[Geographical distribution of Mycobacterium avium complex in environment and serovars of Mycobacterium avium complex isolates from patients with and without AIDS]

Abstract

Mycobacterium avium complex (MAC) organisms have been isolated from water and soil. It is now generally accepted that environmental sources, especially natural waters, are the reservoirs for most human infections caused by MAC. Previously, we reported that M. avium and M. intracellular were distributed predominantly in the eastern and western part of Japan, respectively. To clarify the factor(s) of the difference, the following experiment was undertaken. MAC was isolated from soil samples collected in Tokai, Kinki and Chugoku districts, by the method of Ichiyama et al. MAC isolates were identified by AccuProbe Confirmation and Identification tests, together with some conventional tests. Seven (11.7%) of 60 isolates were identified as M. avium, twenty (33%) as M. intracellulaer and 33 (55%) as MAC-like organisms. Therefore, it was not found that the difference in the geographical distribution between soil MAC and disease-associated MAC. MAC-like strains possess MAC-specific alpha antigen, and biological and biochemical features of MAC. They reacted with the AccuProbe MAC but not with the AccuProbe M. avium and M. intracellulare. Sequencing analysis of 16s RNA gene implies that MAC-like strains show an intermediate sequence pattern of M. avium and M. intracellulare. HPLC patterns of these strains were compatible with those of MAC. It is known that the major serovars of MAC isolates from patients with or without AIDS are different. Serological aspects in this respect are not yet elucidated well in Japan. The major serovars of MAC from patients with AIDS are 4 and 8 in the USA and Australia, 6 and 4 in Sweden, and 8/21 and 8 in Germany. On the other hand, the major serovars of MAC from patients without AIDS are 8 and 16 (15) in the USA and 6 and 1 in Sweden. According to out recent study the major serovars of MAC from non-AIDS patients are 1 and 8 in the eastern part and 16 and 14 in the western part of Japan. In the present study, 38 MAC isolates from sputum, stool and blood and AIDS patients were identified. All of the isolates were identified as M. avium. Serovars of 15 strains were 4 (4 strains), 8 (3 strains), 9 (3 strains), 3 (2 strains), Darkin (2 strains) and 1 (1 strain). Therefore, it seems that the major serovars of the Japanese MAC strains from AIDS patients are similar to those of the American MAC strains from such patients.