Isolation of Mycobacterium avium complex from water in the United States, Finland, Zaire, and Kenya

Abstract

Disseminated infection with organisms of the Mycobacterium avium complex (MAC) is a common complication of AIDS in the United States and other developing countries, but it is rare or absent in sub-Saharan Africa. To assess the comparative likelihood of exposure to MAC in these geographic areas, we used a standard protocol to culture 91 water samples from environmental sites and piped water supply systems in the United States, Finland, Zaire, and Kenya. MAC was isolated from all geographic areas and from 22 of 91 (24%) samples. Isolation rates were 13 of 47 (28%) for environmental samples and 9 of 44 (20%) for water supply samples. Overall isolation rates were 18 of 52 (35%) samples in the United States and Finland, whereas they were 4 of 39 (10%) samples in Zaire and Kenya (P = 0.015). MAC isolation rates from water supply systems were 8 of 25 (32%) samples in the United States and Finland and 1 of 19 (5%) samples in Zaire and Kenya (P = 0.056). MAC was isolated from hospital water in the United States and Finland but not in hospital water in Zaire and Kenya. Serovar determinations showed that six of eight isolates from the United States were serovar 4 or 8. One MAC isolate from Zaire was identified as an "X" mycobacterium. These data suggest that exposure to MAC in water is likely in diverse areas of the world, but that the likelihood of human exposure to the organism in water may be slightly less in sub-Saharan Africa than in developed countries in the Northern Hemisphere.

PIP: Between March 1990 and February 1992, microbiologists collected 91 water samples from various environmental sites (lakes, ponds, rivers, streams, harbors, marshes, and standing water) and from piped municipal and private water supply systems to determine the likelihood of human exposure to Mycobacterium avian complex (MAC) in New Hampshire and Boston in the US, Finland, Kenya, and Zaire. They wanted to examine the international distribution of MAC to determine whether the observation of AIDS patents in Africa not having MAC infection is association with differences in the environmental distribution of MAC. Overall isolation rates for environmental samples and for water supply samples stood at 28% and 20%, respectively. MAC isolation rates for all samples in the 2 developed countries were significantly higher than they were in the 2 Sub-Saharan African countries (35% vs. 10%; p = .015). The rates for water supply systems were higher in the US and Finland than they were in Kenya and Zaire (32% vs. 5%; p = .056). None of the water supply samples from hospitals in Kenya and Zaire tested positive for MAC, while about 20% in the US and 50% in Finland did. Serovars 4 and 8 of M. avian, which have been linked to infection in AIDS patients, accounted for 75% of the environmental M. avium isolates in the US. An X mycobacterium was found in an MAC isolate from Zaire. These findings indicate that the probability of human exposure to MAC in water is less than Sub-Saharan Africa than it is in developed countries in the northern hemisphere.