Molecular analysis of streptococcal pyrogenic exotoxin genes among group A Streptococcus isolates from Japanese patients with pharyngitis and skin infections

Group A Streptococci (GAS) from patients with pharyngitis and skin infections were examined for T serotypes, emm types, and streptococcal pyrogenic exotoxin gene types. The results were summarized as follows: 1) T and emm types were determined in 130 GAS isolates obtained between 2000 and 2004. Among 85 throat isolates, predominant T/emm types were T12/emm12 (25%), T4/emm4 (19%), and T1/emm1 (14%). Among 45 skin isolates, predominant T/emm types were T28/emm28 (13%), TB 3264/emm89 (13%), Tnontypeable/emm58 (13%), T1/emm1 (11%), and T12/emm12 (11%). Predominant T/emm types of skin isolates in 2000-2004 slightly differed from those during 1990s in our previous report. 2) The presence of streptococcal pyrogenic exotoxin genes in 292 GAS isolates obtained between 1990 and 2004 was examined. Significantly lower proportion of skin isolates, compared with throat isolates, was found to harbor the speA gene (12 versus 26%, respectively; p<0.01), or the speC gene (40 versus 65%, respectively; P<0.01). All but one of tested isolates carried the speB gene. The speB-negative isolate was identified as S. dysgalactiae subsp. equisimilis with the group A antigen. 3) Types of the speA alleles were determined in 59 speA-positive GAS isolates. Among 44 throat isolates, 37 (84%) were speA lineage I (speA1-speA2-speA3-speA6), and 7 (16%) were lineage II (speA4-speA5). Among 15 skin isolates, 11 (73%) were lineage I and 4 (27%) were lineage II. The pairwise associations were observed between emm type and speA allele: emm1 and speA2, emm3 and speA3, emm6 and speA4, emm11 and speA2, emm18 and speA1.