Isolation of nontuberculous, non-avium mycobacteria from patients infected with human immunodeficiency virus

Mycobacterium avium serovars account for 97% of typeable M. avium complex (MAC) organisms causing infection in patients with AIDS. We reviewed 216 consecutive cultures that yielded nontuberculous mycobacteria (NTM) from 212 patients. Only the first isolate of each species of NTM recovered from each patient was analyzed in the study. Among the 92 patients infected with the human immunodeficiency virus, 96 NTM organisms were identified; M. avium was recovered from 50 (77%) of the 65 NTM-positive cultures of blood or bone marrow, while Mycobacterium intracellular and other non-avium NTM accounted for 18% and 5% of the isolates, respectively. Little difference in the susceptibility of isolates to antibiotics was noted between HIV-positive and HIV-negative patients or between M. avium and M. intracellulare. These data demonstrate that HIV-positive patients develop disseminated disease with NTM other than M. avium more frequently than has been previously reported and that these patients do not appear to be infected with NTM that are more resistant to antimicrobial agents than are NTM isolated from HIV-negative patients.