title: Methicillin-resistant Staphylococcus aureus ulcerative keratitis in a Thoroughbred racehorse.
abstract: We report the first case of methicillin-resistant Staphylococcus aureus (MRSA) keratitis in a racehorse. A 5-year-old mare developed punctate keratitis after racing. The corneal ulcer continued to expand despite ophthalmic antimicrobial therapy. On day 6, a conjunctival graft surgery was performed. The mare was euthanized, following colitis and laminitis development on day 10. MRSA was isolated from the corneal swab taken at the time of euthanasia. Immunohistochemical analysis demonstrated gram-positive and anti-S. aureus monoclonal antibody-positive cocci infiltration of the corneal stroma; and a diagnosis of MRSA ulcerative keratitis was made. An ophthalmic antimicrobial against the isolated MRSA did not improve the ocular lesion. The MRSA strain was found to be staphylococcal cassette chromosome mec type II, a strain frequently isolated from humans in Japan.
authors.affiliation: Clinical Science and Pathobiology Division, Equine Research Institute, Japan Racing Association, Tochigi 320-0856, Japan.
authors.forename: Taisuke
authors.initials: T
authors.lastname: Kuroda
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Tochigi 329-0412, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Kinoshita
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Tochigi 329-0412, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Niwa
authors.affiliation: Racehorse Hospital, Ritto Training Center, Japan Racing Association, Shiga 520-3085, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Mizobe
authors.affiliation: Epizootic Research Center, Equine Research Institute, Japan Racing Association, Tochigi 329-0412, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Ueno
authors.affiliation: Clinical Science and Pathobiology Division, Equine Research Institute, Japan Racing Association, Tochigi 320-0856, Japan.
authors.forename: Atsutoshi
authors.initials: A
authors.lastname: Kuwano
authors.affiliation: Kyushu Stallion Station, The Japan Bloodhorse Breeders' Association, Kagoshima 899-8313, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hatazoe
authors.affiliation: Joint Faculty of Veterinary Medicine, Kagoshima University, Kagoshima 890-0065, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Hobo
keywords: corneal ulcer; horse; keratitis; methicillin-resistant Staphylococcus aureus