Effectiveness of ciprofloxacin and ofloxacin in a prophylaxis model of Staphylococcus keratitis

Purpose. To determine the effectiveness of prophylactic fluoroquinolone tre atment against staphylococci in a rabbit keratitis model. Methods. Prophyla ctic ciprofloxacin or ofloxacin was applied as one topical drop 15 minutes before infection or as one drop at three time points (19, 17, and 15 minute s) before infection. In a second experiment, rabbits were treated with two, three, or four drops of ciprofloxacin 1 hour before infection. Approximate ly 250 colony-forming units (CFUs) of Staphylococcus aureus were injected i ntrastromally, and CFUs were determined 5 hours after infection. Results. T he CFUs per cornea in all treatment groups were significantly less than the 5.6 +/- 0.11 log CFUs per cornea in the untreated group (p less than or eq ual to 0.0001). Rabbit eyes treated 15 minutes before infection with Ciloxa n or Ocuflox had 0.96 +/- 0.48 log CFUs per cornea (three of six sterile co rneas) or 1.26 +/- 0.31 log CFUs per cornea (one of six sterile corneas), r espectively (p = 0.5226). Eyes treated with Ciloxan 19, 17, and 15 minutes before infection had 0.0 +/- 0.0 log CFUs per cornea, and all eyes were ste rile, whereas eyes treated with Ocuflox had 0.98 +/- 0.48 log CFUs per corn ea and two of six eyes sterile (p = 0.0435). Eyes treated 1 hour before inf ection with two, three, or four drops of Ciloxan had 2.61 +/- 0.69 log CFUs , 1.23 +/- 0.32 log CFUs, or 0.85 +/- 0.28 log CFUs per cornea, respectivel y, which was significantly less than untreated eyes (p less than or equal t o 0.0001). Conclusions. Multiple topical drops of a fluoroquinolone adminis tered prophylactically were effective for subsequent staphylococcal ocular infection.