Effect of sub-MICs of antibiotics on the hydrophobicity and production of acidic polysaccharide by Vibrio vulnificus

Abstract

Background: Subinhibitory concentrations of antibiotics, which can occur in vivo, have been demonstrated to alter the production of bacterial virulence factors, including the capsule, or the interaction between microorganism and phagocyte by affecting surface hydrophobicity. Methods: Using a microtiter assay system, the effect of subinhibitory concentrations of amikacin, gentamicin, cephalothin and doxycycline on the surface hydrophobicity and production of acidic polysaccharide by Vibrio vulnificus (8 human isolates, 8 environmental isolates) was determined. Results: All four drugs, in a dose-dependent manner, caused alterations in adherence to polystyrene, a measure of surface hydrophobicity, and the production of acidic polysaccharides, as determined by Alcian blue staining. Conclusion: The changes in capsule production and surface hydrophobicity measured in response to sub-MICs of antibiotics appear to be independent variables. Copyright © 2001 S. Karger AG, Basel.