A new scheme for serotyping group-G streptococci.

Ten antisera, prepared against nine selected strains of group-G streptococci and a strain of group-A streptococci of M-type 12, were used to serotype 102 isolates of group-G streptococci by means of precipitation reactions between the sera and hot-acid extracts of the streptococci. Fifty-six (54.9%) of the streptococci could be typed; eight serotypes were identified, of which type VIII was the most common (18.6%). The M12 and the R28 antigens, previously recorded in group-G streptococci, were not detected. The type antigens were trypsin sensitive and resembled the M antigens of group-A streptococci.