幽门螺杆菌对甲硝唑耐药与rdxA基因分型及cagA基因的关系

Study on relationship between drug resistance of helicobacter pylori to metronidazole and rdxA genotype and cagA gene

目的:研究幽门螺杆菌(Helicobacter pylori H.pylori)甲硝唑耐药菌株相关基因的突变与甲硝唑耐药性的关系。方法:将贵阳医学院附属医院胃镜室分离H.pylori采用E-Test法对甲硝唑进行药敏试验后,PCR扩增rdxA、frxA、fdxB和cagA并对该基因进行测序。采用限制性内切酶片段长度多态性分型方法(RFLP)对rdxA基因进行分型。结果:313株H.pylori对甲硝唑耐药率为87.2%。其与NCBI已登录的国际标准菌株H.pylori 26695相应基因序列比对,cagA基因阳性率为100%,cagA基因在某些位点存在共同突变,还存在大量其他位点的随机散在突变,rdxA基因除了存在4个位点共同突变外,还有其他位点的散在突变。rdxA基因可分为两型,Ⅰ型与Ⅱ型的比例为293∶20,Ⅰ型耐药率为86.3%,Ⅱ型耐药率为100%。同时发现fdxB、frxA基因突变呈现出一定的规律性,具有碱基替换、插入和缺失3种类型的突变。结论:我院幽门螺杆菌甲硝唑耐药率较高,rdxA基因以Ⅰ型为主,而rdxA基因Ⅱ型的H.pylori均产生甲硝唑耐药,与H.pylori甲硝唑耐药性密切相关。rdxA基因突变及cagA基因阳性是耐甲硝唑的主要原因。

OBJECTIVE To study on the relationship between mutations of genes relevant to metronidazole drug resistant strains of Helicobacterpylori （H. pylori） and metronidazole drug resistance MEWHODS H. pylori was firstly separated in Gastroscope Room of Affiliated Hospital of Guiyang Medical College. Then drug sensitivity test was carried out to metronidazole Genes of rdxA, frxA, fdxB and cagA proliferated by PCR amplification. The Restricted Fragment Length Polymorphism （RFLP） method was used to genotype rdxA gene.TS Metronidazole resistance rate of 313 H. pylori strains was 87. 2%. Compared to relevant gene se- quence of international standard strain H. pylori 26695 listed by NCBI, the positive rate of cagA was 100%, common mutations exis- ted in some loci of cagA and randomly scattered mutations existed in some other loci; rdxA gene was sparsely mutated in other loci be- sides of common mutations in four loci. rdxA gene could be divided into type I and Ⅱ, and the ratio between type I and type Ⅱ was 293 ：20. The drug resistance was 86. 3% for type and 100% for type Ⅱ. Moreover, three types of mutations including base substitution, insertion and deletion were found in fdxB and frxA, which suggested certain regularity. CONCLUSION H. pylori in our hospital have high resistance to metronidazole The rdxA gene is mainly type L The rdxA gene of type II mainly induces H. pylori resistance to metronidazole. The rdxA gene types are of close relation with H. pylori, radxA gene mutation and positive cagA gene are both the main causes of metronidazole resistance.