A study of rdxA gene deletion in metronidazole resistant and sensitive Helicobacter pylori isolates in Kerman, Iran

Introduction and objective: Metronidazole (Mtz) resistance in Helicobacter pylori has been found to be associated with mutations in rdxA, a gene encoding an oxygen insensitive NADPH nitroreductase, and enhanced by mutations in frxA a gene encoding a NAD(P)H-flavin oxidoreductase. In this study, we examined the prevalence of rdxA deletion among local isolates of H. pylori. Materials and methods: We tested 63 H. pylori isolates obtained from 191 patients referred to endoscopy unit of Afzalipour hospital in Kerman, Iran, during 2009 for their susceptibility to common anti-H. pylori antibiotics using a modified disk diffusion test. Then the metronidazole resistant and sensitive isolates were evaluated for deletion in rdxA gene by PCR methods and compared with each other. Results: From 35 resistant H. pylori isolates in this study only 22.9% (8 isolates) detected with deletion rdxA gene. No rdxA deletion was detected in sensitive isolates. Conclusion: According to rdxA deletion rates in this study, it seems that some other nitroreductases are involved in metronidazole activation or there are other metronidazole resistance mechanisms involved.