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A shared population of epidemic methicillin-resistant staphylococcus aureus 15 circulates in humans and companion animals

Harrison, Ewan M.; Weinert, Lucy A.; Holden, Matthew T. G.; Welch, John J.; Wilson, Katherine; Morgan, Fiona J. E.; Harris, Simon R.; Loeffler, Anette; Boag, Amanda K.; Peacock, Sharon J.; Paterson, Gavin K.; Waller, Andrew S.; Parkhill, Julian; Holmes, Mark A.


Ewan M. Harrison

Lucy A. Weinert

Matthew T. G. Holden

John J. Welch

Katherine Wilson

Fiona J. E. Morgan

Simon R. Harris

Anette Loeffler

Amanda K. Boag

Sharon J. Peacock

Gavin K. Paterson

Andrew S. Waller

Julian Parkhill

Mark A. Holmes


Methicillin-resistant Staphylococcus aureus (MRSA) is a global human health problem causing infections in both hospitals and the community. Companion animals, such as cats, dogs, and horses, are also frequently colonized by MRSA and can become infected. We sequenced the genomes of 46 multilocus sequence type (ST) 22 MRSA isolates from cats and dogs in the United Kingdom and compared these to an extensive population framework of human isolates from the same lineage. Phylogenomic analyses showed that all companion animal isolates were interspersed throughout the epidemic MRSA-15 (EMRSA-15) pandemic clade and clustered with human isolates from the United Kingdom, with human isolates basal to those from companion animals, suggesting a human source for isolates infecting companion animals. A number of isolates from the same veterinary hospital clustered together, suggesting that as in human hospitals, EMRSA-15 isolates are readily transmitted in the veterinary hospital setting. Genome-wide association analysis did not identify any host-specific single nucleotide polymorphisms (SNPs) or virulence factors. However, isolates from companion animals were significantly less likely to harbor a plasmid encoding erythromycin resistance. When this plasmid was present in animal-associated isolates, it was more likely to contain mutations mediating resistance to clindamycin. This finding is consistent with the low levels of erythromycin and high levels of clindamycin used in veterinary medicine in the United Kingdom. This study furthers the “one health” view of infectious diseases that the pathogen pool of human and animal populations are intrinsically linked and provides evidence that antibiotic usage in animal medicine is shaping the population of a major human pathogen.


Harrison, E. M., Weinert, L. A., Holden, M. T. G., Welch, J. J., Wilson, K., Morgan, F. J. E., …Holmes, M. A. (2014). A shared population of epidemic methicillin-resistant staphylococcus aureus 15 circulates in humans and companion animals. mBio, 5(3), Article ARTN e00985-13.

Journal Article Type Article
Acceptance Date Apr 3, 2014
Online Publication Date May 13, 2014
Publication Date May 13, 2014
Deposit Date Jun 12, 2015
Publicly Available Date Jun 12, 2015
Journal mBio
Print ISSN 2150-7511
Electronic ISSN 2150-7511
Publisher American Society for Microbiology
Peer Reviewed Peer Reviewed
Volume 5
Issue 3
Article Number ARTN e00985-13
Keywords Staphylococcus aureus 15, Methicillin resistance, Drug resistance, Antibiotics
Public URL
Publisher URL
Additional Information Copy of article first published in: mBio, 2014, v.1, issue 13


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