北京地区猩红热样红斑患儿咽部A族链球菌分离株的emm基因型和超抗原分布特征

Distribution characteristics of emm genotype and superantigen of Group A Streptococcus isolated from the pharynx of children with scarlet fever-like erythema in Beijing

目的分析北京地区猩红热样红斑患儿咽拭子分离的A族链球菌(GAS)的基因特征。方法回顾性研究。收集2019年6月至2020年2月在首都医科大学附属北京儿童医院皮肤科就诊的猩红热样红斑患儿咽部GAS分离株,采用PCR和测序检测菌株emm基因分型和超抗原基因(speA、speB、speC、speF、speG、speH、speI、speJ、speK、speL、speM、ssa和smeZ)。组间比较采用χ^(2)检验或Fisher′s确切概率法。结果共收集147株GAS菌株,emm型别主要为emm1.0型76株(51.70%)和emm12.0型60株(40.82%),其他7种emm型的菌株均少于5株。speF、smeZ、speG、speC、speB和ssa的检出率高,分别为100.00%(147/147株)、100.00%(147/147株)、99.32%(146/147株)、95.24%(140/147株)、94.56%(139/147株)、92.52%(136/147株),speA、speJ、speI、speH和speM检出率低,分别为51.70%(76/147株)、49.66%(73/147株)、32.65%(48/147株)、23.81%(35/147株)和4.08%(6/147株),未检测到speK及speL。emm1.0型菌株speA和speJ的携带率[85.53%(65/76株)、84.21%(64/76)株]明显高于emm12.0型[6.67%(4/60株)、10.00%(6/60株)],而speH和speI的携带率[9.21%(7/76株)、2.63%(2/76株)]明显低于emm12.0型[46.67%(28/60株)、75.00%(45/60株)],差异均有统计学意义(均P<0.001)。结论北京地区猩红热样红斑患儿咽部分离的GAS菌株以emm1.0和emm12.0型为主,emm1.0更多见;菌株emm与携带超抗原基因谱存在相关性,emm1.0型菌株1型超抗原基因谱携带率显著高于emm12.0型,而后者2、3、4型超抗原基因谱携带率显著高于前者。

Objective To analyze the genetic characteristics of Group A Streptococcus(GAS)isolated from the pharynx of children with scarlet fever-like erythema.Methods Pharyngeal GAS isolates were collected retrospectively from children with scarlet fever-like erythema admitted in the Department of Dermatology,Beijing Children′s Hospital,Capital Medical University from June 2019 to February 2020.PCR and sequencing were used to detect emm genotyping and superantigen genes(speA,speB,speC,speF,speG,speH,speI,speJ,speK,speL,speM,ssa and smeZ)of the isolates.Data were compared by the chi-square test or Fisher′s exact test between groups.Results A total of 147 GAS strains were collected.The main emm genotypes were emm1.0 in 76 strains(51.70%)and emm12.0 in 60 strains(40.82%).Other 7 emm genotypes were all found in less than 5 strains.The detection rate of speF,smeZ,speG,speC,speB and ssa were as high as 100.00%(147/147 strains),100.00%(147/147 strains),99.32%(146/147 strains),95.24%(140/147 strains),94.56%(139/147 strains)and 92.52%(136/147 strains),respectively.speA,speJ,speI,speH and speM had a low detection rate of 51.70%(76/147 strains),49.66%(73/147 strains),32.65%(48/147 strains),23.81%(35/147 strains)and 4.08%(6/147 strains),respectively.No speK and speL were detected.The frequencies of speA and speJ in emm1.0 strains(65/76 strains,85.53%and 64/76 strains,84.21%)were significantly higher than those in emm12.0 strains(4/60 strains,6.67%and 6/60 strains,10.00%).However,the frequencies of speH and speI in emm1.0 strains(7/76 strains,9.21%and 2/76 strains,2.63%)were significantly lower than those in emm12.0 strains(28/60 strains,46.67%and 45/60 strains,75.00%)(all P<0.001).Conclusions At present,emm1.0 and emm12.0 are the main GAS strains isolated from the throat of children with scarlet fever-like erythema in Beijing,and emm1.0 is more common.There is a correlation between emm genotyping and the superantigen gene profile.Type 1 superantigen gene profile is significantly more frequently detected in emm1.0 strains than in emm12.0 strains.Type 2,3 and 4 superantigen gene profiles are significantly more frequently detected in emm12.0 strains than in emm1.0 strains.