Introduction.Staphylococcus pseudintermedius, an opportunistic pathogen of dogs and cats, is rarely reported to cause infection in humans. Here, we describe a case of severe skin infection caused by S. pseudintermedius, in a 47-year-old male, a dog owner; to the best of our knowledge, this is the first such case reported from Scotland. Case presentation. The patient presented with a short history of a severe ecthyma-like lesion on his forehead, with smaller lesions on his abdomen and legs. Bacterial culture revealed Clostridium perfringens, thought to be colonizing the wound, and a Staphylococcus species, identified as S. pseudintermedius by matrix-assisted laser desorption/ionization-time of flight MS and confirmed by molecular methods using a PCR-RFLP approach. The patient was treated with flucloxacillin, penicillin V and Fucibet cream, and recovered fully. Zoonotic infection was considered likely; however, screening swabs from his dogs grew S. pseudintermedius of a different clonal type. Both patient and dog strains carried Staphylococcus intermedius exfoliative toxin and leucocidin I, closely related to Panton-Valentine leucocidin, possibly contributing to the severity of the infection. S pseudintermedius, although coagulase positive, is normally negative by rapid slide clumping and latex agglutination tests routinely used to identify Staphylococcus aureus. Hence, S. pseudintermedius may easily be misidentified as a coagulase-negative staphylococcus and considered insignificant. Conclusion. This is, to the best of our knowledge, the first reported case of a human S. pseudintermedius infection in Scotland. Zoonotic transmission of S. pseudintermedius between pets and owners has been shown. However, in this case zoonosis could not be confirmed.

Elizabeth D Wright

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