Staphylococcus pseudintermedius Infections in Humans, an Incipient Zoonosis

Staphylococcus pseudintermedius , a coagulase-positive Staphylococcal species, colonizes the skin and mucosal surfaces of almost all dogs, and to a lesser extent, cats. A member of the Staphylococcus intermedius group of coagulase-negative staphylococci, it is known to cause opportunistic infections in these animals. After the initial reports of wound and skin infections in humans, S. pseudintermedius is now considered to be a potential zoonotic pathogen. The mounting number of human-dog interactions, coupled with its similar phenotypic, pathogenic, and resistance characteristics to S. aureus , has made S. pseudintermedius an emerging public health concern. We present a case of a 74-year-old woman with breast cancer who presented with a complicated post-mastectomy surgical wound infection involving S. pseudintermedius . Her infection was believed to have been acquired through close contact with her pet dog. Apropos this case, we review the microbiological identification, pathogenesis, antimicrobial resistance, and epidemiologic aspects of this increasingly recognized Staphylococcal species to call attention to its role as a human pathogen, particularly in individuals having close contact with canine companion animals.