CLASSIFICATION OF STREPTOCOCCI 411 



very often fall into identical groups. He believes that by his method 

 many of the air streptococci could be traced to their sources, and 

 that similar relation between source and cultural characteristics 

 could be found for streptococci from milk, from the mouth, from 

 the intestinal tract, and from animal tissues. He concluded that 

 individual groups of streptococci, however, were not specific in their 

 disease production. 



Cultural classification beyond the differentiation into hemolyticus 

 and viridans, therefore, has not helped a great deal in characterizing 

 the streptococci from the pathological point of view. It has been 

 very important, therefore, to study the serological relationships of 

 this group, a problem which, apart from its importance in pure 

 classification, has fundamental bearing upon the questions of diagno- 

 sis and serum therapy. The earlier work of Aronson, 29 Marmorek 30 

 and others showed that, although the serum produced with any race 

 of pyogenic streptococci frequently exerted considerable agglutina- 

 tive and protective action against other strains, these relationships 

 were variable and that antigenically the group was probably poly- 

 valent. There was much confusion at first concerning these matters, 

 but there has never been much doubt about the fact that sera pro- 

 duced with single strains or with only a few could not be relied 

 upon to react with any chance strain obtained from a case. It was 

 not until quite recently that more light has been shed upon this 

 problem. 



In order to deal clearly with the problem, it will be necessary to 

 consider separately the viridans group and the hemolyticus group. 

 The antigenic relationship between the two groups has been studied 

 by Kinsella 31 who finds that there is no absolutely sharp antigenic 

 line between viridans and hemolyticus strains, but that sera immune 

 to hemolytic streptococci were, in a definitely limited way, related 

 to non-hemolytic antigens. On the other hand, sera immune to non- 

 hemolytic strains gave no positive reactions with any of the 

 hemolytic antigens. His work, however, was limited in the number 

 of sera used, and one of his conclusions was that the hemolytic 

 streptococci are probably not heterogeneous, but what he calls 

 "unique." Kinsella and Swift 32 also attempted to classify non- 



29 Aronson, Deut. med. Woch., 29, 1903, 439. 



30 Marmorek, Berl. klin. Woch., 31, 1902, 299. 

 n Kinsella, Jour. Exper. Med., 28, 1918, 181. 



32 Kinsella and Swift, Jour. Exper. Med., 28, 1918, 169. 



