Objective: To evaluate the test performance of microscopic bacteriuria by automated urinalysis for presumptive urinary tract infection (UTI) in young children.
Study design: This is a retrospective cross-sectional study of children aged <2 years evaluated for UTI in a single large emergency department with paired automated microscopic urinalysis and culture. Test characteristics were calculated for automated microscopic bacteriuria and pyuria, and a practical diagnostic threshold of bacteriuria was determined. Standard test performance measures and receiver operator characteristic curves were generated. The diagnostic performance of bacteriuria was compared with microscopic pyuria.
Results: Two thousand five hundred fifty-four children with a median age of 6.1 months were studied, 19% of whom had a positive urine culture. Automated microscopic bacteriuria ≥1+ resulted in a positive likelihood ratio (LR+) of 4.5 (95% CI, 3.9-5.2) and negative LR (LR-) of 0.52 (95% CI, 0.47-0.57). Pyuria alone (≥5 WBC/high-power field) had a LR+ of 4.5 (95% CI, 4.1-5.0) and a LR- of 0.14 (95% CI, 0.11-0.18), whereas the addition of automated microscopic bacteriuria ≥1+ improved the LR+ to 16.3 (95% CI, 12.6-21.1) but raised the LR- to 0.51 (95% CI, 0.47-0.56). Test performance of automated microscopic bacteriuria measured by area under the curve analysis was lower (0.73; 95% CI, 0.70-0.76) than for pyuria (0.92; 95% CI, 0.90-0.93). Isolated automated microscopic bacteriuria without pyuria occurred in only 204 patients (8.0%), among whom only 20 (9.8%) had a positive urine culture.
Conclusions: Microscopic bacteriuria measured by automated urinalysis augments the diagnostic value of pyuria for identifying presumptive UTI in young children aged <2 years. Bacteriuria is diagnostically inferior to microscopic pyuria, and in children with bacteriuria without pyuria, presumptive UTI is unlikely.
Keywords: UTI; bacteria; diagnostics; pediatric; pyelonephritis; urinalysis.
Copyright © 2018 Elsevier Inc. All rights reserved.