Studies on Hemolytic Streptococci

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Abstract
A study of 53 strains of Str. equisimilis was made to determine the typical and variant characters of the species. The type-strain, 1180, which was isolated from a human pathologic source, gave a positive precipitative reaction in serum of group C; it was sensitive to filtered phage B; it fermented trehalose and salicin, but not sorbitol or lactose. 31 other strains agreed with the type strain in all these characters. There were differences in agglutinative properties among the 32 strains, but most of them agglutinated in one or more of the serums of Griffith''s types 7, 20 and 21. The intermediary status of S. equisimilis between S. equi and lactose-negative strains of group A was demonstrated in cross-protective tests which showed that the strains of S. equisimilis are immunologically related to both of these groups. The data show no evidence of immunologic relationship between S. equi and lactose-negative strains of group A. The data presented here, together with a review of the literature, show that S. equisimilis may occur on the normal mucous membrane of man and animals, and it may cause infection in man and in many spp. of animals, including birds. 3.1% of the strains from human pathologic sources were found to belong to the species S. equisimilis. Evidence is presented which indicates that in man the strains of S. equisimilis have a tendency to infect other parts of the body more frequently than the throat. Evidence is presented which indicates that the 2 variant groups which are characterized by failure to ferment salicin and ability to ferment lactose, respectively, possess a greater tendency to infect the genital tract than do the typical strains of S. equisimilis.