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

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. 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. 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. 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.