Clindamycin resistance of skin derived Staphylococcus pseudintermedius is higher in dogs with a previous antibiotic history

BACKGROUND: In the Netherlands there is a lack of data regarding resistance of Staphylococcus pseudintermedius to the systemic antimicrobial drugs used for the treatment of superficial pyoderma. OBJECTIVES: To assess antimicrobial resistance, with emphasis on resistance to clindamycin and meticillin, in clinical isolates of S. pseudintermedius isolated from dogs with superficial pyoderma. Results were compared between dogs with and without a history of systemic antimicrobial therapy during the previous year. ANIMALS: A retrospective study of 237 referral cases presented to an academic teaching hospital between 2014 and 2019, with the clinical and microbiological diagnosis of superficial pyoderma. METHODS AND MATERIALS: All clinical isolates were identified primarily by MALDI-TOF mass spectrometry. Antimicrobial susceptibility was tested either by an agar diffusion method (2014-2016) or by broth microdilution. Antimicrobial history in the preceding year was obtained from medical records. RESULTS: Meticillin-resistant S. pseudintermedius (MRSP) was isolated from 8% of superficial pyoderma cases. Within the meticillin-susceptible S. pseudintermedius (MSSP) population, clindamycin resistance was significantly more common in isolates derived from dogs with histories of antimicrobial treatment (37.7%) compared to dogs with no histories of exposure (21.7%; P = 0.03). CONCLUSIONS: Given the high prevalence of clindamycin resistance in MSSP isolated from dogs with prior antimicrobial exposure, it is recommended that bacterial culture and susceptibility testing be pursued before prescribing systemic antimicrobials. Clindamycin should be regarded as the preferred treatment option if susceptibility is confirmed, due to its narrow spectrum and reduced selective pressure for MRSP