Beware of the pet dog: a case of Staphylococcus intermedius infection.

Staphylococcus intermedius is a common commensal and pathogen in dogs and cats and only rarely has been identified as causing human infection. We report a human case of postoperative sinus infection caused by methicillin-resistant S. intermedius. A 28-year-old woman with a history of endoscopic pituitary adenoma resection presented with 3 weeks of foul smelling nasal discharge. Nasal endoscopy revealed purulent sinus drainage. Cultures, initially misidentified as coagulase-negative Staphylococcus and then as Staphylococcus aureus, revealed the presence of S. intermedius. Cultures from the patient's pet dog also grew S. intermedius strains that were confirmed to be identical to those of the patient's by pulse field gel electrophoresis analysis. The patient was successfully treated with endoscopic debridement and a prolonged antibiotic regimen with vancomycin and linezolid. Our case illustrates the possibility of transmission of antibiotic-resistant bacteria causing infection from pets to humans.