脓疱病儿童A族链球菌 emm分型、毒力基因及菌株分离部位相关性研究

Correlation of the emm genotyping and virulence genes with the isolation sites of Group A Streptococcus strains from children with impetigo

目的探讨A族链球菌(GAS)emm基因型、毒力基因及菌株分离部位之间的关系。方法回顾性研究。采集2006年至2008年就诊首都医科大学附属北京儿童医院的脓疱病患儿标本进行GAS分离鉴定, 从16例脓疱病患儿中共分离出24株GAS菌株, 其中7对菌株分别分离自7例患儿的咽喉和皮肤, 1对菌株分离自1例患儿的外阴和皮肤, 其余8株GAS分离自8例患儿的皮肤脓液样本。应用聚合酶链反应方法检测emm基因型及携带13种毒力基因(speA、speB、speC、speF、speG、speH、speI、speJ、speK、speL、speM、smeZ和ssa)情况, 对GAS菌株emm基因型、毒力基因及分离部位的关系进行分析。结果本研究检测出4种emm基因型[emm1.0(15/24)、emm12.0(4/24)、emm22.0(2/24)、emm160.0(1/24)]及1种亚基因型[emm12.19(2/24)]。13种毒力基因speA、speB、speC、speF、speG、speH、speI、speJ、speK、speL、speM、smeZ及ssa的携带率分别为58.3%、100%、91.7%、100%、50.0%、12.5%、54.2%、66.7%、16.7%、25.0%、12.5%、100%和91.7%。所有菌株均携带5~11种毒力基因, 并全部携带speB、speF及smeZ。在不同emm基因型的菌株中, speA与speJ的携带率比较, 差异均有统计学意义(均P<0.05)。在皮肤来源菌株和咽喉来源菌株之间, 包含5个emm1.0型配对的菌株, 其毒力基因分布比较, 差异均无统计学意义(均P>0.05)。结论脓疱病儿童GAS的毒力基因分布与emm基因型密切相关, 但与分离部位无关。

Objective To investigate the correlation of the emm genotypes and virulence genes with the isolation sites of Group A Streptococcus(GAS).Methods It was a retrospective study.The specimens were collected from children with impetigo in Beijing Children′s Hospital,Capital Medical University from 2006 to 2008 for GAS isolation and identification.A total of 24 GAS strains were isolated from 16 children with impetigo,among which 7 pairs of strains were isolated from the throat and skin of 7 children,and 1 pair of strains was isolated from the vulva and skin of one child,and the remaining 8 GAS strains were isolated from the skin pus samples of 8 children.Polymerase chain reaction was applied to detect the emm genotypes and 13 virulence genes(speA,speB,speC,speF,speG,speH,speI,speJ,speK,speL,speM,smeZ and ssa).The correlation of the emm genotypes and virulence genes with the isolation sites of GAS strains was analyzed.Results In this study,four emm genotypes were detected,including emm1.0(15/24),emm12.0(4/24),emm22.0(2/24)and emm160.0(1/24),and one subtype emm12.19(2/24)was detected as well.The carrying rates of 13 virulence genes speA,speB,speC,speF,speG,speH,speI,speJ,speK,speL,speM,smeZ and ssa were 58.3%,100%,91.7%,100%,50.0%,12.5%,54.2%,66.7%,16.7%,25.0%,12.5%,100%and 91.7%,respectively.All strains carried 5 to 11 virulence genes and they all carried speB,speF and smeZ.There were significant differences in the carrying rate of speA and speJ among the strains with different emm genotypes(all P<0.05).There was no significant difference in the distribution of virulence genes between skin isolates and pharyngeal isolates,including the 5 pairs of strains carrying the emm1.0 genotype(all P>0.05).Conclusions The distribution of virulence gene of GAS in children with impetigo is significantly correlated with the emm genotype,rather than the isolation site.