上海市嘉定地区感染患儿分离的化脓链球菌分子流行病学分析

Molecular epidemiological analysis of Streptococcus pyogenes isolated from children in Jiading,Shanghai

目的了解上海市嘉定地区感染患儿分离的化脓链球菌emm分型及其耐药特点,为临床治疗和感染控制提供相关信息。方法收集2014年11月至2015年7月在上海交通大学医学院附属瑞金医院北院门诊就诊的急性上呼吸道感染、急性扁桃体炎、急性咽炎等患儿或带菌者咽拭子样本分离的化脓链球菌75株。应用API 20 Strep链球菌鉴定板条进行菌株鉴定,并用纸片扩散法检测菌株对8种常用抗菌药物的敏感性。应用聚合酶链反应(PCR)扩增编码M蛋白的emm基因,对PCR扩增后的emm基因产物进行测序,通过比对,获得菌株的emm分型结果。采用脉冲场凝胶电泳(PFGE)分析不同emm基因型菌株的特征,并将75株化脓链球菌结果导入Bio Numerics软件进行聚类分析。结果上海市嘉定地区化脓链球菌对红霉素、克林霉素的耐药率分别为94.7%和97.3%,对红霉素和克林霉素的双重耐药率为93.3%。具有相同emm基因型的菌株在PFGE带型上高度聚集,其中存在占优势的PFGE型。在临床分离的75株化脓链球菌中,emm1基因型菌株25株(33.3%,25/75),emm12基因型菌株49株(65.3%,49/75),emm22基因型菌株仅1株(1.3%,1/75)。结论目前上海市嘉定地区儿童咽拭子样本分离得到的化脓链球菌对红霉素普遍耐药,且与克林霉素存在较严重的交叉耐药现象。emm12或emm1基因型菌株是上海市嘉定地区儿童主要感染的化脓链球菌类型。

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 Outpatientchildren 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 collectedby pharyngeal swab culture. The isolates of Streptococcus pyogenes were identified by API 20 Strep. Antimicrobialsusceptibility test was done by Kirby-Bauer method for 8 kinds of commonly-used antibiotics. The emm gene encodingM protein was amplified by polymerase chain reaction(PCR),and the gene product of PCR was sequenced. Throughcomparison,the emm genotypes were obtained. The characteristics of different emm genotypes were analyzed bypulsed-field gel electrophoresis(PFGE). BioNumerics software was used to analyze PFGE results from 75 isolates ofStreptococcus pyogenes for cluster analysis. Results The erythromycin and clindamycin resistance rates of Streptococcuspyogenes in Jiading,Shanghai were 94.7% and 97.3%,respectively. The double resistance rate to erythromycin andclindamycin was 93.3%. The isolates with the same emm genotype in PFGE band were in high cluster. There weremajor PFGE genotypes. Among 75 isolates of Streptococcus pyogenes,25 isolates(33.3%,25/75) contained emm1genotype,49 isolates(65.3%,49/75) contained emm12 genotype,and only 1 isolate(1.3%,1/75) containedemm22 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 emm12or emm1 genotype is the main epidemic pathogen among children in Jiading,Shanghai.