Comparison of topical antibiotics for treating Mycobacterium fortuitum keratitis in an animal model
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1UCLA Ocular Inflammatory Disease Center.
Abstract:
The efficacy of three topical antibiotic treatments for Mycobacterium fortuitum (strain ATCC-6841) keratitis were compared in rabbits. Rabbits 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 in treated eyes compared to untreated, control eyes (all P values < .001). No significant difference in treatment efficacy was found between the three treatment groups (all P values > or = .48), although ciprofloxacin (3 mg/ml) was more effective than clarithromycin (20 mg/ml) after excluding outliers (P = .01). All treatments stabilized or reduced the size of stromal infiltrates after four days of therapy, whereas infiltrates continued to enlarge in untreated eyes. These results suggest that topical clarithromycin, topical ciprofloxacin, and combined amikacin and vancomycin may all be clinically useful for treating M. fortuitum keratitis. Both clarithromycin and ciprofloxacin were better tolerated than combined amikacin and vancomycin. This study supports the further development of clarithromycin, a new macrolide antibiotic, as a topical drug for treatment of M. fortuitum keratitis.
Insights
Topical antibiotics like ciprofloxacin and clarithromycin effectively treat Mycobacterium fortuitum keratitis in rabbits. These treatments reduced bacterial load and improved stromal infiltrates, with clarithromycin showing promise as a new topical option.
Area of Science:
- Ophthalmology
- Infectious Diseases
- Microbiology
Background:
- Mycobacterium fortuitum keratitis is a challenging ocular infection.
- Limited effective topical treatments are available for this condition.
Purpose of the Study:
- To compare the efficacy of three topical antibiotic regimens for treating Mycobacterium fortuitum keratitis in a rabbit model.
- To evaluate the clinical utility and tolerability of ciprofloxacin, clarithromycin, and a combination of amikacin and vancomycin.
Main Methods:
- A rabbit model of Mycobacterium fortuitum keratitis was established.
- Eyes were treated topically with ciprofloxacin (3 mg/ml), clarithromycin (20 mg/ml), or amikacin (100 mg/ml) plus vancomycin (50 mg/ml).
- Bacterial load and stromal infiltrate size were assessed and compared to untreated controls.
Main Results:
- All three topical antibiotic treatments significantly reduced bacterial counts compared to controls (P < .001).
- No significant differences in efficacy were observed between the treatment groups (P >= .48), though ciprofloxacin showed superiority over clarithromycin after outlier exclusion (P = .01).
- All treatments stabilized or reduced stromal infiltrates, unlike untreated eyes where infiltrates enlarged.
Conclusions:
- Topical clarithromycin, ciprofloxacin, and combined amikacin/vancomycin are potentially effective for treating M. fortuitum keratitis.
- Clarithromycin and ciprofloxacin demonstrated better ocular tolerability than the amikacin/vancomycin combination.
- Clarithromycin shows promise as a novel topical antibiotic for M. fortuitum keratitis.