Objective To investigate the genetic structure of Streptococcus pneumoniae serotype 19F isolates from children in Beijing. Methods A total of 130 isolates were identified as serotype 19F among 1033 S. pneumoniae strains collected from 1997 to 2006 and 2010. There were 120 isolates characterized by antibiotic susceptibility, macrolide resistance gene and multilocus sequence typing(MLST). Results Among the 120 strains, only five strains were nonsuscep-tible to penicilln and the nonsusceptibility rate to cephalosporins increased from 1997 to 2010. There were 119(99.2%) strains resistant to erythromycin; 115(96.6%) carried the ermB gene and 64(53.8%) carried mefA gene, 60(50.4%) carried both genes. All isolates belonged to 31 sequence types, ST983 was the most prevalent ST, followed by ST271. From 1997 to 2010, the percentage of CC271 increased from 14.3% in 1997-1998 to 92% in 2010, whereas CC983 decreased from 64.3% to 0%. CC271 showed higher nonsuscetibility rate to β-lactam antibiotics than CC983. Conclusion The prevalence of serotype 19F of S.pneumoniae increases from 1997 to 2010 in Beijing. The increase of nonsusceptibility rate to β-lactam antibiotics is associated with the spread of international resistance clone CC271 due to the selection of antibiotics overuse.%目的 了解1997至2010年分离自北京儿童医院急性呼吸道感染患儿的19F型肺炎链球菌的抗生素敏感性及分子流行病学特征.方法 于1997-2006年以及2010年在北京儿童医院门诊病例中分离19F型肺炎链球菌,以120株经荚膜肿胀实验鉴定为19F型的肺炎链球菌为研究对象,采用E-test法和纸片扩散法检测菌株对9种抗生素的敏感性,聚合酶链式反应(PCR)检测红霉素耐药基因ermB和mefA,采用多位点序列分型(MLST)确定其序列分型(ST).结果 120株19F型肺炎链球菌中青霉素不敏感菌株5株,占4.2％,均为中介.红霉素不敏感率高达99.2％.从1997年到2010年头孢类抗生素敏感性逐年降低,头孢曲松敏感性从1997至1998年的100％下降到2010年的68.0％,头孢克洛敏感性则从100％下降到4.0％.在119株耐红霉素菌株中,115株(95.8％)携带ermB基因,64株(53.3％)携带mefA基因,60株(50.4％)同时携带两种耐药基因.MLST共分出31种ST,ST983最常见(共39株,占32.5％),其次是ST271(共13株,占10.8％).从1997到2010年,克隆群CC983的构成比下降(从1997至1998年的64.3％降为2010年的0),CC271的构成比升高(从14.3％升为92％),耐药性分析发现CC271对β-内酰胺类抗生素耐药率明显高于CC983.结论 1997-2010年19F型在肺炎链球菌中分离率升高,对β-内酰胺类抗生素耐药性增强,上述变化与抗生素选择压力下,高β-内酰胺类抗生素耐药性的国际流行克隆群CC271的输入和播散有关.
展开▼
