Investigation of Biofilm-Forming Capacity and Antimicrobial Resistance in Staphylococcus aureus Isolates from Canine Skin Lesions

Abstract

Canine bacterial skin infections are frequently associated with staphylococci

and biofilm formation together with antimicrobial resistance (AMR) may compromise treatment outcomes. This study investigated biofilm production

carriage of the biofilm-associated genes icaA and icaD

and antimicrobial susceptibility in canine S. aureus isolates from skin infections. Swabs (n=130) from dogs with skin lesions were cultured

and S. aureus was confirmed by 23S rRNA PCR. Biofilm formation was quantified using a microtiter plate assay

icaA/icaD were detected by PCR

and antimicrobial susceptibility was determined by disk diffusion according to CLSI guidelines. 72 (55.4%) samples were confirmed as S. aureus. Most isolates produced biofilm

and 23.6% were classified as high biofilm producers. Overall

70.8% of isolates carried at least one of icaA or icaD

but icaA positivity was significantly less frequent among high than low biofilm producers (p=0.002). icaD showed no significant association with biofilm category. Multidrug resistance was common (56.9%)

and high biofilm producers showed a higher proportion of non-susceptibility to amoxicillin-clavulanate than low producers (p=0.049). These findings indicate a substantial burden of biofilm-associated

antimicrobial-resistant S. aureus in canine skin infections and a complex

partly ica-independent relationship between biofilm phenotype and genotype with implications for empirical therapy.