Environmental Methicillin-ResistantStaphylococcus aureusin a Veterinary Teaching Hospital During a Nonoutbreak Period

Abstract

Concurrent to reports of zoonotic and nosocomial transmission of methicillin-resistant Staphylococcus aureus (MRSA) in veterinary settings, recent evidence indicates that the environment in veterinary hospitals may be a potential source of MRSA. The present report is a cross-sectional study to determine the prevalence of MRSA on specific human and animal contact surfaces at a large veterinary hospital during a nonoutbreak period. A total of 156 samples were collected using Swiffers Ò or premoistened swabs from the small animal, equine, and food animal sections. MRSA was isolated and identified by pre-enrichment culture and standard microbiology procedures, including growth on Mueller-Hinton agar supplemented with NaCl and oxacillin, and by detection of the mecA gene. Staphylococcal chromosome cassette mec (SCCmec) typing and pulsed-field gel electrophoresis profile were also determined. MRSA was detected in 12% (19/157) of the hospital environments sampled. The prevalence of MRSA in the small animal, equine, and food animal areas were 16%, 4%, and 0%, respectively. Sixteen of the MRSA isolates from the small animal section were classified as USA100, SCCmec type II, two of which had pulsed-field gel electrophoresis pattern that does not conform to any known type. The one isolate obtained from the equine section was classified as USA500, SCCmec type IV. The molecular epidemiological analysis revealed a very diverse population of MRSA isolates circulating in the hospital; however, in some instances, multiple locations/surfaces, not directly associated, had the same MRSA clone. No significant difference was observed between animal and human contact surfaces in regard to prevalence and type of isolates. Surfaces touched by multiple people (doors) and patients (carts) were frequently contaminated with MRSA. The results from this study indicate that MRSA is present in the environment even during nonoutbreak periods. This study also identified specific surfaces in a veterinary environment that need to be targeted when designing and executing infection control programs.

Presence, Distribution, and Molecular Epidemiology of Methicillin-ResistantStaphylococcus aureusin a Small Animal Teaching Hospital: A Year-Long Active Surveillance Targeting Dogs and Their Environment

“…Location, selection, and sample collection of environmental surfaces On the basis of results obtained in a preliminary study in 2007 (Hoet, et al 2011), specific services of the small animal hospital were targeted for MRSA monitoring. These were: Community Practice (examination room and treatment area), Dermatology (treatment room and wards), Intensive Care Unit, and Surgery (presurgery room, anesthesia room, surgery suits, and wards).…”

“…These were: Community Practice (examination room and treatment area), Dermatology (treatment room and wards), Intensive Care Unit, and Surgery (presurgery room, anesthesia room, surgery suits, and wards). These areas were targeted because they previously tested positively to MRSA contamination (Hoet et al 2011) and because the presence of this pathogen represents an important risk for nosocomial infection of the patients visiting these services.…”

“…The number and type of surfaces to be sampled were determined based on the results from the previous pilot surveillance (Hoet et al 2011). An average of 48 samples were collected each month for 1 year: Community Practice (5 samples/month), Dermatology (11 samples/month), Intensive Care Unit (8 samples/month), and Surgery (21 samples/month).…”

“…Dry electrostatic cloths/Swiffer Ò (for larger surfaces) or sterile premoistened cotton swabs (for smaller surfaces) were used to sample the different contact surfaces, either as individual or pooled samples, as previously described (Hoet et al 2011). Immediately after sampling, electrostatic cloths were folded and placed into sterile bags, and 90 mL of BPW (BD BBLÔ Buffered Peptone Water, Becton, Dickinson and Company, Sparks, MD) was added before incubating them at 35°C for 24 hours.…”

“…The presence of MRSA in veterinary environments has been reported during outbreaks or limited periods of surveillance (Weese et al 2004, Loeffler et al 2005, Heller et al 2009, Murphy et al 2010, Hoet et al 2011. The environment in the equine section of a veterinary teaching hospital was sampled after the recognition of a cluster of MRSA infections in horses and humans (Weese et al 2004).…”