Distribution and epidemiological relatedness of methicillin-resistant Staphylococcus aureus isolated from companion dogs, owners, and environments

This study aimed to investigate the distribution and epidemiological relatedness of methicillin-resistant Staphylococcus aureus (MRSA) isolates from companion dogs, owners, and residential environments of 72 households. Sampling was performed twice from January to June 2018 and a total of 2,592 specimens were collected. The specimens collected from each household were streaked on CHROM agar S. aureus and the colonies grown on the medium were further identified using a mass spectrometry microbial identification system. Antimicrobial susceptibility testing, Panton-Valentine-Leukocidin (PVL) gene PCR, staphylococcal cassette chromosome mec (SCCmec) typing, Staphylococcus aureus Protein A (spa) typing, pulsed-field gel electrophoresis (PFGE), and multi-locus sequence typing (MLST) were conducted to evaluate the phenotypic and genotypic characteristics of the MRSA isolates. A total of 65 S. aureus strains (2.5%) were isolated and 49 (1.9%) of 65 strains were MRSA displaying cefoxitin-resistance with mecA carriage. MRSA strains were isolated from dogs (n=6, 9.2%), owners (n=27, 41.5%), and residential environments (n=16, 24.6%), respectively. Overall prevalence of non-duplicated MRSA was 16.7% (12/72 households) at household level. ST72-SCCmec IVc MRSA clones predominantly appeared in MRSA-positive families. Furthermore, PFGE analyses showed that ST72-SCCmec IVc-t324 is shared between dog owners and dogs. To our knowledge, this is the first study to report the sharing of ST72 MRSA between dogs and their owners.