2011年北京市朝阳区儿童A组溶血性链球菌的emm基因分型及耐药性分析

摘要

Objective To understand the genotypes of emm gene and the drug-resistance of group A Streptococcus pyogens (GAS) in Chaoyang district, Beijing. Methods Seventy one GAS strains were isolated from the throat swabs taken from hospitalized children. Polymerase chain reaction (PCR) was conducted to amplify and emm gene and the erythrocin resistance related genes: mefA, erinA, ermB and Tn916 gene. The strains' drag susceptibilities to erythromycin and clindamycin were detected with E-test. Results The GAS strains with emm12. 0 gene accounted for the highest proportion (87. 4% ), followed by the strains with emml.O gene (9. 8% ), the strains with emn22.0 gene (1.4% ) and strains with emm75. 0 gene (1. 4% ). All of the GAS strains were erythromycin resistant, 95. 8% were clindamycin resistant and 95. 8% were cross resistant to both antibiotics. The carriage rates of ermA, ermB, mefA and Tn916 genes were 5.6% , 90. 1% , 4. 2% and 90. 1% respectively. Conclusion The most common genotype of GAS strains isolated from the sick children in Chaoyang was emm12.0. The drug resistant rates to erythromycin and clindamycin were high. The ermB gene was the most important erythromycin resistance determinant, while the Tn916 gene was the important determinant of the drug resistance spread in GAS.%目的 了解2011年北京市朝阳区儿童感染A组溶血性链球菌(GAS)的emm基因分型及对红霉素和克林霉素的耐药情况及耐药基因谱的特点.方法 从猩红热或咽峡炎及扁桃体炎儿童患者的咽拭子培养分离获得71株GAS,应用PCR扩增emm基因及红霉素耐药基因mefA、ermA、ermB和转座子基因Tn916;采用E-test法进行药敏试验并分析耐药情况.结果 北京市朝阳区儿童感染GAS的emm12.0基因型占87.4％,其次为emm1.0型(9.8％)、emm22.0型(1.4％)、emm75.0型(1.4％);GAS对红霉素和克林霉素的耐药率为100％和95.8％,两种药物的交叉耐药率为95.8％;耐药基因ermA、ermB、mefA和转座子基因Tn916的携带率分别为5.6％、90.1％、4.2％和90.1％.结论 北京市朝阳区2011年儿童感染GAS的主要流行株为emm12.0型,对红霉素普遍具有较高的耐药率且与克林霉素之间存在显著的交叉耐药;ermB基因是决定本地区2011年儿童感染GAS对红霉素耐药的重要基因;而Tn916转座子基因在GAS菌株间耐药基因扩散中起重要作用.