Epidemiological profiling of methicillin-resistant Staphylococcus aureus-positive dogs arriving at a veterinary teaching hospital.

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as an important zoonotic and nosocomial pathogen in veterinary settings. Even though human risk factors for MRSA infection and colonization are well known, this information in animals is lacking. The objective of this study was to identify risk factors associated with MRSA carrier dogs on their arrival at a veterinary teaching hospital. A total of 435 dogs were enrolled in the MRSA active surveillance program at The Ohio State University-Veterinary Medical Center over a 1-year period. Dogs were screened for MRSA on arrival, regardless of health status, sex, breed, or age. In addition, an epidemiological survey and medical history were obtained for each dog to identify potential risk factors up to 1 year prior to the appointment. Of 435 dogs included in the study, 25 (5.7%) were MRSA positive, with 86.5% of the isolates classified staphylococcal chromosome cassette mec (SCCmec) type II and USA100. Four of the 25 MRSA carrier dogs were healthy, 20 had health issues unrelated to MRSA, and 1 had an active MRSA infection. MRSA was detected in the nares (72%, 18/25), skin lesions (24%, 6/25), and the perianal area (16%, 4/25). Except for previous surgery <90 days (odds ratio [OR]=4.9; 95% confidence interval [CI] 1.4-17.6; p value 0.01), none of the variables related to the previous medical history, dog's management, home environment, and other potential exposures were associated with the MRSA carrier status. However, the profession of the owner was significantly associated, and dogs owned by veterinary students were 20.5 times (95% CI 4.5-93.6; p value≤0.01) more likely to be MRSA positive than dogs owned by clients with different occupations. MRSA-positive dogs were dispersed in different categories, preventing the creation of an epidemiological profile that would allow their early recognition upon arrival to a veterinary hospital. However, the association between veterinary students with MRSA-positive dogs is a concern that deserves further evaluation.