Combined activity of trospectomycin and colloidal bismuth subcitrate against Helicobacter pylori in vitro.

The combined activities of trospectomycin, a spectinomycin analogue, and colloidal bismuth subcitrate against Helicobacter pylori were investigated, the agar dilution method being employed. Forty-seven strains of H. pylori were examined. An additive effect was observed in 89%, and a synergistic interaction in 11% of the isolates. There was no antagonism observed. The MIC50 of trospectomycin against H. pylori was 2 mg/l; the MIC ranged from 0.5 to 4 mg/l.