The Serological Classification ofStreptococcus pyogenes

The haemolytic streptococci associated with scarlet fever, tonsillitis, septic conditions, etc., belong to one group or species designated Streptococcus pyogenes . Cultural and serological aids to the identification of Str. pyogenes are described. The epidemiologically significant types of Str. pyogenes appear to be about 20 in number, though probably more than thirty type sera will be necessary for the complete analysis of the group. So far twenty-seven individual serological types have been defined. The irregularities which have been observed in the agglutination reactions of streptococcal cultures are ascribed chiefly to variations in type-specificity. Different colonies may give “type-specific” or “group” agglutination, and these distinctions are revealed macroscopically in the case of certain types by growth on homologous agglutinating serum agar. Some examples are given of observations on the epidemiology of streptococcal infections in schools and other institutions. The principles involved in the serological classification of a bacterial group are discussed.