Meticillin-resistant Staphylococcus aureus colonisation and infection in Thoroughbred racehorses and veterinarians in Japan.

This study investigated the risk of methicillin-resistant Staphylococcus aureus (MRSA) colonisation among Thoroughbred racehorses and veterinarians in Japan. The research found that while MRSA was not detected in healthy horses or office staff, about 30% of veterinarians tested were colonized with MRSA. Interestingly, the MRSA strains identified in the veterinarians showed a high genetic similarity to strains previously found in infected horses, suggesting a probable transmission between the veterinarians and the horses.

Research Objectives and Context

• The study aimed to investigate the sources of MRSA infections that have been confirmed in hospitalized Thoroughbred racehorses at two training centers in Japan since 2009.
• To do this, the researchers examined the rate of nasal MRSA colonisation in a population that included healthy Thoroughbred racehorses, veterinarians, and office staff at the racehorse hospitals of the two training centres.

Methods

• Samples were collected from 600 Thoroughbred racehorses, 53 veterinarians, and 16 office staff for MRSA detection.
• The MRSA strains were categorized using staphylococcal cassette chromosome mec (SCCmec) typing, a method used to classify different strains of MRSA, and multilocus sequence typing.
• Pulsed-field gel electrophoresis analysis, a technique used for the separation of large DNA molecules by applying a variable electrical field, was further used to evaluate the genetic relatedness of these MRSA strains.

Results

• No MRSA strains were isolated from healthy Thoroughbred racehorses or office staff.
• However, MRSA was detected in 16 veterinarians, which constituted approximately 30% of the sampled population.
• Furthermore, the MRSA strains isolated from veterinarians were genetically identical or very similar to the MRSA strains identified in infected horses from the same hospitals between 2009 and 2013.

Implications

• This study contributes important information to the understanding of MRSA transmission in veterinary health settings.
• The researchers provided evidence for probable transmission of MRSA between racehorses and veterinarians in these hospital settings.
• The results underscore the need for implementing biosecurity measures and infection control practices to mitigate the risk of MRSA transmission in veterinary hospitals.