We’ve seen reasonably good evidence of the potential involvement of pets in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) for a few years, and a study recently published in the Journal of Hospital Infection (Loeffler et al 2010) sheds a little more light on the subject.

In this UK study, they tested 608 veterinary staff and pet owners in contact with pets that were carrying MRSA or methicillin-susceptible S. aureus (MSSA). MRSA carriage was identified in 12.3% of veterinarians that treated MRSA-infected animals and in 7.5% of their owners (although the chicken vs egg conundrum comes up, i.e. are vets that treated MRSA -infected pets more likely to have MRSA because they got it from the pet or because they already had MRSA and infected their patient?). These numbers are relatively consistent with a small number of other studies that have looked at these groups, and are higher than the expected carriage rates in the general population. This is highlighted by the results from people that had contact with animals only carrying methicillin-susceptible S. aureus, since MRSA was only identified in 4.8% of veterinary staff and 0% of owners in this group. Veterinary personnel were significantly more likely to carry MRSA than pet owners. As expected, virtually all MRSA from people and pets in the study were the predominant strains present in human hospitals in the UK.

We shouldn’t fear MRSA or our pets, but we should respect the potential for infection and act accordingly. Mainly, this involves basic practices like:

  • Good hygiene: washing hands regularly after handling pets
  • Avoiding contact with infected body sites in pets, and preventing pets from having contact with infected body sites in people
  • Prudent antibiotic use in both veterinary and human medicine
  • Proper and timely diagnostic testing to identify MRSA infections, to permit proper treatment and earlier implementation of appropriate infection control practices.

Ultimately, MRSA in pets is a human-borne disease. Most pets that have MRSA presumably acquire it from a close human contact, so efforts at controlling MRSA in pets need to be directed at both the pet and human aspects. Uncontrolled MRSA in people will lead to increased risk for pets, and for pets to be a source of subsequent human infection.

Image: Seven-month-old British Shorthair (photo credit: Tamila Aspen)