This is a question I get a few times a week. Because methicillin-resistant Staphylococcus pseudintermedius (MRSP) infections are becoming so common and people are aware of potential concerns regarding transmission of methicillin-resistant Staphylococcus aureus (MRSA) from pets to people, it’s a logical concern.
Here’s my basic thought process when answering this common question:
- Staphylococcus pseudintermedius is very common on the skin and in the nose of healthy dogs. A large percentage of dogs are carrying this bacterium on any given day, and you can never tell who’s a carrier by looking at them. Therefore, a large number of people are exposed to this bacterium on any given day.
- Staphylococcus pseudintermedius is a common cause of infection in dogs, particularly skin infections.
- Staphylococcus pseudintermedius can be found in the nasal passages of a small but appreciable percentage of healthy people, most likely acquired from their dogs.
- Despite the frequent exposure, S. pseudintermedius infections in people are extremely rare.
So, the risk of getting a S. pseudintermedius infection from a pet is quite low. What about the methicillin-resistant version of this bug?
- MRSP and the susceptible version differ by the presence of antibiotic resistance, and not necessarily anything else. Methicillin-resistance does not, to our knowledge, increase the virulence of this bacterium or make it more transmissible.
- If transmission of S. pseudintermedius from pets to humans is very rare, and methicillin-resistance doesn’t increase the risk of transmission, there should be no greater likelihood of someone getting MRSP from a dog compared to susceptible S. pseudintermedius.
So in the end there’s not too much to be concerned about. Yes, there is a reasonable chance that MRSP can be passed between people and pets, but that’s different than getting sick. Transmission of MRSP from healthy and sick pets to owners probably occurs on a regular basis, but since MRSP is not a normal bacterial inhabitant of people and it is not well adapted to cause disease in humans, not much happens.
But the disclaimer I always put in is "rarely doesn’t mean never." The risks are very low, but they are not zero. While the odds of me picking up MRSP from a dog are very low, I’d rather not have an infection with a highly drug-resistant bacterium. Accordingly, the use of proper hygiene and infection control measures, particularly around an animal with an active infection, is always important. These measures include:
- Frequent handwashing after contact with the pet.
- Avoiding contact with the infected site.
- Keeping the infected site covered with an impermeable dressing, whenever possible.
- Reducing contact with the nose of the infected animal, since it may also be carrying the bacterium there. In general, reducing close contact (e.g. snuggling, nuzzling, hugging, kissing) during the period of infection is a good idea.
- Regular washing (in hot water with hot air drying, whenever possible) of pet beds and other items that come into close and frequent contact with the pet.
Is all that overkill? Probably. But it’s also an easy and practical plan, and a reasonable approach to reduce the already-low risks.
More information about MRSP is available on the Worms & Germs Resources page.
(Photo credit: John Haslam)