Phage therapy against methicillin-resistant Staphylococcus pseudintermedius: a novel strategy for canine pyoderma

Introduction Methicillin-resistant Staphylococcus pseudintermedius (MRSP) poses a major public health challenge due to its multidrug resistance. Phages represent an innovative therapeutic strategy with considerable potential against drug-resistant bacterial infections. Methods In this study, dogs clinically diagnosed with pyoderma were recruited to establish an epidemiological dataset, and multidrug-resistant S. pseudintermedius strains (including 6 MRSP isolates) were obtained from bacterial cultures. Three high-efficiency lytic phages were isolated using these MRSP strains as hosts and characterized. The combined efficacy of phages and antibiotics was evaluated in a pyoderma model via clinical scoring, histopathological examination, and tissue bacterial load quantification. Results Notably, these phages enhanced MRSP susceptibility to antibiotics, with genomic and proteomic analyses identifying key mediators of phage-mediated S. pseudintermedius lysis. The phage-antibiotic combination exhibited the most significant therapeutic effect on pyoderma, followed by the phage-only group. In contrast, the antibiotic-only group showed no significant improvement compared to the control group, with both yielding poor outcomes. Discussion This study provides a promising therapeutic strategy for the clinical management of canine pyoderma in veterinary medicine and offers valuable insights for safeguarding public health security.