Numerical classification of Mycobacterium farcinogenes, Mycobacterium senegalense and related taxa.

Sixteen strains designated Mycobacterium farcinogenes, fifteen Mycobacterium senegalense, and ten Nocardia farcinica were, together with strains of Mycobacterium and Nocardia, subjected to numerical phenetic analyses using 96 unit characters. The data were examined using the simple matching (SSM), Jaccard (SJ) and pattern (DP) coefficients and clustering achieved using the unweighted average linkage algorithm. Cluster composition was not markedly affected by the coefficient used or by test error, estimated at 2.5%. The N. farcinica strains formed a distinct and homogeneous cluster in an aggregate taxon corresponding to the genus Nocardia. The M. farcinogenes and M. senegalense strains were recovered in well-defined and homogeneous phena within the genus Mycobacterium. Mycobacterium senegalense consistently showed a high overall similarity with clusters equated with M. chelonei and M. fortuitum, while the M. farcinogenes cluster was not closely associated with any of the mycobacterial clusters. The results are discussed in the light of other developments in the taxonomy of the bovine farcy bacteria.