Identification of nontuberculous mycobacteria isolated from clinical materials and some comments on it

: Six mycobacterial strains which were isolated and identified with some suspicions in five hospitals in Japan were retested for their biological and biochemical characteristics for correct identification at the Department of Microbiology and Immunology, Shimane Medical University. One strain originally classified as Group IV Mycobacterium, and two unidentified strains were presently identified as Mycobacterium nonchromogenicum complex. Two strains originally identified as M. xenopi were identified by us as M. szulgai and M. avium complex, respectively. Finally, one strain originally identified as M. phlei was identified by us as M. fortuitum. In these cases, inexactly controlled examinations for growth rate, growth at 45 degrees C, Tween 80 hydrolysis, and pigment production or lack of tests for certain key characters of a given organism seemed to be main causes of initial incorrect identification.