STREPTOCOCCUS PYOGENES 89 



abscesses, suppuration of the parotid, idiopathic cerebro - spinal 

 meningitis, strumitis, and suppurative peripleuritis. The albus is 

 also often present in these infections mixed infection being frequent. 



STREPTOCOCCUS PYOGENES. 



Microscopical Appearances. Micrococci from 0*3 to 1 /x in 

 diameter, arranged in more or less long chains. 

 Motility. Non-motile. 



Staining Reactions. Easily stained with all the basic anilin dyes, 

 and by the Gram and Cladius methods. 



Biological Characters. Facultative anaerobe, the optimum tem- 

 perature for its growth being 30 to 37 C. ; it also grows at room tem- 

 perature. 



On Gelatine Plates it develops in the form of small white granular 

 colonies which do not liquefy the gelatine. Under a high power chains 

 can be observed projecting from the sides of the discs. 



In Gelatine Stab Cultures the growth is not confluent, but individual 

 colonies are arranged next each other along the track of the needle. A 

 similar growth occurs in agar stab cultures. 



Bouillon, which is an excellent medium for streptococci, is not clouded 

 throughout, but a flaky, creamy deposit is formed. 



On Potatoes the growth is extremely scanty. 



Milk is coagulated. 



Vitality. In cultures the streptococcus dies much sooner than the 

 staphylococcus, only living about four months. In order to keep 

 streptococci cultures virulent, Petruschky uses gelatine cultures, and 

 renews them every five days, and keeps them in the ice-chest. 



Pathogenesis. Material containing streptococci, when rubbed on 

 an abrased surface on a rabbit's ear, causes an erysipelatous inflamma- 

 tion ; when introduced into mice or rabbits a septicaemia results, 

 with or without a local abscess. Intravenous injection causes 

 septicaemia. Many suppurative processes spread by means of the 

 lymphatics, causing lymphangitis and lymphadenitis. It was in these 

 suppurative changes that Rosenbach first obtained a pure culture of the 

 Streptococcus pyogenes. It is also found in pyaemia. In puerperal 

 pyaemia the streptococci are found in emboli in the bloodvessels of 

 the kidneys. They are also found in severe forms of arthritis, acute 

 endocarditis, in many cases of secondary infection following scarlet 

 fever, and in diphtheritic false membranes. 



