Failed Treatment of Helicobacter pylori Infection Associated with Resistance to Clarithromycin

BACKGROUND: Resistance of Helicobacter pylori to clarithromycin is uncommon. Initial studies have suggested that primary resistance has a significant adverse effect on bacteriological cure rates and acquired resistance develops frequently with failure of treatment following regimens containing clarithromycin. MATERIALS AND METHODS: H. pylori isolates were obtained from patients with duodenal ulcer treated with clarithromycin and omeprazole and examined for susceptibility to clarithromycin using the E-test method. A 13C urea breath test was used to confirm infection with H. pylori and successful treatment. RESULTS: H. pylori infection was successfully treated in 101 patients, all with susceptible isolates, and persisted in 30 patients of whom 4 had resistant isolates. Of 16 patients with bacteriological cure failure who had susceptible isolates pretreatment, 11 (68.8%) had resistant isolates post-treatment. CONCLUSIONS: This study confirms previous reports that acquired resistance of H. pylori to clarithromycin develops frequently (68.8-96%) in individuals with failed dual therapy regimens. Primary resistance, although uncommon (3%), was 100% predictive of treatment failure with the regimen used in this study. Effective treatment of H. pylori infection should help to prevent the development of resistance to clarithromycin.