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目的 探讨幽门螺杆菌 (Helicobacterpylori,Hp)rdxA基因型及其与甲硝唑耐药性的关系及耐药的分子机制。方法 对 5 4例包括胃炎、消化性溃疡、胃癌患者的Hp分离株进行甲硝唑敏感实验 ,得到敏感株和耐药株 ;提取Hp基因组DNA ,PCR扩增rdxA基因 ,并进行限制性片段长度多态性(RFLP)分型 ;统计学分析基因型和耐药性关系 ;对 1株敏感株和 2株耐药株rdxA基因测序分析突变情况。结果 rdxA基因可分为两型 :Ⅰ型和Ⅱ型。Ⅰ型中的敏感株和耐药株所占比例为 5 6 %和44 %,Ⅱ型中的敏感株占 16 %,耐药株占 84%。经统计学分析 ,rdxA基因Ⅱ型与耐药性有相关性。rdxA基因测序分析显示耐药株存在编码区碱基置换及插入造成的移码突变 ;非编码区亦存在单个碱基缺失及置换突变。结论 rdxA基因Ⅱ型与Hp的甲硝唑耐药性密切相关 ,耐甲硝唑株主要表现为Ⅱ型。rdxA基因突变是耐甲硝唑的主要原因。
Objective To investigate the relationship between rdxA genotypes of Helicobacter pylori (Hp) and the drug resistance of metronidazole and the molecular mechanism of drug resistance. Methods 54 cases of Hp isolates including gastritis, peptic ulcer and gastric cancer were subjected to metronidazole susceptibility test to get sensitive strains and resistant strains. Hp genomic DNA was extracted and the rdxA gene was amplified by PCR. The restriction fragment length (RFLP) typing. The relationship between genotypes and drug resistance was analyzed statistically. The mutations of rdxA gene in one sensitive strain and two resistant strains were sequenced and analyzed. Results rdxA gene can be divided into two types: type Ⅰ and type Ⅱ. The sensitive strains and resistant strains accounted for 56% and 44% respectively in type Ⅰ, 16% in type Ⅱ and 84% in resistant strains. The statistical analysis, rdxA gene type Ⅱ and drug resistance are related. The rdxA gene sequencing analysis showed that the resistant strains had the frameshift mutation caused by the base substitution and insertion in the coding region. The non-coding region also had the single base deletion and the substitution mutation. Conclusion The rdxA gene type Ⅱ is closely related to the resistance of metronidazole to Hp, while the metronidazole resistant strains are mainly type Ⅱ. The rdxA gene mutation is the main reason for metronidazole resistance.