Staphylococcus pseudintermedius is an opportunistic pathogen of dogs and has emerged as a leading cause of skin, wound and surgical site infections worldwide. Methicillin resistance is common and clinical infections as a result of methicillin-resistant S. pseudintermedius (MRSP) pose a clinical challenge. In other staphylococci, biofilm formation has been shown to be a virulence factor for infection, however, it has received little attention in S. pseudintermedius. The objectives of this study were to evaluate the biofilm forming ability of clinical isolates of S. pseudintermedius obtained from dogs using phenotypic and genotypic techniques.

Objective—To evaluate the association between preoperative carriage of methicillin-resistant Staphylococcus pseudintermedius (MRSP) and the development of surgical site infections (SSIs) following tibial plateau leveling osteotomy (TPLO) in dogs. Design—Prospective multicenter study. Animals—549 dogs. Procedures—At 7 veterinary hospitals, swab specimens were obtained from the pharynx, nares, rectum, and skin of dogs admitted for TPLO. Specimens were submitted for culture of MRSP. For each dog, information regarding preoperative and postoperative antimicrobial administration, comorbidities, contact with other dogs, and whether the dog developed an SSI was obtained. Univariable and multivariable analyses were performed to identify variables associated with preoperative and postoperative MRSP colonization and the development of an SSI. Results—Of the 549 study dogs, 24 (4.4%) were identified as MRSP carriers before TPLO and 37 (6.7%) developed an SSI after TPLO. Bacteriologic culture was performed on specimens obtained from 32 of the 37 SSIs, and MRSP was isolated from 11 (34%). Carriers of MRSP (OR, 6.72; 95% confidence interval [CI], 2.12 to 21.4) and Bulldogs (OR, 11.1; 95% CI, 2.07 to 59.3) were at risk for development of an SSI after TPLO, whereas postoperative administration of antimicrobials (OR, 0.36; 95% CI, 0.15 to 0.91) appeared to protect against development of an SSI. Conclusions and Clinical Relevance—Results indicated that carriage of MRSP were a risk factor for development of an SSI after TPLO and measures to rapidly identify and treat MRSP carriers are warranted. Postoperative administration of antimicrobials protected against development of an SSI after TPLO.