The Serological Grouping of Streptococcus equinus

Abstract
Streptococci isolated from horse faeces and corresponding to the description of Streptococcus equinus Andrews and Horder (1906) were found to belong to the serological group D. The group D antigen was produced by all the strains examined, but was not always extractable from whole organisms by HC1 or formamide; broken organisms, however, always gave group D antigen. Collections of S. equinus and S. bovis strains were found to be physiologically similar, but distinguishable.