Genome sequencing reveals strain dynamics of methicillin-resistant Staphylococcus aureus in the same household in the context of clinical disease in a person and a dog

- We identified cases of MRSA in a dog owner and his dog through a controlled trial.
- We sampled the dog owner, dog, a household member, and home surfaces over time.
- We compared MRSA strains using whole genome sequencing and other typing methods.
- The isolate from the dog's bed clustered with the dog's subsequent infecting isolate.
- The dog's infecting isolate did not cluster with subsequent human colonizing isolates.

The strain dynamics of methicillin-resistant Staphylococcus aureus (MRSA) isolates from people and the household dog were investigated. The isolates were identified in the context of a randomized controlled trial that tested household-wide decolonization of people. Genotypic comparison of MRSA isolates obtained from two household members, the dog, and home surfaces over a three-month period failed to implicate the pet or the home environment in recurrent colonization of the household members. However, it did implicate the pet's bed in exposure of the dog prior to the dog's infection. Whole genome sequencing was performed to differentiate the isolates. This report also describes introduction of diverse strains of MRSA into the household within six weeks of cessation of harmonized decolonization treatment of people and treatment for infection in the dog. These findings suggest that community sources outside the home may be important for recurrent MRSA colonization or infection.