Mycobacterium avium-intracellulare complex pneumonia in a non-HIV-infected individual: an increasingly recognized disease.

In the past, Mycobacterium avium complex (MAC) was considered a colonizing microbe in the immunocompetent host. Today it should be considered a potential pathogen. We present a case of MAC necrotizing pneumonia in a 27-year-old man who tested negatively for the human immunodeficiency virus, had no typical granulomas, and responded rapidly to antimicrobial therapy.