Five-year sequential changes in secondary antibiotic resistance of Helicobacter pylori in Taiwan

To determine changes in the antibiotic resistance of Helicobacter pylori (H. pylori) in southern Taiwan after failure of first-line standard triple therapy.

We analyzed 137 H. pylori-infected isolates from patients who experienced eradication failure after standard first-line triple therapy from January 2010 to December 2014. The H. pylori strains were tested for susceptibility to amoxicillin, clarithromycin, levofloxacin, metronidazole and tetracycline using the E-test method. The minimal inhibitory concentration (MIC) was determined by the agar dilution test. MIC values of ≥ 0.5, ≥ 1, ≥ 1, ≥ 4 and ≥ 8 mg/L were considered to be the resistance breakpoints for amoxicillin, clarithromycin, levofloxacin, tetracycline and metronidazole, respectively.

A high resistance rate was found for clarithromycin (65%-75%) and metronidazole (30%-40%) among patients who failed first-line standard therapy. The resistance levels to amoxicillin and tetracycline remained very low; however, levofloxacin resistance was as high as 37.5% in 2010 but did not increase any further during the past 5 years. The rates of resistance to these antibiotics did not show a statistically significant upward or downward trend.

Antibiotic resistance of H. pylori remains a problem for the effective eradication of this pathogen and its associated diseases in Taiwan. High clarithromycin resistance indicated that this antibiotic should not be prescribed as a second-line H. pylori eradication therapy. Moreover, levofloxacin-based second-line therapy should be used cautiously, and the local resistance rates should be carefully monitored.