Assessment of FUS-200 Performance: Comparison with Quantitative Urine Culture Shows that Identifying the Right Cutoff for Optimizing Analyzer Performance Is Challenging

Performance of automated urine analyzers using flow cytometric and digital image-based technology in routine urinalysis

The purpose of this study was to evaluate the analytical performances of Sysmex UF-5000 and Dirui FUS-200 and to compare the results with manual microscopy and between each other. Two hundred fifty urine samples were analyzed for evaluation. Mid-stream specimens were studied sequentially using Dirui FUS-200 and Sysmex UF-5000, and also with manual microscopy within one hour. The physical and chemical components of urinalysis, and sediment results were investigated. The precision results of the FUS-200 and UF-5000 for WBCs, RBCs, and ECs were acceptable. The both analyzers demonstrated good linearity (r > 0.97), with no carry-over. The comparisons of FUS-200 and UF-5000 with manual microscopy for RBCs, WBCs, and ECs on 250 samples exhibited good agreement with little bias (R > 0.780). Only, the moderate agreements were obtained for calcium oxalate for both analyzers (R = 0.512, and 0.648, respectively). The sensitivities of the FUS-200 and UF-5000 were 75.8% and 86.8%, with specificities of 92.3% and 87.8% for WBCs, for RBCs the sensitivities were 91.1%, and 84.4% with specificities of 82.2%, and 89.6% for both analyzers. Kappa values of the UF-5000 were higher than FUS-200 for WBCs, RBCs, ECs, and calcium oxalate. The FUS-200 and UF-5000 urine analyzers, are both accurate, very precise systems and can be safely used in clinical laboratories. However, due to the technological characteristics of the UF-5000 analyzer, its positive impacts on the morphologic recognition and enumeration of RBCs and WBCs should be taken into account, particularly in university hospital laboratories with high patient volumes.

Evaluation of the new Sysmex UF-5000 fluorescence flow cytometry analyser for ruling out bacterial urinary tract infection and for prediction of Gram negative bacteria in urine cultures

BACKGROUND

We evaluated the new flow cytometer UF-5000 with a blue semiconductant laser as a screening tool for ruling out urine samples negative for UTI and its ability to predict Gram negatives in culture.

METHODS

Flow cytometry and microbiological analysis were performed on 2719 urine samples, sent to our microbiology laboratory with a request for urine culture.

RESULTS

UF-5000 showed a very good performance in the screening process. Carryover and cross-contamination was negligible. 797 samples were culture positive at a cut-off of ≥10⁵CFU/mL. ROC curve analysis for BACT count demonstrated AUC between 0.973, on 2714 samples, 0.959, on 1516 female samples, and 0.988 on 1198 male samples, respectively. At the cut-off of BACT ≥58/μL AND/OR YLC ≥150/μL, SE was 99.4%, SP 78.2%, PPV 65.4% and NPV 99.7%; false negatives were 0.6%, avoiding unnecessary cultures in 55.5% of specimens. "Gram Neg?" flag predicted Gram negatives in culture with a SE of 81.6% and SP of 93.3%.

CONCLUSION

The new Sysmex UF-5000 showed high diagnostic accuracy in UTI-screening with a very low rate of false negatives. The instrument is capable of predicting Gram negatives with a good SE and a high agreement with the culture, even if this performance needs further evaluation.