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

SUMMARY: 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 physio-logical 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 sero-logical 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. The work reported here was carried out in the course of an investigation of the epidemiological significance of group D streptococci in outbreaks of neonatal diarrhoea. Whilst there have been several reports on serological types in this group, there has been little correlation between types designated by various workers. Much of the work has been concerned with the ‘enterococci’, not always specifically defined, but mainly comprising heat-resistant faecal strep to-cocci. Of the earlier workers, Takeda (1935) ’ together with Shigeno (1937)’ differentiated 31 types among the ‘enterococci’, and Meyer (1937) was able to identify six of his serological types with those of Takeda and Shigeno. Grumbach & Schnetz (1938), Grumbach (1943), and recently Skadhauge (1950), have also divided collections of ‘ enterococci ’ by agglutination. Wit