Effect of cast molded rifampicin/silicone on Staphylococcus epidermidis biofilm formation

Infection is one of the most common catheter-related complications, especially in shunt systems used to treat hydrocephalus. Staphylococcus epidermidis is directly related to biomaterial infections owing to its ability to form a biofilm on implanted materials. In this study, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to investigate the effect of the antibiotic rifampicin on the colonization and growth of S. epidermidis 35984 on the surface of silicone. A cast molding method was used to load rifampicin into the silicone precursor before it was cured. Bacteria with a diameter of 800-1000 nm and height of 200-500 nm were found to be embedded in the biofilm. Compact multilayer biofilm structures were found on silicone surfaces upon incubation for 4 and 24 h. On the other hand, sparser biofilm structures were observed on rifampicin-loaded surfaces after incubation for the same duration. Deformation of bacteria was observed by AFM. Moreover, different bacterial colony structures on the surfaces of silicone and rifampicin-loaded silicone were observed by AFM and SEM.