Wednesday, March 26, 2008

MRSA in Pets

I have a considerable interest in MRSA, having had an up close and personal experience with it that nearly ended fatally, and that necessitated my premature retirement from veterinary practice.

I won't burden you with all of the messy details, but briefly, mine started with a severe pain in my right foot which quickly progressed to MRSA sepsis --- what used to be called "blood poisoning." The germ got into my blood stream and traveled all over my body. I spent a year in hospitals and nursing homes re-learning how to walk, and still get around with the assistance of a quad cane. My neck had to be fused, so I'm now carrying around a titanium implant holding the whole mess together. I lost 2 toes, but on the LEFT foot. (The right foot, where it all started, is fine.) I nearly lost the third finger on my right hand when the big knuckle joint (the PIP joint for those who speak the lingo) blew up with MRSA septic arthritis. After two surgeries, I still have the finger, but that joint is gone, and the finger is slowly curling outward as the bone ends slowly collapse. Eventually, I'll need a third operation, this time to fuse the finger in a gently curved position.

Since I contracted MRSA, many people have asked where I caught it, and specifically, if I could have caught it from the animals.

No one knows to this day where it came from; all I know is that on Sunday evening, January 29th, 2006, one day after my 64th birthday, my foot began to hurt so severely that before long, I was completely unable to walk. At first, I thought it was gout, a problem I've been dealing with for decades, but it soon became apparent that this was something far more serious. There was not a mark on the foot, so the germ's route of entry will never be known.

The answer to the second question is not quite so clear. At the time I got sick, the consensus among both physicians and veterinarians was that except perhaps in rare instances, MRSA was not a zoonosis --- in other words, could not infect domestic animals because it was strictly a human pathogen. We --- veterinarians --- were taught that animals didn't even get Staph. aureus, but got a related, far less pathogenic species named Staph. intermedius.

Since that time, though, there has been increasing evidence that the consensus was wrong --- as is so often the case. Reports have begun to come in which thoroughly and painstakingly document the simultaneous infection of humans and cats or dogs in the same household with identical strains of MRSA. Some of the patients, both human and animal, were asymptomatic carriers --- that is, they showed no signs of illness, but nasal cultures proved that they were carrying the germ. Others had various non-healing or recurring problems which turned out to be infections caused by the germ, and which responded to appropriate treatment.

The latest such report is this one from Germany, which appeared in the March 13, 2008 New England Journal of Medicine:
NEJM -- Methicillin-Resistant Staphylococcus aureus in a Family and Its Pet Cat.

Here are a couple of older references from 2006, when the problem was just becoming apparent (and while I was bedridden in the hospital). There's this from the CDC: MRSA in Cat and Owner | CDC EID, and another from my alma mater, Cornell: Superbugs: Is there a Human-Cat Connection?.

By now, I think it's apparent that:

  • there is, indeed, a human-cat connection, as well as a human-dog connection, and
  • in general, the pets catch it from the people, rather than the other way around --- but two-way transmission also occurs, necessitating simultaneous treatment of both owner and pets in order to eradicate the infection.

This is not good news for those of us who consider our 4-legged friends to be members of the family, but neither is it reason to panic. While documented reports of simultaneous human-animal MRSA infection are no longer unheard of, neither are they common.

So what do pet-owners need to do? Mostly, place a renewed emphasis on the basic rules of hygiene that we all learned as children.

The most effective single measure we can take to prevent the spread of any kind of infection is frequent and thorough hand-washing with soap and water.

Despite all the advertising, those hand sanitizers are NOT a substitute for hand-washing. If you really want to use them, it should be as a supplement, after washing thoroughly with warm water and soap. In fact, one tidbit I learned during the course of my extended illness is that hand sanitizers are totally ineffective against another dangerous pathogen, Clostridium difficile, known as C-diff for short. The source of that information is the board-certified infectious disease specialist who was treating me for both MRSA and the C-diff I contracted as a result of the intensive antibiotic therapy needed to save my life.

Bottom line: after you touch the cat, the dog, or their food and water dishes, before you touch anything else, wash your hands with soap and water. Teach the kids to do the same. Insist on it until it's second nature. Discourage pets (usually, but not exclusively, dogs) from licking you, particularly your face. Understand, and be sure the kids understand, that you're doing this not only so we don't catch anything from the pet, but so the pet doesn't catch anything from us.

If you or your family should experience any of the sort of problems described in these references, don't try to diagnose yourself, your children, or your pets. Even qualified professionals cannot diagnose MRSA by looking at the patient, and neither can you! If you have reason to be concerned, consult the appropriate type of doctor early, before the situation can get out of hand, and don't hesitate to ask questions. It's always appropriate to have a frank discussion with your physician or veterinarian. (If either of them is not yet aware of these recent developments, print out these references and insist that they read them.)


  1. Mort, after reading this post, I have decided that, since your medical problem started the day after you turned 64, it MUST have been a diabolical plot by the Social Security Adminstration to prevent you from reaching 65 and collecting any benefits.