Rapid identification of Mycobacterium species

Identification of Mycobacterium species is currently a long and fastidious procedure. We have developed a rapid (5-h) standard method using the API-ZYM system and rapid nitratase, urease and catalase tests. Pigmentation and growth rate were noted (but were only necessary for complete identification of 6% of strains). The tests were assigned numerical values from which a profile number was derived. A total of 716 strains were studied: 434 belonging to the M. tuberculosis complex and 282 other mycobacteria including 21 from M. avium complex. All M. tuberculosis complex strains were differentiated from all other mycobacteria and M. bovis was clearly separated from M. tuberculosis. All M. avium complex strains were differentiated from other mycobacteria. Among mycobacteria other than tubercle bacilli, 97% of the strains studied were identified. The method has proven to be simple, rapid and standardizable. It is suggested that the use of a code list could permit identification of most mycobacteria.