Randomized trial of omeprazole and metronidazole with amoxycillin or clarithromycin for Helicobacter pylori eradication, in a region of high primary metronidazole resistance:: the HERO study

Background: The efficacy of omeprazole-based eradication therapies has been determined mostly in populations with low to moderate prevalence of metronidazole resistant Helicobacter pylori, yet resistance is high in many regions. Aim and Methods: The H. pylori eradication and duodenal ulcer healing rates after 1 week of either omeprazole 40 mg mane, amoxycillin 500 mg t.d.s. and metronidazole 400 mg t.d.s. (OAM) or omeprazole 20 mg b.d., metronidazole 400 mg b.d. and clarithromycin 250 mg b.d. (OMC) were compared in a randomized trial in Australia and New Zealand. Patients had a further 1 week of omeprazole 20 mg. Outcome was assessed at 6 weeks with stringent criteria (endoscopy, biopsies and C-13-urea breath test). Results: Of 220 subjects randomized, the H. pylori eradication rates (all patients treated/per protocol) were 82%/85% for OMC and 58%/63% for OAM (P= 0.001). Pre-treatment metronidazole resistance was present in 56% and clarithromycin resistance in 6%. The eradication rate for primary metronidazole resistance isolates treated with OMC was 80% (CI: 65-90%) compared with 45% (CI: 29-62%) for OAM, whereas for sensitive organisms, the eradication rates were 94% (CI: 79-99%) and 79% (CI: 62-91%), respectively. Duodenal ulcer healing was 96% for OMC and 87% for OAM. Compliance was excellent and both treatments were well-tolerated. Conclusions: OMC is a well-tolerated, effective therapy for H. pylori eradication and duodenal ulcer healing in this region despite the high metronidazole resistance rate. OAM is less effective, largely due to the impact of metronidazole resistance.