中文摘要：

目的：研究不同耐药淋球菌菌株多传递耐药（mtr）系统反向重复序列（IR）区基因突变与mtrC基因转录水平的差异性，进一步探索mtr系统介导耐药的机制。方法：采用琼脂稀释法测定抗生素对菌株的最小抑菌浓度（MIC），PCR扩增含IR区的目的基因并对扩增产物测序，同时采用反转录（RT）-PCR检测mtrC基因mRNA表达水平的变化。结果：5株敏感株及5株仅耐青霉素菌株无IR区基因突变，16株多重耐药菌株中IR区均有碱基A／T缺失。敏感株mtrC转录水平显著低于耐药株（P〈0．05），而耐药菌株组中IR区碱基突变组mtrC转录水平显著高于无突变组（JP〈0．05）。结论：淋球菌染色体mtrR启动子区域的IR区基因突变会引起mtrC基因转录增加，进而提高奈瑟淋球菌的耐药性。

英文摘要：

Objectives： To study the difference of gene mutation in IR domain of mtr succession together with the variability of transcriptional levels in mtrC gene among different antibiotic resistant Neisseria gonorrhoeae（NGs）. Methods： The susceptibility of the isolated strains was tested by agar plate dilution method for minimum inhibitory concentrations （MICs）. The mtr system＇s IR gene of NGs was sequenced after amplification by polymerase chain reaction （PCR）. Transcriptional levels in mtrC gene were also tested by reverse transcriptional polymerase chain reaction （RT-PCR）. Results： A/T deletions were found in IR domain of all the 16 multiple-antibiotic-resistant strains. However, there was no gene mutation detected in IR domain of 5 sensitive strains and 5 penicillin-resistant strains. Transcriptional levels in mtrC gene of sensitive strains were significantly lower than those of resistant strains （P〈0.05）. Among multiple-antibiotic-resistant strains, transcriptional levels in mtrC gene of IR domain mutation groups were significantly higher than those of no mutation groups （P〈 0.05）. Conclusions： Mutation in IR domain of NG mtrR promoter region may enhance transcription of mtrC gene and further elevate the drug resistance of NGs.