2004 OMIG, Abstract 15

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Biofilm Formation by E. faecalis on Intraocular Lens Material
S Kobayakawa¹, M Gilmore². ¹Department of Microbiology and Immunology, U. Of Oklahoma, Oklahoma City, Oklahoma ²Department of Ophthalmology, U. Of Oklahoma, Oklahoma City, Oklahoma

Purpose: As biofilms have received increasing attention as the cause of highly refractory infections, including those of the eye, the aim of this study was to compare the ability of Enterococcus faecalis to form biofilms on various intraocular lens (IOL) materials.
Methods: Ten Enterococcus faecalis strains varying in pathogenic potential [cytolysin (Cyl) positive and negative, enterococcal surface protein (Esp) +/- in background FA2-2, Esp +/- in the wild type background (WT), and strains varying in both Cyl and Esp] were used to seed biofilms. Biofilms were cultivated on sample disks (6.0mm dia. X 1.0mm) of various (silicone, polymethylmethacrylate, acrylic) IOL materials in Tryptic Soy Broth with glucose. Biofilms were stained with crystal violet (CV) and the optical density of CV extracted from stained biofilms used as an index of the extent of biofilm formation. Bacterial population within biofilms was determined following homogenization. Biofilms were also examined by confocal microscopy in situ.
Results: The three Esp positive strains showed significantly greater biofilm formation than negative strains on all materials tested (p<0.001). There was no significant difference in the biofilm formation and the bacterial population within biofilms between IOL materials after 24 hours incubation. However, after 48 and 72 hours incubation, silicone supported the least amount of biofilm formation compared to PMMA and acrylic lOLs (p<0.05). At 72 hours incubated, acrylic IOL supported the greatest amount of CV-stainable biofilm (p<0.0005). After 48 and 72 hours incubation, the bacterial population within biofilms on PMMA material was significantly greater than either silicone or acrylic IOL material (p<0.005). Confocal microscopy confirmed the relative lack of biomass on silicone IOL.
Conclusions: Among three IOL materials tested, E. faecalis biofilms formed more readily on PMMA and acrylic compared to silicone. The phenotype of E. faecalis strains appears to significantly impact the ability to form biofilms on IOL materials. An understanding of bacteria-polymer interactions may be important in preventing lOL-associated intraocular infections.

PHS grant EY08289 and an unrestricted grant from Research to Prevent Blindness, Inc.

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