肺炎链球菌对大环内酯-林可酰胺-链阳菌素的耐药监测及耐药机制研究

Resistance and genotypes of streptococus pneunmoniae isolates to macrolide-lincosamide-streptogramin

目的研究肺炎链球菌对大环内酯-林可酰胺-链阳菌素类抗菌素的耐药机制。方法K-B纸片法测定肺炎链球菌对红霉素、克林霉素、泰利霉素和喹奴普汀/达福普汀的耐药性。对全部红霉素耐药菌株和部分红霉素敏感菌株用聚合酶链反应(PCR)检测ermB和mefA基因。结果97株肺炎链球菌对红霉素、克林霉素、泰利霉素和喹奴普汀/达福普汀的耐药率分别为60.8%、58.8%、0和0。59株红霉素耐药菌株均检出ermB和/或mefA基因,其中34株(57.6%)ermB阳性,18株(30.5%)ermB和mefA同时阳性,7株(11.8%)mefA阳性。5株敏感菌株ermB和mefA基因均为阴性。结论本研究显示肺炎链球菌对泰利霉素和喹奴普汀/达福普汀高度敏感,而对红霉素和林可霉素则表现出较高的耐药性。肺炎链球菌对大环内酯-林可酰胺-链阳菌素的耐药机制以ermB基因介导的靶位改变为主。

Objective To investigate the prevalence and genotypic characterization of macrolide-resistant S.pneumoniae.Methods Between 2006 and 2008,97 S.pneumoniae isolates were collected and tested for susceptibility by Kirby-Bauer method.59 strains of erythromycin-resistant and 5 strains of erythromycin-susceptible S.pneumoniae isolates were examined by PCR for the presence of macrolide resistance genes(ermB,mefA).Results Of the 97 pneumococcal isolates,the resistance rates to erythromycin,clindamycin,telithromycin and Quinupristin/dalfopristin were 60.8%,58.8%,0 and 0,respectively.All erythromycin-resistant isolates had ermB and /or mefA gene of these strains,57.6% had ermB,30.5% had both ermB and mefA,and 11.9% had mefA of the 97 isolates.Conclusion Telithromycin and Quinupristin/dalfopristin appears to have fine antimicrobial activity against S.pneumoniae.The target modification mediated by ermB methylase is the predominant mechanism of macrolide-resistance in S.pneumoniae isolated.