Comparative efficacy of topical gatifloxacin with ciprofloxacin, amikacin, and clarithromycin in the treatment of experimental Mycobacterium chelonae keratitis.

OBJECTIVE To determine the comparative efficacy of topical gatifloxacin with ciprofloxacin, fortified amikacin, and clarithromycin against Mycobacterium chelonae keratitis in an animal model. METHODS Experimental M chelonae keratitis was induced via intrastromal inoculation in a rabbit model. Thirty-five rabbits were randomly divided into 5 groups and each group was treated hourly for 12 hours with topical 0.9% balanced salt solution, 0.3% gatifloxacin, 0.3% ciprofloxacin hydrochloride, a combination of topical fortified amikacin sulfate (50 mg/mL) and clarithromycin (10 mg/mL), or a triple combination of topical 0.3% gatifloxacin, fortified amikacin sulfate (50 mg/mL), and clarithromycin (10 mg/mL). Antibacterial efficacy of each regimen was determined by quantitative bacteriologic analysis. RESULTS Treatment with 0.3% gatifloxacin or the triple combination of 0.3% gatifloxacin, topical fortified amikacin sulfate (50 mg/mL), and clarithromycin (10 mg/mL) reduced the number of mycobacterial organisms more significantly than the controls that were treated with a topical balanced salt solution (both P<.001). Therapy with 0.3% gatifloxacin was more effective than 0.3% ciprofloxacin alone (P<.001) and demonstrated synergy by enhancing the efficacy of the combination of fortified amikacin (50 mg/mL) and clarithromycin (10 mg/mL) (P<.001). Neither 0.3% ciprofloxacin nor the combination of fortified amikacin (50 mg/mL) and clarithromycin (10 mg/mL) demonstrated a significant difference in activity against mycobacteria compared with the topical balanced salt solution. CONCLUSION These results suggest that topical 0.3% gatifloxacin ophthalmic solution can be a new initial treatment agent against M chelonae keratitis.Clinical Relevance Topical gatifloxacin 0.3% may provide an initial alternative in therapy of M chelonae keratitis.