The purposes of this study were (1) to describe the population of dogs with biofilm-forming Escherichia coli (E. coli)UTIs, and (2) to determine whether there were clinical differences between dogs with biofilm-forming E. coli UTIs and dogs with non-biofilm-forming E. coli UTIs. We hypothesized there would be no difference in the two population characteristics of dogs whereas biofilm-formation would be more prevalent in dogs whose UTIs are chronic, complicated, and/or asymptomatic.
This was a retrospective cross-sectional study in which we evaluated 76 client-owned animals with E. coli UTIs, divided into two groups based on the in vitro biofilm-forming capability of the E. coli isolates. Biofilm formation was established using a crystal violet assay. Medical records of the dogs were reviewed and their population characteristics (age, sex, breed, weight, body condition score) and infection characteristics (infection class, chronicity, exposure to antibiotics, pyuria, multi-drug resistance, clinical signs) were compared.
The majority (52.6%) of our isolates showed biofilm-forming capability. Dogs with biofilm-forming E. coli UTIs had a lower likelihood of multi-drug resistance (p < 0.001) than those with non-biofilm-forming E. coli UTIs. There were no other statistically significant differences between the population characteristics or infection characteristics of the two groups<./p>
We concluded that because there are no reliable clinical indices by which biofilm-formation can be ruled out, consideration should be given to the possibility of biofilm-formation whenever E. coli UTIs are diagnosed. Additionally, the association of MDR and non-biofilm-forming E. coli may antimicrobial tolerance conferred by biofilm formation.
Resident, Small Animal Internal Medicine
North Carolina State University
Zachary Kern is a second-year small animal internal medicine resident at NC State University. He graduated from the University of Pennsylvania School of Veterinary Medicine in 2014 and completed a rotating internship at BluePearl Veterinary Partners in New York City and specialty internship in internal medicine at the Veterinary Specialists and Emergency Services in Rochester, NY. His interests are urinary tract disorders, immune-mediated disease, and pedagogy.
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