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Meticillin-resistant Staphylococcus aureus colonisation and infection in Thoroughbred racehorses and veterinarians in Japan
  1. T. Kuroda, DVM1,
  2. Y. Kinoshita, DVM2,
  3. H. Niwa, DVM, PhD2,
  4. Y. Shinzaki, DVM3,
  5. N. Tamura, DVM1,
  6. S. Hobo, DVM, PhD4 and
  7. A. Kuwano, DVM, PhD1
  1. 1Clinical Science & Pathobiology Division, Equine Research Institute, Japan Racing Association, Tokami-Cho 321-4, Utsunomiya, Tochigi 320-0856, Japan
  2. 2Microbiology Division, Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shiba 1400-4, Shimotsuke, Tochigi 329-0412, Japan
  3. 3Racehorse Clinic, Ritto Training Center, Japan Racing Association, Misono 1028, Ritto, Shiga 520-3085, Japan
  4. 4Department of Domestic Animal Internal Medicine, Clinical Veterinary Science, Veterinary Medicine, Joint Faculty of Veterinary Medicine, Kagoshima University, Korimoto 1-21-24, Kagoshima, Kagoshima 890-0065, Japan
  1. E-mail for correspondence: Taisuke_Kuroda{at}


Meticillin-resistant Staphylococcus aureus (MRSA) infections have been confirmed in hospitalised Thoroughbred racehorses at the hospitals of two training centres in Japan since 2009. To investigate the source of infection, the authors examined the rate of nasal MRSA colonisation in 600 healthy Thoroughbred racehorses, 53 veterinarians and 16 office staff at the racehorse hospitals of the two training centres. MRSA was not isolated from healthy Thoroughbred racehorses or hospital office staff. However, MRSA was isolated from 16 veterinarians (30.1 per cent), and the colonisation rate was significantly higher in veterinarians than in the office staff of the same hospitals. Also, 10 of the 16 MRSA strains (62.5 per cent) isolated from veterinarians were classified as type II by staphylococcal cassette chromosome mec (SCCmec) typing and ST5 by multilocus sequence typing. Pulsed-field gel electrophoresis analysis demonstrated that these 10 MRSA strains of SCCmec type II and ST5 were genetically identical or very similar to 9 MRSA strains isolated from infected horses hospitalised at these hospitals between 2009 and 2013. These results indicate that SCCmec type II and ST5 MRSA strains were probably transmitted between veterinarians and infected horses.

  • MRSA
  • horse
  • veterinarian

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