Methods: Forty-three patients positive for Helicobacter pylori by histology and culture of antral biopsies (n = 40) or histology alone (n = 3) were investigated. They received either regimen 1--tripotassium dicitrato bismuthate 120 mg q.d.s. and tetracycline 250 mg q.d.s. for 4 weeks, with metronidazole 200 mg q.d.s. for the first 2 weeks, or regimen 2--omeprazole 20 mg b.d., amoxycillin 500 mg t.d.s., tetracycline 500 mg q.d.s. each for 3 weeks. Gastric antral biopsies were scored (0-3) histologically for mucus depletion, polymorphonuclear and mononuclear cell infiltrate. H. pylori eradication was assessed by biopsy and culture 1 month after the cessation of treatment.
Results: With regimen 1, pre-treatment mucus depletion was significantly higher where eradication was successful (median score 2) compared to where it was not (median score 1, P < 0.01); there were no differences in the scores for polymorphonuclear or mononuclear cell infiltrates. In patients receiving regimen 2, there were no differences in either mucus depletion or polymorphonuclear or mononuclear cell infiltrate, between those where eradication was successful and those where it was not. Metronidazole minimum inhibitory concentrations rose when eradication with regimen 1 was unsuccessful (median before 0.19 mg/L, median after treatment 16 mg/L; P = 0.04).
Conclusion: Pre-treatment mucus depletion is identified as a factor affecting H. pylori eradication. Preservation of mucus may facilitate acquisition of metronidazole resistance.