Prevalence and evolution of Helicobacter pylori resistance to 6 antibacterial agents over 12 years and correlation between susceptibility testing methods.

The aim of this study was to evaluate Helicobacter pylori antibacterial resistance in 2005 to 2007, resistance evolution since 1996 to 1999, and performance of breakpoint susceptibility testing (BST) compared with E test for clarithromycin or agar dilution method (ADM) for metronidazole, amoxicillin, tetracycline, and ciprofloxacin. Resistance in 613 untreated adults, 91 treated adults, and 75 untreated children was 25%, 48.4%, and 16% for metronidazole; 17.8%, 45.1%, and 18.7% for clarithromycin; 4.4%, 13.3%, and 2.7% for tetracycline; and 7.7%, 18.2%, and 6.8% for ciprofloxacin, respectively. Resistance to amoxicillin (0.9%) and nitrofurantoin (1.3%) was uncommon. Three strains (0.4%) exhibited triple resistance to amoxicillin, metronidazole, and clarithromycin. Primary resistance rates in adults and children were comparable. Metronidazole resistance was less common in ulcer adults than in the rest. Primary clarithromycin resistance increased significantly from 10% in 1996 to 1999 to 17.9% in 2005 to 2007. Many strains (26.4%) from treated adults showed resistance to metronidazole and clarithromycin. Category agreement between the BST and E test or ADM results was good (93.3-100%). In conclusion, the increasing clarithromycin resistance and presence of multidrug resistance are worrying. Fluoroquinolones should be used with caution for H. pylori eradication in treated patients.