Nontuberculous mycobacterial trends at the Veterans Administration Medical Center in Oklahoma City.

Laboratory culture results, dating back to 1960, were reviewed at the Veterans Administration Medical Center in Oklahoma City. Nontuberculous mycobacterial incidence increased substantially during the 21-year period as tuberculosis incidence decreased. Nontuberculous mycobacteria were found to represent 13.7% of all mycobacterial isolates, with Mycobacterium kansasii and M intracellulare-avium complex the predominant species. When the dates of first positive cultures were evaluated, a significant month-to-month variation was found in M tuberculosis but not nontuberculous mycobacteria, suggesting a different mode of transmission for the two. There was no significant difference in the racial distribution or age of individuals with nontuberculous mycobacteria.