TEXT-BOOK OF BACTERIOLOGY. 327 



XXIII. STREPTOCOCCUS PYOGENES. 



The Streptococcus pyogenes is a species of bacteria which plays 

 an important part in producing suppuration. It is met with fre- 

 quently alone, more rarely with staphylococci, in abscesses, etc. 

 An exact and detailed description of its properties is superfluous, 

 as it would be necessary to repeat all that has been said regarding 

 Fehleisen's streptococcus of erj-sipelas. In fact, both micro-organ- 

 isms cannot be satisfactorily distinguished. Neither their appear- 

 ance nor the mode and rapidity of growth on culture media, etc., 

 supplies any distinctive criterion, and experiments on animals lead 

 to surprisingly similar results. Most investigators, as Baumgar- 

 ten, E. Fraenkel, and others, are, for this reason, of the opinion 

 that erysipelas cocci and streptococci are identical and should be 

 regarded as such. 



This view is, however, somewhat objectionable. How can it be 

 imagined that the same micro-organism causes at one time a typi- 

 cal, well-defmed disease, and another time, the establishment of 

 purely purulent changes ? 



This apparent contradiction may, however, be explained. When 

 discussing Fraenkel's pneumonia bacterium, it was found to be a 

 micro-organism appearing as the cause of croupous pneumonia and 

 of otitis media, and considered able to accompUsh diverse results 

 on the supposition that we had to deal with a widely diffused 

 exciter of inflammation whose action terminated differently, ac- 

 cording to locality and mode of entrance. 



The streptococcus is very similarly situated. On the one hand, 

 it is found very frequently in the saliva, in nasal secretion, in vagi- 

 nal mucus, and in the uretha of healthy individuals; on the other 

 hand, it regularly appears whenever the normal conditions of the 

 tissue is disturbed by some morbid process. It was seen to appear 

 in typhoid and diphtheria as a " secondary " bacterium concomitant 

 with certain changes; it gives rise to a mixed infection in pneu- 

 monia, tuberculosis, pleuritis, scarlet fever, etc.; it may, in many 

 cases, be the cause of more severe conditions than the legitimate 

 micro-organism. 



Fnally, the streptococcus, by itself, may produce sharply-char- 

 acterized inflammatory processes. When it reaches the valves of 

 the heart, it causes a typical endocarditis (hence a third exciter of 

 infection); if transplanted to the endometnum of lying-in women, 

 it causes puerperal fever, and it does so exclusively, according to 

 all investigations hitherto made; on entering the lymphatic ves- 

 sels of the cutis, it gives rise to erysipelas; if admitted to the sub- 



