Diagnostic accuracy of urinary biomarkers in infants younger than 3 months with urinary tract infection

Evaluation of diagnostic accuracy of urine neutrophil gelatinase-associated lipocalin in patients with symptoms of urinary tract infections: a meta-analysis

Introduction

Early and accurate diagnosis of urinary tract infection (UTI) can prevent serious sequelae including chronic kidney disease. Multiple individual studies have identified urine neutrophil gelatinase-associated lipocalin (uNGAL) as a promising biomarker for early diagnosis of UTI. We sought to understand the distribution and diagnostic accuracy of uNGAL values in patients presenting with UTI symptoms.

Methods

Our systematic literature reviews in PubMed, Embase, and Cochrane Reviews up to March 2024, identified 25 studies reporting mean/median, standard deviation/quartiles, and detection limits of uNGAL in symptomatic patients with and without culture-confirmed UTI. Seventeen studies were in children. Meta-analyses were performed using the quantile estimation (QE) method estimating the distributions of uNGAL, which were then compared between the UTI and non-UTI groups for identifying the best cut-off points maximizing the Youden index. Sensitivity analyses were performed on all 25 studies including adult patients.

Results

We found that uNGAL levels were significantly higher in samples with confirmed UTI compared to those without. In pediatric studies, median and 95% confidence interval (CI) of uNGAL values were 22.41 (95% CI of 9.94, 50.54) ng/mL in non-UTI group vs. 118.85 (95% CI of 43.07, 327.97) ng/mL in UTI group. We estimated the cut-off point of 48.43 ng/mL with highest sensitivity (96%) and specificity (97%) in children. Sensitivity analysis including both pediatric and adult studies yielded similar results.

Discussion

The level of uNGAL in symptomatic patients with confirmed UTI is much higher than that reported in patients without UTI. It may be used as a diagnostic tool to identify UTI early among symptomatic patients. The range of uNGAL concentrations and cut-off points reported in subjects with UTI is much lower than that reported in patients with acute intrinsic kidney injury.

Systematic Review Registration

https://www.crd.york.ac.uk/, PROSPERO (CRD42023370451).

Urinary tract infections: a review of the current diagnostics landscape

Urinary tract infections are the most common bacterial infections worldwide. Infections can range from mild, recurrent (rUTI) to complicated (cUTIs), and are predominantly caused by uropathogenic Escherichia coli (UPEC). Antibiotic therapy is important to tackle infection; however, with the continued emergence of antibiotic resistance there is an urgent need to monitor the use of effective antibiotics through better stewardship measures. Currently, clinical diagnosis of UTIs relies on empiric methods supported by laboratory testing including cellular analysis (of both human and bacterial cells), dipstick analysis and phenotypic culture. Therefore, development of novel, sensitive and specific diagnostics is an important means to rationalise antibiotic therapy in patients. This review discusses the current diagnostic landscape and highlights promising novel diagnostic technologies in development that could aid in treatment and management of antibiotic-resistant UTIs.

Biomarkers for febrile urinary tract infection in children

Background

The current reference standard for pediatric urinary tract infection (UTI) screening, the leukocyte esterase (LE) dipstick test, has suboptimal accuracy. The objective of this study was to compare the accuracy of novel urinary biomarkers to that of the LE test.

Methods

We prospectively enrolled febrile children who were evaluated for UTI based on their presenting symptoms. We compared the accuracy of urinary biomarkers to that of the test.

Results

We included 374 children (50 with UTI, 324 without UTI, ages 1-35 months) and examined 35 urinary biomarkers. The urinary biomarkers that best discriminated between febrile children with and without UTI were urinary neutrophil gelatinase-associated lipocalin (NGAL), IL-1β, CXCL1, and IL-8. Of all examined urinary biomarkers, the urinary NGAL had the highest accuracy with a sensitivity of 90% (CI: 82-98) and a specificity of 96% (CI: 93-98).

Conclusion

Because the sensitivity of the urinary NGAL test is slightly higher than that of the LE test, it can potentially reduce missed UTI cases. Limitations of using urinary NGAL over LE include increased cost and complexity. Further investigation is warranted to determine the cost-effectiveness of urinary NGAL as a screening test for UTI.

Selective biomarkers for inflammation and infection are associated with post-operative complications following transperineal template prostate biopsy (TTPB): a single-centre observational clinical pilot-study

Background

Prostate cancer (PCa) and benign prostatic hyperplasia (BPH) are the most common prostate disorders in the UK, which cause considerable ill health in older men. Transperineal template prostate biopsy (TTPB) has emerged as a reliable procedure for the histopathological diagnosis of PCa and BPH due to its higher cancer detection rates. Although antiseptic preparation and antibiotic prophylaxis are used to ensure safety in patients undergoing surgical intervention, post-operative complications, such as infection and bleeding are still unavoidable, resulting in re-admissions, with resource implications. Currently, there is no biomarker profile to predict outcomes or monitor patients during the post-operative course. The main aim of this single-centre observational clinical pilot-study was to investigate the role of inflammatory and infection biomarkers following TTPB and their association with post-operative complications.

Methods

Forty-five patients scheduled for elective TTPB were recruited after informed consent at the Wrexham Maelor and Glan Clwyd Hospitals, North Wales, UK (n = 45). Prior to surgery, venous blood samples were collected at baseline and subsequently at 30, 120, and 240 min post-operatively. Urine samples were collected before and 120 min after the procedure. Serum procalcitonin (PCT), serum ferritin, and urine B₂MG analysis were done using enzyme-linked fluorescent assay (ELFA) and the magnetic Luminex^® multiplex performance assay was used to analyse IL-6, IL-8, IL-10 and TNF-α plasma concentrations. Data on clinical outcomes were collected from patients’ medical records.

Results

Following TTPB, significant (p ≤ 0.05) increases were observed in uB₂MG, IL-6, IL-8, IL-10 and TNF-α. Significant decreases were observed in ferritin (p ≤ 0.05). No significant change was observed in PCT concentration (p ≥ 0.05). One patient developed an infection and severe haematuria post-operatively following TTPB.

Conclusion

Although not confirmative, changes seen in biomarkers such as uB₂MG, IL-10 and TNF-α in our observational clinical pilot-study may warrant further investigation, involving larger cohorts, to fully understand the role of these biomarkers and their potential association with post-operative complications such as infection and bleeding which can develop following TTPB for the diagnosis of PCa and BPH.

Urinary tract infections in children: Testing a novel, noninvasive, point-of-care diagnostic marker

OBJECTIVES

Urinary neutrophil gelatinase-associated lipocalin (uNGAL) appears highly accurate to identify urinary tract infections (UTIs) when obtained via catheterization. Our primary aim was to determine the agreement in uNGAL levels between paired catheter and bag urine specimens. Our secondary aim was to compare the diagnostic test characteristics of quantitative uNGAL, dipstick uNGAL (a potential point-of-care test), and urinalysis (UA).

METHODS

This was a prospective study of febrile children < 24 months evaluated for UTIs. We evaluated quantitative uNGAL at a previously identified threshold of 39.1 ng/mL, dipstick uNGAL at its built-in threshold of >50 ng/mL, and UA at standard thresholds for leukocyte esterase (LE). A positive urine culture was defined as >100,000 CFUs/mL of a pathogen.

RESULTS

A total of 211 patients were included (10% with positive urine cultures); 116 had paired catheterized and bagged samples. The agreement between catheterized and bagged samples at a quantitative uNGAL cutoff of ≥39.1 ng/mL was 0.76 (95% confidence interval [CI] = 0.67 to 0.83) and 0.77 (95% CI = 0.68 to 0.84) at a uNGAL dipstick threshold of >50 ng/mL. The area under the receiver operating characteristic curve for uNGAL from a catheterized sample was 0.96 (95% CI = 0.89 to 1.00) compared to 0.93 (95% CI = 0.87 to -0.99) from a bagged sample. The sensitivities of catheterized sample quantitative and dipstick uNGAL (90.5%) were higher than UA at a LE threshold of ≥1+ (57.1%). Bagged-sample uNGAL had lower quantitative and dipstick specificities (both 73.8%) than from catheterized samples (94.3% and 95.3% respectively), similar to UA.

CONCLUSIONS

uNGAL from bagged and catheterized samples showed insufficient agreement to be used interchangeably. The low specificity of uNGAL from bagged samples suggests that sampling technique affects uNGAL levels.

Biomarkers for febrile urinary tract infection in children

BACKGROUND

The sensitivity and specificity of the leukocyte esterase test for the diagnosis of urinary tract infection (UTI) are suboptimal. Recent studies have identified markers that appear to more accurately differentiate children with and without UTI. The objective of this study was to determine the accuracy of these markers, which included CCL3, IL-8, CXCL1, TNF-alpha, IL-6, IFN-gamma, IL-17, IL-9, IL-2, and NGAL, in the diagnosis of UTI.

METHODS

This was a prospective cross-sectional study to compare inflammatory proteins between urine samples from febrile children with a UTI, matched febrile controls without a UTI, and asymptomatic healthy controls.

RESULTS

We included 192 children (75 with febrile UTI, 69 febrile controls, and 48 asymptomatic healthy controls). Urinary proteins that best discriminated between febrile children with and without UTI were NGAL, a protein that exerts a local bacteriostatic role in the urinary tract through iron chelation; CCL3, a chemokine involved in leukocyte recruitment; and IL-8, a cytokine involved in neutrophil recruitment. Levels of these proteins were generally undetectable in asymptomatic healthy children.

CONCLUSIONS

NGAL, CCL3, and IL-8 may be useful in the early diagnosis of UTI.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01391793) A higher resolution version of the Graphical abstract is available as Supplementary information.

Exploring Inflammatory Status in Febrile Seizures Associated with Urinary Tract Infections: A Two-Step Cluster Approach

BACKGROUND

Urinary tract infections (UTIs) are considered common facilitating factors, along with other infections, in triggering febrile seizures (FS). The main purpose of our study was to identify specific inflammatory patterns of UTI cases from other infections in a specific cluster, using a combination of inflammatory biomarkers to differentiate UTIs from other bacterial diseases triggering FS.

METHOD

This prospective study included a number of 136 patients with 197 distinct FS events, from patients hospitalized in the Pediatric Clinical Hospital Sibiu, among which 10.2% were diagnosed with UTIs.

RESULTS

In one-third of the patients with UTIs (20 cases), the symptoms were limited to fever and FS. Using two-step cluster analysis, a distinct UTI inflammatory pattern has emerged: highest platelet values (PLT), median value 331 × 103/mm3 and intermediate C-reactive protein (CRP), median value 15 mg/dL, platelet distribution width (PDW), median value 9.65%, platelet-large cell ratio (P-LCR), median value 14.45%, mean platelet volume (MPV), median value 8.60 fL and neutrophil-to-lymphocyte values (NLR), median value 3.64. Furthermore, higher PDW (median value 12.25%), P-LCR (median value 28.55%), MPV (median value 10.40 fL), CRP (median value 74.00 mg/dL) and NLR values (median value 4.11) were associated mainly (85.7%) with bacterial lower respiratory infections. UTIs were highly unlikely in these patients with significantly increased CRP values and normal values of platelet indices.

CONCLUSIONS

Considering the nonspecific clinical picture of UTIs at an early age, to optimize the management of FS, a fast diagnosis of UTI is mandatory. The analysis of the inflammatory biomarker clusters (rather than individual parameters) correlated with urine leukocyte and nitrite stick evaluation for specific age groups could help in identifying even oligosymptomatic UTIs patients. The study limitation (20 UTI cases) recommends future multicentric trials on larger datasets to validate the model.

Neutrophil gelatinase-associated lipocalin for urinary tract infection and pyelonephritis: a systematic review

BACKGROUND

The sensitivity and specificity of the leukocyte esterase test are relatively low for a screening test for urinary tract infection (UTI). More accurate tests could reduce both overtreatment and missed cases. This study aimed to determine whether neutrophil gelatinase-associated lipocalin (NGAL) can replace leukocyte esterase in the diagnosis of UTI and/or whether NGAL accurately identifies children with acute pyelonephritis.

METHODS

Data sources-MEDLINE and EMBASE. We only considered published studies that evaluated the results of an index test (NGAL) against the results of urine culture (for UTI) or against the results of dimercaptosuccinic acid (for acute pyelonephritis) in children aged 0 to 18 years. Two authors independently applied the selection criteria to all citations and independently extracted the data.

RESULTS

A total of 12 studies met our inclusion criteria. Four studies (920 children) included data on NGAL for UTI; eight studies (580 children) included data on NGAL for pyelonephritis. We did not pool accuracy values because the included studies used different cutoff values. For the diagnosis of UTI, urinary NGAL appeared to have better accuracy than the leukocyte esterase test in all included studies. For the diagnosis of pyelonephritis, neither plasma NGAL nor urinary NGAL had high sensitivity and/or specificity. The number of studies was the main limitation of this systematic review.

CONCLUSIONS

Urinary NGAL appears promising for the diagnosis of UTI; however, larger studies are needed to validate this marker as a replacement for leukocyte esterase. The use of NGAL for diagnosing acute pyelonephritis requires further study.

Biomarkers in urinary tract infections - which ones are suitable for diagnostics and follow-up?

Introduction: Urinary tract infections (UTIs) are one of the most common infections worldwide. Under special circumstances, clinicians must rely on laboratory findings, which might have a weak predicting value, misguiding the practitioners and leading to incorrect diagnosis and overuse of antibiotics. Therefore, there is an urgent need for reliable biomarkers in UTIs. Methods: We performed a literature search for biomarkers used in UTIs from January 1999 until May 2020. We used "urinary tract infection" and "biomarker" as the main key words in the PubMed, Medline and Cochrane databases. After peer review, we excluded the duplicates and identified the suitable articles, from which we collected the data and divided the available biomarkers into 5 groups: i) conventional markers; ii) promising, thoroughly studied biomarkers; iii) promising biomarkers that need further studies; iv) biomarkers of unknown significance; v) controversial, not useful markers. Results: We found 131 articles, mostly from the paediatric population. Neutrophil gelatinase-associated lipocalin (NGAL) and interleukins (IL) have a leading role in diagnosing and differentiating UTIs based on a lot of observational, comparative trials. Heparin Binding Protein (HBP), Lactoferrin (LF), Heat-Shock Protein-70 (HSP-70), Human Defensin-5 (HD-5), Lipopolysaccharide Binding Protein (LBP) and mass spectrometry studies are promising, but confirming data are lacking. The measurable components of the innate immune system and local host cell response could be appropriate biomarkers, but their significance is currently unknown. Conclusions: Conventional biomarkers for UTIs have low specificity. The use of urinary NGAL and interleukins could improve the sensitivity and specificity of laboratory diagnosis of UTIs.

Discriminatory Precision of Neutrophil Gelatinase-Associated Lipocalin in Detection of Urinary Tract Infection in Children: a Systematic Review and Meta-Analysis

INTRODUCTION

There is a significant discrepancy between studies on diagnostic precision of neutrophil gelatinase-associated lipocalin (NGAL) in diagnosis of urinary tract infection (UTI). Therefore, the present systematic review and meta-analysis was designed to assess the diagnostic value of NGAL in diagnosis of UTI in children and adolescents.

METHODS

An extensive search was performed on Medline, Embase, Scopus and Web of Science databases by the end of 2019. Two independent researchers screened and summarized the data. Discriminatory precision of urinary and serum NGAL was assessed by reporting area under the curve, sensitivity, specificity and diagnostic odds ratio with 95% confidence interval (95% CI).

RESULTS

Data from 12 studies were included. The area under the curve of urinary and serum NGAL for diagnosis of UTI in children and adolescents at the best cut-off point (between 30-39.9 ng/ml) was 0.95 (95% CI: 0.93 to 0.97) and 0.83 (95% CI: 0.80 to 0.86), respectively. Sensitivity, specificity and diagnostic odds ratio on urinary NGAL at these cut-off points were 0.89 (95% CI: 0.64 to 0.97), 0.89 (95% CI: 0.71 to 0.97) and 67 (95% CI: 5 to 891), respectively. Sensitivity, specificity and diagnostic odds ratio of serum NGAL in UTI detection were 0.85 (95% CI: 0.70 to 0.90), 0.81 (95% CI: 0.69 to 0.88) and 9.53 (95% CI: 1.52 to 59.65), respectively.

CONCLUSION

The present meta-analysis showed that urinary NGAL had a high diagnostic value in detection of UTI in children and adolescents with an optimum cut-off point in the range of 30-39.9 ng/ml.

Biomarkers that differentiate false positive urinalyses from true urinary tract infection

BACKGROUND

The specificity of the leukocyte esterase test (87%) is suboptimal. The objective of this study was to identify more specific screening tests that could reduce the number of children who unnecessarily receive antimicrobials to treat a presumed urinary tract infection (UTI).

METHODS

Prospective cross-sectional study to compare inflammatory proteins in blood and urine samples collected at the time of a presumptive diagnosis of UTI. We also evaluated serum RNA expression in a subset.

RESULTS

We enrolled 200 children; of these, 89 were later demonstrated not to have a UTI based on the results of the urine culture obtained. Urinary proteins that best discriminated between children with UTI and no UTI were involved in T cell response proliferation (IL-9, IL-2), chemoattractants (CXCL12, CXCL1, CXCL8), the cytokine/interferon pathway (IL-13, IL-2, INFγ), or involved in innate immunity (NGAL). The predictive power (as measured by the area under the curve) of a combination of four urinary markers (IL-2, IL-9, IL-8, and NGAL) was 0.94. Genes in the pathways related to inflammation were also upregulated in serum of children with UTI.

CONCLUSIONS

Urinary proteins involved in the inflammatory response may be useful in identifying children with false positive results with current screening tests for UTI; this may reduce unnecessary treatment.

Diagnostic accuracy of urine neutrophil gelatinase-associated lipocalin and urine kidney injury molecule-1 as predictors of acute pyelonephritis in young children with febrile urinary tract infection

Introduction

We assessed whether two urinary biomarkers of acute kidney injury, neutrophil gelatinase associated lipocalin (uNGAL) and kidney injury molecule-1 (uKIM-1), can be useful for predicting acute pyelonephritis (APN) in children aged 1-24 months with the first febrile urinary tract infection (UTI).

Material and methods

A prospective study included 54 children divided into two groups (24 with APN, 30 with lower UTI), according to the dimercaptosuccinic acid (DMSA) renal scintigraphy results. Laboratory tests: uNGAL, uKIM-1, procalcitonin (PCT), C-reactive protein (CRP), white blood count (WBC) were performed.

Results

We did not find significant differences in normalized and non-normalized values of uNGAL and uKIM-1 in children with APN and lower UTI. Positive correlations were determined between uNGAL and pyuria (r = 0.28, p < 0.05) and between uNGAL/uCr and uKIM-1/uCr (r = 0.53, p < 0.001) in the all UTI groups. Univariate logistic regression analysis demonstrated that only PCT (p < 0.0001) and CRP (p < 0.05) were important diagnostic factors of APN. Receiver operating curve (ROC) analysis showed good diagnostic profiles of PCT with the best cut-off value of 1.66 ng/ml and of CRP with the best cut-off value of 4.3 mg/dl for predicting APN (area under the curve [AUC]: 0.894 and 0.719, sensitivity: 75% and 96%, specificity: 93% and 43%, respectively).

Conclusions

uNGAL and uKIM-1 are not effective diagnostic markers for APN in young children with febrile UTI and cannot be used in clinical practice to differentiate APN from lower UTI.

Serum neutrophil gelatinase-associated lipocalin for predicting acute pyelonephritis in infants with urinary tract infection

Introduction

Fever and elevated inflammatory markers have been used for diagnosis of acute pyelonephritis (APN) in infants with urinary tract infection (UTI).

The aim of the study was to compare the usefulness of serum neutrophil gelatinase-associated lipocalin (sNGAL) with inflammatory markers for predicting APN in infants with UTI.

Material and methods

The prospective study included 46 infants with a first episode of UTI, divided into two groups (APN 23, lower UTI 23), according to the DMSA scan results. The following laboratory tests were performed: sNGAL, PCT, CRP, WBC, and ESR.

Results

Significantly elevated levels of sNGAL, PCT, CRP, and ESR were observed in infants with APN compared to those with lower UTI. Higher sNGAL, CRP, and ESR values, presence of fever, and longer duration of fever before antibiotic treatment were associated with APN [odds ratio (OR) 1.02, 1.27, 1.03, 13.46, 2.12, respectively]. Receiver operating characteristic (ROC) analysis showed better diagnostic profiles for sNGAL, PCT, and CRP than for ESR for predicting APN [area under the curve (AUC) 0.808, 0.819, 0.841, and 0.750, respectively]. The appropriate cut-off values of sNGAL, PCT and CRP were 100.8 ng/ml, 0.15 ng/ml, 5.3 mg/dl (all sensitivity and specificity 82.6%), and that of ESR was 40 mm/h (sensitivity 78.3%, specificity 60.9%).

Conclusions

sNGAL shows similar usefulness as PCT and CRP for predicting APN in infants with UTI, the diagnostic value of ESR is smaller, and WBC is not useful at all. The presence of fever and longer duration of fever are important predictors of APN in infants with UTI.