Fungal and Parasitic Infections USMLE Step 1 Practice Question
A 31-year-old man with advanced HIV presents with profuse watery diarrhea for 3 weeks and 12-pound weight loss. Vital signs: BP 104/68, HR 102, RR 18, Temp 37.2°C, SpO2 98% on room air. CD4 count is 78 cells/μL. Stool examination reveals acid-fast oocysts; bacterial cultures remain negative. Abdominal examination shows mild distension without rebound tenderness. Which organism most likely causes this patient's symptoms?
Answer choices
- AMicrosporidia
- BCyclospora cayetanensis
- CGiardia lamblia
- DEntamoeba histolytica
- ECryptosporidium parvumCorrect answer
- FIsospora belli
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