Clinical prevalence and antimicrobial susceptibility of Staphylococcus aureus and Staph. intermedius in dogs


Correspondence to: R.J.L. Paulton, Department of Biology (Microbiology), Trinity Western University, 7600 Glover Road, Langley, B.C., Canada, V2Y 1Y1 (e-mail:


Aims: This study was undertaken to investigate whether the antibiotic resistance of Staphylococcus aureus and Staph. intermedius varies with the site of isolation, sex or age of dogs.
Methods and Results: A total of 867 isolates of Staph. aureus and 1339 isolates of Staph. intermedius were obtained from nose, eye, ear, reproductive extremity, urine, abscess, skin and throat isolates. Staphylococcus intermedius isolates were isolated most frequently and adult and male dogs were more common compared with juveniles and/or female dogs. Antimicrobial resistance was commonly found for penicillin G, lincomycin, tetracycline and trimethoprim-sulphamethoxazole in both Staphylococcus species. Surprisingly, we detected significant resistance to cloxacillin in male (67·1%) and female (69·4%) Staph. aureus isolates, irrespective of the anatomical site of isolation. The resistance or susceptibility of isolates of Staph. aureus from reproductive extremities and isolates of Staph. intermedius from ear, eye and abscess sites was associated with the age of the animal.
Conclusions: Antimicrobial susceptibilities in Staph. aureus and Staph. intermedius often differed with regard to the site of isolation, sex and age of the animal.
Significance and Impact of the Study: Increasing antimicrobial resistance in staphylococci in veterinary medicine complicates the empirical selection of antimicrobial agents. These complications reveal a continuously evolving, complicated multifactoral process of the site of isolation, sex and age of the animal.