【摘要】 目的研究和比较上海成人和儿童患者分离的A群链球菌(GAS)耐药、克隆分型、emm分型、生物膜形成及毒力因子携带等分子特征,为感染控制及治疗提供临床流行病学信息。方法 39株成人(13株)和儿童(26株)患者分离的GAS,用K-B纸片法测定对9种常用抗菌药物的敏感性;采用多位点序列分型(MLST)方法进行克隆分型;采用编码M蛋白的emm基因序列分析进行基因分型;采用脉冲场凝胶电泳(PFGE)方法分析不同emm型菌株的基因组特征;采用半定量生物膜形成试验分析其生物膜形成。聚合酶链反应(PCR)方法检测20个包括超抗原在内的GAS主要毒力基因。结果 39株GAS主要基因型为emm12-ST36(64.1%),emm1-ST28(17.9%);成人和儿童均以emm12-ST36为主。儿童菌株对红霉素和克林霉素的耐药率显著高于成人(P=0.008 7)。相同emm分型-克隆分型菌株在PFGE脉冲场带型中呈现高度聚集。生物膜形成与emm1型菌株明显相关(P=0.005),与红霉素和克林霉素耐药密切相关(P=0.000 3),儿童菌株的生物膜形成强于成人菌株(P<0.000 1)。毒力基因speG、speB、sdaB、Mac全部阳性;speA、speJ、spd3与emm1型菌株有明显相关(分别为P<0.000 1、P=0.005 5、P<0.000 1);speI、sic与emm12型菌株有明显相关(均为P<0.000 1);speH、ssa在emm12和emm1型菌株中有明显分布差异(分别为P=0.036 4、P=0.025 8);20个毒力基因在成人和儿童emm12型菌株中均没有明显分布差异(均为P>0.05)。结论 emm分型与克隆分型、PFGE、毒力基因有很好相关性。成人和儿童菌株在耐药情况、生物膜形成中均存在差异。特定emm型菌株与抗生素耐药和致病力密切相关,为感染控制提供依据。重要毒力基因将是未来研制新型疫苗降低GAS感染的新型靶标。更多还原

【Abstract】 Objective To investigate and compare the molecular epidemiological characteristics of Streptococcus pyogenes isolates from Shanghai adult and pediatric patients in terms of antimicrobial susceptibility,clone type,emm type,biofilm formation and virulence for better infection control and treatment.Methods Thirty-nine nonduplicate clinical isolates of S.pyogenes from adult and pediatric patients were analyzed by determining the susceptibility to antimicrobial agents by Kirby-Bauer method;clonal typing by multilocus sequence typing(MLST); genotyping by emm gene sequence analysis,which encoding M protein;genomic characteristics of different emm type strains by pulsed field gel electrophoresis(PFGE);and biofilm formation by semiquantitative biofilm formation test.Twenty main virulence genes of S.pyogenes,including 12 superantigen genes and 8other key genes were detected by PCR and gel electrophoresis.Results A total of 39 nonduplicate S.pyogenesisolates were analyzed.The most common genotype was emm12-ST36(64.1%)and emm1-ST28(17.9%).Isolates from adult and pediatric patients had the same dominant genotype,emm 12-ST36.The isolates from children showed significantly higher resistance rate to erythromycin and clindamycin than those from adult patients(P<0.000 1).Particular emmtype and clone type were frequently identified in the same PFGE cluster.Statistical analysis showed that biofilm formation was significantly associated with emmtype 1(P=0.005)and erythromycin/clindamycin resistance(P=0.000 3).The strains from children showed higher biofilm formation than those from adult patients(P<0.000 1).We found that virulence genes speA,speJand spd3 were significantly associated with emmtype 1(P<0.000 1,P=0.005 5,P<0.000 1),while speIand sic were significantly associated with emmtype 12(both P<0.000 1).We also found that the prevalence of speC,speH,ssa,smeZ,and sdaDgenes was significantly different between emmtype 12 and emmtype 1(P=0.023 8,P<0.000 1,P<0.000 1,P=0.000 3,and P =0.006 8,respectively).The prevalence of virulence genes speH,smeZ and sdaD was significantly different between the emmtype 12 strains from children and those from adults(all P<0.000 1).Conclusions There is a strong agreement between emmtype,clone type,virulence genes and the clusters defined by PFGE profiling of S.pyogenes.S.pyogenes isolates from adult and pediatric patients are different in terms of antibiotic resistance and biofilm formation.Certain emmtype is significantly associated with antibiotic resistance and virulence,which is useful for infection control.Dominant virulence genes may be the potential target for developing new vaccine to reduce S.pyogenesinfection in the future.更多还原