1. Streptococcus pyogenes Rosenbach, 1884. (Fehleisen, Ueber Erysipel, Deut. Zeit. f. Chir., 16, 1882, 391; Erysipelkokken, Fehleisen, Die Aetiologie des Erysipels, Berlin, 1883; Rosenbach, Mikroorganismen bei den Wundinfectionskrankheiten des Menschens, 1884, 22; Streptococcus enjsip- elatos (sic) Rosenbach, lac. cit.; Micrococcus scarlaiinae and Streptococcus scarlatinae Klein, Report of the Medical Officer of the Local Government Board for 1885-1886, No. 8, 1887, 85; Streptococcus hemolyticus Roily, Cent. f. Bakt., I Abt., Orig., 61, 1911, 87; Streptococcus epidemicus Davis, Jour. Am. Med. Assoc, 58, 1912, 1852; Jour. Inf. Dis., 15, 1914, 378; ibid., 19, 1916, 236.) py.o'ge.nes. Gr. noun pyum pus; Gr. v. (jennaio to produce; M.L. adj. pyogenes pus- producing. Spherical or ovoid cells, 0.6 to 1 micron in diameter in cultures, usually spherical in blood and inflammatory exudates, oc- curring in chains or pairs; in broth culture, usually long chains. Gram-positive. Serology: Constitutes Lancefield's group A (Jour. Exp. Med., 57, 1933, 571). May be subdivided into serological types by the precipitin technique on the basis of the cap- sular protein M antigen. This antigen, which can be destroyed by certain proteolytic en- zymes, is associated with virulence, and the antibodies to which it gives rise are pri- marily concerned with the specific protec- tive action of immune sera (Lancefield, The Harvey Lectures, Ser. XXXVI, 1940-1941, 251). At least 40 types have been identified. May also be subdivided into types by the agglutination technique (Griffith, Jour. Hyg., 34, 1934, 542) on the basis of the cap- sular T substance. The T substance is not associated with virulence. The M and T sub- stances are independent and may occur in various combinations in different strains. Some strains may lack either or both type- specific antigens. Action on blood: Surface and submerged colonies are beta hemolytic (Brown, Rocke- feller Inst. Med. Res., Monograph 9, 1919, 14). In rare instances, some strains have been noted to lose their hemolytic proper- ties when cultured aerobically. Two soluble antigenic hemolysins (streptolysins) pro- duced in fluid cultures; influenced by con- stitution of medium and presence of serum. Streptolysin O is reversibly oxygen-labile; streptolysin S is very sensitive to heat and acids but is stable to oxygen (Todd, Jour. Path. Bact., ^7, 1938, 423). Colony form: Mucoid, matt and glossy variants are ordinarily observed (Todd, Brit. Jour. Exp. Path., 9, 1928, 1). The matt colony type contains the type-specific M substance and may or may not be virulent. Mucoid variants also possess the M sub- stance in addition to the serologically in- active capsular substance, hyaluronic acid (Kendall et ah. Jour. Biol. Chem., 118, 1937, 61). The glossy forms are always avirulent and contain little or no M substance. Fibrinolytic (Tillett, Bact. Rev., 2, 1938, 161). Only very rare strains fail to dissolve human fibrin. Temperature relations: Optimum tem- perature, approximately 37° C. 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 in skim milk contain- ing 0.1 per cent methylene blue. No growth in broth adjusted to pH 9.6 or on blood agar containing 40 per cent bile. Litmus milk: Acid, seldom curdled, lit- mus reduced slowly or not at all. Final pH in glucose broth, 4.8 to 6.0. Acid characteristically produced from glucose, maltose, lactose, sucrose, salicin and trehalose. No acid from inulin, raffinose, arabinose, glycerol, mannitol, sorbitol or dulcitol. Rare strains noted that fail to ferment lactose, salicin or trehalose, or may ferment mannitol. Starch not actively hydrolyzed, although some strains are reported to hydrolyze this substance under certain conditions (Crow- ley, Jour. Gen. Microbiol., 4, 1950, 156). Gelatin is not liquefied, and casein is not digested as detected by the usual cultural methods. However, under certain conditions some strains elaborate an extracellular pro- teinase that destroys the type-specific M antigen (except for type 28) . It also is able to digest casein, gelatin and fibrin (Elliott, Jour. Exp. Med., 81, 1945, 573). Sodium hippurate not hydrolyzed. Es- culin usually split. Ammonia produced from arginine.
