mycobacteria

Organisms belonging to the genus Mycobacterium.

- atypical m. species of m. other than M. tuberculosis or M. bovis that can cause disease in immunocompromised humans; being replaced by the designation of MOTT (M. Other Than Tuberculosis).

- Runyon group I m. m. that produce a bright yellow color when grown in the presence of light. Organisms placed in this group include Mycobacterium kansasii. SYN: photochromogens.

- Runyon group II m. m. that produce a yellow pigment even when grown in the dark; when grown in the light, the pigment is orange. These organisms behave as saprophytes do in humans and are usually nonpathogenic to laboratory animals. SYN: scotochromogens.

- Runyon group III m. m. that are either colorless or that slowly produce a light yellow pigment when grown in the presence of light. Organisms placed in this group include Mycobacterium avium and M. intracellulare. SYN: nonchromogens.

- Runyon group IV m. m. that grow rapidly and that do not produce pigment. Organisms placed in this group belong to such species as Mycobacterium ulcerans and M. marinum.

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my·co·bac·te·ria (mi″ko-bak-tēr-eə) plural of mycobacterium.