This prospective, observational case-control study aimed to evaluate and potentially identify environmental and nosocomial risk factors associated with canine P aeruginosa otitis.
Seventy-seven dog–household combinations were included in the study population: 38 dogs were identified as cases with culture-confirmed P aeruginosa otitis, and 39 controls had otitis due to bacteria other than P aeruginosa. After instruction on proper collection technique, pet owners collected swab samples from various items in their home as well as oral swabs from themselves and any other dogs or cats in the household. Additionally, a 22-question survey was completed to help identify any potential risk factors for community acquisition. Molecular typing was performed on all isolates to determine clonal relatedness of the various samples submitted.
The study found that, as suspected, in most cases of P aeruginosa otitis, the isolates found in the ears were genetically homologous to those found in household water sources or in the oral cavity of human or animal housemates. Additionally, a high proportion of dogs with typable P aeruginosa otic isolates had clonal strains isolated from their own mouth. In a multivariate analysis of potential risk factors, history of visiting a dog park or swimming in a pool was independently associated with a 64% increase in prevalence of being a Pseudomonas spp case.