Mycology/Parasitology USMLE Step 1 Practice Question
A 45-year-old construction worker from Arizona presents with 2-week fever (38.5°C), productive cough, and erythema nodosum. Vitals show HR 102 bpm, RR 22, SpO2 98% on room air. Chest X-ray reveals bilateral hilar infiltrates with nodules. Coccidioidal serology is positive; sputum cultures remain negative. He denies hemoptysis. Taking no immunosuppressive medications. Which of the following best describes the pathogenesis of coccidioidomycosis?
Answer choices
- ADemonstrates thermal dimorphism with yeast in soil at 25°C
- BForms pseudohyphae and budding cells exclusively in lung tissue
- CDimorphic fungus with mycelial form in soil; spherules with endospores in lungsCorrect answer
- DYeast form at body temperature; hyphae at environmental temperature
- EProduces aflatoxins causing pulmonary hemorrhage and inflammation
- FMonomorphic organism with spore formation in both environmental and host tissues
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