Antibacterials: daptomycin limitation: 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 · Antibacterials: daptomycin limitation

Sample item

A patient on a ventilator has MRSA-positive ventilator-associated pneumonia. The team considers using daptomycin because the organism is susceptible in vitro. Why is it unsuitable in this infection?

AIt is inactivated by pulmonary surfactant, so it is ineffective for pneumoniaBIt lacks bactericidal action against Gram-positive cocciCIt is not absorbed after intravenous infusionDIt is not active against MRSA

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

The answer and the reasoning

A. It is inactivated by pulmonary surfactant, so it is ineffective for pneumonia

Daptomycin is a lipopeptide that depolarises Gram-positive bacterial membranes in a calcium-dependent manner and is rapidly bactericidal, useful for MRSA bacteraemia and skin infection. Pulmonary surfactant binds and inactivates it, so it must not be used for pneumonia. Linezolid or vancomycin are used for MRSA pneumonia, and creatine kinase should be monitored with daptomycin.

Option by option

A. It is inactivated by pulmonary surfactant, so it is ineffective for pneumonia (correct)
Correct. Surfactant binding makes daptomycin ineffective in the lung.
B. It lacks bactericidal action against Gram-positive cocci
Daptomycin is rapidly bactericidal against Gram-positive cocci.
C. It is not absorbed after intravenous infusion
It is given intravenously, so absorption is not an issue.
D. It is not active against MRSA
Daptomycin is active against MRSA, which is why it was considered.

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 Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, It is inactivated by pulmonary surfactant, so it is ineffective for pneumonia. Daptomycin is a lipopeptide that depolarises Gram-positive bacterial membranes in a calcium-dependent manner and is rapidly bactericidal, useful for MRSA bacteraemia and skin infection.

Why is "It lacks bactericidal action against Gram-positive cocci" not the answer?

Daptomycin is rapidly bactericidal against Gram-positive cocci.

Why is "It is not absorbed after intravenous infusion" not the answer?

It is given intravenously, so absorption is not an issue.

Why is "It is not active against MRSA" not the answer?

Daptomycin is active against MRSA, which is why it was considered.

What concept does this question test?

It tests Antibacterials: daptomycin limitation in Pharmacology. Pulmonary surfactant binds and inactivates it, so it must not be used for pneumonia. Linezolid or vancomycin are used for MRSA pneumonia, and creatine kinase should be monitored with daptomycin.

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 Antibacterials: daptomycin limitation?

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.