This study systematically analyzed the antibiotic resistance of Staphylococcus pseudintermedius isolated from dogs with otitis externa and healthy dogs, revealing the widespread existence of drug-resistant strains in canines and their potential zoonotic transmission risk. The research highlights the necessity for prudent antibiotic use and continuous resistance monitoring in veterinary clinics.
Literature Overview
This article, titled 'Antimicrobial Resistance Profile of Staphylococcus pseudintermedius Isolated from Dogs with Otitis Externa and Healthy Dogs: Zoonotic Implications,' published in the journal Antibiotics, reviews and summarizes the resistance characteristics of Staphylococcus pseudintermedius isolated from dog ears, with special focus on the clinical and public health impacts of methicillin-resistant strains (MRSP) and multidrug-resistant strains (MDR). The research data were collected from multiple veterinary clinics in Timisoara, Romania, covering canine ear swab samples collected between 2022 and 2025. The analytical methods include traditional microbial culture, MALDI-TOF MS identification, and antimicrobial susceptibility testing using the VITEK® 2 Compact system.
Background Knowledge
Staphylococcus pseudintermedius is a common opportunistic pathogen in dogs, associated with various diseases including otitis externa and skin infections. In recent years, the emergence of antimicrobial resistance, particularly methicillin-resistant (MRSP) and multidrug-resistant (MDR) strains, has become a significant challenge in veterinary medicine and public health. Mediated by the mecA gene, MRSP is not only resistant to β-lactam antibiotics but may also carry additional resistance genes, leading to cross-resistance to multiple antimicrobials. As companion animals, dogs may transmit these resistant strains to humans through direct contact, potentially causing skin abscesses, bloodstream infections, and pneumonia. Therefore, continuous monitoring of S. pseudintermedius resistance and standardization of veterinary prescription practices are among the key global antimicrobial stewardship priorities.
Research Methods and Experiments
Between 2022 and 2025, 400 canine otitis externa samples and 360 samples from healthy dogs’ ears were collected from veterinary clinics in Timisoara, Romania. All samples were cultured using traditional microbiological techniques and identified as S. pseudintermedius via MALDI-TOF MS. Antimicrobial susceptibility testing was performed using the VITEK® 2 Compact system, following the CLSI VET01 Edition 5 standards, with 14 antimicrobial agents across 11 drug classes tested. The study also calculated the prevalence of multidrug-resistant (MDR) and methicillin-resistant (MRSP) strains and conducted risk difference and relative risk analysis.
Key Conclusions and Perspectives
Research Significance and Prospects
This study highlights the widespread distribution and complex resistance profile of S. pseudintermedius in dogs, especially in cases of otitis externa. The emergence of MDR and MRSP strains underscores the urgent need for improved antimicrobial stewardship in veterinary practice to mitigate the risk of resistant gene transfer to human pathogens. Future studies should focus on the molecular characterization of resistance genes, host adaptation mechanisms, and geographic distribution of resistant strains. Integrating whole-genome sequencing and molecular epidemiology may help elucidate transmission routes and host-pathogen interaction networks, providing evidence for global antimicrobial management strategies.
Conclusion
This study systematically evaluated the isolation rates and antimicrobial resistance profiles of Staphylococcus pseudintermedius in dogs with otitis externa and healthy dogs, revealing its widespread presence and high tetracycline resistance in canine populations. Although isolates remain susceptible to human-specific antibiotics such as linezolid, vancomycin, teicoplanin, and tigecycline, the emergence of MRSP and MDR strains necessitates stringent antimicrobial management in veterinary clinics. The study recommends enhanced antimicrobial susceptibility testing and establishment of surveillance systems to support sustainable antimicrobial use and reduce the risk of zoonotic transmission. Moreover, healthy dogs, as potential reservoirs of resistant strains, should be included in public health prevention strategies to curb the spread of antimicrobial resistance.
