Molecular and epidemiological characterization of caninePseudomonasotitis using a prospective case‐control study design

Abstract

BackgroundPseudomonas aeruginosais an opportunistic pathogen of the canine ear canal and occupies aquatic habitats in the environment. Nosocomial and zoonotic transmission ofP. aeruginosahave been documented, including clonal outbreaks.Hypothesis/ObjectivesThe primary objective of this study was to assess various environmental exposures as potential risk factors for caninePseudomonasotitis. It was hypothesized that isolates derived from infected ears would be clonal to isolates derived from household water sources and the mouths of human and animal companions of the study subjects.AnimalsSeventy seven privately owned dogs with otitis were enrolled, along with their human and animal household companions, in a case‐control design.MethodsData on potential risk factors forPseudomonasotitis were collected. Oral cavities of all study subjects, their human and animal companions, and household water sources were sampled. Pulsed field gel electrophoresis was used to estimate clonal relatedness ofP. aeruginosaisolates.ResultsIn a multivariate model, visiting a dog park was associated with 77% increased odds of case status (P= 0.048). Strains clonal to the infection isolates were obtained from subjects’ mouths (n= 18), companion pets’ mouths (n= 5), pet owners’ mouths (n= 2), water bowls (n= 7) and water taps (n= 2). Clonally relatedP. aeruginosaisolates were obtained from dogs that had no clear epidemiological link.Conclusions and clinical importanceGenetic homology between otic and environmental isolates is consistent with a waterborne source for some dogs, and cross‐contamination with other human and animal members within some households.