BACKGROUND Antimicrobial resistance of Helicobacter pylori (H pylori) affects the efficacy of eradication therapy. The aim of this study was to estimate the prevalence of primary and secondary resistance of H pylori isolates to antibiotics in Korea.

METHODS The present study was performed from 2003 to 2018. Primary resistance was evaluated in 591 patients without any history of eradication and secondary resistance in 149 patients from whom Helicobacter pylori was cultured after failure of eradication. A minimal inhibitory concentration test was performed for amoxicillin, clarithromycin, metronidazole, tetracycline, levofloxacin, and rifabutin using the agar dilution method.

RESULTS An increase in the primary resistance rate was found in clarithromycin (P < .001), metronidazole (P < .001), and both levofloxacin (P < .001) during the study period. The primary resistance rates of amoxicillin and tetracycline were low and stable during the study period. The secondary resistance rate significantly increased in metronidazole and levofloxacin (P = .022 and .039, respectively).

CONCLUSIONS The primary and secondary resistance rates of clarithromycin, metronidazole, and levofloxacin for Helicobacter pylori in Korea were high and increased over time. However, the primary and secondary resistance rates of amoxicillin and tetracycline were low and stable over time. These results will help in selecting effective eradication regimens of H pylori in Korea in the future.