Bacteriology: Lyme disease: 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: Lyme disease

Sample item

A hiker in New England develops an expanding annular erythematous rash with central clearing on the thigh 7 days after a tick bite, with mild fever and fatigue. What is the most appropriate management?

ACiprofloxacin for 3 daysBMetronidazole for 7 daysCOral doxycycline for about 10 to 14 days, without waiting for serologyDGentamicin intravenously for 5 days

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

The answer and the reasoning

C. Oral doxycycline for about 10 to 14 days, without waiting for serology

The rash is erythema migrans, which is pathognomonic of early Lyme disease caused by Borrelia burgdorferi, transmitted by Ixodes ticks. The diagnosis is clinical, because serology is often negative early. Doxycycline is first-line, and amoxicillin or cefuroxime are alternatives.

Option by option

A. Ciprofloxacin for 3 days
Fluoroquinolones are not recommended for Lyme disease.
B. Metronidazole for 7 days
Metronidazole has no activity against Borrelia.
C. Oral doxycycline for about 10 to 14 days, without waiting for serology (correct)
Correct. Erythema migrans is diagnosed clinically and treated with oral doxycycline.
D. Gentamicin intravenously for 5 days
Aminoglycosides are not used for Lyme disease and are inactive against Borrelia.

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, Oral doxycycline for about 10 to 14 days, without waiting for serology. The rash is erythema migrans, which is pathognomonic of early Lyme disease caused by Borrelia burgdorferi, transmitted by Ixodes ticks.

Why is "Ciprofloxacin for 3 days" not the answer?

Fluoroquinolones are not recommended for Lyme disease.

Why is "Metronidazole for 7 days" not the answer?

Metronidazole has no activity against Borrelia.

Why is "Gentamicin intravenously for 5 days" not the answer?

Aminoglycosides are not used for Lyme disease and are inactive against Borrelia.

What concept does this question test?

It tests Bacteriology: Lyme disease in Microbiology. The diagnosis is clinical, because serology is often negative early. Doxycycline is first-line, and amoxicillin or cefuroxime are alternatives.

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 Bacteriology: Lyme disease?

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.