What is the major GAS serotype classification system?
Regardless of mechanism, M protein appears to be the key virulence factor of GAS and is commonly used to classify GAS into serotypes. Associations between M- (or “emm”-) serotype and pathogenicity are described (i.e., rheumatogenic strains versus those associated with pyoderma or other GAS manifestations), although these associations are not uniform across host population groups and geography. This fact, along with the vast diversity in M serotypes, has been a major impediment to success despite extensive GAS vaccine development efforts.
