Bacterial Infections USMLE Step 1 Practice Question
A 34 year old woman presents with several weeks of fatigue, migratory joint pain, and intermittent palpitations. Two months ago she removed a tick after hiking in Connecticut and noted an expanding circular rash on her thigh. Electrocardiogram now shows second degree atrioventricular block. Which of the following organisms is the most likely cause of this illness?
Answer choices
- ABabesia microti
- BTreponema pallidum
- CAnaplasma phagocytophilum
- DRickettsia rickettsii
- EBorrelia burgdorferiCorrect answer
- FEhrlichia chaffeensis
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.