Taxonomic study of lancefield streptococcal groups C, G, and L (Streptococcus dysgalactiae) and proposal of S. dysgalactiae subsp. equisimilis subsp. nov.

Streptococcus dysgalactiae consists of at least five distinct subgroups on the basis of serogroups, biotypes, and hosts. A chemotaxonomic and phenotypic examination of 80 S. dysgalactiae strains representing the known diversity within this species and 49 reference strains representing all members of the streptococcal pyogenic species group revealed two subpopulations of strains within S. dysgalactiae. The name S. dysgalactiae subsp. dysgalactiae is proposed for strains of animal origin. These strains belong to Lancefield serogroups C and L, are alpha-, beta-, or nonhemolytic, and do not exhibit streptokinase activity on human plasminogen or proteolytic activity on human fibrin. The name S. dysgalactiae subsp. equisimilis is proposed for human isolates. These strains belong to Lancefield serogroups C and G, are beta-hemolytic, and exhibit streptokinase activity on human plasminogen and proteolytic activity on human fibrin.