Evaluation of Sysmex UF-100 Urine Flow CytometervsChamber Counting of Supravitally Stained Specimens and Conventional Bacterial Cultures

Abstract

A b s t r a c tWe evaluated the Sysmex UF-100 urine flow cytometer (TOA Medical Electronics, Kobe, Japan) The development of automated blood cell analyzers has prompted several attempts to produce similar devices for urinalysis. The first commercially available instruments were the Yellow IRIS (International Remote Imaging Systems, Chatsworth, CA) in the United States' and the Sysmex UA series (TOA Medical Electronics, Kobe, Japan) in Japan. 2Demands for a higher level of automation and satisfactory differentiation of specific urine particles have been the driving forces for improvement.We evaluated a second-generation urine flow cytometer, the Sysmex UF-100 (TOA Medical Electronics) by comparing its performance with chamber counting of Sternheimerstained noncentrifuged specimens and with conventional bacterial cultures on cystine-lactose-electrolyte-deficient (CLED) agar plates. Routine reflectometric test strip measurements and morphologic analyses based on the Finnish recommendations 3 were also performed for comparison. The characterization of formed elements with the UF-100 analyzer is based on flow cytometry of particles doublestained for DNA and membranes; particle identification involves measurement of forward-scattered light intensity and fluorescent light intensity, and the widths of these signals. Conductivity of the sample is measured before it enters the flow cell to adjust a constant electrical current in the flow cell for the impedance measurement. The final differentiation is accomplished with multiparametric algorithms (adaptive cluster analysis). A quantitative report is given for RBCs, WBCs, (large) epithelial cells, bacteria, and casts. Additional information flags are provided to indicate the presence of inclusional casts (granular or cellular casts),

Quantitative Urine Particle Analysis: Integrative Approach for the Optimal Combination of Automation with UF-100 and Microscopic Review with KOVA Cell Chamber

“…4). The reason for the incorrect classification of RBCs was mainly the presence of crystals, yeast, sperm, and a large number of bacteria, as already pointed out by others (12,13 ). The selecting gate for RBCs in the scattergram overlaps partly with these particles.…”

“…Bacteria were counted by UF-100 with high precision (CVs Ͻ5%). Flow cytometry for bacterial counting has been recommended for use in the screening of urinary tract infections because its sensitivity is ϳ55% and its specificity is ϳ90% (13 ).…”

“…An incongruent result was defined as follows: (a) the semiquantitative dipstick result was negative/trace and the cell number in the KOVA chamber was Ͻ10, but the cell count with UF-100 was Ͼ21 and up to 1200 ϫ 10 6 /L; (b) samples with a positive dipstick result whose cell count was more than twice as high on the KOVA system as on the UF-100, or vice versa, and had, in addition, an abnormal scattergram and/or a flag. Particles such as casts, small round cells (SRCs), yeast, sperm, crystals, and dysmorphic RBC were taken into account because a large number of these particles can influence the classification of cells in the scattergram (5,12,13 ). The reason for each discordant result was determined (e.g., influence of yeast, sperm, or crystals on RBC).…”

Automated urinalysis: first experiences and a comparison between the Iris iQ200 urine microscopy system, the Sysmex UF-100 flow cytometer and manual microscopic particle counting

“…Automation may be helpful in solving these problems and improves the accuracy and precision of urine sediment analysis. Several studies compared automated image-based analysis systems and/or flow cytometer-based systems with manual microscopy (6,(19)(20)(21)(22)(23)(24)(25)(26)(27), and most recognized the accuracy and precision of automated systems (28)(29)(30)(31)(32), as well as their feasibility as routine screening tools (8,10,17,18,33,34).…”

Urinary infections in patients with spinal cord injury

“…Criteria for a positive urinary sediment were as follows: more than 25 leucocytes and more than 250 bacteria per microlitre (as determined by flow cytometry; UF-100, TOA Medical Electronics, Kobe, Japan). 9,10 Susceptibility testing is only performed on bacteria considered significant. Repetitive isolates are not retested within a 14-day period.…”