Evaluation of a rapid immunoassay for bacteriuria in dogs

Abstract
Background: The ability to detect bacteriuria in dogs with a point-of-care test might
improve medical care and antimicrobial stewardship.
Hypothesis and Objective: A rapid immunoassay (RIA; RapidBac) will provide acceptable sensitivity and specificity for diagnosis of bacteriuria.
Animals: Forty-four client-owned dogs with a clinical indication for urinalysis and aerobic bacterial urine culture.
Methods: Prospective study. Urine, collected by cystocentesis, was submitted for urinalysis and culture at a diagnostic laboratory. Owners completed an enrollment questionnaire regarding their dogs’ clinical signs. The RIA was performed according to the
manufacturer’s guidelines. Results were compared to culture.
Results: Forty-four urine specimens were evaluated from 44 dogs. The sensitivity
and specificity of the RIA test to detect bacteriuria compared to urine culture were
81.8% (95% CI, 65.7%-97.9%) and 95.5% (95% CI, 86.8%-99.9%), respectively. For
cultures yielding ≥103 CFU/mL, sensitivity increased to 90.0% (95% CI, 76.9%-100%)
and specificity was similar at 95.2% (95% CI, 86.1%-99.9%). Malodorous urine, bacteriuria, and pyuria were more likely to be present in dogs with positive RIA or urine
culture results compared to dogs with negative results.
Conclusions and Clinical Importance: The RIA was easy to perform and had good
sensitivity and excellent specificity in this group of dogs. The RIA might be a useful
screening test for decision-making regarding antimicrobial therapy in dogs with a clinical indication for urine culture. Consideration could be given to amending the International Society for Companion Animal Infectious Disease definition of bacterial
cystitis as the presence of signs of lower urinary tract disease together with positive
culture or a positive RIA.

KEYWORDS
bacteriuria, RapidBac, RIA, urinary tract infection