Antibacterial properties of lansoprazole alone and in combination with antimicrobial agents against Helicobacter pylori.

The activities of various types of anti-ulcer agents against Helicobacter pylori (Hp) strains were determined using an agar dilution method. Among the compounds tested, proton pump inhibitors were found to exhibit significant activity against this organism. The activity of lansoprazole was four times more potent than that of omeprazole and bismuth subsalicylate, with MICs ranging from 1.56 to 25 micrograms/ml. Exposure of Hp to lansoprazole led to extensive loss of viability and suppression of virulence factors such as motility, adhesiveness to epithelial cells, and urease activity. Lansoprazole produced aberrant bacterial morphology characterized by elongation and constriction of the cells and collapse of cell surface structures. The combination of lansoprazole with antimicrobial agents such as penicillins, cephalosporins, macrolides, tetracyclines, aminoglycosides, quinolones, and metronidazole produced an additive or synergistic growth inhibition of Hp.