肺炎链球菌对红霉素耐药机制的研究

Resistance mechanism of erythromycin in Streptococcus pneumoniae

目的 研究北京地区肺炎链球菌对红霉素的耐药机制。方法 收集本院 1998～ 1999年分离的对红霉素耐药的肺炎链球菌 116株 ,采用“荚膜肿胀”技术进行血清分型 ,聚合酶链反应(PCR)检测对红霉素耐药的基因erm/mef,脉冲场凝胶电泳 (PFGE)和青霉素结合蛋白 (PBP)基因印迹技术追踪菌株之间的同源性。结果 116株红霉素耐药株的血清型主要为 2 3F(30 0 % ) ,6A(19 0 % ) ,19F(13 8% ) ,15 (7 8% ) ,2 3A(5 2 % )。 95 7%的青霉素不敏感株同时也耐红霉素 ;85 %的菌株表现为MLS表型 ,即同时耐克林霉素 ;86 4 %的红霉素耐药株具有erm基因 ,6 %的菌株同时有erm和mef基因 ,1 7%的菌株只有mef基因 ,4 2 %未能检测到erm或mef基因。PFGE发现 2种耐药克隆 :1个是青霉素耐药的血清型为 2 3F的克隆株 ,另 1个是青霉素敏感而红霉素耐药的、血清型为 6A的克隆株。结论 核糖体突变 (erm基因编码 )是北京地区肺炎链球菌耐红霉素的主要机制 ,2种耐药克隆值得关注。

Objective To investigate resistance mechanism against erythromycin in Streptococcus pneumoniae from Beijing region. Methods 116 strains of erythromycin resistant Streptococcus pneumoniae were collected from 1998 to 1999 at Peking Union Medical College Hospital Serotyping was done with 'capsular swelling' technique erm/mef genes were detected with PCR, pulsed field gel electrophoresis (PFGE) and penicillin binding protein (PBP) fingerprinting technique were used to detect the DNA of resistant strains Results The prevalent serotypes in the 116 erythromycin resistant strains were 23F(30 0%),6A(19 0%),19F(13 8%),15(7 8%),23A(5 2%) 95 7% of penicillin resistant strains were also macrolide resistant, most (85%) expressing the MLS phenotype with co resistance to clindamycin The macrolide resistance determinant in 86 4% of erythromycin resistant strains was the erm gene, both the erm and mef genes were found in 6%, mef alone in 1 7% and no mechanism in 4 2% PFGE identified two clones: one a serotype 23F clone resistant to penicillin; and the other a penicillin susceptible and macrolide resistant serotype 6A clone Conclusions Ribosomal modification (erm gene coded) was the main resistance mechanism against erythromycin in Streptococcus pneumoniae in Beijing region Two resistance clones bear concern