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Abstract
Numerical analyses of 165 strains of rapidly growing, nonphotochromogenic mycobacteria were carried out with 104 characters in one case and 84 in another. The results showed that the following taxa are distinct: Mycobacterium fortuitum; M. chelonei subsp. chelonei; M. chelonei subsp. abscessus; M. smegmatis; M. chitae; and “M. agri” (names in quotation marks are not on the Approved Lists of Bacterial Names, 1980). The distinctness of “M. agri” was confirmed by using 29 test strains. Strains of M. smegmatis were divided into two subgroups, “M. smegmatis subsp. smegmatis” and “M. smegmatis subsp. lacticola” on the basis of amidase patterns. Clusters of M. fortuitum, M. chelonei subsp. chelonei, and M. chelonei subsp. abscessus were distinguished at a level of 89% similarity by a numerical taxonomy method in which 84 characters were used, and these three clusters were connected to each other to form a large cluster at a level of 88%. Therefore, these three taxa were regarded as belonging to a complex. Within the cluster M. fortuitum, four subclusters were observed, but about one-half of the M. fortuitum strains studied did not belong to any of the four subclusters. The 78 strains of M. fortuitum studied were regarded as homogeneous, even though several biovars could be differentiated. Neither subcluster nor biovar of the M. fortuitum strains was shown to be significantly associated with disease in humans. Because Mycobacterium agri was not included on the Approved Lists of Bacterial Names, it is herein proposed as a revived name. The type strain of M. agri is 90012 (= ATCC 27406).
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