Section 7.9
Mycology
SITUATION: After a vacation to the Southwestern United States, a midwesterner complained of flulike symptoms with fever, chills, nonproductive cough, and chest pain. Microscopic exam of sputum, cleared with KOH, revealed large, thick-walled spherules containing endospores. Upon culture, the mold phase showed septate hyphae and alternating barrel-shaped arthroconidia. Which organism is most likely the cause of this pneumonia?