Adhesion of Enterococcus faecalis 1131 grown under subinhibitory concentrations of ampicillin and vancomycin to a hydrophilic and a hydrophobic substratum

The effect of two subinhibitory antibiotic concentrations of ampicillin and vancomycin during growth on the adhesion of Enterococcus faecalis 1131 to glass and silicone rubber was studied in a parallel plate flow chamber. Ini tial deposition rates and numbers of adhering bacteria after 4 h were highe r on hydrophilic glass than on hydrophobic silicone rubber, regardless of g rowth conditions. The presence of 1/4 minimal inhibitory concentration (MIC ) of ampicillin during growth reduced enterococcal adhesion to both substra ta, but growth in the presence of 1/4 MIC vancomycin did not affect the adh esion of E faecalis. Moreover, enterococcal adhesion increased after growth in the presence of 1/8 MIC vancomycin. The increased adhesion after growth in the presence of subinhibitory concentrations of vancomycin may have str ong implications for patients living with implanted biomaterials, as they m ay suffer adverse effects from use of this antibiotic, especially since bac teria once adhered are less sensitive to antibiotics. (C) 2001 Federation o f European Microbiological Societies. Published by Elsevier Science BN. All rights reserved.