中文摘要：

目的了解肺炎支原体（MP）对大环内酯类抗生素的耐药分子机制。方法对370例咽拭子标本进行MP分离培养,应用巢式PCR扩增MP种特异16S rRNA基因对临床分离株进行分子鉴定;通过体外药物敏感试验测定MP临床分离株对红霉素的最小抑菌质量浓度（MIC）,并筛选出耐药株;除23S rRNA结构域Ⅴ区外,通过PCR扩增与大环内酯类抗生素耐药性有关的23S rRNA结构域Ⅱ区及核糖体蛋白L4、L22的基因,扩增产物进行全自动DNA测序,测得序列与美国国立生物信息中心已登录的MP标准株M129的相应基因序列作比对。结果370例咽拭子标本中分离MP50株。其中敏感株4株,耐药株46株。耐药株的红霉素MIC显著升高。50株临床分离株和标准株FH均未出现23S rRNA结构域Ⅱ区的基因突变。在核糖体蛋白L4中,其中6株临床分离株和标准株FH分别出现了58位C→A、66位T→G、81位G→T、162位C→A和（或）430位A→G点突变。在核糖体蛋白L22中,50株临床分离株和标准株FH均出现了508位T→C点突变,且其中11株和标准株FH还分别出现了62位C→A、65位T→A和（或）279位T→C点突变。结论MP对大环内酯类抗生素耐药现象严重,23S rRNA结构域Ⅴ区中心环的药物作用靶位基因突变是耐药性产生的主要机制。在使用大环内酯类药物治疗的过程中,有体内诱导出耐药株的可能性。

英文摘要：

Objective To investigate the molecular mechanisms of macrolides resistance on mycoplasma pneumoniae（MP）. Methods Three hundred and seventy throat swab specimens were cuhured to isolate MP, clinical isolates were identified by nested polymerase chain reaction（PCR） for MP specific 16S rRNA gene, antibiotic susceptibility test was done to identify macrolide - resistant strains through their minimal inhibitory concentration （MIC） of erythromycin. Beside domain V of 23S rRNA, nucleotide sequences of domain Ⅱ of 23S rRNA and ribosoinal proteins IA and L22, which were associated with erythroinycin resistance,were amplified by PCR followed by direct automatic sequencing method. The DNA sequences were compared to the corresponding sequences of MP M129 to find molecular mechanisms of drug resistance. Results Fifty clinical strains were isolated fi＇om 370 throat swab specimens. Of 50 strains ,4 strains were susceptible to macrolide ,46 strains were macrolide - resistant. MIC of resistant strains to erythromycin were elevated. There was no gene mutation of domain Ⅱ of 23S rRNA in all strains used in the study. About ribosomal protein IA ,6 clinical strains and FH apeared mutations C58A,T66G, GS1T,CI62A and（or） A430G, respectively. About ribosomal protein L22, mutation T508C was observed in all strains except for M129 ,furthermore, 11 clinical strains and FH also appeared mutations C62A,T65A and（or）T279C,respectively. Conclusions Macrolide resistance in MP is very serious,the target mutation in domain Vof 23S rRNA is predominant mechanism that contribute to the macrolide resistance. Furthermore,there is possibility to induce macrolide - resistant MP in vivo during using macrolide drugs for therapy.