The serological typing of group D streptococci associated with outbreaks of neonatal diarrhoea.

By the preparation of specific type sera 24 types of streptococci within group D are designated on the basis of agglutination tests. Subtypes associated with three of these types are indicated by reciprocal absorption. Precipitin tests with absorbed sera substantiate the division of types by agglutination. Of 353 strains of streptococci identified serologically as group D and further specified by physiological characters, 281 were typed by slide agglutination ; the remaining 72 did not fall into any of the 24 types. Whilst there is no absolute correlation between serological type and physiological characteristics, a broad division can be made between Streptococcus faecalis and its varieties on the one hand and Strep. durans, Strep. bovis and various unclassified strains on the other.