Bacterial Infections USMLE Step 1 Practice Question
A 56-year-old man from Missouri presents in July with fever (39.2°C), malaise, and frontal headache 6 days after removing a tick from his leg. Vital signs show BP 128/82 mmHg, HR 94/min, RR 18/min, SpO2 98% on room air. Laboratory studies reveal leukopenia (WBC 3.2K/μL), thrombocytopenia (platelets 98K/μL), elevated transaminases (AST 156 U/L), and basophilic inclusions within monocytes on blood smear. He denies rash. Which organism is most likely responsible?
Answer choices
- AAnaplasma phagocytophilum
- BEhrlichia chaffeensisCorrect answer
- CRickettsia rickettsii
- DCoxiella burnetii
- EBorrelia burgdorferi
- FBabesia microti
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.