Growth of group E streptococci and production of antigens in a chemically defined medium.

Group E streptococci were grown in a modification of a chemically defined medium (CDM) originally formulated for streptococci of group A. Ten of 12 strains studied produced greater or equal cultural densities and growth rates in CDM than in the complex medium (Todd-Hewitt broth). All strains produced similar amounts of group antigen in both media. Eight strains of demonstrable serotype produced comparable amounts of type antigen in both media. cells grown in CDM were less resistant to phagocytosis than those grown in the complex medium, but all strains produced antiphagocytic factor when cultured in either medium to which 10% porcine serum had been added.