emm typing and validation of provisional M types for group A streptococci

This report discusses the following issues related to typing of group A str eptococci (GAS): The development and use of the 5' emm variable region sequ encing (emm typing) in relation to the existing serologic typing system; th e designation of emm types in relation to M types; a system for validation of new emm types; criteria for validation of provisional M types to new M-t ypes; a list of reference type cultures for each of the M-type or emm-type strains of GAS; the results of the first culture exchange program for a qua lity control testing system among the national and World Health Organizatio n collaborating centers for streptococci; and dissemination of new approach es to typing of GAS to the international streptococcal community.