Topical treatment of Pseudomonas aeruginosa otitis of dogs with a bacteriophage mixture: A before/after clinical trial

In an evaluation of a bacteriophage treatment for infection, ten dogs were included with chronic Pseudomonas aeruginosa otitis. Each received, directly into the auditory canal of one ear, a single dose of a topical preparation containing approximately 1 × 105 plaque forming units (PFU) of each of 6 bacteriophage strains, active against P. aeruginosa. At the time of bacteriophage administration and 48 h later each dog's core temperature was taken, its ear was assigned a clinical score (higher = worse condition) and aural swabs were taken for bacteriophage and P. aeruginosa counts. Forty eight hours after treatment the clinical score and P. aeruginosa count of all ears had fallen (mean score fall: 30.1%, range 7.7–56.3%, p < 0.0001; mean count fall: 67%, range 29.4–96.8%, p < 0.001). The bacteriophage counts had risen from the administered dose (mean rise: 99.1-fold, range 2.8–433.3-fold). No treatment related inflammation or other adverse events were detected during the trial period. This is the first report of a veterinary clinical trial of a bacteriophage treatment of infection. The results show that administration of this topical bacteriophage mixture leads to lysis of P. aeruginosa in the ear without apparent toxicity and that it has potential to be a convenient and effective treatment for P. aeruginosa otitis in dogs.