Sequencing emm-specific PCR products for routine and accurate typing of group A streptococci

Abstract

Rapid sequence analysis of specific PCR products was used to accurately deduce emm types corresponding to the majority of the known group A streptococcal (GAS) M serotypes. The study involved 95 M type reference GAS strains and a survey of 74 recent clinical isolates. A high percentage of agreement between M type serology and the previously published 5' sequences of the emm genes of M type reference strains was noted. The 5' sequences for six established M protein genes-the emm-32, emm-34, emm-38, emm-40, emm-42, and emm-71 genes-were determined to supplement the existing emm sequence database. Rapid sequence analysis differentiated serologically M-nontypeable strains and was used to establish the probable clonal relationship between seven GAS isolates from one hospital outbreak.