New Insights into Molecular Characterization, Antimicrobial Resistance and Virulence Factors of Methicillin-Sensitive Coagulase-Positive Staphylococcus spp. from Dogs with Pyoderma and Otitis Externa

The first Tunisian national molecular survey of coagulase-positive staphylococci (CoPS) isolated from dogs with pyoderma and otitis externa was conducted to evaluate the prevalence of CoPS and identify its phenotypic and genotypic diversities. A total of 99 out of the 195 samples collected from 39 sick dogs were identified across multiple sites as methicillin-susceptible CoPS belonging to the species S. pseudintermedius (64.4%), S. aureus (20.2%), S. coagulans (10.1%), and S. hyicus (5%). Fifteen sampled dogs carried more than one Staphylococcus species. Their antibiotic resistance and virulence factors were determined using conventional and molecular methods. Of the S. pseudintermedius isolates found, 17.4% were multidrug-resistant, whereas high rates of virulence genes were observed among the S. aureus isolates. On polystyrene surfaces, 75% of S. aureus isolates were biofilm producers, of which 15% were classified as strong producers. The capsular polysaccharide cap8 genotype was predominant among them. A MultiLocus Sequence Typing (MLST) analysis clustered the S.aureus isolates into five distinct sequence types (STs), with four assigned for the first time. Our findings highlight the spread of CoPS among diseased dogs and, especially, the emergence of S. hyicus, S. coagulans, multidrug-resistant S. pseudintermedius and S. aureus isolates with high genetic variability. The precise characterization of these strains, as well as their continuous monitoring, is necessary for the implementation of preventive strategies given the significant public health risk.