The role of serum proteins in Staphylococcus aureus adhesion to ethylene glycol coated surfaces

Bacterial adhesion on implants is a first step in the development of chronic foreign body associated infections. Finding strategies to minimize bacterial adhesion may contribute to minimize such infections. It is known that surfaces with oligo-ethylene-glycol (EG(3)OMe) or poly-ethylene-glycol (PEG2k) terminations decrease unspecific protein adsorption and bacterial adhesion. However, little is known about the influence of serum and its components on bacterial adhesion. We therefore prepared two coatings on gold surface with HS-(CH2)(11)EG(3)OMe (EG(3)OMe) and PEG2k-thiol and studied the role of bovine serum albumin (BSA), gamma-globulins, and serum on Staphylococcus aureus adhesion. While BSA and lysozyme showed no adherence even when applied at very high concentrations (100 mg/ml), gamma-globulins adsorbed already from 10 mg/ml on. The adsorption of gamma-globulins was, however, significantly decreased when it was mixed with BSA in a ratio of 3:1, as it is in the serum. Pretreatment of EG(3)OMe and PEG2k coatings with gamma-globulins or serum strongly promoted adherence of S. aureus when resuspended in buffer, suggesting that gamma-globulins play a pivotal role in promoting S. aureus adhesion by its IgG binding proteins; the finding that a spa-deletion mutant, lacking the IgG binding protein A, showed decreased adherence corroborated this. Similarly, when S. aureus was pretreated with serum or gamma-globulins its adherence was also significantly decreased. Our findings show that particularly gamma-globulins bind to the coated surfaces thus mediating adherence of S. aureus via its protein A. As pretreatment of S. aureus with serum or gamma-globulins significantly decreased adherence, treatment of patients with gamma-globulins before implant surgery might lower the risk of implant-associated infections. (C) 2014 Elsevier GmbH. All rights reserved.