2003-2008年北京儿童医院脓疱疮患儿A组β溶血性链球菌分离株耐药基因检测及emm分型研究

The Characteristics of Streptococcus pyogenes from Chinese children with impetigo between 2003 and 2008

目的研究北京儿童医院脓疱疮患儿临床分离A组β溶血性链球菌(GAS)及其对抗菌药物的敏感性情况。方法收集北京儿童医院2003—2008年收治的1735例脓疱疮儿童皮损部位分离出的52株GAS菌株,采用琼脂稀释法测定9种抗菌药物的最低抑菌质量浓度(MIC)值;用聚合酶链反应方法对上述菌株进行大环内酯类抗生素耐药基因ermB、ermA和mefA检测以及emm分型情况。结果分离株对四环素及大环内酯类抗生素耐药率均为100%,MIC>256mg/L;对青霉素、头孢拉啶及氧氟沙星的敏感率高达100%。大环内酯类抗生素耐药基因ermB、ermA和mefA和阳性率分别为92.30%、7.70%和0;分离株的emm分型最常见的为emm12.0(53.85%),emm1.0(36.54%)。结论北京儿童医院收治的脓疱疮儿童GAS感染流行菌株对大环内酯类抗生素耐药率很高,主要耐药机制为ermB编码的23SrRNA甲基化酶导致靶位改变,在北京地区青霉素类和头孢菌素类抗生素仍是治疗GAS感染首选药物。

Objective To investigate the characteristics of Streptococcus pyogenes （Group A Streptococcus, GAS） isolated from Chinese children with impetigo.Methods The sensitivity of 52 GAS to nine antibiotics （penicillin,cephadine, ofloxacin, chloramphenicol, tetracycline, erythromycin, clarithromycin, clindamycin and azithromycin） was measured as minimal inhibitory concentration （MICs）. The macrolide-resistance genes and M protein gene （emm gene） were detected by polymerase chain reaction （PCR）.Results Among 52 GAS strains isolated from 1735 patients with impetigo, 100% （52/52） were resistant to tetracycline and the macrolide antibiotics erythromycin, clarithromycin, clindamycin and azithromycin; No isolates were detected with both ermB and ermA, and no isolates were detected with the mefA gene. The most common strains were emm 12.0 （28/52, 53.85% ）, and emm 1.0 （19/52, 36.54%）. Rare strains were emm 4.0 （1/52, 1.92%）, emm 8.0（1/52, 1.92%）, emm 22.0 （1/52, 1.92%）, emm 101 （1/521.92%）, and emm 114 （1/52, 1.92%）.Conclusion The most prevalent types were emml.0 and emml2.0. GAS strains had a high percentage of resistance to macrolide antibiotics and tetracycline. Most expressed the ermB gene and were sensitive to penicillin,cephadine and ofloxacin.