Influence of metronidazole resistance on efficacy of quadruple therapy for Helicobacter pylori eradication.

Background: Metronidazole-containing eradication therapies are less effective for metronidazole resistant Helicobacter pylori. Although early data suggested improvement of the efficacy of bismuth triple therapy after the addition of acid suppressives, these findings were based on studies with small numbers of patients, incomplete post-eradication follow up, or omission of pretreatment susceptibility testing.

Aims: To study the efficacy of quadruple therapy in the Amsterdam area, where the efficacy of bismuth triple therapy has been proved to be affected by metronidazole resistance.

Patients And Methods: Eighty two consecutive dyspeptic H pylori positive patients with either metronidazole susceptible (group I) or metronidazole resistant H pylori strains (group II) received quadruple therapy for one week: omeprazole 20 mg twice daily; colloidal bismuth subcitrate 120 mg four times a day; tetracycline 500 mg four times a day; metronidazole 500 mg three times a day. Susceptibility to metronidazole was determined by the E-test.

Results: Intention to treat analysis showed that H pylori infection had been cured in 42/43 patients (98%) in group I and 32/39 patients (82%) in group II (p = 0.02).

Conclusion: The efficacy of quadruple therapy is significantly impaired in patients infected with metronidazole resistant H pylori. Therefore a non-metronidazole-containing regimen should preferably be used in areas known to have a high prevalence of pretreatment metronidazole resistance.