Genotypic study of Helicobacter pylori antibiotic resistance pattern in paraffin embedded gastric biopsy specimens obtained from patients with gastric cancer

Abstract

Introduction: Helicobacter pylori is involved in many common gastrointestinal disorders including gastritis, , peptic ulcer, adenocarcinoma. For treatment, antibiotics such as metronidazole, amoxicillin, clarithromycin, ciprofloxacin with proton pump inhibitors and bismuth salts are used. Due to antibiotic resistance, it is difficult to eradicate this bacterium.Purpose: The aim of this study is to Genotypic study of Helicobacter pylori antibiotic resistance pattern and its relationship with Cag A virulence factor genotype in gastric biopsy paraffin samples obtained from patients with gastric cancer Methods: 80 biopsy specimens prepared from patients referred to Imam Reza Hospital in Tabriz was collected in the age range of 55-103. At first, the presence of Helicobacter pylori was confirmed by urease polymerase chain reaction (PCR). In the next step, using real-time PCR, the resistance of clarithromycin and metronidazole related point mutations were evaluated using special probes and the melting temperature was evaluated. Finally, the results were obtained using sequencing methods. Were also confirmed by real-time PCR. In this study, we also examined the Cag A gene in bacteria present in tissue samples.Results: The frequency of clarithromycin resistance in cancer patients is higher than non-cancer patients, but this difference was not statistically significant. Also, the amount of frameshit mutations in frxA gene is more than rdxA gene also missense mutations in rdxA gene are more than frxA, but this difference is not statistically significant. No association was found between Cag A gene and antibiotic resistance in these patients.Conclusion: The resistance to metronidazole and clarithromycin antibiotics is higher in gastric cancer patients than in control groups, which indicates that the bacteria cannot be eradicated with this group of antibiotics. there is no signifant difference between clarithromycin and metronidazole resistance and 23SrRNA, frxA, rdxAa and Cag A gene mutations.