Transmission of MRSA from Dogs

MRSA is a growing concern in the health community. As always the case with news involving public health, there is a certain amount of hysteria from the media. Thankfully there are voices of moderation as well. Blogger medpundit advises restraint:


A recent article in the New York Times puts things in perspective with a chart that points out that your chances of dying from MRSA is 1 in 197, compared to 1 in 84 from a car accident, and a 1 in 63 chance of dying from influenza. And Physician Executive posted about politicians getting in their 2-cents photo-op worth as well.

Less concern is being given to the risks for dog owners and people who work in close proximity of dogs, since the same strain of MRSA has shown up in dogs and their human counterparts.

Outbreaks of MRSA in extended care facilities like hospitals and nursing homes are not uncommon. Patients and the staff that care for them can test positive for the bacteria after simply being in close proximity of each other. If caught early on, however, it can be treated before it becomes a serious infection.

A Tale of Carrier Pets

Concerns started to pop up when cured patients kept coming down with Methicillin-Resistant Staphylococcus aureus subsequent times, even after testing negative at their release from the hospital. This led to an investigation of home environments, and in some cases, was found that the family pet was also a carrier of the MRSA bacteria. Often, the dogs did not show any signs or symptoms of infection, and other family members may even test negative.

This was true of a nurse in the Netherlands. She, her daughter, and her dog all tested positive for MRSA, while other family members in the same home had negative tests. Samples were taken, and tests were done, determining that all three cases seemed to be identical.

Further testing determined that the MRSA from all three were indistinguishable and belonged to an epidemic MRSA cluster. This was the same strain that had been found in nursing homes during several outbreaks a few years prior. The assumption became that the dog had become infected when the nurse brought the MRSA bacteria home after caring for an infected patient. The dog could then have re-infected the mother or child.

After the tests, all three were treated with antibiotics to cure the infections. The treatments cured the infection, and follow up cultures were negative for all three of them at 2 months. The mother, who previously experienced re-infection, tested negative at nine months as well.

Same Strains as Owners

MRSA is a major cause of bacterial infections both in hospitals and the community around the world. At the same time, there have been few cases of MRSA infections in dogs. There have been reports of dogs and their human owners testing positive for the same strain of MRSA after an owner was diagnosed with an infection. Recurrence of the infection was only stopped after the dog had been treated and no longer tested positive as an MRSA carrier.

As a result of this study, it is thought that your pets can become colonized with the same MRSA as you can. If your pets are not identified as carriers and treated, their human companions can continue to become infected despite treatments. So if there is an unexplained infection or recurrence in an infection, the family pet should be looked at as a possible source. Therapy on both the pet and the person can eliminate the risk of re-infection.