B群链球菌对红霉素及克林霉素耐药机制研究

The study of resistance mechanisms for group B Streptococcus to erythromycin and cli ndamycin

目的研究东莞地区孕产妇携带的GBS对大环内酯类的主要耐药表型及对红霉素、克林霉素的耐药机制。方法采用D试验筛查51株孕产妇携带的GBS对大环内酯类耐药表型;采用PCR方法检测GBS红霉素耐药基因erm TR、erm B、mef A/E及克林霉素耐药基因lin B,进行基因测序及BLAST序列比对分析。结果 51株GBS经D试验筛查,35株为c MLSB耐药表型,7株为M耐药表型,9株为L耐药表型,未检测到i MLSB耐药表型;PCR检测到erm B 40株、mef A/E 23株、lin B 5株,未检测到erm TR耐药基因;c MLSB耐药表型中37.14%(13/35)GBS同时检出erm B和mef A/E基因。结论 东莞地区孕产妇携带的GBS菌株大环内酯类耐药表型以c MLSB为主;erm B编码的23S r RNA甲基化酶是介导红霉素耐药的主要耐药机制;检测到新型耐药基因lin B。东莞地区c MLSB耐药表型高而M耐药表型低,提示克林霉素作为预防和治疗GBS感染的二线药物在该地区可能会受到一定的限制。

Objective The purpose of this investigation was to analyse Maternal carry GBS isolates collected in Dongguan in respect to their macrolide resistence phenotypes, erythromycin and clindamycin resistence mechanisms. Methods All 51 isolates were detected by D-trials for macrolide resistance phenotypes, The presence of erythromyein, clindamycin resistance gene such as ermTR, ermB, mefA/E, linB were determined by PCR amplification and analysed by sequencing. Results Of 51 GBS strains were tested by D-trials, there were 35 cMLSB, 7M, 9 L resistant phenotype, iMLSB resistant phenotype was not detected; 40 isolates harboured ermB genes, 23 isolates harboured mefA/E genes, linB gene was deteced in 5 strains, there were a failure to amplify ermTR genes by PCR. 37.14% of the strains exhibited a combination of ermB and mefA/E genes in cMLSa phenotypes. Conclusion In our study, there was a predominance of cMLSB phenotypes, indicating that erythromycin resistance was mediated by the principal methylation of 23S ribosomal RNA. The linB genes were detected. Clindamycin should not be recommended as the second-line antimicrobial in Dongguan city.