People, Pets And MRSA

MRSA – methicillin-resistant Staphylococcus aureus – has been making news recently. A particularly virulent strain of this common bacterium is credited with turning relatively minor cuts and abrasions into difficult-to-cure pimples, boils and abscesses.

Staphylococcus aureus is a common microbe. According to the CDC, approximately 32% of the population carry S. aureus without ill effect, usually in the nasal passages or on the skin; roughly 0.8% carry MRSA.

Most transmission of MRSA is person-to-person, either by direct contact or by touching a surface that has been contaminated by someone else. Careful cleaning and frequent hand-washing are usually the best ways to break the infection chain. In the last few years, however, another possible mode of MRSA transmission has raised its head – the family pet.

Today's issue of the New England Journal of Medicine describes just such a situation. An otherwise healthy adult woman was suffering from recurring MRSA-infected abscesses. Her husband and two of her three children were carriers of MRSA, but had no active infections. To remove the likely source of the woman's recurring infections, her husband and all three children were treated with nasal ointments and antiseptic washes.

But, even though her family members no longer carried MRSA, the patient continued to experience repeated infections. So her doctors decided to test the three apparently-healthy family cats. One of the cats proved to be carrying the offending MRSA strain.

All three cats were subjected to an antimicrobial treatment, which eliminated the MRSA. Four weeks later, the woman's abscesses had cleared up permanently. She, her husband, and her three children were retested and were all negative for MRSA. The family declined to retest the cats.

This is not the first time that a family pet has been reported to carry MRSA. In 2005, Dutch researchers reported a similar situation involving a family and their dog. And a 2006 report described the transmission of a strain of MRSA between animals and veterinary staff at a clinic in the UK.

Transmission of MRSA from family pets to their human companions is uncommon, but not unheard of. If you are struggling with a mysterious recurring MRSA infection, it might be worth testing the family pets.