Evaluation of Sysmex UF-100 urine flow cytometer vs chamber counting of supravitally stained specimens and conventional bacterial cultures

We evaluated the Sysmex UF-100 urine flow cytometer (TOA Medical Electronic s, Kobe, Japan) with 269 uncentrifuged urine specimens by comparing it with Sternheimer staining and particle counting in 1-mu L disposable chambers w ith both brightfield and phase-contrast microscopy (the reference method). Results of routine test strip analysis, sediment microscopy (182 specimens) , and bacterial culture (204 specimens) were also available. Detection of u rinary WBCs and RBCs was highly reliable with the UF-100 compared with manu al chamber counting (r = .98 and .88, respectively). Identification of bact eria was equal to that with visual microscopy of uncentrifuged specimens; s ensitivity was 55%, and specificity 90%, compared with bacterial cultures a t a cutoff of >10(3) colony-forming units per milliliter Renal damage was d ifficult to evaluate even with manual methods because of the low counts of renal tubular cells and casts; with standard manual Sternheimer-stained sed iment analysis, sensitivity was 65% to 69% and specificity 66% to 91%, comp ared with the uncentrifuged chamber method at a cutoff of 3 and 10 particle s per microliter; respectively. Renal damage was demonstrated with the UF-1 00 with a sensitivity of 26% to 69% and specificity 92% to 94%, compared wi th chamber counts. Automated urinalysis with the UF-100 urine flow cytomete r offers considerable savings in time and labor When high sensitivity is ne eded, visual microscopic review should be performed to detect renal disease .