Sysmex UF-1000i flow cytometer to screen urinary tract infections: the URISCAM multicentre study

Analysis of factors with low positive predictive value in the diagnosis of urinary tract infection by flow cytometry

PURPOSE

Culture-negative urine specimens can be rapidly screened by urine flow cytometry (UFC), while low positive predictive value (PPV) limits the clinical application. We explored the factors associated with a low PPV.

METHODS

A total of 5095 urine specimens were analyzed with UFC and culture. Diagnostic performance of leukocytes, bacteria, and BACT-info flags was evaluated by sensitivity, specificity, PPV, and negative predictive value (NPV). The association of contaminated culture and squamous epithelial cell count and BACT-info flag was performed by logistic regression analysis.

RESULTS

The NPVs of parallel combination of bacteria and leucocytes were 98.9% in males and 97.9% in females, and PPVs of serial combination were 86.6% and 77.8% in men and women, respectively. The PPV of Gram-negative flag was higher than that of Gram-positive flag. The proportions of contamination in the urine culture results of false positive specimens were 86.9% in males and 98.5% in females at the cutoff points of the serial combination, and these parameters were 53.2% in males and 85.6% in females for the Gram-positive flag. There was a statistically significant association between contaminated cultures and squamous epithelial cells count in females, but not in males. Associations between contaminated cultures and Gram-positive flags or Gram-pos/-neg flags were statistically significant, but there was no association between contaminated cultures and Gram-negative flags.

CONCLUSIONS

A serial combination of leukocytes and bacteria may maximize PPV in the diagnosis of bacterial urinary tract infection by urine flow cytometry, and contamination is the main reason for a low PPV.

Antibiotic Guideline Adherence at the Emergency Department: A Descriptive Study from a Country with a Restrictive Antibiotic Policy

BACKGROUND

Denmark has a low level of antimicrobial resistance (AMR). Patients hospitalized with suspected infection often present with unspecific symptoms. This challenges the physician between using narrow-spectrum antibiotics in accordance with guidelines or broad-spectrum antibiotics to compensate for diagnostic uncertainty. The aim of this study was to investigate adherence to a restrictive antibiotic guideline for the most common infection in emergency departments (EDs), namely community-acquired pneumonia (CAP).

METHOD

This multicenter descriptive cross-sectional study included adults admitted to Danish EDs with a suspected infection. Data were collected prospectively from medical records.

RESULTS

We included 954 patients in the analysis. The most prescribed antibiotics were penicillin with beta-lactamase inhibitor at 4 h (307 (32.2%)), 48 h (289 (30.3%)), and day 5 after admission (218 (22.9%)). The empirical antibiotic treatment guidelines for CAP were followed for 126 (31.3%) of the CAP patients. At 4 h, antibiotics were administered intravenously to 244 (60.7%) of the CAP patients. At day 5, 218 (54.4%) received oral antibiotics.

CONCLUSION

Adherence to CAP guidelines was poor. In a country with a restrictive antibiotic policy, infections are commonly treated with broad-spectrum antibiotics against recommendations.

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

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.

Improved diagnostics of infectious diseases in emergency departments: a protocol of a multifaceted multicentre diagnostic study

BACKGROUND

The major obstacle in prescribing an appropriate and targeted antibiotic treatment is insufficient knowledge concerning whether the patient has a bacterial infection, where the focus of infection is and which bacteria are the agents of the infection. A prerequisite for the appropriate use of antibiotics is timely access to accurate diagnostics such as point-of-care (POC) testing.The study aims to evaluate diagnostic tools and working methods that support a prompt and accurate diagnosis of hospitalised patients suspected of an acute infection. We will focus on the most common acute infections: community-acquired pneumonia (CAP) and acute pyelonephritis (APN). The objectives are to investigate (1) patient characteristics and treatment trajectory of the different acute infections, (2) diagnostic and prognostic accuracy of infection markers, (3) diagnostic accuracy of POC urine flow cytometry on diagnosing and excluding bacteriuria, (4) how effective the addition of POC analysis of sputum to the diagnostic set-up for CAP is on antibiotic prescriptions, (5) diagnostic accuracy of POC ultrasound and ultralow dose (ULD) computerized tomography (CT) on diagnosing CAP, (6) diagnostic accuracy of specialist ultrasound on diagnosing APN, (7) diagnostic accuracy of POC ultrasound in diagnosing hydronephrosis in patients suspected of APN.

METHODS AND ANALYSIS

It is a multifaceted multicentre diagnostic study, including 1000 adults admitted with suspicion of an acute infection. Participants will, within the first 24 hours of admission, undergo additional diagnostic tests including infection markers, POC urine flow cytometry, POC analysis of sputum, POC and specialist ultrasound, and ULDCT. The primary reference standard is an assigned diagnosis determined by a panel of experts.

ETHICS, DISSEMINATION AND REGISTRATION

Approved by Regional Committees on Health Research Ethics for Southern Denmark, Danish Data Protection Agency and clinicaltrials.gov. Results will be presented in peer-reviewed journals, and positive, negative and inconclusive results will be published.

TRIAL REGISTRATION NUMBERS

NCT04661085, NCT04681963, NCT04667195, NCT04652167, NCT04686318, NCT04686292, NCT04651712, NCT04645030, NCT04651244.

Evaluation of a Novel Laboratory Candiduria Screening Protocol in the Intensive Care Unit

Background

Since urine cultures are only guaranteed for patients with obvious urinary symptoms in most cases, most of candiduria episodes are ignored in clinic.

Objective

This study aimed to design a screening protocol to improve diagnostic efficiency of candiduria, and provide information of Candida species and drug susceptibility.

Methods

All patients, who were admitted to the intensive care unit (ICU) of our hospital during December 1, 2018 and October 1, 2019, were enrolled in this study. Urinalysis was performed every three days for each subject from the first day of ICU admission. Urine specimens were sampled for fungal culture with either condition: (1) yeast-like cell counting (YLCC) ≥200; (2) positive YLCCs were observed in two consecutive tests, and at least one YLCC ≥100.

Results

The screening protocol dramatically improved the candiduria diagnostic rate of ICU patients from 2.28% to 17.27%. However, compared to the historical control, the screening protocol has no time-saving advantage in candiduria diagnosing. Higher percentage of C. albicans in screening protocol-identified candiduria patients was observed, although there was no statistical difference. Our results indicated that female gender, pneumonia, diabetes and infarction/hemorrhage patients were more prone to develop candiduria. Non-candiduria patients showed a better tendency for survival and shorter ICU stay length. Multisite colonization was common in the surveyed candiduria patients, who were up to 70.83% showed Candida positive cultures in sputum.

Conclusion

The screening protocol established in the study was a convenient and practical tool for early warning and feasible management of candiduria and IC.

Cost Analysis of the Automated Examination of Urine with the Sysmex UN-Series™ in a Spanish Population

BACKGROUND

Current practice for urinalysis mainly entails different manual or semi-automated procedures that generate substantial financial costs, as well as a high and time-consuming workload for laboratory personnel.

OBJECTIVE

The aim of this study was to assess whether the availability of integrated and fully automated urinalysis systems such as the UN-Series™ from Sysmex could resolve such concerns.

METHODS

The target population was established based on 92,459 urine samples, which is the total average number of urine samples collected in the clinical and microbiology laboratory department of La Mancha Centro Hospital over a 10-year period (2008-2018). Financial data were retrieved from the eSalud database. Reference and test scenarios were defined based on clinical features found in reports from public websites. The cost and savings analyses were based on total costs over a 1-year time frame for the reference and test scenarios. The total average annual time savings for laboratory personnel were also calculated.

RESULTS

The comparison of annual costs for current practice versus the automated examination of urine samples found average cost savings of €340,003 per year. Assessment of body fluids using the automated analysis system would provide average annual savings of €1063. The use of the UN-Series™ would save 1615 h annually for laboratory personnel.

CONCLUSION

Implementing the UN-Series™ for the automated analysis of urine samples within routine practice in clinical laboratories could minimise costs, provide substantial savings for investment and improve laboratory procedures. Furthermore, the UN-Series™ could contribute to synergy between clinical analysis and microbiology laboratories in Spain.

Urinary Tract Infection in Children

BACKGROUND

Urinary Tract Infection (UTI) is a common infection in children. Prompt diagnosis and appropriate treatment are very important to reduce the morbidity associated with this condition.

OBJECTIVE

To provide an update on the evaluation, diagnosis, and treatment of urinary tract infection in children.

METHODS

A PubMed search was completed in clinical queries using the key terms "urinary tract infection", "pyelonephritis" OR "cystitis". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature and the pediatric age group. Patents were searched using the key terms "urinary tract infection" "pyelonephritis" OR "cystitis" from www.google.com/patents, http://espacenet.com, and www.freepatentsonline.com.

RESULTS

Escherichia coli accounts for 80 to 90% of UTI in children. The symptoms and signs are nonspecific throughout infancy. Unexplained fever is the most common symptom of UTI during the first two years of life. After the second year of life, symptoms and signs of pyelonephritis include fever, chills, rigor, flank pain, and costovertebral angle tenderness. Lower tract symptoms and signs include suprapubic pain, dysuria, urinary frequency, urgency, cloudy urine, malodorous urine, and suprapubic tenderness. A urinalysis and urine culture should be performed when UTI is suspected. In the work-up of children with UTI, physicians must judiciously utilize imaging studies to minimize exposure of children to radiation. While waiting for the culture results, prompt antibiotic therapy is indicated for symptomatic UTI based on clinical findings and positive urinalysis to eradicate the infection and improve clinical outcome. The choice of antibiotics should take into consideration local data on antibiotic resistance patterns. Recent patents related to the management of UTI are discussed.

CONCLUSION

Currently, a second or third generation cephalosporin and amoxicillin-clavulanate are drugs of choice in the treatment of acute uncomplicated UTI. Parenteral antibiotic therapy is recommended for infants ≤ 2 months and any child who is toxic-looking, hemodynamically unstable, immunocompromised, unable to tolerate oral medication, or not responding to oral medication. A combination of intravenous ampicillin and intravenous/intramuscular gentamycin or a third-generation cephalosporin can be used in those situations. Routine antimicrobial prophylaxis is rarely justified, but continuous antimicrobial prophylaxis should be considered for children with frequent febrile UTI.

Coherent fluctuation nephelometry as a promising method for diagnosis of bacteriuria

Objectives

Specialized analyzers are used to automate the diagnosis of bacteriuria in laboratory practice. They are based on analysis of microorganisms concentration in urine samples or recording the growth of urine microflora. Coherent fluctuation nephelometry (CFN) has high sensitivity and allows analyzing both parameters simultaneously. The aim of the study is to compare the effectiveness of CFN-based and flow cytometry based analyzers.

Design and methods

Total 117 urine samples from children were studied in parallel using the CFN-analyzer and UF-1000i (Sysmex), the results were confirmed by conventional microbiological methods.

Results

In 21 urine samples (18%), significant bacteriuria was determined (≥10⁴ CFU/ml). The best diagnostic indicators were obtained while testing urine samples using the CFN-analyzer. The most efficient bacteriuria diagnosis is achieved by simultaneous analyses of microorganisms concentration in urine and growth of urine microflora (sensitivity - 95.2%, specificity - 96.9%, positive predictive value - 87%, negative predictive value - 98.9%, diagnostic odds ratio - 81.7, positive likelihood ratio - 30.5, negative likelihood ratio- 0.049, area under curve in ROC-analysis - 0.987). The CFN-analyzer allows the preliminary selection of negative urine samples, which do not require further analysis by conventional microbiological methods, thereby decreasing the number of cultures by 80.3%.

Conclusions

This study suggests that the CFN-analyzer is the effective tool for bacteriuria screening in children.