Analysis of biofilm formation and susceptibility to antimicrobials in P. aeruginosa isolated from chronic otitis externa in dogs and creation of a strain bank for phage selection.

• Grant number: 24/17671-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2024
• End date: November 30, 2025
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Natália Carrillo Gaeta
• Grantee: Thais de Souza Rodrigues
• Host Institution: Universidade de Santo Amaro (UNISA). São Paulo , SP, Brazil

Abstract

External otitis (EO) is one of the most common ailments in dogs, raising significant concern in veterinary medicine. Frequently associated with bacterial and fungal infections, Pseudomonas aeruginosa is one of the most concerning pathogens, identified in up to 35% of chronic cases. Antibiotic resistance, particularly in P. aeruginosa, poses a growing challenge, as strains of this bacterium often exhibit resistance to multiple antibiotics, complicating effective treatment of chronic OE. This study addresses the interaction between animal and human health within the "One Health" framework, emphasizing the need for integrated policies to combat antimicrobial resistance. The overall aim of the research is to characterize the antimicrobial susceptibility profile and biofilm formation capability of P. aeruginosa isolated from dogs diagnosed with chronic OE, as well as to create a strain bank for phage selection. The methodology will involve recruiting up to 50 dogs diagnosed with chronic OE at the Veterinary Hospital of Universidade Santo Amaro (UNISA). Samples from the external auditory canal will be collected and analyzed in the laboratory, where they will be plated on MacConkey agar and incubated at 37°C. Identification of P. aeruginosa will be confirmed using MALDI-TOF technology. The antimicrobial susceptibility profile will be assessed using the disk diffusion method with various antibiotics. Biofilm formation analysis will be conducted using a protocol that quantifies biofilm production through crystal violet staining. Strains with varying susceptibility profiles and biofilm formation capabilities will be stored to create the strain bank. This research is expected to yield results that provide a detailed understanding of the resistance profile of P. aeruginosa in dogs with chronic EO, contributing to epidemiological surveillance and facilitating the selection of bacteriophages as a therapeutic alternative through the establishment of a strain bank.