COMPARISON OF TOPICAL ANTIBIOTICS FOR TREATING MYCOBACTERIUM-FORTUITUM KERATITIS IN AN ANIMAL-MODEL

The efficacy of three topical antibiotic treatments for Mycobacterium fortuitum (strain ATCC-6841) keratitis were compared in rabbits. Rabbi ts were treated with ciprofloxacin (3 mg/ml) or clarithromycin (20 mg/ ml) or a combination of amikacin (100 mg/ml) and vancomycin (50 mg/ml) . All three treatments significantly reduced the number of organisms i n treated eyes compared to untreated, control eyes (all P values <.001 ). No significant difference in treatment efficacy was found between t he three treatment groups (all P values greater than or equal to.48), although ciprofloxacin (3 mg/ml) was more effective than clarithromyci n (20 mg/ml) after excluding outliers (P =.01). All treatments stabili zed or reduced the size of stromal infiltrates after four days of ther apy, whereas infiltrates continued to enlarge in untreated eyes. These results suggest that topical clarithromycin, topical ciprofloxacin, a nd combined amikacin and vancomycin may all be clinically useful for t reating M. fortuitum keratitis. Both clarithromycin and ciprofloxacin were better tolerated than combined amikacin and vancomycin. This stud y supports the further development of clarithromycin, a new macrolide antibiotic, as a topical drug for treatment of M. fortuitum keratitis.