Distribution of emm genotypes among group A streptococcus isolates from patients with severe invasive streptococcal infections in Japan, 2001–2005

We surveyed emm genotypes of group A streptococcus (GAS) isolates from patients with severe invasive streptococcal infections during 2001–2005 and compared their prevalence with that of the preceding 5 years. Genotype emm1 remained dominant throughout 2001 to 2005, but the frequency rate of this type decreased compared with the earlier period. Various other emm types have appeared in recent years indicating alterations in the prevalent strains causing severe invasive streptococcal infections. The cover of the new 26-valent GAS vaccine fell from 93·5% for genotypes of isolates from 1996–2000 to 81·8% in 2001–2005.