An 82 year old man was hospitalized for pneumonia. He was treated with penicillin and discharged after
7 days when his symptoms subsided. Two weeks later, the man was readmitted to the hospital for prem
nin. No bacteria or viruses were cultured from a biopsy specimen. Broad-spectrum antibiotic therapy w
administered. The patient developed pneumonia again after returning home from an 8-day hospital stay
A bronchoscopy showed septate hyphae in his lung tissue. An investigation of his home showed that he did
not keep pets, but some sparrows had nested outside the living room window, he was not a gardener or out
doorsman. Aspergillus was cultured from his humidifier,

a. What is your preliminary identification of the pathogen?
b. Why was the diagnosis delayed?
c. Why did the man's infection recur?