Emerg Infect DiseidEmerging Infectious Diseases1080-60401080-6059Centers for Disease Control102218772640698Research Articleemm typing and validation of provisional M types for group A streptococci.FacklamR.rrf2@cdc.govBeallB.EfstratiouA.FischettiV.JohnsonD.KaplanE.KrizP.LovgrenM.MartinD.SchwartzB.TotolianA.BessenD.HollingsheadS.RubinF.ScottJ.TyrrellG.Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.Mar-Apr199952247253

This report discusses the following issues related to typing of group A streptococci (GAS): The development and use of the 5' emm variable region sequencing (emm typing) in relation to the existing serologic typing system; the 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-types; 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 quality control testing system among the national and World Health Organization collaborating centers for streptococci; and dissemination of new approaches to typing of GAS to the international streptococcal community.