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S.A. Baillif, L. Kodjikian, E. Casoli, K. Marion, C. Roques, G. Pellon, D. Hartmann, J. Freney, C. Burillon; A New in vitro Model To Study Staphylococcal Biofilm Formation on Intraocular Lenses Under Hydrodynamic Conditions . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5080.
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Purpose: To develop a new in vitro model to study Staphylococcus epidermidis biofilm formation on intraocular lenses including the primary attachment phase as well as the biofilm accumulation one. The model was designed to replicate the in vivo conditions as closely as possible especially by taking into account intraocular hydrodynamic conditions. Methods: The model consisted in a Tygon® tubing connected to a vial containing the intraocular lenses. Three septums, placed along the Tygon tubing, allowed respectively the arrival of the pseudo aqueous humor, its elimination and the inoculation of the bacterial suspension. A first pump allowed the movement of the pseudo aqueous humor along the circuit, whereas a second one regulated the flow at which the nutritive environment was regenerated. Per experiment, 16 acrylic hydrophobic intraocular lenses were linked to 4 supporting metallic structures fixed to the head of the vial. The whole circuit was placed in a 32°C water bath. Every 2 to 4 hours, 4 lenses were taken from this environment. Bound bacteria were removed by scraping of both optical faces. All data were presented as means, standard deviations and coefficients of variation. Comparisons among experiments were performed by one–way analysis of variance (ANOVA).Results: Calculated coefficients of variation were inferior to 30 showing that biofilm formation on lenses was homogeneous and didn’t depend on lenses’ localisation in the vial. Differences between experiments were considered non significant as p value was superior to 0.05 for each removal time. This developed model provided the full kinetic of Staphylococcus epidermidis biofilm growth on acrylic hydrophobic intraocular lenses: the stationary phase was reached after 28 hours of incubation. Conclusions: Biofilm development in Staphylococci is modulated by a large number of variables including environmental factors such as temperature, medium composition and hydrodynamic flows. Our developed model, by taking into account the influence of the surrounding medium, mimics as closely as possible in vivo intraocular circumstances. This model will allow us to improve the study of bacterial biofilm formation from primary adhesion to biofilm maturation on intraocular lenses.
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