Some Zoonotic MRSA May Originate in HumansBy Kentucky Equine Research Staff · January 19, 2010

Researchers continue to investigate the zoonotic transmission of methicillin-resistant Staphylococcus aureus (MRSA). In a recent study of 533 S. aureus isolates cultured from a variety of animals, including cats, dogs, horses, pigs, rabbit, hamster, and rat, scientists found that 36.4% of all S. aureus identified were MRSA. Of the 12 horses cultured, 10 (83.3%) had MRSA.

The researchers were able to group the isolates into five major virulence profiles, and noted that the presence of human MRSA clones in these animals could suggest possible reverse zoonotic transmission.

MRSA is a concern for human health, particularly in hospital settings, due to its resistance to common antibiotics. A report from the University of Florida indicates that 0-5% of horses carry MRSA in their nasal passages, and may also have it on their skin or in their intestinal tracts. Horses on farms with a history of MRSA infections have carrier rates of up to 50%. Additionally, people who work with horses have a higher incidence of MRSA. One study of equine veterinarians reported colonization rates of 10-14%.

The best way to prevent the transmission of MRSA is to practice good hygiene; wash your hands before and after touching different horses, and always before you touch your face or eat.

The study, "Evidence of multiple virulence subtypes in nosocomial and community-associated MRSA genotypes in companion animals from the Upper Midwestern and Northeastern United States," was published in Clinical Medicine & Research. -Erin Ryder