Erythrogenic toxin associated with scarlet fever rash produced by most strains. Source: Originally isolated from infected wounds by Rosenbach (op. cit., 1884, 22). Also found in the human mouth, throat and respiratory tract and in inflammatory exudates, blood stream and lesions in human disease of varied character. Occasionally encountered in the udder of the cow and in laboratory animals. May be found in dust from sick rooms, hospital wards, schools, theaters and other public places. Habitat: Primarily the human body, where it causes the formation of pus or even fatal septicemias. 2. Streptococcus equisiniilis Frost and Engelbrecht, 1936. (Type B, Ogura, Jour. Jap. Soc. Vet. Sci., 8, 1929, 174; Frost and Engelbrecht, A Revision of the Genus Strep- tococcus, privately published, 1936, 3 pp.; also see The Streptococci, 1940, 45; Human C, Sherman, Bact. Reviews, 1, 1937, 35.) e.qui.si'mi.lis. L. noun equvs horse; L. adj. similis resembling; M.L. adj. equisi- inilis literally horse-like, but intended to mean "resembling Streptococcus equi". Morphology and general cultural charac- teristics resemble those of Streptococcus pyogenes. Matt colonies are characteris- tically produced. Gram-positive. Serology: Belongs to Lancefield's group C. Several types have been established. Griffith's agglutinative types 7, 20 and 21 belong to this species. The type-specific antigens are proteins digestible with tryp- sin. Action on blood: Beta hemolytic. Soluble hemolysins produced, one of which is iden- tical with streptolysin O. Fibrinolytic. Temperature relations: No growth at 10° or 45° C. Does not survive 60° C. for 30 minutes. Tolerance tests : Fails to grow in presence of 6.5 per cent NaCl or at pH 9.6. Does not grow in skim milk containing 0.1 per cent methylene blue, but Edwards (Kentucky Agr. Exp. Station Bull. 356, 1935) reported growth in an infusion-casein digest broth containing 0.000025 molar methylene blue, thus indicating a tolerance to methylene blue higher than that of Streptococcus pyo- genes. Occasionally grows on 40 per cent bile blood agar. Litmus milk: Lactose-fermenting strains produce an acid reaction. Milk may be curdled; litmus not reduced before curdling. P^inal pH in glucose broth, between 4.6 and 5.4. Acid from glucose, maltose, sucrose and trehalose. Glycerol fermented when incu- bated aerobically. May or may not ferment lactose and salicin. No acid from arabinose, raffinose, inulin, mannitol or sorbitol. Starch and esculin may or maj- not be hydrolyzed. Gelatin not liquefied. Sodium hippurate not hydrolyzed. Ammonia produced from arginine. Distinctive characters: Members of this species may be confused with Streptococcus pyogenes but may be differentiated from the latter by their ability to ferment glycerol aerobically and to hydrolyze starch and by their generally greater tolerance to methyl- ene blue and bile. For positive identifica- tion, the Lancefield precipitin technique must be relied upon. Source: Occasionally associated with erysipelas and puerperal fever. The normal human nose and throat, vagina and skin. Sometimes found in respiratory tract of domestic animals. Habitat: Human upper respiratory tract and vagina. 3. Streptococcus zooepidcniicus Frost and Engelbrecht, 1936. (Animal pj-ogenes, Type A of Edwards, Jour. Bact., 27, 1934, 527; Frost and Engelbrecht, A Revision of the Genus Streptococcus, privately pub- lished, 1936, 3 pp. ; also see The Streptococci, 1940, 25; Streptococcus pyogenes animalis Seelemann, Deutsche tierarzt. Wchnschr., 50, 1942, 8 and 48.) zo.o.e.pi.de'mi.cus. Gr. noun zoum an animal; Gr. adj. epidemius among people, prevalent, epidemic; M.L. adj. zooepidemi- cus prevalent among animals. Morphology and general cultural charac- teristics resemble those of Streptococcus pyogenes. Mucoid colonies are common. May produce capsular hyaluronic acid. Serology: Belongs to Lancefield's group C. Action on blood: Beta hemolvtic. The
