Randomized trial of omeprazole and clarithromycin combined with either metronidazole or amoxycillin in patients with metronidazole-resistant or -susceptible Helicobacter pylori strains

The impact of metronidazole resistance on the efficacy of proton pump inhibitor based triple therapies remains unclear. To study whether metronidazole resistance affects Helicobacter pylori eradication rates in patients treated for 1 week with either omeprazole 20 mg b.d., metronidazole 400 mg b.d. and clarithromycin 250 mg b.d. (OMC), or omeprazole 20 mg b.d., amoxycillin 1000 mg b.d. and clarithromycin 500 mg b.d. (OAC). A randomized, single blind, single centre study with parallel groups was conducted. H. pylori positive patients were enrolled in a metronidazole-resistant (MR; MIC > 8 microgram/mL) or a metronidazole-susceptible group (MS; MIC < 4 microgram/mL), as determined by E-test. Within the strata patients were randomized to either OAC or OMC. One hundred and twenty-two patients were included. The per protocol cure rate for OAC was 52 out of 57 (91%) (MS 23 out of 26 (89%); MR 29 out of 31 (94%)) and for OMC 46 out of 55 (84%) (MS 19 out of 22 (86%); MR 27 out of 33 (82%)). One-week OAC and OMC are effective therapies. OAC and OMC were equally effective in patients with metronidazole-susceptible strains of H. pylori. Using the OMC regimen, neither equality nor significant differences in treatment outcome could be shown between patients with metronidazole-resistant or -susceptible strains of H. pylori