Impact of surface coating on the adherence of slime producing and nonproducing Staphylococcus epidermidis

The ability of Staphylococcus epidermidis to grow in the form of a biofilm not only facilitates its persistence in the host, but also allows it to survive at antibiotic concentrations several orders higher than the Minimum Inhibitory Concentration (MIC). We evaluated different surface treatments of hardened polystyrene in order to develop a model system for growth of S. epidermidis as a biofilm. We assayed for biofilm growth of S. epidermidis clinical isolates on unmodified polystyrene, on polystyrene modified by chemical abrasion and on polystyrene modified by sulfonation, using either Tryptic Soya Broth or Brain Heart Infusion as a growth medium. We concluded that sulfonated polystyrene and Brain Heart Infusion provided the best growth system for predicting the ability of a clinical isolate to form biofilm (Akaike value 23.680). Using this method, biofilm formation was detected in 14 (70%) of ica-positive strains and negative in 16 (80%) of ica-negative strains.