Adhesion of staphylococci to polyurethane and hydrogel-coated polyurethane catheters assayed by an improved radiolabelling technique.

Adhesion of Staphylococcus epidermidis NCTC 11047 to the external surface of polyurethane catheters was quantified by a radiolabelling assay. Maximum adhesion was achieved with an initial cell concentration of 3 x 10(8)/ml after incubation for 120 min. The assay was tested for reproducibility by analysis of variance. Adhesion of clinical strains of S. epidermidis and S. aureus to uncoated polyurethane and hydrogel (Hydromer)-coated polyurethane catheters was compared. Hydrogel coating significantly reduced adhesion for both S. epidermidis and S. aureus (mean percentage reduction 71% for S. epidermidis, 69% for S. aureus). Clinical isolates were also tested for adhesion to polystyrene by a modified microtitration well adhesion assay; there was no correlation between staphylococcal adhesion to polyurethane catheters and adhesion to polystyrene. Cell surface hydrophobicity values varied widely for both species. Positive correlations were found between cell surface hydrophobicity and adhesion to polystyrene and uncoated polyurethane catheters for S. epidermidis but not for S. aureus.