Antimicrobial activity of esomeprazole versus omeprazole against Helicobacter pylori

Objective: Esomeprazole is an enantiomorph of omeprazole, which inhibits gastric acid secretion more effectively than omeprazole. As proton pump inhibitors also exert an antibacterial activity, we aimed to compare esomeprazole and omeprazole for their antimicrobial activity against Helicobacter pylori in vitro. Methods: We studied 52 H. pylori isolates obtained from gastric biopsies and inoculated onto agar plates containing the acid-converted drugs at different concentrations. The minimal concentrations that inhibited the growth of 50% and 90% of isolates were defined as MIC(50) and MIC(90). Results: The MIC(50) and MIC(90) of esomeprazole were 16 and 32 mg/L; and those of omeprazole were 32 and 64 mg/L. Overall, 63.5% of isolates showed the same susceptibility to both drugs; 17 isolates were two- to 64-fold more susceptible to esomeprazole and two isolates were two-fold more susceptible to omeprazole. Conclusions: The increased antimicrobial activity in vitro of esomeprazole against H. pylori could contribute to improving the outcome of the eradication treatment of such an infection.