Effest of Sub-MICs of antibiotics on the hydrophobicity and production of acidic polysaccharide by Vibrio vulnificus

Background: Subinhibitory concentrations of antibiotics, which can occur in vivo, have been demonstrated to a Iter the production of bacterial virulen ce factors, including the capsule, or the interaction between microorganism and phagocyte by affecting surface hydrophobicity. Methods: Using a microt iter assay system, the effect of subinhibitory concentrations of amikacin, gentamicin, cephalothin and doxycycline on the surface hydrophobicity and p roduction of acidic polysaccharide by Vibrio vulnificus (8 human isolates, 8 environmental isolates) was determined. Results: Ail four drugs, in a dos e-dependent manner, caused alterations in adherence to polystyrene, a measu re 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 a ntibiotics appear to be independent variables. Copyright (C) 2001 S. Karger AG, Basel.