Objective:To analyze emm type

macrolide-resistance genes and superantigen gene profile of GAS isolates from children with pharyngitis in Chongqing.Methods:A total of 44 clinical isolates of GAS were obtained from children with pharyngeal diseases in 2007

Chongqing.The macrolide-resistant genotype(ermB

ermTR and mefA) and superantigen gene of group A streptococcal isolates(ssa、SMEZ、speA、speC、speG、speH、speI and speJ)were detected by PCR.Emm types were applied by PCR and sequencing.Results:Emm12 was the most common emm type(26 isolates

59.1%).Emm1 was the second(7 isolates

15.9%).Emm22 had 2 isolates

emm6 had 2 isolates

emm3 had 2 isolates

and emm80

emm63

emm102

stG485 and st1815 had 1 isolate respectively.All 44 isolates were detected ermB gene(100%)

33 isolates were detected erm TR gene(75.0%)

and 3 isolates were detected mefA gene(6.8%).All of the isolates were detected ssa

SMEZ and speH.The detection rates of other superantigen genes were speG(84.1%)

spec(81.2%)

speI(63.6%)

speA(50%)and speJ(15.9%).Six in 7 isolates of emm1 type were detected speA gene(85.7%)

and 7 in 26 isolates of emm12 type were detected speA gene(26.9%).The distribution of speA in emm1 and emm12 had a statistically significant difference(P=0.008

<0.05).The distribution of macrolide-resistant genotypes was at random

and had no correlation with emm types.Conclusion:The most prevalent emm types in pharyngeal isolates in Chongqing were emm12 and emm1.The macrolide-resistant mechanism was mostly determined by the change of target site in the 23SrRNA methylase encoded by erythromycin resistance methylase B(ermB) genes.Emm type was not apparantly related to macrolide-resistance genes

and the distribution of speA was mainly related to emml.