中文摘要：

目的：探讨沙眼衣原体对大环内酯类药物的分子耐药机制。方法：13例沙眼衣原体临床敏感株经红霉素、阿奇霉素、交沙霉素诱导耐药后与未耐药之前的敏感株和标准株E—UW-5／Cx比较，检测基因23SrRNA和核糖体蛋白L4的位点突变。结果：耐药株显现出对红霉素、阿奇霉素和交沙霉素低耐药性，MIC较敏感株分别增加了16、16、8倍。药物敏感性结果显示相对于红霉素、阿奇霉素，沙眼衣原体治疗交沙霉素的易感性最好。敏感株和耐药株的L4的PCR扩增产物的序列均出现G274A、C276T、C339T、C466G位点突变，考虑与大环内酯类药物耐药无关。耐药株的23SrRNA基因PCR扩增产物中出现了A2057G、A2059G和T2611C的突变。结论：沙眼衣原体对大环内酯类药物的耐药分子基础是23SrRNA基因的点突变。

英文摘要：

Objective： To study molecular mechanisms of macrolide resistance in Chlamydia trachomatis. Methods：Thirteen strains of Chlamydia trachomatis were exposed to subinhibitory concentrations of erythromycin （0.5 ug/ml）, azithromycin （0.5 ug/ml）, and josamycin （0.04 ug/ml） to select macrolide-resistant mutants with serial passages. Results： The Chlamydia trachomatis mutants presented with low-level resistance to erythromycin, azithromycin, and josamycin for which a sixteenfold increase, a sixteenfold increase and an eightfold increase, respectively, in the MICs for the mutant strains compared to the MIC for the susceptible strains were found. The results of chemosensitivity showed that josamycin had the highest susceptibility rate compared to erythromycin and azithromycin in the treatment of Chlamydia trachomatis. The ribosomal protein L4 and 23S rRNA genes of the susceptible and resistant strains of Chlamydia trachomatis were partially sequenced. A double mutation was found in the mutants, leading to Prol09 （CCG）→ Leu （CTG）, and Prol51 （CCG）→Ala ribosomal protein L4 of （GCC） （Escherichia coli numbering） in the corresponding protein, but these mutations were also found in parent strains. An investigation into the sequences of 23S rRNAs in the mutants revealed point mutations of A2057G, A2059G, and T2611C （Escherichia eoli numbering）. Conclusion： The molecular mechanism of macrolide resistance in Chlamydia trachomatis is point mutation in 23S rRNA.