Identification of Mycobacterium avium complex isolated in eastern and central Japan by using DNA probes

An attempt was made to identify Mycobacterium avium and Mycobacterium intracellulare in the M. avium intracellulare complex (MAC) isolated in the Tohoku (38 strains) and Tokai (30 strains) districts of Japan by using DNA probes which are specific for M. avium, M. intracellulare and M. tuberculosis complex, respectively. The incidence of M. avium infection (82%) by far exceeded that of M. intracellulare infection in the Tohoku district of eastern Japan. In the Tokai district of central Japan, the incidence of M. avium infection (57%) were slightly larger than that of M. intracellulare infection. Five of 68 strains showed a positive reaction with two different DNA probes. Thus a possibility of mixed infection could not be ruled out, because reference strains showed a positive reaction with only one species-specific DNA probe.