Methicillin-resistant Staphylococcus aureus in horses at a veterinary teaching hospital: frequency, characterization, and association with clinical disease.

The research article investigates the incidence, characterization and relationship with clinical disease of Methicillin-resistant Staphylococcus aureus (MRSA) in horses at a veterinary teaching hospital.

Research Background and Methodology

• The research was instrumental in understanding an emerging equine pathogen, Methicillin-resistant Staphylococcus aureus (MRSA), and the potential for its nosocomial and zoonotic transmission.
• Throughout the research, MRSA screening was implemented for all horses admitted to the Ontario Veterinary College Veterinary Teaching Hospital. This involved collecting nasal swabs on arrival, weekly throughout their time in the hospital, and upon discharge.

Findings

• MRSA was discovered in 120 (5.3%) out of 2,283 horses. At the time of admission, 50.8% (61) of these horses were carriers of MRSA. During hospitalization, an additional 44.2% (53) horses were found to be carriers, while 6 horses couldn’t be confirmed because entry-swabs were not taken.
• Approximately 11.7% (14) of the 120 horses either arrived with or developed clinical infections from MRSA.
• The overall rate of colonization upon admission as determined by this study was 27 in every 1000 admissions.
• Possibly the significant finding of the study is that horses found to be carriers of MRSA on arrival were much more likely to develop clinical MRSA infections as compared to those who were not. The odds ratio for this finding was 38.9, with a confidence interval of 9.49 to 160 and P < 0.0001 demonstrating statistical significance.
• The overall hospital-acquired (nosocomial) MRSA colonization rate was identified to be 23 per 1,000 admissions. Nosocomial MRSA infection occurred at a rate of 1.8 per 1,000 admissions, and a density incidence of 0.88 per 1,000 patient days.

Risk Factors and Implications

• The sole risk factor identified as being linked to hospital-acquired MRSA colonization was treatment with ceftiofur or aminoglycosides during the hospitalization period.
• The findings emphasize the usefulness of MRSA screening for identifying both community-associated and hospital-acquired colonization and infection. Additionally, this study provides establishing benchmarks for monitoring infection control practices in veterinary settings.