Resistance Genes and Virulence Factor Genes in Coagulase-Negative and Positive Staphylococci of the Staphylococcus intermedius Group (SIG) Isolated from the Dog Skin

Staphylococci are common pathogens in dogs, causing a variety of dermatological problems. This study aimed to characterize the prevalence, antibiotic resistance, and biofilm-forming potential of <i>Staphylococcus</i> species isolated from the skin of shelter dogs. Overall, 108 samples were collected from the hairless skin areas of dogs in a shelter over one year. Isolates were cultured using standard microbiological methods and identified through biochemical testing, MALDI-TOF MS, and multiplex PCR. A total of 67 <i>Staphylococcus</i> isolates were identified, with <i>S. pseudintermedius</i> being the most prevalent. Antibiotic susceptibility was assessed using disk diffusion and MIC methods, revealing high resistance to ampicillin, erythromycin, and tetracycline. Notably, 12 multidrug-resistant SIG (<i>S. intermedius</i> group; <i>S. pseudintermedius</i>) and 4 CoNS strains (coagulase-negative staphylococci; <i>S. equorum</i>) were identified. Biofilm production was evaluated using a crystal violet assay, showing variable biofilm-forming capabilities among isolates and PCR, to confirm genes associated with biofilm formation. These findings highlight the presence of multidrug-resistant <i>Staphylococcus</i> species in shelter dogs, emphasizing the need for careful monitoring and antibiotic stewardship to manage potential risks to both animal and human health.