An inhibitor typing scheme applicable to Lancefield group E streptococci.

A previously described inhibitor typing scheme for hemolytic streptococci has been utilized to test 12 well-characterized strains of group E streptococci. These strains were differentiated into five inhibitor production (P) types and four inhibitor sensitivity (S) types: seven different strain "fingerprints" (combinations of P-type and S-type) being demonstrated. Inhibitor production by group E streptococci was increased under conditions of anaerobic incubation. The inhibitor fingerprints were stable on repeated testing of strains and it is suggested that the scheme is of value both for the labelling of serologically untypable strains and for subdividing strains belonging to existing serotypes.