Isolation of potentially pathogenic mycobacteria in the Finnish environment.

Atypical mycobacteria have become more common in clinical samples, and their reservoirs, known to be in the environment, are poorly identified. In the Finnish natural environment, mycobacteria can be cultivated from surface waters in a mean of 1500 CFU/l and from soil samples in a mean of 3.6 x 10(5) CFU/g dry weight. The majority of isolates are not pathogenic to man. Less than 10% of cultivable mycobacteria belong in species which are also found in human samples, either as infectious agents or as harmless colonizers of human epithelia. The two most important potentially pathogenic atypical mycobacteria in Finland, the Mycobacterium avium-intracellulare-scrofulaceum (MAIS) complex and M. malmoense, were detected in 40% and 4%, respectively, of the examined waters.