To know the frequency of environmental mycobacterium isolations in Chile in the year 2008. Methods: 600 AFB (acid fast bacilli) positive cultures from 22 laboratories of Tuberculosis Bacteriology of the different Network Health Services that constitute the Tuberculosis Control Program of the country were studied, during four months at 2008. 545 (90.8%) were pulmonary and 55 (9.2%) extra pulmonary. Acid fast bacilli smears were confi rmed by Ziehl Neelsen and identifi cation of mycobacteria species or complex were identifi ed by traditional tests according to Runyon classifi cation and biochemical tests, genetic probes and pattern analysis restriction (PRA). Results: 585 cultures were appropriated for inclusion in the study. In 91.3% (n = 534) of the cases Mycobacterium tuberculosis was isolated while 0.3% was Mycobacterium bovis subspecie BCG (n = 3) and 8.4% (n = 48) corresponded to environmental mycobacterium. Of the latter, Mycobacterium kansasii (2.6%), Mycobacterium avium-intracellulare (1.5%) and Mycobacterium chelonae (1.0%) were the most commonly isolated. Conclusion: According to the fi gures of this study and comparing them with studies of previous years (1988 and 1998) it is concluded that the number of environmental mycobacterium isolated has been relatively constant during the last decade, as well as the species, more commonly isolated.

Restriction pattern analysis is a rapid identification method for non tuberculous mycobacterial strains.