the operation.

What concept does this question test?

It tests Infection control: surgical antibiotic prophylaxis in Microbiology. It is repeated for long operations or major blood loss and is generally stopped within 24 hours. Prolonged courses do not lower infection but promote resistance.

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 Infection control: surgical antibiotic prophylaxis?

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.