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Purpose: Upon reviewing literature, information regarding occurrence and characteristics of antibiotic-resistant bacteria obtained from ocular surfaces of horses in Europe is scarce. The aim of this study was to determine the occurrence of methicillin resistant Staphylococcus aureus (MRSA) on ocular surfaces of horses undergoing ophthalmic manipulation (paracentesis, biopsy, surgery). Methods: Conjunctival swabs were collected from 47 horses (49 eyes) (group 1: n = 8 conjunctivitis/blepharitis, group 2: n = 9 keratitis, group 3: n = 32 uveitis). All specimens were immediately processed and identification and susceptibility testing of colonies suspected to be S. aureus was carried out using Vitek2 system (bioMerieux, Lyon) and the presence of MRSA was verified by PCR. Genetic relatedness of all MRSA isolates were investigated by pulsed-field gel electrophoresis (PFGE) and spa-typing. Result: MRSA
was isolated from 6/49 (12.2%) samples. While none of the horses of the first group were found MRSA positive, 3/9 (30.0%) horses of the second and 3/32 (9.8%) of the third group showed MRSA positive swabs. PFGE analysis revealed a very close relatedness (>90%) of the six MRSA isolates, all assigned to spa-type t011, a spa type commonly associated with the European livestock-associated MRSA lineage of the clonal complex (CC) 398. Conclusion: The study demonstrated a high prevalence of MRSA on the ocular surfaces of equine ophthalmic patients – especially in those with keratitis (30%) – supporting the need for constant bacterial surveillance.