NON-BETA-HEMOLYTIC GROUP M-REACTING STREPTOCOCCI OF HUMAN ORIGIN.

Rifkind, David (National Institutes of Health, Bethesda, Md.) and Roger M. Cole. Non-beta-hemolytic group M-reacting streptococci of human origin. J. Bacteriol. 84:163-168. 1962.-In 8 years, 14 strains of alpha- and gamma-hemolytic streptococci, reacting only with group M antiserum, were isolated from a variety of human sources. Two alpha-hemolytic strains from the blood of endocarditis patients were compared biochemically and immunologically with the two original canine beta-hemolytic strains of Fry (ATCC 9934 and 9935). The human strains do not produce ammonia or ferment glycogen, whereas the animal strains do. The animal strains share two trypsin-labile antigens with the human strains, and one of them (ATCC 9935) also shares at least four trypsin-stable antigens with the human strains. The other strain of Fry (ATCC 9934) appears to lack these trypsin-stable antigens. These results indicate that the human strains correspond to those designated biotype I whereas ATCC 9935 belongs to biotype II and ATCC 9934 to biotype III. The nature of the group M antigen is undefined, but the gel-diffusion methods employed in this work suggest that several antigens may be responsible for precipitates seen as positive reactions to group M antisera when testing is done by the usual methods in tubes.