Methicillin-resistant Staphylococcus pseudintermedius in a veterinary teaching hospital in Atlantic Canada

Methicillin-resistant (MR) staphylococci have been implicated as an important cause of nosocomial infections in human and veterinary hospitals. Since 2010 an infection control program at the Atlantic Veterinary College Veterinary Teaching Hospital (AVC-VTH) has focused its efforts on reducing transmission and persistence of MR Staphylococcus pseudintermedius (MRSP) in patients and the hospital environment. The objectives of this study were (1) to determine if MRSP isolates recovered from hospital environments are clonal to isolates recovered from patients associated with that area, and (2) if epidemiologically related patients with MRSP have clonal strains. It was hypothesized that hospital and patient strains and isolates from epidemiologically associated patients would be clonal. Environmental specimens were collected using an electrostatic cloth. Culture of cloths was accomplished by using an enrichment broth, followed by routine plating methodology. Patient and environmental isolates were identified by colony morphology, coagulase production, and resistance to oxacillin. Methicillin-resistance was confirmed by penicillin-binding protein 2a (PBP2') latex agglutination. Species-level identification was achieved by using a multiplex PCR assay for coagulase-positive staphylococci. MR isolates were typed by sequence analysis of the mecassociated direct repeat units (dru typing.) Epidemiologically related isolates of the same dru type were compared using pulsed-field gel electrophoresis (PFGE). Preliminary analysis of isolates from 2010 to date indicated that 35 patients were positive for MRSP at the AVC-VTH and MRSP was isolated from 9 environmental samples. Molecular work has been completed for all isolates from 2010 to 2012. All isolates were confirmed to be S. pseudintermedius by PCR. Typing results have shown that strains isolated from VTH areas were the same dru type as temporally associated patient strains. PFGE provided further evidence to suggest that patients were contaminating the hospital environment. There were two instances where hospital-acquired infections were suspected. In one instance, the dru types of the isolates were the same. PFGE analysis of these isolates revealed clonal strains, further suggesting hospital-acquired transmission. Results from this study will provide support for the development and application of policies in veterinary infection control programs.