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L. E. Fernandez de Castro, H. P. Sandoval, D. T. Vroman, K. D. Solomon; Prophylactic Treatment of Methicillin-Resistant Staphylococcus Aureus Keratitis Using Fourth Generation Fluoroquinolones in a Rabbit Model. Invest. Ophthalmol. Vis. Sci. 2007;48(13):763.
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The purpose of this study was to investigate the prophylactic use of fourth generation fluoroquinolones (gatifloxacin and moxifloxacin) to prevent methicillin-resistant Staphylococcus aureus (MRSA) keratitis in a rabbit model.
Thirty NZW rabbits were randomly placed into Group A (10 rabbits) where they received one drop of 0.3% gatifloxacin (Zymar, Allergan, Inc., Irvine, CA) in their right eye every 15 min for one hour, Group B (10 rabbits) where they received one drop of 0.5% moxifloxacin (Vigamox, Alcon Laboratories, Inc., Fort Worth, TX) in their right eye every 15 min for one hour, or Group C (10 rabbits) where they received one drop of balance salt solution (BSS) in their right eye every 15 min for one hour. Following this treatment regimen, the right cornea of each rabbit was injected with 0.01mL saline containing 103 colony forming units of a clinical isolate of MRSA. After the inoculum injection, the treatment regimen continued: Group A (1 drop of 0.3% gatifloxacin) and Group C (1 drop of BSS) immediately post-injection and four times a day for 5 days; Group B (1 drop of 0.5% moxifloxacin) immediately post-injection and three times a day for 5 days. Rabbits were examined for clinical signs of infection/inflammation in a masked fashion every 24 hrs. Five rabbits per group were sacrificed on days 3 and 5 (48, and 96 hrs) post-injection. Corneas, aqueous and vitreous humors were collected to determine the number of viable bacteria on days 3 and 5.
At day 1, significant differences among the groups were found in conjuctival/scleral injection, presence of fibrin, and limbal injection (P <.05) and at day 4 in corneal infiltrates (P <.05). Bacterial recovery of MRSA was evident in the moxifloxacin and control groups in both the aqueous and vitreous humor at day 3.
Gatifloxacin-treated eyes demonstrated less inflammation, infection, and approximately 94% lower bacterial recovery compared to the 0.5% moxifloxacin and BSS groups. It is important to further investigate the clinical implications from this prophylactic study.
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