耐甲硝唑幽门螺杆菌cagA基因检测与rdxA基因突变研究

Mutation of cagA gene and rdxA gene of Helicobacter pylori resistant to metronidazole

目的研究cagA基因、rdxA基因变异与幽门螺杆菌(Hp)甲硝唑耐药的关系。方法收集临床分离Hp 180株,用E-test法检测对甲硝唑的最低抑菌浓度(MIC),PCR扩增cagA、rdxA基因,并对rdxA基因进行测序。结果幽门螺杆菌对甲硝唑的耐药率为43.3%,其中甲硝唑高水平耐药菌54株,占69.2%;rdxA基因突变率为56.7%;cagA阳性菌中高耐药菌所占的比例和rdxA基因的突变率均明显高于cagA阴性菌。结论本地区幽门螺杆菌感染以高毒力菌株为主,rdxA基因突变在cagA基因阳性菌对甲硝唑产生高水平耐药可能起一定作用。

Objective To investigate the prevalence of cagA gene and the relationship between cagA gene and rdxA gene mutation in Helicobacter pylori resistant to metronidazole.Methods A total of 180 H.pylori were tested for cagA and rdxA gene by PCR,and the fragments of rdxA genes were directly suquenced.The metronidazole susceptibility testing was done by E-test to minimum inhibitory concentrations.Results The percentage of H.pylori isolates resistant to metronidazole was 43.3%,and 54（69.2%） were high-level metronidazole resistant strains.The mutation rate of rdxA gene was 56.7%.The quantity of high-level metronidazole-resistant strains and the mutation rate of rdxA gene in the H.pylori harboring cagA gene were higher than those without cagA gene.Conclusions The H.pylori infection was mainly due to high-toxicity strains.The H.pylori harboring both cagA gene and mutation of rdxA gene may play an important role in high-level resistant to metronidazole.