Evaluation of the therapeutic efficacy of bacteriophages in the treatment of dogs with superficial pyoderma associated with Staphylococcus pseudintermediu

• Grant number: 25/09317-4
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2026
• End date: January 31, 2029
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Bruno Alonso Miotto
• Grantee: Bruno Alonso Miotto
• Host Institution: Universidade de Santo Amaro (UNISA). São Paulo , SP, Brazil
• City of the host institution: São Paulo
• Associated researchers: Ana Cristina Gales

Abstract

Superficial pyoderma is one of the most common dermatological diseases in dogs and a leading cause of antibiotic prescriptions in veterinary practice. With a multifactorial etiology and frequently recurrent nature, its main causative agent is Staphylococcus pseudintermedius, a commensal bacterium of canine skin often associated with pyoderma. Prolonged use of antibiotics to treat this condition has contributed to the emergence of multidrug-resistant strains, making clinical management of affected animals increasingly challenging. Amid the growing global crisis of antimicrobial resistance, phage therapy-the therapeutic use of bacteriophages, viruses that exclusively infect bacteria-has emerged as a promising alternative. In addition to retaining lytic activity even against multidrug-resistant strains, phages have a high safety profile, with few adverse effects reported. Despite growing scientific interest, the clinical application of phages in dogs, especially in cases of pyoderma, remains incipient.The aim of this project is to isolate and characterize bacteriophages targeting Staphylococcus pseudintermedius, and to implement an in vitro phage training protocol to broaden their host range and therapeutic potential. Once these steps are completed, the study will evaluate the efficacy of a personalized phage cocktail containing trained phages with expanded host range in the treatment of dogs with superficial pyoderma caused by S. pseudintermedius. Therapeutic efficacy will be assessed through an uncontrolled clinical trial involving 30 dogs treated at the veterinary hospital of Universidade Santo Amaro, all diagnosed with superficial pyoderma unresponsive to antibiotic therapy. The dogs will receive topical therapy for 21 days with a customized cocktail of trained phages, and efficacy will be evaluated by comparing clinical, microbiological, and behavioral parameters observed before and throughout the treatment period (six assessments: at 1, 3, 7, 14, 21, and 30 days post-treatment).In addition to therapeutic application, the study also proposes full-genome sequencing of the phages before and after training, to identify genetic modifications associated with host range expansion. This approach may support future phage genome engineering strategies and contribute to the development of AI-based therapeutic prediction tools. A key element for the project's feasibility is the strategic partnership with the Federal University of São Paulo (UNIFESP), through collaboration with the research group led by Prof. Dr. Ana Cristina Gales. Thus, this proposal represents the first clinical trial to employ trained phages for the treatment of canine pyoderma, combining biotechnological innovation, scientific rigor, and clinical applicability. By offering a safe and effective alternative to antibiotic therapy, and aligning with the One Health approach, the project contributes to tackling antimicrobial resistance and advancing precision veterinary medicine, paving the way for future clinical applications of phage therapy in various species, including humans. (AU)