Antibiotic resistance in Helicobacter pylori: is it a problem in New Zealand?

Infection with Helicobacter pylori requires antibiotic treatment when associated with upper gastrointestinal symptoms. Antibiotic susceptibility tests on this pathogen are rarely carried out and there is little information available on the incidence of antibiotic resistant strains in New Zealand. The aim of this study was to assess the susceptibility of H. pylori (cultured from gastric biopsies in Dunedin) to antibiotics that are commonly used in treatment.

Over a 13-month period, gastric biopsies were obtained from selected patients undergoing endoscopy at Dunedin Public Hospital because of upper gastrointestinal symptoms. Biopsies were cultured for H. pylori and examined histologically. Fifty isolates from 50 patients with histological findings compatible with H. pylori infection were tested for sensitivity to metronidazole, clarithromycin, amoxycillin, and tetracycline using the epsilometer (E-) test.

Metronidazole resistance was detected in 10 (20%) isolates. These isolates were highly resistant to metronidazole and were not inhibited by 250 mg/L. Resistance to clarithromycin, amoxycillin, and doxycycline was not detected.

Clinicians should be aware that resistance to metronidazole appears to be common in H. pylori in New Zealand and that treatment regimens including this antibiotic may be less effective as a result. Although clarithromycin resistance was not detected, it is becoming increasingly problematical overseas and has been recorded in Auckland.