The susceptibility of Campylobacter pylori to antiulcer agents and antibiotics.

The antibacterial activities of antiulcer agents and antibiotics against Campylobacter pylori were studied. The MIC90 values of three kinds of antibiotics--macrolides, beta-lactams, and metronidazole--were 0.05-0.78, 0.39-1.56, and 12.5 micrograms/ml, respectively. They were more active than antiulcer agents such as H2-blockers and cetraxate with MIC90 values of greater than or equal to 1,600 and greater than 1,600 micrograms/ml, respectively. Especially, clarithromycin, a new derivative of erythromycin, showed an MIC90 of 0.05 microgram/ml. However, the other antiulcer agents such as sofalcone and tripotassium dicitrate bismuthate (TDB) also had MIC90 values of 50 and 6.25 micrograms/ml, respectively. Clarithromycin, sofalcone, and TDB showed bactericidal activity against C. pylori CLO2. The bactericidal actions of these drugs could be observed under electron microscopy.