Primary antibiotic resistance of helicobacter pylori in vietnamese patients with peptic ulcer disease

Background: Helicobacter pylori is a group 1 carcinogen. The genes cagA and vacA are the most studied, as they are crucial virulence factors linked to the pathogenicity of this bacterium. Antibiotic resistance is the main cause of failure in H.pylori eradication. Updating the antibiotic resistance situation of H.pylori in each region is important for recommending appropriate treatment regimens for the population and optimizing the effectiveness of H.pylori eradication treatment for each region and country. In addition, the polymorphism of the enzyme CYP2C19 alters the metabolism of proton pump inhibitors (PPIs), thereby affecting treatment outcomes in patients with peptic ulcer disease (PUD) and the eradication of H.pylori. Objective: To determine the rate of primary antibiotic resistance of H.pylori strains to Amoxicillin (AMX), Clarithromycin (CLA), Levofloxacin (LEV), Metronidazole (MET), and Tetracycline (TET) and investigate the prevalence of H.pylori virulence factors cagA, vacA and the phenotypes of CYP2C19 enzyme polymorphism. Subject and method: A cross-sectional descriptive study was performed on 216 patients at the American International Hospital from October 2019 to September 2022.Patients with peptic ulcer disease who underwent endoscopy and antibiotic culture by Epsilometer test (E-test) and the cagA, vacA genes, and CYP2C19 enzyme-encoding genes were identified using PCR techniques. Result: Among 216 patients, the mean age was 42.85 ± 11.76. The rate of primary resistance to CLA was the highest at 96.30%, while the rates of resistance to LEV, MET, and AMX were 58.8%, 8.80%, and 2.78%, respectively. In the study, there were no cases of primary antibiotic resistance to Tetracycline, with a resistance rate of 0%. There was no statistically significant difference in the rate of resistance to each antibiotic between the male and female groups (p>0.05). The rate of dual resistance to two antibiotics was very high, with 161/216 cases (74.54%). H.pylori strains with CagA (+) virulence factor accounted for 72.69%, while CagA (-) strains accounted for 27.31%. There was no significant gender difference in CagA distribution (p=0.488). All patients with peptic ulcer disease harbored H.pylori strains with VacA virulence, with the s1m1 type being the most common (50%). Patients with intermediate CYP2C19 metabolism phenotypes had the highest prevalence at 49.07%, followed by strong metabolizers (39.35%) and poor metabolizers (11.58%). There was no significant difference in CYP2C19 enzyme metabolism phenotypes between males and females (p=0.454). Conclusion: The very high rate of resistance to Clarithromycin indicates that the standard triple regimen is no longer effective and should not be used in clinical practice. The regimen with Levofloxacin should be combined with Bismuth to enhance treatment effectiveness. The rates of resistance to Amoxicillin, Tetracycline, and Metronidazole were low, so a Bismuth quadruple or a combination of these three drugs may be very effective in eradicating H.pylori. In untreated patients with H.pylori -induced peptic ulcer disease, CagA (+) genotype and VacA s1m1 genotype were predominant. These strains are associated with more severe tissue damage and higher activity levels compared to others. Patients with intermediate and strong CYP2C19 metabolizer phenotypes were relatively common. These patients may experience altered metabolism of proton pump inhibitors, which could impact treatment outcomes for peptic ulcer disease and H.pylori eradication.