Future Challenge: Assessing the Antibiotic Susceptibility Patterns of Staphylococcus Species Isolated from Canine Otitis Externa Cases in Western Romania

Abstract

Introduction: Antimicrobial resistance (AMR) has surfaced as a critical challenge to public health on a global scale. The precise and swift identification of resistance to antimicrobial agents, along with timely and suitable antimicrobial therapy paired with effective stewardship practices, is crucial for managing the rise and dissemination of antimicrobial resistance. The objective of our investigation was to outline the antimicrobial resistance profile of Staphylococcus spp., a significant contributor to canine otitis, a prevalent condition in dogs, isolated in Western Romania.

Methods and materials: All data were collected from clinical cases of canine otitis externa which presented at the University Clinic of the Faculty of Veterinary Medicine in Timișoara/Romania. A clinical evaluation was conducted, from which era swabs are usually collected and sent for analysis at the laboratory. Laboratory analysis included the microbiological examination for identifying Staphylococcus spp. and determining antibiotic susceptibility phenotypes. Statistical analysis was implemented on all data that were collected. The ear swabs were processed with standard procedures for cultivating and identifying bacteria. The resulting subcultures were processed to determine the staphylococcal species on the GP ID Cards of the Vitek^® 2 automatic system. The antimicrobial susceptibility profiles were detected by the Vitek^® 2 system using an AST-GP80 card. These isolated Staphylococcus spp. strains were further processed by real-time PCR and PCR-RFLP.

Results: Of all the auricular exudate samples analyzed, 76 were positive for Staphylococcus spp. (59.38%). Within these, in 82% of auricular samples, six distinct Staphylococcus spp. were identified (Staphylococcus (S.) pseudintermedius, S. intermedius, S. hyicus, S. delphiny, S. shleiferi, and S. aureus). Our data indicate that the PCR-RFLP assay is a practical approach to S. pseudintermedius identification, allowing for discrimination from the other Staphylococcus Intermedius Group (SIG) species and important staphylococcal pathogens of dogs. The highest frequency of resistant S. pseudintermedius isolates was detected against tetracycline (21/34; 61.76%; p-value 0.003), gentamicin (20/34; 58.82%), and kanamycin (20/34; 58.82%).

Conclusions: These results are essential to guide the prudent use of antibiotics in veterinary medicine. They will also help design efficient control strategies and measure their effectiveness.

Keywords: Staphylococcus; antimicrobial resistance; dog; otitis externa.