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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., (© 2020 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of the European Society of Veterinary Dermatology and the American College of Veterinary.)

Keratinocytes (KC) are the main cellular components of the stratum corneum that constitutes a solid physical skin barrier representing the first line of defense against pathogens. Moreover, KC are potent producers of inflammatory mediators and antimicrobial peptides (AMP) when activated through their pattern recognition receptors. In atopic dermatitis (AD) the protective skin barrier may be compromised due to barrier disruption, secondary infection and accelerated secretion of inflammatory cytokines which may also affect AMP expression in the skin. In the present study, we addressed the responses of a canine KC cell line upon exposure to Staphylococcus pseudintermedius, typically found on canine atopic skin during secondary infections, and stimulation by individual AD-associated ligands and cytokines. All stimuli induced a significant increase in expression of the pro-inflammatory cytokine genes tumor necrosis factor (TNF)-α and interleukin (IL)-8, but with different kinetics. Limited effects were observed on AMP gene expression except for K9CATH which was significantly upregulated upon bacterial infection but with none of the individual AD-associated ligands. Interestingly, K9CATH possessed antimicrobial activity towards Staphylococcus pseudintermedius, indicating that K9CATH expression is a specific defense reaction towards bacterial infection and not part of a general pro-inflammatory profile of KC., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

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