444 DESCRIPTION OF SOME SPECIES OF MILK BACTERIA 



Biology: cultural characters {includ- 

 ing biochemical features) — Grows 

 at room temperature, but better at 

 37° C, on all media. 



Bouillon — Marked uniform 

 cloudiness ; delicate pellicle ; some 

 sediment. 



Gelatine plates and tubes — Small 

 irregular, round colonies, yellowish- 

 white to yellow in colour ; slow 

 liquefaction ; structure somewhat 

 coarsely granular. In stab-culture, 

 liquefaction along needle track in 

 2 to 3 days (conical, and later cylin- 

 drical) ; deposit pigmented yellow ; 

 degree of liquefaction varies. 



Agar plates and tubes — Round 

 orange - yellow colonies, even 

 margin ; granulation sometimes 

 well marked. Feeble growth in 

 stab-culture ; good surface growth ; 

 smooth, shining, orange - yellow. 

 In streak culture, similar growth ; 

 condensation fluid cloudy ; pre- 

 cipitate, light orange in colour ; 

 odour like glue or stale paste ; most 

 rapid method of isolation is by 

 using agar. 



Potato — At first white growth, 

 becoming yellow — elevated, shin- 

 ing ; old cultures widely spread, 

 deep orange in colour, and dry. 

 The best medium for chromogenic 

 effects. 



Milk — Firm coagulation in i to 

 8 days (Passet). Lactic acid pro- 

 duced. 



Pigment produced only in pres- 

 ence of oxygen. 



Anaerobic or aerobic — Grows well 

 aerobically, less well anaerobically. 



Vitality — Considerable powers 

 of vitality have been proved in the 

 body ; in cultures, also tenacious of 

 life. Alive after 56 to 100 days' 

 desiccation ; 70° C. kills them if 

 moist ; alive after 66 days in ice 

 (Prudden). 



Pathogenic — Much variation in 

 virulence ; passage through animals 

 and anaerobic cultivation increases 

 virulence ; relative susceptibility to 

 infection is shown in the following 

 decreasing series — horse, dog, man, 

 cattle, sheep, rabbits, guinea-pigs, 

 and mice least of all. Chief patho- 

 logical conditions set up are sup- 

 purative. Intravenous injection 

 causes endocarditis. 



S. pyogenes albus is almost 

 identical with the S. pyogenes 

 aureus, except that its colour pro- 

 duction is white and not orange- 

 yellow. 6". pyogenes citreus is also 

 similar, but that its colour in culture 

 is lemon. It does not coagulate 

 milk, and its liquefaction of gelatine 

 is slow, with production of gas 

 bubbles. 



STREPTOCOCCUS PY0GBNE3S 



(Rosenbach). 



Source and habitat — In soil, water, 

 outside the body — and in suppura- 

 tive diseases inside the body. 

 Milk, etc. 



Morphology — Chains of cocci, long 

 in fluid, short on solid medium. 



Staining reaction — Ordinary stains 

 and Gram's method. 



Capsule — Definite mucoid capsule 

 occasionally seen about the chain. 



Biology : cultural characters {includ- 

 ing biochemical features) — Growth 

 rather slow, best at 37° C. ; above 

 47° C. no growth. As a rule, more 

 luxuriantly upon fully acid medium. 

 Non-chromogenic. No gas forma- 

 tion. 



Bouillon — Varies from diffuse 

 cloudiness to compact sediment 

 with clear medium. No indol. 



Gelatine plates and tubes — Small 

 white, round, flat colonies ; slow 

 growth, smooth margin. In stab- 

 cultures, at first thread-shaped, and 

 later with small nodules. 



