Biofilm formation by Staphylococcus epidermidis on intraocular lens material

PURPOSE. To compare biofilm formation by Staphylococcus epidermidis on different intraocular lens (IOL) materials. METHODS. The S. epidermidis strains, ATCC 12228 ( American Type Culture Collection) and ATCC 35984 (biofilm-producer) were used. Biofilms were cultivated on disks of different IOL materials: silicone, PMMA (polymethylmethacrylate), acrylic, or MPC (2-methacryloyloxyethyl phosphorylcholine) surface-modified acrylic. Biofilms were stained with crystal violet ( CV) which served as an index of biofilm formation. The bacterial population was enumerated after biofilm homogenization. Biofilms were also examined by scanning electron microscopy (SEM). RESULTS. Among the four materials tested, the least amount of biofilm formed on silicone. Biofilm production was significantly different between acrylic and MPC surface-modified acrylic lenses at 48 hours (P < 0.05-0.01). The bacterial populations were significantly different between acrylic and silicone over 72 hours (P < 0.05-0.01). The population on acrylic and MPC surface-modified acrylic continued to increase over 72 hours. The biofilm was recognized after a 24-hour incubation. Rates of biofilm-positive SEM fields, which were defined as being occupied by biofilm over at least half of the area, were significantly different between acrylic and silicone at 72 hours (P < 0.05-0.01). CONCLUSIONS. S. epidermidis formed biofilm most intensely on acrylic among the four IOL materials tested. MPC surface-modified acrylic has a preventive effect on biofilm formation.