Accuracy of a urine culture test for detecting bacteria in dogs

Abstract

OBJECTIVE To evaluate the clinical performance of a commercially available compartmentalized urine culture and antimicrobial susceptibility test plate (CCSP) for identification of canine bacteriuria and assessment of isolate antimicrobial susceptibility. DESIGN Cross-sectional study. ANIMALS 71 dogs. PROCEDURES Urine samples (n = 84) were divided into 3 aliquots. One aliquot (reference culture) was plated on culture medium ≤ 1 hour after collection for quantitative culture and testing by standard laboratory methods, another was stored at 4°C for 24 hours (to mimic storage practices at primary care facilities) and then processed by standard methods, and the third was applied to a CCSP ≤ 1 hour after collection to be processed and interpreted according to manufacturer instructions. Results were compared with those for reference culture, which was used as the criterion reference standard. Sensitivity, specificity, positive and negative predictive values, and agreement between methods was evaluated. RESULTS 43 isolates (25 single and 9 multiple isolates) were identified in 34 reference cultures. All results for stored cultures were identical to those for reference cultures. Overall sensitivity of the CCSP method to detect bacteriuria was 93%, and specificity was 100%. Thirty-three of 43 (77%) and 19 of 33 (58%) CCSP bacterial isolates were correctly identified to the genus and species level, respectively. The CCSP antimicrobial susceptibility results matched those for reference cultures for 13 of 33 (39%) isolates evaluated. CONCLUSIONS AND CLINICAL RELEVANCE Limitations of the CCSP method included inaccuracy of some antimicrobial susceptibility test results and failure to correctly identify bacteriuria in some dogs.