Atypical mycobacteria in the Niagara Peninsula.

From 1960 to 1965, 44,629 cultures were performed on persons attending chest clinics in the Niagara Peninsula.Tubercle bacilli were cultured from 965 biological specimens (2.16%) and atypical mycobacteria from 281 specimens (0.62%).Twelve subjects had more than one variety of atypical mycobacterium in their secretions, suggesting the occurrence of mutation. The administration of antituberculous drugs may have contributed to the emergence of atypical mycobacteria in some instances, but 41 patients had never received antituberculous drugs.Of 113 persons from whom atypical mycobacteria were cultured only two had lung infection primarily due to the atypical mycobacterium isolated.