Abstract:

Objective To study the emm genotype in Streptococcus pyogenes isolated from children in Jiading,Shanghai and its drug resistance,and to provide a reference for infection control and treatment.Methods Outpatient children diagnosed with acute respiratory infection,acute tonsillitis and acute pharyngitis or carriers in Ruijin Hospital（North） from November 2014 to July 2015 were enrolled,and 75 isolates of Streptococcus pyogenes were collected by pharyngeal swab culture. The isolates ofStreptococcus pyogenes were identified by API 20 Strep. Antimicrobial susceptibility test was done by Kirby-Bauer method for 8 kinds of commonly-used antibiotics. The emm gene encoding M protein was amplified by polymerase chain reaction（PCR）,and the gene product of PCR was sequenced. Through comparison,the emm genotypes were obtained. The characteristics of different emm genotypes were analyzed by pulsed-field gel electrophoresis（PFGE）. BioNumerics software was used to analyze PFGE results from 75 isolates of Streptococcus pyogenes for cluster analysis. Results The erythromycin and clindamycin resistance rates of Streptococcus pyogenes in Jiading,Shanghai were 94.7% and 97.3%,respectively. The double resistance rate to erythromycin and clindamycin was 93.3%. The isolates with the same emm genotype in PFGE band were in high cluster. There were major PFGE genotypes. Among 75 isolates of Streptococcus pyogenes,25 isolates（33.3%,25/75） contained emm1 genotype,49 isolates（65.3%,49/75） contained emm12 genotype,and only 1 isolate（1.3%,1/75） contained emm22 genotype. Conclusions There is a high erythromycin resistance rate of Streptococcus pyogenes isolated from children in Jiading,Shanghai. The cross resistance with clindamycin is high. Streptococcus pyogenes containing emm12 or emm1 genotype is the main epidemic pathogen among children in Jiading,Shanghai.

Key words: Streptococcus pyogenes, Erythromycin, emm genotypes, Bacteria, Drug resistance