UF-1000i™ flow cytometry is an effective screening method for urine specimens

This study was undertaken to evaluate the UF-1000i™ (UF) flow cytometer to count urine constituents including bacteria. The objective was to screen urine samples and determine what white blood cell (WBC) and/or bacteria screening criteria would minimize the number of specimens cultured yet ensuring that all true positives were cultured. UF screening and culture on CHROMagar™ Orientation (CO) medium were performed on 2496 specimens. Various combinations of WBC/bacterial counts were assessed as screening criteria and correlated with significant growth on CO medium. A bacterial count of ≥20 from UF gave an overall screening sensitivity of 92.6%, allowing 35% of specimens to be screened out and not cultured. The sensitivity was 99.2% and 85.0% for Gram-negative and Gram-positive organisms, respectively, using the same bacterial count. Our study indicated that UF was a simple, rapid, and reliable method for urine screening when the bacterial count of ≥20 was used as the sole screening criterion.