Members of the genus Mycobacterium.
- anonymous m. — see opportunist (atypical) mycobacteria (below).
- nontubercular m. — see opportunist (atypical) mycobacteria (below).
- opportunist (atypical) m. — saprophytic mycobacteria which may cause disease in animals. Included are M. chelonae, M. fortuitum, M. phlei, M. smegmatis. Called also anonymous and nontuberculous. See also runyon classification, opportunist mycobacterial granuloma.
- rapid growing m. — a distinguishing characteristic used for classifying mycobacteria, based on growth rate in cultures. Rapid growth is defined as less than 7 days. This group includes the saprophytic or opportunist mycobacteria, only some of which are associated with disease.
- slow growing m. — these mycobacteria take more than 7 days for the appearance of colonies. This group includes the tubercle bacilli, M. avium, M. bovis and M. tuberculosis, and many of the others pathogenic for animals and humans.
