876 MANUAL OF DETERMINATIVE BACTERIOLOGY 



Slender filaments, straight or slightly curved rods, frequently irregular in form 

 with only slight and occasional branching. Often stain unevenly, i.e., show variations 

 in staining reaction within the cell (beading). Xo conidia. Non-motile. Aerobic. 

 Gram-positive. Acid-fast. t Pathogenic species grow slowly (several weeks); 

 those from soil, water and vegetation more rapidly (several days). 



There is a single genus Mycobacterium Lehmann and Neumann. 



Genus I. Mycobacterium Lehmann and Neumann. 



{Coccothrix Lutz, Zur Morphologic des Mikroorganismus der Lepra. Dermatolo- 

 gische Studien, Heft 1, 1886, 22; Schleroihrix Metschnikoff, Arch. f. path. Anat. 

 u. Physiol., 113, 1888, 70; Lehmann and Neumann, Bakt. Diag., 1 Aufl., 2, 1896, 108; 

 Mrjcomonas Orla-Jensen, Cent. f. Bakt., II Abt., 22, 1909, 329; Eumrjces Battaglia, 

 Soc. Internaz. Microbiol. Boll. Sez. Ital., 10, 1938, 166.) From Greek myces, fungus 

 and bacterium, a little rod. 



Characters as for the family. 



The type species is Mycobacterium tuberculosis (Schroeter) Lehmann and Neumann. 



Key to the species of t/enus Mycobacterium. 



I. Parasites in warm-blooded animals; grow slowly on all media. 



A. Grow slowly on glycerol agar in atmospheric air; experimentally infect 



guinea pigs and fowls. 



1. Experimentally produces generalized tuberculosis in guinea pigs but 



not in rabbits and fowls. Growth enhanced by the addition of 

 glycerol to most media. Generally pale yellow to orange pigmenta- 

 tion on serum media. 



la. Mycobacterium tuberculosis var. hominis. 



2. Experimentally produces generalized tuberculosis in guinea pigs and 



rabbits but not in fowls. Growth not enhanced by addition of 

 glycerol to media. Never pigmented. 



lb. Mycobacterium, tuberculosis var. bovis. 



3. Experimentally produces generalized tuberculosis in fowls and rab- 



bits but not in guinea pigs. 



2. Miicobadcrium avium. 



B. Grows in primary culture on glycerol agar only when extracts of, or heat- 



killed acid-fast bacilli are added. Experimentally fails to infect guinea 

 pigs or fowls. 



3. Mycobacterium, paraiuberculosis. 



C. Have not been grown on culture media thus far devised. Exi)erimentally 



fail to infect guinea pigs or fowls. 



1. Has not experimentally been transmitted to any animal species. 



4. Mycobacterium leprae. 



2. Occurs in wild rats, and can be experimentally transmitted to rats and 



some strains of mice. 



5. Mycobacterium lepraemurium. 



t Most acid-fast bacteria treated with carbol-auramin and decolorized with NaCl- 

 HCl-alcohol show fluorescence under the microscope when they are radiated by long 

 wavelength ultraviolet light (Haitinger, Fluorescenz-mikroskopie, Leipzig, 1938, 108 

 pp.; Ellinger, Biol. Revs., 15, 1940, 323-350; Richards, Jour. Bact., U, 1942, 721). 



For a discussion of the influence of environment on acid-fastness, see Salle and 

 Moser, Internat. Jour. Leprosy, 5, 1937, 163. 



