316 



MANUAL OF DETERMINATIVE BACTERIOLOGY 



colonies to remain discrete. Growth in- 

 creased bj' addition of blood or native 

 proteins. Pairs or short chains in surface 

 growth and longer chains in condensation 

 fluid of slants. 



Broth: Flocculent sediment of tangled, 

 chains, supernatant broth often clear 

 except in very young cultures. No 

 pellicle. 



Potato: Very slight or no visible 

 growth. 



Litmus milk : Acid, seldom curdled, 

 and litmus reduced slowly or not at all. 



Acid from glucose, maltose, lactose, 

 sucrose, salicin and trehalose. No acid 

 from inulin, raffinose, arabinose, glycerol, 

 mannitol, sorbitol or dulcitol. 



No hydrolysis of sodium hippurate, 

 starch or esculin. 



Ammonia is produced from peptone. 



Temperature relations : Optimum tem- 

 perature around 37°C. No growth at 

 10°C or 45°C. Does not survive 60°C 

 for 30 minutes. 



Chemical tolerance : Tolerates 2 per 

 cent NaCl but not 4 per cent and 6.5 per 

 cent. Final pH in glucose broth 4.8 to 

 6.0; no growth at pH 9.6. Methylene 

 blue 0.01 per cent and 0.1 per cent not 

 tolerated and not reduced. Inhibited by 

 bile but not soluble. 



Action on blood : Superficial and deep 

 colonies cause hemolysis in blood agar, 

 usually with a wide zone surrounding the 

 colony, which may have a well-defined 

 margin circumscribed by a zone of con- 

 centrated hemoglobin ; the margin of the 

 zone is ill-defined with some strains. 

 Conditions defined by Brown (Rocke- 

 feller Inst. Med. Res., Monograph 9, 

 1919, 14) known as beta hemolysis. 

 Soluble antigenic hemolysin of more than 

 one kind produced in fluid cultures; in- 

 fluenced by constitution of medium and 

 presence of serum; one is oxygen-sensi- 

 tive and another is oxygen-stable. 

 Special precautions necessary for its 

 demonstration (F. Smith, Jour. Bact., 

 S.^, 1937, 585,603). 



Toxin: An erythrogenic toxin is pro- 



duced ; commonly associated with scarlet 

 fever. Relatively thermostable. 



Fibrinolysin: Dissolves human fibrin 

 but not fibrin of rabbit or ox blood. 

 Markedly thermostable. 



Serology : Constitutes Group A of 

 Lancefield (C substance ; polysaccharide) 

 (Jour. Exp. Med., 57, 1933, 571). Types 

 within the species are distinguishable 

 (M substance; protein) ; 23 identified by 

 Griffith (Jour. Hyg., 34, 1934, 542). 

 Antigen common to the group (P sub- 

 stance; nucleo-protein) also present in 

 other Gram-positive cocci. 



Facultative anaerobe. Occasionally in 

 primary culture from lesions, pus, etc. 

 grows only in anaerobic culture. 



Source : Human mouth, throat and 

 respiratory tract ; inflammatory exudates, 

 blood stream and lesions in human disease 

 of very varied character. Occasionally in 

 milk and udder of cows. Dust in sick 

 rooms, hospital wards and other contami- 

 nated sites. 



Habitat : In human infections of many 

 varied types. Occasionally in udder in- 

 fections of cattle and perhaps other 

 animal sources. 



2. Streptococcus zooepidemicus Frost 

 and Engelbrecht. (Animal pyogenes. 

 Type A of Edwards, Jour. Bact., 27, 

 1934, 527; Frost and Engelbrecht, A 

 Revision of the Genus Streptococcus, 

 privately published, 1936, 3 pp. and The 

 Streptococci, 1940, 25; Streptococcus pyo- 

 genes animalis Seelemann, Deutsche 

 tierarzt. Wchnschr., 50, 1942, 8 and 48.) 

 From M. L., derived to mean animal 

 cpideynicus. 



Morphology and general cultural char- 

 acters resemble Streptococcus pyogenes. 

 Mucoid colonies are common. Capsules 

 are constantly demonstrable and promi- 

 nent. Gram-positive. 



Gelatin stab: No liquefaction. 



Litmus milk: May be curdled, litmus 

 not reduced or slowly after curdling. 



Acid from glucose, lactose and 

 sorbitol. Acid may be produced from 

 maltose, sucrose and salicin. No acid 



