Infectious diseases: Coxiella endocarditis: practice question

A General Medicine 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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General Medicine · Infectious diseases: Coxiella endocarditis

Sample item

A 45-year-old abattoir worker with a known bicuspid aortic valve has 2 months of fever and weight loss. Three sets of blood cultures are negative, and echocardiography shows a vegetation. Which test most directly identifies the cause?

AWeil-Felix test for OX-KBPaul-Bunnell heterophile testCWidal agglutinationDSerology for phase I IgG to Coxiella burnetii

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

The answer and the reasoning

D. Serology for phase I IgG to Coxiella burnetii

Culture-negative endocarditis in an animal-exposed worker with valve disease suggests Q fever. High titres of phase I IgG identify chronic Q fever, and treatment is prolonged doxycycline with hydroxychloroquine.

Option by option

A. Weil-Felix test for OX-K
Weil-Felix OX-K is the reaction used for scrub typhus.
B. Paul-Bunnell heterophile test
The Paul-Bunnell test detects heterophile antibodies of infectious mononucleosis.
C. Widal agglutination
The Widal test detects typhoid antibodies and is not relevant here.
D. Serology for phase I IgG to Coxiella burnetii (correct)
Correct. High phase I IgG titres identify chronic Q fever endocarditis.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is D, Serology for phase I IgG to Coxiella burnetii. Culture-negative endocarditis in an animal-exposed worker with valve disease suggests Q fever.

Why is "Weil-Felix test for OX-K" not the answer?

Weil-Felix OX-K is the reaction used for scrub typhus.

Why is "Paul-Bunnell heterophile test" not the answer?

The Paul-Bunnell test detects heterophile antibodies of infectious mononucleosis.

Why is "Widal agglutination" not the answer?

The Widal test detects typhoid antibodies and is not relevant here.

What concept does this question test?

It tests Infectious diseases: Coxiella endocarditis in General Medicine. High titres of phase I IgG identify chronic Q fever, and treatment is prolonged doxycycline with hydroxychloroquine.

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 Infectious diseases: Coxiella endocarditis?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.