Genotypic relatedness and characterization of Staphylococcus pseudintermedius associated with post-operative surgical infections in dogs.

Staphylococcus pseudintermedius is a commensal organism of dogs that can also be implicated in surgical site infections (SSIs) in dogs. Particularly with the recent emergence and spread of the ST71-t02-SCCmecII-III multidrug-resistant S. pseudintermedius clonal lineage (MDRSP), it is important to understand the clonal diversity of S. pseudintermedius in SSIs in dogs. The study reported here investigated the genotypic relatedness of 124 S. pseudintermedius isolates from the surgical wounds of 90 dogs admitted to a referral practice in the UK. This study also aimed to understand whether MDRSP is better adapted to survival and persistence in different environments compared with other S. pseudintermedius. Whilst no individual S. pseudintermedius clonal type was primarily responsible for S. pseudintermedius-associated SSIs in dogs, we found that MDRSP was the most represented clonal type among the isolates studied. However, we observed no difference in the level of biofilm production, susceptibility to biocides or carriage of specific virulence determinants between MDRSP and other S. pseudintermedius isolates studied. Interestingly, in the competitive fitness study, MDRSP did not outcompete any member of the other S. pseudintermedius isolates studied in each environment. Our data suggest that the determinants that promote S. pseudintermedius-associated SSIs in dogs are distributed among S. pseudintermedius as a species and are not restricted to a few clonal types. They also provide evidence to support the suggestion that MDRSP is not better adapted to survival or persistence in different environments and is no more virulent than other S. pseudintermedius isolates.