Efficacy of a nitroimidazole containing tripletherapy regime in Singapore

There has been a gradual increase in the proportion of Singapore patients with metronidazole resistant strains of Helicobacter pylori. We studied the efficacy of a nitroimidazole containing regime in eradicating H. pylori.

Consecutive treatment naive patients with peptic ulcer disease and culture proven H. pylori were recruited. From each patient, two antral biopsies were taken for rapid urease test and two for histology. Two biopsies each from the gastric antrum and corpus were taken for H. pylori culture. Antibiotic sensitivity to amoxycillin, metronidazole, clarithromycin and tetracycline were tested using the disc diffusion method. Patients were treated with lansoprazole 30 mg bd, tinidazole 500 mg bd and clarithromycin 500 mg bd for seven days. Successful eradication was defined as either negative urea breath tests 4 and 12 weeks after treatment, or negative histology and culture at least four weeks after the end of treatment.

A total of 64 patients were culture positive (51 males, 13 females). Forty-two patients had duodenal ulcers (DU), 17 gastric ulcers (GU), and 5 DU and GU. Metronidazole resistance was detected in 16 patients (25%). Three of the 16 patients (19%) had a mixed population of resistant and sensitive strains of H. pylori. None of the H. pylori isolates were resistant to amoxycillin, tetracycline or clarithromycin. Overall, eradication was achieved in 51/64 patients (80%). Eradication rate was 88% (42/48) among those with metronidazole sensitive strains, and 56% (9/16) among those with metronidazole resistant strains (p < 0.02).

A high proportion of our patients with metronidazole resistant strains of H. pylori failed eradication therapy when a nitroimidazole containing regime was used. It may not be appropriate to use a nitroimidazole containing without prior knowledge of the antibiotic sensitivity pattern of the H. pylori isolate.