Effect of ornidazole and clarithromycin resistance on eradication of Helicobacter pylori in peptic ulcer disease

Aliment Pharmacol Ther. 2000 Mar;14(3):305-9. doi: 10.1046/j.1365-2036.2000.00717.x.


Background: Clarithromycin and nitroimidazoles such as metronidazole and ornidazole are among the most frequently used antibiotics for curing Helicobacter pylori infection. However, controversial data exist on whether their in vitro resistance has a negative impact on treatment outcome.

Methods: Patients with H. pylori positive active peptic ulcer disease were randomly assigned to receive lansoprazole 30 mg o.d., amoxycillin 1 g b.d. and ornidazole 500 mg b.d. (LAO) or lansoprazole 30 mg o.d., amoxycillin 1 g b.d. and clarithromycin 500 mg b.d. (LAC) for 2 weeks. Pre-treatment resistance to ornidazole and clarithromycin was assessed by Epsilometer (E-) test. Four weeks after completion of treatment, patients underwent a 13C urea breath test to assess H. pylori status.

Results: Data from 80 patients with active peptic ulcer disease and positive H. pylori status were analysed. The prevalence of primary drug resistance was 25% for metronidazole and 7.5% for clarithromycin. In patients treated with LAO, effective treatment was achieved in 87% of metronidazole-susceptible, but only 30% of metronidazole-resistant strains (P < 0.01). In the LAC group, therapy was successful in 81% of clarithromycin-susceptible strains, whereas treatment failed in all patients with primary clarithromycin resistance (n = 3).

Conclusion: Resistance against nitroimidazoles significantly affects treatment outcome in H. pylori eradication therapy.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • 2-Pyridinylmethylsulfinylbenzimidazoles
  • Adolescent
  • Adult
  • Aged
  • Amoxicillin / therapeutic use
  • Anti-Bacterial Agents / therapeutic use*
  • Anti-Ulcer Agents / therapeutic use
  • Clarithromycin / therapeutic use*
  • Drug Combinations
  • Drug Resistance, Microbial
  • Endoscopy, Gastrointestinal
  • Female
  • Helicobacter Infections / drug therapy*
  • Helicobacter Infections / microbiology
  • Helicobacter pylori*
  • Humans
  • Lansoprazole
  • Male
  • Middle Aged
  • Omeprazole / analogs & derivatives
  • Omeprazole / therapeutic use
  • Ornidazole / therapeutic use*
  • Penicillins / therapeutic use
  • Peptic Ulcer / drug therapy*
  • Peptic Ulcer / microbiology
  • Treatment Outcome


  • 2-Pyridinylmethylsulfinylbenzimidazoles
  • Anti-Bacterial Agents
  • Anti-Ulcer Agents
  • Drug Combinations
  • Penicillins
  • Lansoprazole
  • Ornidazole
  • Amoxicillin
  • Clarithromycin
  • Omeprazole