幽门螺杆菌对两种抗生素的耐药性及相关基因突变分析

目的分析浙江地区26株幽门螺杆菌（Helicobacter pylori,H.pylori）对克拉霉素和左氧氟沙星的耐药性,探讨H.pylori对克拉霉素、左氧氟沙星的耐药性,及其与23SrRNA基因、gyrA基因突变的关系。方法采用E-test法测定H.pylori对克拉霉素和左氧氟沙星的最低抑菌浓度（MIC）,提取H.pylori基因组DNA,采用PCR法扩增23SrRNA和gyrA基因片段,并对扩增产物进行测序、分析。结果药敏实验结果显示26例临床分离株中,6例对克拉霉素耐药,6例对左氧氟沙星耐药,8例对克拉霉素和左氧氟沙星双重耐药。所有克拉霉素耐药菌株23SrRNA基因都存在A2143G突变；左氧氟沙星耐药菌株gyrA基因中的喹诺酮类耐药决定区（quinolone-resistance-determining region,QRDR）存在突变,主要在第87和91位氨基酸。结论 23SrRNA基因的A2143G突变是导致H.pylori对克拉霉素耐药的主要原因；gyrA基因的87和91位氨基酸突变是导致H.pylori对左氧氟沙星耐药的主要原因。

Resistance of Helicobacter Pylori to two Antibiotics and its Related Gene Mutation

Objective To analyze resistance of Helicobacter pylori to clarithromycin and levofloxacin,and explore the resistance-related gene mutations of 23SrRNA and gyrA.Method Minimum inhibitory concentration（MIC）of H.pylori was tested for clarithromycin and levofloxacin by E-test.Genomic DNA of H.pylori was extracted,followed by PCR amplification and DNA sequencing for 23SrRNA and gyrA fragments.Results The results showed that among 26clinical isolates,6were found to be resistant to clarithromycin,6to levofloxacin,and 8to both antibiotics.-The A2143Gpoint mutation of 23SrRNA was noted in all isolates that are resistant to clarithromycin.The quinolone-resistance-determining region（QRDR）of gyrA gene was found in the strains resistant to quinolone,dominantly at amino acid residuals 87and 91.Conclusions A2143Gmutation of 23SrRNA leads to the bacteria resistance to clarithromycin whereas mutations at amino acid residuals 87and 91of gyrA are associated with the levofloxacin-resistance of H.pylori.