Improved technique for isolation of Mycobacterium kansasii from water.

A new concentration procedure, together with a new isolation medium, resulted in a 10- to 100-fold increase in the possibility of identifying Mycobacterium kansasii from water samples in comparison to a previously used procedure. In a survey which included both potable and natural water samples from many sites within the state of Texas, nine isolations of high-catalase strains of M. kansasii were obtained from 232 water samples tested. Acid-fast smear results were compared with mycobacterial isolations. An isolate from a river in central Texas is the first high-catalase strain of M. kansasii encountered in a natural water supply. Surveys of water samples from two Texas towns indicate that chlorine levels may influence the number of recoverable mycobacteria in water supplies.