This is an increasingly common question, because MRSP is increasingly common. I’ve had two calls about it this week, and it’s only Wednesday.

It’s a good question to ask because MRSP (methicillin-resistant Staphylococcus pseudintermedius) is a highly drug-resistant bacterium that causes a lot of problems in dogs, and because of the high profile of its relatively distant relative, MRSA (methicillin-resistant Staphylococcus aureus), in people.

The short answer is: Yes, MRSP can infect people

BUT… (and it’s a big and important but):

It’s exceedingly rare and the overall risk is very low.

Here’s my reasoning behind this answer:

1) Reports of MRSP infections in people are very rare.

  • I think there are only two such published reports at the moment. There have probably been more infections than the number that are published, and there’s the potential for MRSP to be misdiagnosed by some human diagnostic labs (meaning some MRSP infections may be mistaken for something else), but I think it’s fair to sayl this a very rare infection in humans.

2) MRSP is not well adapted to infect people.

  • MRSP is not inherently any more likely to cause infection than methicillin-susceptible strains of S. pseudintermedius (MSSP).
  • MSSP can be found on basically every dog.
  • A large percentage of the human population has contact with dogs every day.
  • So, a large percentage of people encounter MSSP every day. Yet, reports of MSSP infection in people are very rare. To me, that indicates that this bacterium is poorly adapted to be a human pathogen.

3) Veterinary dermatologists are not extinct.

  • MRSP is very common in dogs with skin infections. In some practices, it’s the main cause of these infections.
  • That means veterinary dermatologists encounter a lot of MRSP every day.
  • I have yet to hear a report of a veterinary dermatologist getting an MRSP infection (carriers yes, disease no). I wouldn’t be surprised if there actually have been some infections, but dermatologists can be considered the canaries in the mine when it comes to human MRSP risk, and I’m not aware of any real issues.

4) All dogs are biohazardous

  • While this may not comfort the people calling me who are worried about the health of their families, it’s important to put things into perspective. All dogs are carrying multiple microorganisms that could cause disease in people under the right circumstances (and the same goes for all cats, horses, people etc. for that matter).
  • If you screened the average dog, you’d find things that are of greater concern that MRSP. In fact, MRSP probably barely cracks my "Top 10 List" of things I’m worried about the average dog spreading.

So, yes, there’s a risk of MRSP infection when a person has contact with a dog infected with or carrying MRSP. There’s also a risk of infection from methicillin-susceptible S. pseudintermedius, the version of the bug that basically all dogs carry, and a whole range of other bugs.

There will never be a zero-risk pet when it comes to zoonotic diseases. It’s impossible. The risks may be very low but we can never eliminate all risk, just like we can never eliminate all risk from walking down the street. For some people, that slight degree of uncontrollable risk might be too much to handle, and they probably shouldn’t own a pet. For most, the positive aspects of pet ownership outweigh the risks, and some basic hygiene practices (e.g. handwashing, avoiding licking, avoiding contact with the dog’s mouth, nose and bum) can reduce that already low risk even further.