An 82 year old man is hospitalized with pneumonia. He was treated with penicillin...

An 82 year old man is hospitalized with 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 pneumonia. No bacteria or viruses were cultured from a biopsy specimen. Broad-spectrum antibiotic therapy was administered. The patient developed pneumonia again after returning home from an 8-day hospital stay. A bronchoscopy showed septate hyphae in his lung tissue.Aspergillus was cultured from his humidifier.

1. What is your preliminary identification of the pathogen?
2. Why was the diagnosis delayed?
3. Why did his infection recur?