重庆地区幽门螺杆菌对甲硝唑的耐药性和耐药机制的研究

Prevalence and molecular mechanism of Helicobacter pylori resistant to metronidazole in Chongqing area

目的了解重庆地区幽门螺杆菌(Heliobacter pylori,Hp)对甲硝唑的耐药情况,探讨Hp对甲硝唑耐药的分子机制,以助于指导临床用药。方法分离培养获得96株Hp,采用琼脂稀释法进行体外抗生素敏感试验,检测Hp对甲硝唑的耐药率,比较主城区和周边区县的差异。挑选甲硝唑耐药Hp 44株,提取细菌DNA,PCR扩增rdxA基因。T-A克隆后测序,比较NCTC11637和44株临床分离株的基因序列。结果重庆地区Hp对甲硝唑的耐药率为91.67%,主城区和周边区县耐药率无统计学差异(P>0.05)。与NCTC11637的基因序列比较,耐药Hp的rdxA基因出现插入突变和碱基替换突变。结论重庆地区Hp对甲硝唑的耐药率较高,因此,甲硝唑不应再用于抗Hp治疗。另外,部分甲硝唑耐药Hp存在rdxA基因突变,故rdxA基因突变可能是重庆地区甲硝唑耐药的重要原因。

Objective To investigate the prevalence and resistance mechanism of Helicobacter pylori （Hp） resistant to metronidazole in Chongqing area,and instruct clinical medication. Methods Ninety six Hp clinical isolates were cultured. The susceptibilities of the strains to metronidazole were tested by agar dilution test. Then compared the prevalence of Hp resistant to metronidazole in urban and in rural area. Of 44 Hp resistant strains to metronidazole were selected. The DNAs of Hp were extracted and prepared for PCR to amplify rdxA gene. The PCR amplification products were sequenced after T-A cloning. Then, the sequences were compared with NCTC11637. Results The prevalence of Hp resistant to metronidazole in Chongqing area was 91.67 %. There was no statistically significant difference between the urban areaand the rural area （P〉0. 05）. In comparison with NCTC11637, mutations caused by base insertion and substitution in rdxA of the resistance isolates were found. Conclusions The results indicated that the prevalence of Hp resistant to metronidazole in Chongqing area was higher. In this aspect, metronidazole was used to treat Hp no longer. Additionally, the majority of metronidazole-resistant Hp strains in Chongqing have gene mutation in rdxA, it may be the key factor that causes metronidazole-resistant Hp in Chongqing.