Corneal Infection Treatment

Silver sulfadiazine (a topical drug frequently used to treat burns) could be an effective treatment against common corneal fungal infections, according to researchers at Purdue University.

Fungal keratitis is a serious, painful corneal disease that is a common and frustrating clinical problem. It accounts for about a third of all corneal infections in horses. The disease can require prolonged and often expensive treatment, and in severe cases, it can cause blindness or require complete removal of the eye.

"Silver sulfadiazine has been shown in a previous clinical trial in humans to be an effective therapy for fungal keratitis and causes little conjunctival (pertaining to the mucous membrane that lines the eyelids and eyeball) or corneal irritation," explained Caroline Betbeze, DVM, MS, a visiting instructor at Purdue. "It has also been shown to be absorbed through intact and ulcerated corneas into the bloodstream, aqueous humor (the transparent liquid in parts of the eye), and corneas of rabbits when used topically."

Betbeze and her colleagues isolated fungi from deceased horses' eyes infected with fungal keratitis. Fungal cultures from the 17 ocular samples yielded six different fungi--Fusarium spp, Aspergillus spp (the two most common fungi cultured in equine corneas), Curvularia, Scopulariopsis, Penicillium, and Chrysosporium spp. Researchers treated each isolate with silver sulfadiazine at varied concentrations.

Silver sulfadiazine killed 50-90% of the fungi in each isolate at concentrations between 1 and 64 ìg/mL.

"The study suggests that silver sulfadiazine is an effective antifungal medication for horses with fungal keratitis," Betbeze said. "The limitations of the study are that the drug was not tested in live animals, so results in vivo may be different than in vitro results."

Other researchers included in the study were Ching Ching Wu, DVM, PhD; Sheryl Krohne, DVM, MS; and Jean Stiles, DVM, MS, Dipl. ACVO. The study was published in the October 2006 American Journal of Veterinary Research, Vol. 67, No. 10, p. 1788.

About the Author

Chad Mendell

Chad Mendell is the former Managing Editor for .

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