Inhibitory activity of clarithromycin on biofilm synthesis with Pseudomonas aeruginosa

Inhibitory activity of clarithromycin (CAM) on biofilm synthesis with Pseudomonas aeruginosa was observed both qualitatively and quantitatively. Using scanning electron microscopy it was seen that biofilms on a Teflon sheet with CAM decreased markedly in a dose-dependent manner as compared with a control Teflon sheet without CAM. The quantity of hexose, a key biofilm ingredient, decreased with increasing concentrations of CAM, even though CAM has no direct bactericidal activity against P. aeruginosa. The results indicated that CAM inhibits the synthesis of biofilm via inhibition of polysaccharides synthesis. This inhibition of CAM was confirmed at 10 micrograms/ml or higher, levels attainable in human tissue at clinical dosage. We concluded that CAM has a considerable potential in the treatment of intractable infection caused by biofilm.