(First published May 2010 in The Mayor’s Alliance for Mayor’s Alliance for NYC’s Animals newsletter, Out of the Cage!)
For those of you who haven’t heard the buzz, there’s a “new” strain of bacteria that is resistant to widely used antibiotics like penicillins and cephalosporins. MRSA stands for methicillin-resistant Staphylococcus aureus, a bacteria that has acquired a gene that prevents certain antibiotics from binding to it. Obviously, a pathogen that is drug-resistant can be dangerous, and this has been a growing problem in the past 10–15 years.
Most of the time, MRSA infections occur in hospital settings, especially when invasive procedures are performed. There is also a form that can be acquired in the community in areas like the changing room of a gym or correctional facility. These are genetically different strains, but either can be the cause of a serious infection.
There have been increasing numbers of reports of MRSA infecting dogs and cats, so what does that imply for your pet’s health (and your own health)? What precautions can or should you take?
Interspecies transmission can occur, but infection does not always cause illness. In fact, it usually does not. Dogs, cats, and people can carry MRSA on surfaces like nasal passages or the digestive tract without ever getting sick. The immune system eventually clears the bacteria without the aid of drugs.
Pets can infect owners, and owners can infect pets, so we can’t necessarily know which way transmission occurred. Routine screening is not necessarily helpful or recommended. Our primary concern is to protect those who are at risk of getting sick, such as an immunocompromised patient or someone weak or debilitated.
Hygiene! Hygiene! Hygiene! It’s what mother always told us: Wash your hands! Avoid high-risk contact. Most (if not all) pets clear the infection on their own, and good hygiene prevents re-infection. Treating an asymptomatic carrier with antibiotics is counterproductive because it can ultimately increase resistance.
Forgive the pun in the title, but there actually is a “MRSI” (mercy!). Methicillin-resistant Staphylococcus intermedius preferentially infects dogs, so it is much less likely to infect people.
It’s also less pathogenic, but all of the usual precautions should be taken. Most common household disinfectants kill both MRSI and MRSA in the environment.
The bottom line is, your greatest risk of exposure to a MRSA is out in the community from an asymptomatic person. As long as you are healthy, if you do get an infection, it should be mild. Most staph infections are treatable, and even MRSA can infect you or your pet without causing symptoms.
Now, go wash your hands!