CHAPTER XXII 



THE STREPTOCOCCI 



AMONG the pyogenic cocci, there is a large and important group of 

 organisms which multiply by division in one plane of space only, and 

 thus give rise to appearances not unlike chains or strings of beads. 

 The term streptococcus or chain-coccus is, therefore, a purely morpho- 

 logical one which includes within its limits microorganisms which may 

 differ from each other considerably, both as to cultural and pathogenic 

 properties. Thus, cocci which form chains may be isolated from water, 

 milk, dust, and the feces of animals and man. These may have little 

 but their morphological appearance in common with the pyogenic 

 streptococci which are so important as the incitants of disease. The 

 interrelationship between streptococci from different sources, how- 

 ever, is by no means fully understood, and we are forced at present to 

 content ourselves with the recognition of a large morphological group, 

 in no individual case taking the pathogenic or more special cultural 

 characteristics for granted. 



STREPTOCOCCUS PYOGENES 



Of paramount importance among the streptococci are those which 

 possess the power of giving rise to disease processes in animals and in 

 man, and which, because of their frequent association with suppura- 

 tive inflammations, are roughly grouped under the heading of Strep- 

 tococcus pyoyenes. 



The same researches upon surgical infections which led to the dis- 

 covery of the staphylococci, laid the basis for our knowledge of the 

 streptococci. The fundamental studies of Pasteur and Koch 1 were fol- 

 lowed, in 1881, by the work of Ogston, 2 who was the first to 

 differentiate between the irregularly grouped staphylococci and the 

 chain-cocci. 



i Koch, " Untersuch. iiber Wundinfektion," etc., 1878. 

 Ogston, Brit. Med. Jour., 1881. 

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