Virology USMLE Step 1 Practice Question
A 39-year-old man with advanced HIV infection (CD4+ count 45 cells/μL) presents with 2 weeks of progressive dyspnea and nonproductive cough. Vital signs show BP 118/76 mmHg, HR 102/min, RR 28/min, temperature 37.8°C, and SpO2 89% on room air. Chest radiograph reveals diffuse bilateral interstitial infiltrates. Bronchoalveolar lavage fluid demonstrates cup-shaped cysts on silver stain. He denies fever or night sweats. Which organism is most likely responsible?
Answer choices
- ACryptococcus neoformans
- BPneumocystis jiroveciiCorrect answer
- CAspergillus fumigatus
- DCandida albicans
- EHistoplasma capsulatum
- FMucor species (mucormycosis)
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