Methicillin-resistant Staphylococcus aureus (MRSA) is an important (and high profile) cause of disease in people, and an emerging problem in animals. Evaluating the types of MRSA that we find in pets can help us understand what is happening with MRSA in pets and why.
A few different studies have evaluated the types of MRSA found in pets, using different molecular typing methods. The common result from all these studies is that the MRSA types found in pets are typically the same as those found in people in the same area. Even in different countries where there are different MRSA strains, the strains most commonly found in people are the same as the ones most commonly found in pets. Also, as the types of MRSA found in people in different regions change, so do the types found in pets. For example, USA300 (which can be a particularly nasty strain of MRSA) emerged a few years ago as a leading cause of MRSA infections in people in the general population (i.e. community-associated MRSA) in the US. Shortly thereafter, we started to see this strain in pets too. As USA300 began to crop up in people in Ontario, we also started finding it in pets. These results strongly suggest that MRSA in pets is closely related to MRSA in humans, and that most MRSA infections in pets ultimately started off in a person. Remember, though, that pets can still transmit MRSA once they’ve been infected.
It’s inevitable that we will see more changes in MRSA types in people in the future, and it’s almost certain that these changes will then be reflected in animals. In some ways, we can use humans as sentinels for what we are going to see in pets. By monitoring what is happening with MRSA in people and how it is being addressed, we can perhaps figure out the best (and worst!) ways to address the problem in animals.