FAMILY I. MYCOBACTERIACEAE 695 



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. 



