中文摘要：

目的 研究外源指导序列（external guide sequence，EGS）在体外逆转淋球菌多重耐药株为敏感株中的作用。方法 构建针对多传递耐药（multiple transferable resistance，mtr）系统中MtrC基因，并含卡那霉素抗性基因的EGS重组质粒pET-28a（＋）-EGS-MtrC，采用常规CaCl2法将重组质粒导入临床分离的多重耐药淋球菌中，通过菌落PCR进行鉴定，并利用分光光度计检测阳性转化菌在含不同浓度氨苄西林的培养基中的生长情况，测定淋球菌转化前后对阿奇霉素、结晶紫、红霉素、TritonX-100、四环素的最小抑菌浓度（MIC）。结果 PCR结果显示阳性转化菌含有预期大小的转化片段；多重耐药淋球菌在浓度为50、100ug／ml的氨苄西林培养基中生长良好，而导入EGS-MtrC的转化菌在含100ug／ml氨苄西林的培养基中不能生长，在50ug／ml氨苄西林培养基中生长受抑制。导入EGS-MtrC的转化菌对阿奇霉素、结晶紫、红霉素、TritonX-100、四环素的MIC值均有明显下降。结论 pET-28a（＋）-EGS-MtrC转化淋球菌成功；导入EGS-MtrC的转化菌部分恢复了对氨苄西林的敏感性；转化菌对阿奇霉素、结晶紫、红霉素、TritonX-100、四环素的敏感性增加。

英文摘要：

Objective To study the possibility of converting the multiple drug-resistant isolates of Neisseria gonorrhoeae into drug-sensitive ones by using external guide sequence （EGS） technique in vitro. Methods Recombinant plasmid encoding EGS-MtrC （an important protein of multiple transferable resistance efflux system） and kanamycin drug resistant gene, named pET-28a（＋）-EGS-MtrC, was constructed. Routine CaCl2 method was used to introduce the plasmid into multiple drug-resistant clinical isolates Neisseria gonorrhoeae. PCR was used to identify the bacteria and spectrophotometer was used to detect the growth rate in liquid and solid culture medium containing ampicillin. The MIC of Neisseria gonorrhoeae was detected before and after conversion respectively. Results The multiple drug-resistant clinical isolates Neisseria gonorrhoeae grew well in ampicillin-containing （50 and 100 ug/ml） medium, whereas the transformants with pET-28a（＋）-EGS-MtrC failed to grow in 100 ug/ml ampicillin-containing medium and inhibited in 50 ug/ml ampicillin-containing medium. Conclusion PET-28a（＋）-EGS- MtrC was transfected into Neisseria gonorrhoeae successfully. The sensitivity to ampicillin, azithromycin, crystal viole, eryrhromycin, TritonX-100 and tetracycline in transformants with pET-28a（＋）-EGS-MtrC was partly reversed.