Dai Ning, Zhou Gang, Yan Jie
The Sir Run Run Shaw Hospital, College of Medical Sciences, Zhejiang University, Hangzhou 310016, China.
Zhejiang Da Xue Xue Bao Yi Xue Ban. 2003 Feb;32(1):37-40. doi: 10.3785/j.issn.1008-9292.2003.01.010.
To demonstrate the correlation of rdxA gene mutation and metronidazole (MTZ) resistance of H.pylori isolates in the local area.
Clinical strains of H.pylori were isolated from gastric biopsy of patients. Resistance to metronidazole of the isolates was determined by using diffusion test and two fold dilution test. Genome DNAs of the isolates were prepared for PCR to detect rdxA gene. The target amplification products were sequenced after T-A cloning. The sequences were compared with the reported sequences from Hp26695 and 134 other strains of H.pylori.
MTZ resistance rate was 76.1% in 21 clinical isolates. The target fragment 886 bp in length containing rdxA gene could be successfully amplified. In comparison with the reported corresponding sequence of H.pylori stain 26695, homologies of the nucleotide sequences from the amplification products were 90.1% approximate, equals 95.1%. Mutations caused by base insertion/deletion and substitution in the MTZ resistance isolates were found. Among these mutations, two types of insertion mutations have not been reported in literatures. No same mutations were present in the MTZ sensitive isolates.
The rdxA gene mutation may play an important role in MTZ resistance of H.pylori.
探讨本地幽门螺杆菌（H.pylori）分离株rdxA基因突变与甲硝唑（MTZ）耐药性的相关性。
从患者胃活检组织中分离H.pylori临床菌株。采用纸片扩散法和二倍稀释法检测分离株对甲硝唑的耐药性。提取分离株的基因组DNA，进行PCR扩增检测rdxA基因。将扩增产物进行T-A克隆后测序，所得序列与Hp26695及其他134株幽门螺杆菌的报道序列进行比较。
21株临床分离株中MTZ耐药率为76.1%。成功扩增出长度为886 bp的含rdxA基因的目的片段。与报道的幽门螺杆菌菌株26695的相应序列相比，扩增产物核苷酸序列的同源性约为90.1%，等同于95.1%。在MTZ耐药分离株中发现了由碱基插入/缺失和替换引起的突变。其中两种插入突变类型未见文献报道。MTZ敏感分离株中未出现相同突变。
rdxA基因突变可能在幽门螺杆菌对MTZ耐药中起重要作用。
