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New Orleans-When selecting a topical antibiotic for endophthalmitis prophylaxis in cataract surgery, consideration should be given only to one of the newer generation fluoroquinolones, either moxifloxacin 0.5% (Vigamox, Alcon Laboratories) or gatifloxacin 0.3% (Zymar, Allergan), said Francis S. Mah, MD.
"For some years, fluoroquinolones have been the standard topical antimicrobial agents used in ophthalmology. However, the previous generation fluoroquinolones (ciprofloxacin, ofloxacin, and levofloxacin) have lost much of their initial potency, and we feel they should be replaced with the newer products, which offer increased antibacterial potency, including against the gram-positive bacteria that are the most important pathogens in endophthalmitis, as well as improved penetration into the anterior chamber," said Dr. Mah, assistant professor of ophthalmology, Charles T. Campbell Ophthalmic Microbiology Laboratory, University of Pittsburgh.
To study whether a newer-generation topical fluoroquinolone could effectively eradicate bacterial pathogens in the anterior chamber and prevent endophthalmitis, Dr. Mah and colleagues tested the efficacy of moxifloxacin in a rabbit model of endophthalmitis. Animals received an intraocular challenge with 5x104 colony-forming unites of a clinical isolate of Staphylococcus aureus. One group of animals received moxifloxacin drops every 15 minutes for 1 hour prior to the challenge and for four more doses over the next 24 hours. A control group was treated at the same intervals with saline.
Slit-lamp observations from an ophthalmologist masked to treatment assignment showed that at 24 hours after inoculation, no animals treated with moxifloxacin developed endophthalmitis whereas all of the saline-treated control eyes had clinical evidence of disease.
"This published study provides proof of principle that topical treatment with this fourth-generation fluoroquinolone pre- and postintraocular bacterial challenge could prevent bacterial endophthalmitis," said Dr. Mah.