Figure 3.

Staphylococcus aureus alters the permeability of cultured RPE cells to live bacteria. Intact monolayers of human RPE cells in 8.0-μm transwells were infected with S. aureus 8325-4 at a concentration of 10⁴ cfu/mL (MOI = 0.01), and diffusion of bacteria across the monolayer was assessed by removing the entire contents of the bottom chamber and replacing with fresh cell culture medium at 2, 4, 6, and 8 hours after inoculation of the top chamber. Pretreatment of RPE monolayers with Triton X-100 to obliterate the cellular barrier resulted in detectable bacteria in the lower chamber at all time points, with 4.77 × 10⁷ (±9.49 × 10⁷) cfu/mL at 8 hours post infection, and was not significantly different from S. aureus infection alone without pretreatment with Triton X-100 (P = 0.5). Values represent the mean concentration of S. aureus in the bottom chamber ± SD (N ≥ 3 at each time point).