Study shows same MRSA bacteria circulates in both humans and pets

A new study published in the American Society for Microbiolog's mBio journal this week showed that a shared population of methicillin-resistant Staphylococcus aureus (MRSA) bacteria circulates in humans and companion animals.

MRSA lives on the skin of humans and animals, causing difficult-to-treat infections in both.

"Our study demonstrates that humans and companion animals readily exchange and share MRSA bacteria from the same population," Mark Holmes, the senior author of the study and a senior lecturer in preventive veterinary medicine at the University of Cambridge in England, said. "It also furthers the 'one health' view of infectious diseases that the pathogens infecting both humans and animals are intrinsically linked, and provides evidence that antibiotic usage in animal medicine is shaping the population of a major human pathogen."

Holmes studied the genomes of 46 MRSA samples collected from dogs and cats in two U.K. veterinary hospitals between August 2003 and August 2007. Holmes and his colleagues found that the samples were similar to those associated with MRSA strands in humans.

The study also revealed that all animal infections fell in the same family: Epidemic MRSA 15 (EMRSA-15) (sequence type ST22). The placing of the bacteria, which is similar to human bacteria, showed that the companion animal bacteria likely originated in humans.

The animal MRSA were shown to have less resistance to the antibiotic erythromycin than the bacteria found in humans, though they were more resistant to the antibiotic clindamycin, which is popular in U.K. veterinary medicine.