Array of M Protein Gene Subtypes in 1064 Recent Invasive Group A Streptococcus Isolates Recovered from the Active Bacterial

Using sequence analysis to detect variation within the hy-pervariable M protein N terminus, we found 41 emm types encompassing 81 subtypes, among 1064 consecutive invasive group A streptococcus isolates from a recent multistate, population-based surveillance. Seventeen of the 30 emm types represented by multiple isolates displayed multiple sub-types. Most subtypes differed from reference strain emm se-quences as a result of single base substitutions or other al-terations likely to be stably inherited. The Centers for Disease Control and Prevention database (available at