Combinations containing amoxicillin-clavulanate and tetracycline are inappropriate for Helicobacter pylori eradication despite high in vitro susceptibility

Background: The purpose of the present paper was to evaluate the efficacy and tolerability of amoxicillin-clavulanate and tetracycline-based quadruple therapy as an alternative second-line treatment for H. pylori infection. Methods: The study subjects consisted of 54 patients infected with H. pylori, in whom initial triple therapy had failed. Subjects were randomized to receive the following 7-day therapies: (i) pantoprazole 40 mg b.i.d., tripotassium dicitrate bismuthate 300 mg q.i.d., amoxicillin-clavulanate 1000 mg b.i.d., and tetracycline 500 mg q.i.d. (PBAT); or (ii) pantoprazole 40 mg b.i.d., tripotassium dicitrate bismuthate 300 mg q.i.d., metronidazole 500 mg t.i.d., and tetracycline 500 mg q.i.d. (PBMT). Eradication rates based on antibiotic susceptibility, drug compliance and side-effect rates were evaluated and compared. Results: The H. pylori eradication rates were 16.0%/17.4% with PBAT and 65.5%/70.4% with PBMT by intention-to-treat (P < 0.001) and per-protocol analyses (P < 0.001), respectively. In patients who received PBAT, the eradication rates were only 16.7% (2/12) for both amoxicillin and tetracycline-susceptible H. pylori strains. Drug compliance and side-effect rates were similar in the two groups. Conclusions: Despite high individual in vitro antimicrobial activity, amoxicillin-clavulanate and tetracycline-based quadruple therapy showed low eradication rates, which strongly suggests that it should not be considered as a therapeutic option for H. pylori eradication.