scholarly journals Use of Sysmex UF-5000 flow cytometry in rapid diagnosis of urinary tract infection and the importance of validating carryover rates against bacterial count cut-off

2021 ◽  
Vol 70 (12) ◽  
Author(s):  
Kjersti Haugum ◽  
Maria Schei Haugan ◽  
Jannicke Skage ◽  
Mariann Tetik ◽  
Aleksandra Jakovljev ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Bacterial Growth ◽  
Roc Curve ◽  
Urine Culture ◽  
Bacterial Count ◽  
Urine Flow ◽  
Urine Samples ◽  
Rapid Screening ◽  
Cross Contamination ◽  
Rule Out

Introduction. Urinary tract infections are common bacterial infections worldwide. Urine culture is the gold standard method to identify and quantify the presence or absence of bacteria in urine. Flow cytometry, which can differentiate and quantify multiple particles (including bacteria) in the urine, presents an alternative method for rapid screening to rule out bacteriuria. Hypothesis. Adding flow cytometry to identify urine samples without bacteriuria could substantially reduce the number of urine samples that need to be cultured as well as the response time for negative results. However, the level of instrument rinsing between samples could affect sample-to-sample carryover rate, a concept given little attention in previous studies. Aim. We aimed to evaluate urine flow cytometry as a rapid screening method to identify urine samples without significant bacterial growth, including analyses of cross-contamination and sample-to-sample carryover rate. Methodology. We analysed 3919 urine samples by quantitative urine culture and flow cytometry screening (Sysmex UF-5000). Receiver operator characteristic (ROC) curve analyses were used to test method agreement to identify: (a) positive vs. negative culture and (b) mixed vs. pure culture. In addition, we performed carryover and cross-contamination studies. Results. ROC curve analyses identified bacterial count (BACT ml−1) and leucocyte count (WBC µl−1) as possible predictors of bacterial growth in the total material and subpopulations, except pregnant women (n=451). This subgroup was excluded from further analyses, leaving a final 3468 urine samples. Area under the ROC curve was 0.94 (95 % CI 0.93–0.95) and 0.81 (95 % CI 0.79–0.82) for bacterial and leucocyte count, respectively. A bacterial count cut-off of 30 BACT ml−1 resulted in 95.2 % sensitivity and 91.2 % negative predictive value, resulting in approximately 30 % of urine samples that could be reported as negative without culture. Use of high-level rinse modes was necessary to ensure carryover rates <0.05 %. Conclusion. Flow cytometry is a suitable and rapid method to rule out urine samples without significant bacterial growth. Rinses between samples should be adjusted, depending on the cut-off used, to prevent sample-to-sample carryover, whereas cross-contamination can be eliminated by the use of separate urine aliquots for flow cytometry analysis and urine culturing respectively.

scholarly journals Accuracy of urine flow cytometry and urine test strip in predicting relevant bacteriuria in different patient populations

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Christian Gehringer ◽  
Axel Regeniter ◽  
Katharina Rentsch ◽  
Sarah Tschudin-Sutter ◽  
Stefano Bassetti ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Bacterial Growth ◽  
Predictive Value ◽  
Urine Culture ◽  
Test Strip ◽  
Urine Flow ◽  
Urine Samples ◽  
Urine Test ◽  
Cell Counts ◽  
Urine Flow Cytometry

Abstract Background Urinary tract infection (UTI) is diagnosed combining urinary symptoms with demonstration of urine culture growth above a given threshold. Our aim was to compare the diagnostic accuracy of Urine Flow Cytometry (UFC) with urine test strip in predicting bacterial growth and in identifying contaminated urine samples, and to derive an algorithm to identify relevant bacterial growth for clinical use. Methods Species identification and colony-forming unit (CFU/ml) quantification from bacterial cultures were matched to corresponding cellular (leucocytes/epithelial cells) and bacteria counts per μl. Results comprise samples analysed between 2013 and 2015 for which urine culture (reference standard) and UFC and urine test strip data (index tests, Sysmex UX-2000) were available. Results 47,572 urine samples of 26,256 patients were analysed. Bacteria counts used to predict bacterial growth of ≥105 CFU/ml showed an accuracy with an area under the receiver operating characteristic curve of > 93% compared to 82% using leukocyte counts. The relevant bacteriuria rule-out cut-off of 50 bacteria/μl reached a negative predictive value of 98, 91 and 89% and the rule-in cut-off of 250 bacteria/μl identified relevant bacteriuria with an overall positive predictive value of 67, 72 and 73% for microbiologically defined bacteriuria thresholds of 105, 104 or 103 CFU/ml, respectively. Measured epithelial cell counts by UFC could not identify contaminated urine. Conclusions Prediction of a relevant bacterial growth by bacteria counts was most accurate and was a better predictor than leucocyte counts independently of the source of the urine and the medical specialty ordering the test (medical, surgical or others).

scholarly journals Comparison of Urine Flow Cytometry on the UF-1000i System and Urine Culture of Urine Samples from Urological Patients

2021 ◽  
pp. 1-10
Author(s):  
Moritz Fritzenwanker ◽  
Marcel Oliver Grabitz ◽  
Borros Arneth ◽  
Harald Renz ◽  
Can Imirzalioglu ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Urine Culture ◽  
Pearson Correlation ◽  
Urine Flow ◽  
Urine Samples ◽  
University Hospital ◽  
Predictive Values ◽  
Colony Forming Units ◽  
Significant Bacteriuria ◽  
Urine Flow Cytometry

<b><i>Introduction:</i></b> The aims of this study were to evaluate urine flow cytometry (UFC) as a tool to screen urine samples of urological patients for bacteriuria and to compare UFC and dipstick analysis with urine culture in a patient cohort at a urological department of a university hospital. <b><i>Methods and Material:</i></b> We screened 662 urine samples from urological patients (75.2% male; 80.7% inpatients; mean age 58 years). UFC results were compared to microbiological urine culture. <b><i>Results:</i></b> The accuracy in using the UFC-based parameters for detecting cultural bacteriuria was 91.99% and 88.97% for ≥10<sup>5</sup> colony-forming units (CFU)/mL and ≥10<sup>4</sup> CFU/mL, respectively. UFC and leukocyte dipstick analysis measured leukocyturia similarly (Pearson correlation coefficient 0.87, <i>p</i> value &#x3c;0.01%), but dipstick analysis scored less accurately on bacteriuria (accuracy 59.37% and 62.69%). UFC remained effective in subgroup analysis of patients of both sexes and with different urological conditions with its overall use only slightly impaired when assessing gross hematuria (NPV 84.62% for ≥10<sup>4</sup> CFU/mL). UFC also reliably removed those urine samples below cutoffs with negative predictive values of 99.28% for ≥10<sup>5</sup> CFU/mL and 95.86% for ≥10<sup>4</sup> CFU/mL. <b><i>Conclusion:</i></b> Counting bacteria with UFC is an accurate and rapid method to determine significant bacteriuria in urological patients and is superior to dipstick analysis or indirect surrogate parameters such as leukocyturia. When UFC is available, we recommend it to be used for the diagnosis of bacteriuria over findings obtained by dipstick analysis.

scholarly journals Diagnosis of Urinary Tract Infections by Urine Flow Cytometry: Adjusted Cut-Off Values in Different Clinical Presentations

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Sabine K. Schuh ◽  
Ruth Seidenberg ◽  
Spyridon Arampatzis ◽  
Alexander B. Leichtle ◽  
Wolf E. Hautz ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Urinary Tract ◽  
Bacterial Growth ◽  
Clinical Presentation ◽  
Urine Culture ◽  
High Sensitivity ◽  
Urine Flow ◽  
Clinical Presentations ◽  
Tract Infections ◽  
Urine Flow Cytometry

Background. Bacterium and leucocyte counts in urine can be measured by urine flow cytometry (UFC). They are used to predict significant bacterial growth in urine culture and to diagnose infections of the urinary tract. However, little information is available on appropriate UFC cut-off values for bacterium and leucocyte counts in specific clinical presentations. Objective. To develop, validate, and evaluate adapted cut-off values that result in a high negative predictive value for significant bacterial growth in urine culture in common clinical presentation subgroups. Methods. This is a single center, retrospective, observational study with data from patients of the emergency department of Bern University Hospital, Switzerland, with suspected infections of the urinary tract. The patients presented with different symptoms, and urine culture and urine flow cytometry were performed. For different clinical presentations, the patients were grouped by (i) age (>65 years), (ii) sex, (iii) clinical symptoms (e.g., fever or dysuria), and (iv) comorbidities such as diabetes and immunosuppression. For each group, cut-off values were developed, validated, and analyzed using different strategies, i.e., linear discriminant analysis (LDA) and Youden’s index, and were compared with known cut-offs and cut-offs optimized for sensitivity. Results. 613 patients were included in the study. Significant bacterial growth in urine culture depended on clinical presentation and ranged from 32.3% in male patients to 61.5% in patients with urinary frequency. In all clinical presentations, the predictive accuracy of UFC leucocyte and UFC bacterium counts was good for significant bacterial growth in urine culture (AUC≥0.88). The adapted LDA95 equations did not exhibit consistently high sensitivity. However, the in-house cut-offs (test positive if UFC leucocytes>17/μL or UFC bacteria>125/μL) were highly sensitive (>90%). In female, younger, and dysuric patients, even higher cut-offs for UFC leucocytes (169/μL, 169/μL, and 205/μL) exhibited high sensitivity. Specificity was insufficient (<0.9) for all tested cut-offs. Conclusions. For various clinical presentations, significant bacterial growth in urine culture can be excluded if flow cytometry measurements give a bacterial count of ≤125/μL or a leucocyte count of ≤17/μL. In female patients, dysuric patients, and patients younger than ≤65 years, the leucocyte cut-off can be increased to 170/μL.

A New Screening Approach For Fast And Accurate Prediction Of Positive And Negative Urine Cultures By SediMAX Compared With The Standard Urine Culture

2021 ◽  
Vol 1 (1) ◽  
pp. 46-55
Author(s):  
Massimo Pieri ◽  
Flaminia Tomassetti ◽  
Paola Cerini ◽  
Roberta Felicetti ◽  
Lucia Ceccaroni ◽  
...  
Keyword(s):  
Blood Cell ◽  
Bacterial Infections ◽  
Urine Culture ◽  
Screening Method ◽  
Significant Proportion ◽  
Bacterial Count ◽  
Urine Samples ◽  
Screening Methods ◽  
Urine Sediment ◽  
Tract Infections

Urinary tract infections (UTI) are the most frequent bacterial infections, and the detection of infection in urine samples is expensive and time-consuming. Also, in laboratories a significant proportion of samples processed yield negative results. For this, screening methods represent an important improvement towards the final UTI diagnosis. SediMAX is an automated microscopy, easier to use in laboratories due to its basic procedure and it is widely used for urine sediment analysis. In our study, we evaluated the performance of SediMAX, applying some screening parameters, compared with the gold standard methods, urine culture, to identify all the positive cases for UTI. We analysed 1185 urine samples from our daily laboratory routine. The basis of our screening model was to establish a cut-off for bacterial count (BACT), as 300 bacteria/µL in order to avoid missing positive cases. However, the sensitivity and the specificity achieved were not enough to identify all UTI infection in urine samples. So, in addition to BACT we have considered other parameters, such as White Blood Cell (WBC), Red Blood Cell (RBC), Yeasts (YEST), Age and Nitrates (NIT). The second screening method reached a sensitivity of 100%, that could be reliably employed in detect of UTIs.

scholarly journals Urine flow cytometry can rule out urinary tract infection, but cannot identify bacterial morphologies correctly

2015 ◽  
Vol 448 ◽  
pp. 86-90 ◽  
Author(s):  
N. Geerts ◽  
A.R. Jansz ◽  
K.J.M. Boonen ◽  
R.P.W.F. Wijn ◽  
E.L. Koldewijn ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Urine Flow ◽  
Urine Flow Cytometry ◽  
Rule Out

scholarly journals Rapid Screening of Urinary Tract Infection and Discrimination of Gram-Positive and Gram-Negative Bacteria by Automated Flow Cytometric Analysis Using Sysmex UF-5000

2018 ◽  
Vol 56 (8) ◽  
Author(s):  
Seon Young Kim ◽  
Yumi Park ◽  
Hyunjin Kim ◽  
Jimyung Kim ◽  
Sun Hoe Koo ◽  
...  
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Bacterial Growth ◽  
Flow Cytometric Analysis ◽  
Discrimination Performance ◽  
Bacterial Count ◽  
Rapid Screening ◽  
Gram Positive ◽  
Gram Negative

ABSTRACT Rapid screening of urinary tract infection is important to determine antibiotic treatment and reduce unnecessary urine culture. We evaluated the performance of the new flow cytometry-based UF-5000 automated urine analyzer (Sysmex, Kobe, Japan). A total of 1,430 urine samples from 1,226 patients were analyzed and compared to urine cultures to which a Previ Isola (bioMérieux, Marcy l'Etoile, France) system was applied. In total, 878 of 1,430 urine cultures (61.4%) produced ≥103 CFU/ml bacterial growth (309 with Gram-negative [GN] bacteria, 517 with Gram-positive [GP] bacteria, and 52 mixed cultures), with 336 samples (23.5%) presenting ≥105 CFU/ml bacterial growth. The ≥105 CFU/ml bacterial growth was detected by a ≥71 bacteria/μl UF-5000 bacterial count with 95% sensitivity and 84% specificity. Using a cutoff of <15 bacteria/μl to determine whether or not to culture, 50.9% of samples were below the cutoff, 94.8 and 99.5% of which presented <104 and <105 CFU/ml of bacterial growth, respectively. The bacterial discrimination performance of the UF-5000 for GN bacteria was superior to that for GP bacteria, and in ≥105 CFU/ml monobacterial samples, the sensitivity and specificity for reporting GN bacteria were 91.7 and 90.0%, respectively. In summary, UF-5000 demonstrated potential utility for the rapid screening of negative bacterial cultures. However, this utility is dependent on the patient population; cutoff optimizations must be performed for specific populations. In addition, UF-5000 presented improved performance in characterizing GP and GN bacteria, although the concurrence rates were not high enough to replace routine cultures.

scholarly journals Accuracy of Automated Flow Cytometry-Based Leukocyte Counts To Rule Out Urinary Tract Infection in Febrile Children: a Prospective Cross-Sectional Study

2016 ◽  
Vol 54 (12) ◽  
pp. 2975-2981 ◽  
Author(s):  
Hong Phuoc Duong ◽  
Karl Martin Wissing ◽  
Nathalie Tram ◽  
Georges Mascart ◽  
Philippe Lepage ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Blood Cell ◽  
Roc Curve ◽  
Cutoff Point ◽  
Cross Sectional ◽  
Predictive Values ◽  
Rule Out

Automated flow cytometry of urine remains an incompletely validated method to rule out urinary tract infection (UTI) in children. This cross-sectional analytical study was performed to compare the predictive values of flow cytometry and a dipstick test as initial diagnostic tests for UTI in febrile children and prospectively included 1,106 children (1,247 episodes). Urine culture was used as the gold standard test for diagnosing UTI. The performance of screening tests to diagnose UTI were established using receiver operating characteristic (ROC) analysis. Among these 1,247 febrile episodes, 221 UTIs were diagnosed (17.7% [95% confidence interval {CI}, 15.6 to 19.8%]). The area under the ROC curve for flow cytometry white blood cell (WBC) counts (0.99 [95% CI, 0.98 to 0.99]) was significantly superior to that for red blood cell (0.74 [95% CI, 0.70 to 0.78]) and bacterial counts (0.89 [95% CI, 0.87 to 0.92]) ( P < 0.001). Urinary WBC counts also had a significantly higher area under the ROC curve than that of the leukocyte esterase (LE) dipstick (0.92 [95% CI, 0.90 to 0.94]), nitrite dipstick (0.83 [95% CI, 0.80 to 0.87]), or the combination of positive LE and/or nitrite dipstick (0.91 [95% CI, 0.89 to 0.93]) test ( P < 0.001). The presence of ≥35 WBC/μl of urine was the best cutoff point, yielding both a high sensitivity (99.5% [95% CI, 99 to 100%]) and an acceptable specificity (80.6% [95% CI, 78 to 83%]). Using this cutoff point would have reduced the number of samples sent to the laboratory for culture by 67%. In conclusion, the determination of urinary WBC counts by flow cytometry provides optimal performance as an initial diagnostic test for UTI in febrile children.

scholarly journals Evaluation of Sysmex UF-1000i® flow cytometer as a screening method for asymptomatic bacteriuria and detection of Group B Streptococcus in pregnancy

2020 ◽  
Vol 33 (3) ◽  
pp. 193-199
Author(s):  
Itziar Angulo López ◽  
Mikel Urrutikoetxea- Gutiérrez ◽  
Julia Aragón-Díez ◽  
Mercedes Fraca Padilla ◽  
José Luis Díaz de Tuesta Del Arco ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Pregnant Women ◽  
Urine Culture ◽  
Screening Method ◽  
Group B Streptococcus ◽  
Asymptomatic Bacteriuria ◽  
Flow Cytometer ◽  
Urine Samples ◽  
Microbial Count ◽  
Group B

Objectives. Nowadays, the use of flow-cytometry for the screening of urine samples is extended, but appropriate cut-off points for each population group are yet to be established. The objective of this study was to evaluate the Sysmex UF-1000i® cytometer as a screening method for detection of asymptomatic bacteriuria (AB) and Group B Streptococcus (GBS) in pregnant women. Material and methods. Urine samples obtained during pregnancy between January-July 2019 were both processed with the Sysmex UF-1000i® and also cultured. Demographic data, flow-cytometry parameters and the result of the urine culture were collected. To assess the performance of the flow-cytometer for detection of AB and GBS, receiver operating characteristic (ROC) curves for the BACT/μL variable were applied. Results. A total of 33,687 urine samples were received, among which 1,443 (4.3%) belonged to pregnant women. Urine culture was positive in 82 (5.7%) samples, 1,295 (89.7%) were negative and 66 (4.6%) were considered contaminated. GBS was isolated in 69 (4.8%) patients and 46 (66.7%) with a microbial count below 10E4 CFU/mL. For AB detection, the cut-off point of 550 BACT/μL yielded a sensitivity of 91.5%, a negative predictive value of 99.3% and could avoid culturing 74.1% of the samples. No cut-off value could be established for GBS detection. Conclusions. Although the Sysmex UF-1000i® system is a valid screening method for the AB detection in pregnant population, it is not useful for the identification of GBS bacteriuria in our area. Therefore, the conventional urine culture is still required during pregnancy.

Automated Flow Cytometry Compared with an Automated Dipstick Reader for Urinalysis

1999 ◽  
Vol 45 (1) ◽  
pp. 118-122 ◽  
Author(s):  
Michel R Langlois ◽  
Joris R Delanghe ◽  
Sophia R Steyaert ◽  
Karel C Everaert ◽  
Marc L De Buyzere
Keyword(s):  
Flow Cytometry ◽  
Leukocyte Count ◽  
Bacterial Count ◽  
Urine Samples ◽  
Yeast Cells ◽  
Computer Assisted ◽  
Light Scatter ◽  
Test Results ◽  
Positive Urine ◽  
Sediment Data

Abstract Recently, the Sysmex UF-100 flow cytometer was developed to automate urinalysis. We compared UF-100 test results with those of an automated dipstick reader. A cross-check of UF-100, dipstick, and microscopic sediment data was performed in 1001 urine samples. Good agreements (P &lt;0.001) were obtained between UF-100 and dipstick data for erythrocytes (r = 0.636) and leukocytes (r = 0.785). Even in urine with low conductivity, the UF-100 could detect lysed erythrocytes. The UF-100 bacterial count was higher among nitrite-positive urine samples (P &lt;0.0001) and was positively correlated with the UF-100 leukocyte count (r = 0.745; P &lt;0.001). In stored urine (24 h), bacterial counts increased, whereas the forward light scatter of leukocytes decreased (P &lt;0.01). Casts and yeast cells reported by the UF-100 should be confirmed by microscopic review because false positives occurred. We suggest that a computer-assisted cross-check of UF-100 and dipstick data allows a clinically acceptable sieving system to reduce the workload of microscopic sediment urinalysis.

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