Seven-Day Bismuth-based Quadruple Therapy as an Initial Treatment for Helicobacter pylori Infection in a High Metronidazole Resistant Area

Background: The prevalence of metronidazole-resistant H. pylori is almost 50% in Thailand which severelylimits the use of this drug for eradication therapy. The aims of this study were to evaluate the efficacy andsafety profiles of 7-day bismuth-based quadruple therapy including metronidazole as an initial treatment for H.pylori infection in a high metronidazole resistance area. Materials and
Methods: This study was performed atThammasat University Hospital and King Chulalongkorn Memorial Hospital during January 2009 to October2010. Patients with non-ulcer dyspepsia (NUD) with active H. pylori infection were assigned to receive sevendays of quadruple therapy (pantoprazole 40 mg bid, bismuth subsalicylate 1,048 mg bid, amoxicillin 1 gm bidand metronidazole 400 mg tid). H. pylori infection was defined as positive H. pylori culture or two positive tests(rapid urease test and histology). Antibiotic susceptibility test for metronidazole by Epsilometer test (E-test)was performed in all positive cultures. At least four weeks after treatment, 13C urea breath test (13C-UBT) wasperformed to confirm H. pylori eradication.
Results: A total of 114 patients were enrolled in this study, 50 malesand 64 females with a mean age of 49.8 years. All 114 patients had a diagnosis of NUD. Overall eradication asconfirmed by negative 13C-UBT was achieved in 94 out of 114 patients (82.5%). 44 patients had positive culturesand success for E-test. In vitro metronidazole resistance was observed in 22/44 (50%) patients. Eradication rate inpatients with metronidazole resistant strains was 16/22 (72.7%) and 20/22 (90.1%) with metronidazole sensitivestrains (72.7% vs 90.1%, p-value=0.12; OR=3.75 [95%CI=0.6-31.5]). Minor adverse reactions included nausea,bitter taste, diarrhea and black stools but none of the patients dropped out from the study.
Conclusions: Initialtreatment with 7-day bismuth-based quadruple therapy including metronidazole, amoxycillin and pantoprazoleis highly effective and well tolerated for metronidazole-sensitive H. pylori infections. However, the efficacymarkedly decline with metronidazole resistance. Longer duration of this regimen might be required to improvethe eradication rate and larger multi-center studies are needed to confirm this hypothesis.