A. Spores formed, but not in sporangia. 1. Spores formed by fragmentation of the mycelium. Family II. Actinomycetaceae, p. 713. 2. Vegetative mj'celium normally remains undivided. Family III. Streptomycetaceae , p. 744. B. Spores formed in sporangia. Family IV. Actinoplanaceae, p. 825. FAMILY I. MYCOBACTERIACEAE CHESTER, 1901. (Chester, Man. Determ. Bact., 1901, 349; Proactinomycetaceae Lehmann and Haag, in Lehmann and Neumann, Bakt. Diag., 7 Aufl., 2, 1927, 674.) My.co.bac.te.ri.a'ce.ae. M.L. neut.n. Mycobacterium type genus of the family; -aceae ending to denote a family; M.L. pl.f.n. Mycobacteriaceae the Mycobacterium family. Cells spherical to rod-shaped; branching not evident on ordinary media. No conidia. Aerobic. Mesophilic. Gram-positive. Found in soil, dairy products and as parasites on ani- mals, including man. Key to the genera of family Mycobacteriaceae. I. Cells usually acid-fast. Rod-shaped cells that do not branch under ordinary cultural conditions. Genus I. Mycobacterium, p. 695. II. Non acid-fast cells so far as observed. Cells generally spherical, occurring singly, in short chains or in clumps. Genus II. Mycococcus, p. 707. Genus I. Mycobacterium Lehmann and Neumann, 1896 * (Coccothrix Lutz,t Zur Morphologic des Mikroorganismus der Lepra. Dermatologische Studien, Heft 1, 1886, 22; Sclerothrix Metchnikoff , Arch. f. path. Anat. u. Physiol., 113, 1888, 70; not Sclerothrix Kuetzing, Species Algarum, 1849, 319; Lehmann and Neumann, Bakt. Diag., 1 Aufl., 2, 1896, 108.) My.co.bac.te'ri.um. Gr. noun myces a fungus; Gr. neut.dim.n. bacterium a small rod; M.L. neut.n. Mycobacterium a fungus rodlet. Acid-fast, slender rods, straight or slightly curved, occasionally slender filaments, but branched forms rarely occur. No conidia. Non-motile. Aerobic. Two species are obligate parasites and have not been cultivated apart from living cells; other species grow slowly on all media, species pathogenic for higher animals requiring two to several weeks, other spe- cies requiring two to several days. Saprophytic species are not so strongly acid-fast as are the parasitic species. Nearly all acid-fast bacteria treated with carbol-auramin and decol- orized with NaCl-HCl-ethyl alcohol fluoresce when they are irradiated by long wavelength
- Completely revised by Dr. Ruth Gordon (saprophytic species and those affecting cold-
blooded animals). Institute of Microbiology, Rutgers University, New Brunswick, New Jersey, Dr. G. B. Reed (species affecting warm-blooded animals except those causing lep- rosy). Queens University. Kingston, Ontario, Canada, and Dr. John H. Hanks (species causing leprosy). Harvard Medical School, Brookline, Massachusetts, July, 1953. t The name Coccothrix has priority over Mycobacterium as the name for this genus but it has never come into general use. A recommendation has been made to the Judicial Com- mission that the name Coccothrix be placed in the list of rejected generic names. Until an Opinion has been issued, the Manual will continue to recognize Mycobacterium.
