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 C-13 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.