Extension of the Lancefield Classification for Group A Streptococci by Addition of 22 New M Protein Gene Sequence Types from Clinical Isolates: emm103 to emm124.
Facklam, Richard F. 1; Martin, Diana R. 6; Marguerite, Lovgren 3; Dwight, Johnson R. 2; Efstratiou, Androulla 4; Thompson, Terry A. 1; Gowan, Sonia 6; Kriz, Paula 5; Tyrrell, Gregory J. 3; Kaplan, Edward 2; Beall, Bernard 1
[Article] Clinical Infectious Diseases. 34(1):28-38, January 1, 2002.

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: Classic M protein serotyping has been invaluable during the past 60 years for the determination of relationships between different group A streptococci (GAS) strains and the varied clinical manifestations inflicted by these organisms worldwide. Nonetheless, during the past 20 years, the difficulties of continued expansion of the serology-based Lancefield classification scheme for GAS have become increasingly apparent. By use of a less demanding sequence-based methodology that closely adheres to previously established strain criteria while being predictive of known M protein serotypes, we recently added types emm94-emm102 to the Lancefield scheme. Continued expansion by the addition of types emm103 to emm124 are now proposed. As with types emm94-emm102, each of these new emm types was represented by multiple independent isolates recovered from serious disease manifestations, each was M protein nontypeable with all typing sera stocks available to international GAS reference laboratories, and each demonstrated antiphagocytic properties in vitro by multiplying in normal human blood.

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