Fluoroquinolone Therapy in an Animal Model of Mycobacterium chelonae Keratitis after Lamellar Keratectomy

Abstract

Abstract: : Objective: To assess and compare the effectiveness of ciprofloxacin, levofloxacin and gatifloxacin in the treatment of an animal model of Mycobacterium chelonae keratitis after lamellar keratectomy. Methods: 28 New Zealand white rabbits underwent unilateral lamellar keratectomy using a manual microkeratome followed by the placement of 1,000 colony-forming units (CFUs) of log-phase Mycobacterium chelonae bacteria under each flap. Eyes (7 per group) were randomized and treated with one of the following agents: sterile balanced salt solution(control), gatifloxacin (0.3%), ciprofloxacin (0.3%) or levofloxacin (0.5%) immediately and on a four time daily regimen for a total of four weeks. Inflammation was graded by two masked observers on a weekly basis for four weeks and the presence or absence of infiltrates and keratitis was determined. The animals were euthanized when severe corneal edema was noted or if the animal appeared to be uncomfortable. Upon sacrifice, all corneas were cultured. The means and standard deviations were calculated and differences among the groups were statistically analyzed. Results: No flap complications occurred during surgery. Of the seven rabbits in each group, the final cultures were positive in 3 of the gatifloxacin, 6 of the levofloxacin, 7 of the ciprofloxacin and 6 of the control group. Prior to the four-week end of the study, all of the levofloxacin group, 5/7 of the ciprofloxacin group and 5/7 of the control were euthanized due to severe corneal edema, dislodged flap or obvious discomfort of the animal. Only 2/7 of the gatifloxacin-treated animals developed keratitis severe enough to require euthanasia. Conclusions: The fourth generation fluoroquinolone, gatifloxacin, is an effective agent in the treatment of multi drug-resistant Mycobacterial keratitis after lamellar keratectomy.

Keywords: keratitis • antibiotics/antifungals/antiparasitics