Objective: To study the incidence of nontuberculous mycobacteria and the range of species isolated between 1996 and 2005 at a regional branch of the Adolfo Lutz Institute-located in the city of São José do Rio Preto, Brazil-and to show the importance of laboratory testing. Methods: Mycobacteria were isolated from pulmonary and extrapulmonary specimens and identified through phenotyping and molecular methods (polymerase chain reaction-restriction enzyme analysis). Results: We isolated 317 nontuberculous mycobacterium strains: ­Mycobacterium avium complex, 182 (57.4%); M. gordonae, 33 (10.4%); M. fortuitum, 25 (7.9%); M. chelonae, 8 (2.5%); M. terrae complex, 8 (2.5%); M. kansasii, 7 (2.2%); and less frequent species, 54 (17%). During this period, 72 cases (33.3%) were characterized as mycobacteriosis, according to bacteriological criteria established by the American Thoracic Society in 2007. Of those 72 cases, 56 were attributed to M. avium complex. Of those 56, 29 (51.8%) were characterized as disseminated disease. Six cases were attributed to M. fortuitum, 3 to M. gordonae, 2 to M. chelonae, 1 to M. abscessus, 1 to M. kansasii, 1 to M. intracellulare, 1 to M. malmoense and 1 to ­Mycobacterium ssp. Conclusions: These results show the importance of the bacteriological diagnosis, since identification of the species enables early and appropriate treatment.

Keywords: Mycobacteria, atypical/isolation & purification; Mycobacteria, atypical/classification; Diagnostic techniques and procedures.