北京市儿童A族链球菌emm基因型别及药敏特征变化分析

Analysis of emm genotypes and drug susceptibility characteristic variations of Group A Streptococcus in children in Beijing

目的了解北京市儿童A族链球菌(GAS)M蛋白基因(emm基因)型别及药敏特征变化。方法回顾性研究。收集2018年、2019年、2021年北京市16区猩红热病原学监测哨点医院儿童临床诊断猩红热及咽部感染病例咽拭子样本分离的GAS菌株。采用PCR扩增及测序进行emm基因分型,采用微量肉汤稀释法测定10种抗生素最低抑菌浓度(MIC)。采用χ^(2)检验和Fisher′s确切概率法进行组间比较。结果共收集GAS菌株557株,检测到11种emm基因型(emm1、emm3、emm4、emm6、emm11、emm12、emm22、emm75、emm89、emm128、emm212)。其中emm1型42.73%(238/557株),emm12型48.65%(271/557株),其他emm型8.62%(48/557株)。emm1、emm12、其他emm型2018年分别为37.50%(105/280株)、57.14%(160/280株)、5.36%(15/280株);2019年分别为49.05%(129/263株)、39.54%(104/263株)、11.41%(30/263株);2021年分别为28.57%(4/14株)、50.00%(7/14株)、21.43%(3/14株)。2018年和2019年≤6岁儿童组中感染emm12型的构成比均高于>6岁儿童组(62.50%比46.88%,46.36%比30.36%),差异均有统计学意义(χ^(2)=7.182、6.973,均P<0.05)。选取225株GAS进行药敏检测,结果对青霉素、左氧氟沙星、美罗培南、利奈唑胺、头孢噻肟、头孢吡肟、万古霉素7种抗生素敏感率均为100.00%,对红霉素、四环素、克林霉素的耐药率分别为:2018年88.57%(93/105株)、87.62%(92/105株)、86.67%(91/105株);2019年94.34%(100/106株)、94.34%(100/106株)、87.74%(93/106株);2021年3种抗生素耐药率100.00%(14/14株)。2018年青霉素MIC_(50)、MIC_(90)均为0.03 mg/L;2019年分别为0.03 mg/L、0.06 mg/L;2021年均为0.06 mg/L。225株GAS中207株存在耐药,且均为联合耐药,红霉素-四环素-克林霉素三重耐药占94.69%(196/207株),红霉素-克林霉素双重耐药占4.35%(9/207株),红霉素-四环素双重耐药占0.97%(2/207株)。结论北京市2018年、2019年、2021年儿童GAS的emm基因型别多样,优势基因型为emm12与emm1,以emm12为主导流行型别。GAS菌株对红霉素、克林霉素、四环素维持较高耐药率,对青霉素等抗生素保持敏感,但青霉素MIC_(50)和MIC_(90)呈递增趋势。

Objective To clarify the M protein(emm gene)types and drug susceptibility characteristic variations of Group A Streptococcus(GAS)in children in Beijing.Methods The GAS strains isolated from throat swab samples of children diagnosed with scarlet fever and pharyngeal infection in scarlet fever etiology surveillance sentinel hospitals in 16 districts of Beijing in 2018,2019 and 2021 were analyzed retrospectively.PCR amplification and sequencing were used for emm genotyping,and the minimum inhibitory concentrations(MIC)of 10 antibiotics were determined by the broth microdilution method.The data were analyzed usingχ^(2) test and Fisher′s exact method between groups.Results A total of 557 GAS strains were collected,and 11 emm genotypes(emm1,emm3,emm4,emm6,emm11,emm12,emm22,emm75,emm89,emm128,and emm212)were detected.Of 557 strains,238 trains were of emm1 type(42.73%),271 strains were of emm12 type(48.65%)and 48 strains were of other emm types(8.62%).The detection rates of emm1,emm12 and other emm type genes in 2018,2019,and 2021 were[37.50%(105/280 strains),57.14%(160/280 strains),5.36%(15/280 strains)],[49.05%(129/263 strains),39.54%(104/263 strains),11.41%(30/263 strains)],and[28.57%(4/14 strains),50.00%(7/14 strains),21.43%(3/14 strains)],respectively.In children infected with emm12 in 2018 and 2019,there were more children under 6 years old than children over 6 years old(62.50%vs.46.88%,46.36%vs.30.36%)(χ^(2)=7.182,6.973;all P<0.05).Drug susceptibility testing results suggested that 225 randomly selected GAS strains were all 100.00%sensitive to 7 antibiotics including Penicillin,Levofloxacin,Meropenem,Linezolid,Cefotaxime,Cefepime and Vancomycin.The rates of resistance to Erythromycin,Tetracycline and Clindamycin were[88.57%(93/105 strains),87.62%(92/105 strains),86.67%(91/105 strains)],and[94.34%(100/106 strains),94.34%(100/106 strains),87.74%(93/106 strains)]in 2018 and 2019,respectively.The test strains were 100.00%(14/14 strains)resistant to the above 3 antibiotics in 2021.MIC_(50) and MIC_(90) values of Penicillin in 2018,2019,and 2021 were(0.03 mg/L,0.03 mg/L),(0.03 mg/L,0.06 mg/L),and(0.06 mg/L,0.06 mg/L),respectively.Among 225 GAS strains,207 strains had drug resistance and were resistant to more than one drug.Specifically,94.69%(196/207 strains)were resistant to Erythromycin,Tetracycline and Clindamycin.About 4.35%(9/207 strains)were resistant to both Erythromycin and Clindamycin.A total of 0.97%(2/207 strains)were resistant to Erythromycin and Tetracycline.Conclusions The emm genotypes of GAS in children in Beijing are diverse in 2018,2019 and 2021.The dominant genotypes are emm12 and emm1,and emm12 is the main epidemiological type.GAS strains maintain highly resistant to Erythromycin,Clindamycin and Tetracycline,and sensitive to Penicillin and other antibiotics.However,MIC_(50) and MIC_(90) of Penicillin shows an ascending trend.