320 Suppuration 



Sternberg found that the streptococci succumb at temperatures of 

 52° to 54°C. if maintained for ten minutes. The ability to resist 

 heat depends somewhat upon the surroundings. In albuminous 

 media they resist more strongly and to kill streptococci in tuber- 

 culous sputum, heating to ioo°C. for some minutes is necessary. 

 Their vitality in culture is slight, and unless frequently transplanted 

 they .die. Bouillon cultures usually die in from five to ten days. 

 On solid media they seem to retain their vegetative and pathogenic 

 powers much longer, especially if kept cool and cultivated beneath 

 the surface of the medium in a deep puncture. They resist drying 

 fairly well. 



Differential Features. — It is not always easy to differentiate 

 Streptococcus pyogenes from the pneumococcus. One of the best 

 methods is to take advantage of the hemolytic activity of the or- 

 ganism first observed by Bordet* and Besredkaf by the employment 

 of hlood-agar plates, suggested by Schottmuller.J Such plates are 

 easily prepared by melting ordinary culture agar-agar, cooling to 

 about 45°C., and then adding about 0.5 cc. of defibrinated human 

 or rabbit's blood to the tube. The blood is first thoroughly mixed 

 with the agar, then the tube inoculated, and poured into a Petri 

 dish. As the Streptococcus pyogenes grows, it produces a hemo- 

 lytic substance that destroys the blood-corpuscles in the vicinity of 

 the colony, thus surrounding each by a clear, pale halo that con- 

 trasts with the red agar. The colonies themselves appear gray. 



The test is not specific. Colonies of the pneumococcus usually 

 appear dark and without hemolysis, but Ruediger§ finds that they 

 also sometimes cause solution of the hemoglobin. There are also 

 certain streptococci whose colonies are green and without hemolysis. 

 These were called Streptococcus viridans by Schottmuller and were at 

 first regarded as practically non-pathogenic, though it is now known 

 that they cause endocarditis in rabbits and in man. 



Pathogenesis. — The streptococcus has been found in erysipelas, 

 • malignant endocarditis, periostitis, otitis, meningitis, empyema, 

 pneumonia, lymphangitis, phlegmons, sepsis, puerperal endo- 

 metritis, and many other forms of inflammation and septic infection. 

 In man it is usually associated with active suppuration and sepsis. 



The relation of the streptococcus to diphtheria is of interest, for, 

 though in all probability the great majority of cases of pseudo- 

 membranous angina are caused by the Klebs-Loffler bacillus, yet a 

 number are met with in which, as in Prudden's 24 cases, no diph- 

 theria bacilli can be found, but which seem to be caused by the 

 streptococcus alone. 



There are few clinical differences between the throat lesions pro- 

 duced by the two organisms, and the only positive method of dif- 



* "Ann. de I'lnst. Pasteur," 1897, xi, 177. 

 t "Ann. de I'lnst. Pasteur," 1901, xv, 880. 

 t"MUnch. med. Wochenschrift," 1903, l, p. 909. ' 

 § "Jour. Amer. Med. Assoc," 1906, XLvn, p. 11 71. 



