In this study, samples for bacterial culture were obtained from 14 dogs with superficial bacterial folliculitis. Samples were obtained from 4 to 6 skin lesions per dog and from the gingiva and perineum, both of which are carriage sites for Staphylococcus pseudintermedius. Skin lesions sampled included pustules, papules, crusts, and epidermal collarettes.
S pseudintermedius isolates were subjected to pulsed-field gel electrophoresis and antimicrobial susceptibility testing to assess the genetic diversity of the isolates. Pustules and papules were associated mostly with pure cultures of S pseudintermedius, whereas crusts and collarettes were often associated with multiple bacterial species, likely due to contamination from the environment or surrounding skin. Extensive S pseudintermedius strain diversity was observed, with multiple distinct strains isolated from 6 of 14 dogs. Up to 4 strains with varying antimicrobial resistance profiles were detected in one dog. Most dogs (12/14) carried the strain associated with infection on either the perineum or gingiva; this supports the view that dogs are typically infected with their own strains of S pseudintermedius rather than as a result of transmission from another animal.