Prevention of Staphylococcus aureus endophthalmitis with topical gatifloxacin in a rabbit prophylaxis model.

Purpose: The aim of this study was to investigate the prophylactic use of 0.3% gatifloxacin drops to prevent endophthalmitis in a rabbit model.
Methods: Forty (40) New Zealand white rabbits were randomly placed into group A (20 rabbits) where they received 1 drop of 0.3% gatifloxacin in their right eye every 15 min (0, 15, 30, and 45 min), or group B (20 rabbits) where they received 1 drop of balanced salt solution (BSS) in their right eye every 15 min (0, 15, 30, and 45 min). Following this treatment regimen, the anterior chamber of each rabbit was injected with 0.025 mL of saline containing 5 x 10(5) colonyforming units of a clinical isolate of Staphylococcus aureus (vancomycin-sensitive). After the inoculum injection, the treatment regimen continued: group A (1 drop of 0.3% gatifloxacin) or group B (1 drop of BSS) immediately postinjection, 6, 12, 18, and 24 h, at which time the animals were examined in a masked fashion, photographed, anesthetized, euthanized, and the aqueous and vitreous humors collected to determine the number of viable bacteria.
Results: The median clinical scores for the gatifloxacin group were significantly lower than the control group (P < 0.05). Bacterial recovery of S. aureus was significantly higher in the control group in both the aqueous and vitreous humor (P < 0.05).
Conclusions: Gatifloxacin-treated eyes demonstrated significantly less inflammation, infection, and culture-positive endophthalmitis (P < 0.05), compared to the control animals. It is important to further investigate the clinical implications from this prophylatic study.