Bone and joint infections: rifampicin in implant infection: practice question

A Orthopaedics 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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Orthopaedics · Bone and joint infections: rifampicin in implant infection

Sample item

A 70-year-old has an acute haematogenous infection of a stable total knee replacement with methicillin-sensitive Staphylococcus aureus. Debridement with implant retention is planned. Which antibiotic is added to the beta-lactam because it acts on bacteria within biofilm?

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

The answer and the reasoning

B. Rifampicin

Rifampicin penetrates biofilm and is active against slow-growing staphylococci on implants, so it improves cure when implants are retained. It must always be combined with a second active drug because resistance develops rapidly when it is used alone.

Option by option

  • A. Colistin

    Colistin targets Gram-negative bacteria and has no role against Staphylococcus aureus.

  • B. Rifampicin (correct)

    Correct. It is active against sessile staphylococci in biofilm and is given with a second active drug.

  • C. Vancomycin

    Vancomycin penetrates biofilm poorly and is inferior to a beta-lactam for sensitive staphylococci.

  • D. Gentamicin

    Gentamicin has limited activity in biofilm and risks nephrotoxicity.

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.

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Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is B, Rifampicin. Rifampicin penetrates biofilm and is active against slow-growing staphylococci on implants, so it improves cure when implants are retained.

Why is "Colistin" not the answer?

Colistin targets Gram-negative bacteria and has no role against Staphylococcus aureus.

Why is "Vancomycin" not the answer?

Vancomycin penetrates biofilm poorly and is inferior to a beta-lactam for sensitive staphylococci.

Why is "Gentamicin" not the answer?

Gentamicin has limited activity in biofilm and risks nephrotoxicity.

What concept does this question test?

It tests Bone and joint infections: rifampicin in implant infection in Orthopaedics. It must always be combined with a second active drug because resistance develops rapidly when it is used alone.

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 Bone and joint infections: rifampicin in implant infection?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.