Adhesion of Coagulase-negative Staphylococci to Biomaterials

Abstract

The adhesion of 2 Staphylococcus epidermidis strains and 1 S. saprophyticus strain to poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP)-fluorocarbon and cellulose acetate was studied in vitro. Both S. epidermidis strains showed a more hydrophobic character than the encapsulated S. saprophyticus as determined by the bacterial affinity towards xylene. S. epidermidis showed a significantly higher adhesion to the hydrophobic FEP than S. saprophyticus. The adhesion of staphylococci to the more hydrophilic cellulose acetate was always low. Treatment of S. epidermidis with pepsin or extraction with aqueous phenol yielded cells with a decreased hydrophobicity, which resulted in a decreased adhesion to FEP. Cells with a decreased hydrophobicity showed a lower rate of reaggregation in suspension. The hydrophobicity and the adhesion to FEP of S. epidermidis were not affected by exposure to a subminimal inhibitory concentration of penicillin. The strong interaction between S. epidermidis and FEP, which appeared not to be influenced by the age or the metabolic stage of the bacteria, is mainly caused by hydrophobic bonding. These results are relevant to infections associated with prosthetic implants and medical devices.