Numerical classification of 280 strains of slowly growing mycobacteria. Proposal of Mycobacterium tuberculosis series, Mycobacterium avium series, and Mycobacterium nonchromogenicum series.

Numerical classification of 280 strains of slowly growing mycobacteria was carried out by testing each strain for 76 characters. The following fourteen clusters were observed: 1. M. tuberculosis, M. bovis, M. africanum, and M. microti; 2. M. haemophilum; 3. M. ulcerans; 4. M. xenopi; 5. M. kansasii; 6. M. szulgai; 7. M. gordonae; 8. M gastri; 9. M. avium, M. intracellulare, M. scrofulaceum, and M. asiaticum; 10. M. marinum; 11. M. simiae; 12. M. nonchromogenicum, "M. novum," M. terrae, and M. triviale; 13 M. malmoense; 14. M. shimoidei. The clusters composed of M. tuberculosis, M. bovis, M. africanum, and M. microti, of M. avium, M. intracellulare, M. scrofulaceum, and M. asiaticum, and of M. nonchromogenicum, "M. novum," M. terrae, and M. triviale appeared to be reduced to a single species each. The names having priority for each species should be M. tuberculosis, M. avium, and M nonchromogenicum, respectively. However, the clusters may, in practice, be called the M. tuberculosis series (complex), the M. avium series (complex), and the M. nonchromogenicum series (complex). The type species of these series are M. tuberculosis, M. avium, and M. nonchromogenicum, respectively. These series were characterized in this study.