In vitro antibacterial activity of bismuth subsalicylate.

This study was undertaken to determine the in vitro activity of bismuth subsalicylate (BSS) and sodium salicylate (SS) against various groups of pathogenic bacteria. BSS had the greatest activity against Clostridium difficile, which had a minimal inhibitory concentration for 90% of the strains (MIC90) of 128 micrograms/mL. The Bacteroides fragilis group also had a relatively low MIC90 of 512 micrograms/mL. BSS had the least activity against Pseudomonas (MIC90, 6,144 micrograms/mL). SS was as active as BSS against aerobic bacteria but was less active against anaerobic bacteria. The MIC90 values of SS for C. difficile and the B. fragilis group were greater than 8,192 and 4,096 micrograms/mL, respectively. This study demonstrates that BSS has antibacterial activity in vitro at levels that should be achievable in the gastrointestinal tract.