A Serological and Biochemical Study of Hemolytic Streptococci

Abstract

Summary Of 880 strains of streptococci isolated in Canada, 96.8 per cent were placed in one or other of 7 precipitative types. No strains belonging to groups H or K were isolated in this series. The strains which were not hemolytic on the surface of blood agar plates included 14 group A, 50 group B, 7 group C and 20 strains not grouped. Of these, all members of group A, 4 group B and 3 ungrouped produced beta hemolysis in deep plates, the others being non-hemolytic. Soluble hemolysin was produced by all the strains tested belonging to groups A, F and G, was not produced by group E and produced by part of the members of groups B, C and D. Of 522 strains examined, 128 of 187 group B strains and 1 other strain not grouped showed pigmented cells. Of 371 strains isolated from pathological conditions in human beings, 360 (97 per cent) belonged to group A, 6 to group B, 1 to group C, 1 to group F and 3 to group G. Of 520 group A strains tested for agglutinative types, 93 per cent were placed in one or other of Griffith's types. The predominating scarlet fever types were 1, 2, 3, 4 and 11. The predominating types from non-scarlatinal infections were 11, 13, 17-23-26, 12, 2, 1, 3, 4, 6 and 14. Of 189 group B strains, 92 per cent were placed in one or other of the 4 types of Stableforth by means of precipitative tests.