Staphylococcus delphini and Methicillin-Resistant Staphylococcus pseudintermedius in Horses at a Veterinary Teaching Hospital

• While rarely reported, MRSP might be overlooked in horses. Misidentification as S. aureus is possible if laboratories assume coagulase positive staphylococci from horses are S. aureus. Since typical phenotypic methods to detect methicillin-resistance in S. aureus are ineffective for S. pseudintermedius, MRSP can be misidentified as methicillin-susceptible S. pseudintermedius or S. aureus. Given the rapid expansion of this pathogen in dogs and its highly resistant nature, ongoing surveillance is indicated.