Molecular epidemiology of environmental MRSA at an equine teaching hospital: introduction, circulation and maintenance.

This research investigates how environmental contamination contributes to Methicillin-resistant Staphylococcus aureus (MRSA) infections in an equine teaching hospital. The study tracks the presence, distribution, and characteristics of MRSA over a year, noting that affected surfaces could act as “hot-spots” for the bacteria, hence suggesting a need for increased cleaning and monitoring.

Introduction and Methodology

• The researchers aim was to understand the role of environmental contamination as a possible reservoir for Methicillin-resistant Staphylococcus aureus (MRSA) in equine veterinary hospitals. This became a point of interest because the environment has only been given a monitoring priority during outbreaks or short time periods.
• The research objectives were to determine the monthly presence, distribution, and characteristics of environmental MRSA at an equine hospital and to establish patterns of contamination over time using molecular epidemiological analyses.
• Active MRSA surveillance was carried out within a year in key areas. Antimicrobial susceptibility testing, SCCmec typing, PFGE typing, and dendrographic analysis techniques were employed to characterize and analyze these isolates.

Findings

• Analysis showed that 8.6% of the surfaces and 5.8% of the horses sampled tested positive for MRSA.
• The most common contaminated surfaces were computers, feed-water buckets, and surgery tables-mats.
• 90% of the isolates had SCCmec type IV, and 62.0% were classified as USA500.
• Molecular analysis indicated that new pulsotypes were constantly introduced into the hospital throughout the year.
• Strain maintenance in the environment was observable when identical clones were detected for 2 consecutive months on the same surfaces.
• Pulsotypes were found circulating throughout several areas and across different contact surfaces of the hospital.

Conclusion and Recommendations

• The research showed a consistent introduction of MRSA into the hospital and its frequent presence in the environment.
• Certain contact surfaces in the hospital possibly act as “hot-spots” for MRSA, suggesting the importance of these areas in disease transmission.
• The study recommends active targeting of these contaminated surfaces for rigorous cleaning and disinfection, as well as regular monitoring to reduce the rates of MRSA infections in the hospital.