Heparin-binding protein: a diagnostic biomarker of urinary tract infection in adults

Comprehensive insights into UTIs: from pathophysiology to precision diagnosis and management

Urinary tract infections (UTIs) are the second most common infectious disease, predominantly impacting women with 150 million individuals affected globally. It increases the socio-economic burden of society and is mainly caused by Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Enterobacter spp., and Staphylococcus spp. The severity of the infection correlates with the host factors varying from acute to chronic infections. Even with a high incidence rate, the diagnosis is mainly based on the symptoms, dipstick analysis, and culture analysis, which are time-consuming, labour-intensive, and lacking sensitivity and specificity. During this period, medical professionals prescribe empirical antibiotics, which may increase the antimicrobial resistance rate. Timely and precise UTI diagnosis is essential for addressing antibiotic resistance and improving overall quality of life. In response to these challenges, new techniques are emerging. The review provides a comprehensive overview of the global burden of UTIs, associated risk factors, implicated organisms, traditional and innovative diagnostic methods, and approaches to UTI treatment and prevention.

Heparin-binding protein as a biomarker for the diagnosis of sepsis in the intensive care unit: a retrospective cross-sectional study in China

OBJECTIVES

This study aims to investigate the diagnostic value of heparin-binding protein (HBP) in sepsis and develop a sepsis diagnostic model incorporating HBP with key biomarkers and disease-related scores for rapid, and accurate diagnosis of sepsis in the intensive care unit (ICU).

DESIGN

Clinical retrospective cross-sectional study.

SETTING

A comprehensive teaching tertiary hospital in China.

PARTICIPANTS

Adult patients (aged ≥18 years) who underwent HBP testing or whose blood samples were collected when admitted to the ICU.

MAIN OUTCOME MEASURES

HBP, C reactive protein (CRP), procalcitonin (PCT), white blood cell count (WBC), interleukin-6 (IL-6), lactate (LAC), Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA) score were recorded.

RESULTS

Between March 2019 and December 2021, 326 patients were enrolled in this study. The patients were categorised into a non-infection group (control group), infection group, sepsis group and septic shock group based on the final diagnosis. The HBP levels in the sepsis group and septic shock group were 45.7 and 69.0 ng/mL, respectively, which were significantly higher than those in the control group (18.0 ng/mL) and infection group (24.0 ng/mL) (p<0.001). The area under the curve (AUC) value of HBP for diagnosing sepsis was 0.733, which was lower than those corresponding to PCT, CRP and SOFA but higher than those of IL-6, LAC and APACHE II. Multivariate logistic regression analysis identified HBP, PCT, CRP, IL-6 and SOFA as valuable indicators for diagnosing sepsis. A sepsis diagnostic model was constructed based on these indicators, with an AUC of 0.901, a sensitivity of 79.7% and a specificity of 86.9%.

CONCLUSIONS

HBP could serve as a biomarker for the diagnosis of sepsis in the ICU. Compared with single indicators, the sepsis diagnostic model constructed using HBP, PCT, CRP, IL-6 and SOFA further enhanced the diagnostic performance of sepsis.

The diagnostic utility of heparin-binding protein among patients with bacterial infections: a systematic review and meta-analysis

BACKGROUND

Bacterial infections are considered a leading cause of hospitalization and death globally. There is still a need for a rapid and feasible biomarker for bacterial infections. Heparin-binding protein (HBP) was shown to be related to bacterial infections. The objective of the study is to investigate the diagnostic accuracy of HBP in bacterial infections.

METHODS

Articles were screened in PubMed, SCOPUS, Web of Science, and Cochrane to recognize eligible studies. We included studies investigating the diagnostic accuracy of HBP and reported the necessary data to construct 2 × 2 tables. A univariate analysis was conducted to determine the pooled sensitivity and specificity, and a bivariate diagnostic random-effects model was used to calculate the optimal cut-off point.

RESULTS

The analysis comprised sixteen studies in total. Plasma HBP showed a sensitivity of 0.90 (95% CI: [0.79, 0.96]) and a specificity of 0.87 (95% CI: [0.66, 0.96]) in diagnosing bacterial infections using blood samples. Pooling data from seven studies revealed that HBP in cerebrospinal fluid (CSF) has sensitivity and specificity of 96% (95% CI: [0.85, 0.99]), and 95% (95% CI: [0.89, 0.97]), respectively, for the diagnosis of bacterial meningitis. In urinary tract infections (UTI), urine-HBP was revealed to have a high diagnostic value in discriminating bacterial from non-bacterial UTI infection at a cut-off value of 32.868 ng/ml with sensitivity and specificity of 87%.

CONCLUSION

HBP has shown a high diagnostic accuracy of bacterial infections, including UTI and meningitis. Further studies are needed to determine its prognostic value and whether it could guide antibiotic therapy.

What is the Diagnostic Accuracy of Novel Urine Biomarkers for Urinary Tract Infection?

Background

Urinary tract infection (UTI) affects half of women at least once in their lifetime. Current diagnosis involves urinary dipstick and urine culture, yet both methods have modest diagnostic accuracy, and cannot support decision-making in patient populations with high prevalence of asymptomatic bacteriuria, such as older adults. Detecting biomarkers of host response in the urine of hosts has the potential to improve diagnosis.

Objectives

To synthesise the evidence of the diagnostic accuracy of novel biomarkers for UTI, and of their ability to differentiate UTI from asymptomatic bacteriuria.

Design

A systematic review.

Data Sources and Methods

We searched MEDLINE, EMBASE, CINAHL and Web of Science for studies of novel biomarkers for the diagnosis of UTI. We excluded studies assessing biomarkers included in urine dipsticks as these have been well described previously. We included studies of adult patients (≥16 years) with a suspected or confirmed urinary tract infection using microscopy and culture as the reference standard. We excluded studies using clinical signs and symptoms, or urine dipstick only as a reference standard. Quality appraisal was performed using QUADAS-2. We summarised our data using point estimates and data accuracy statistics.

Results

We included 37 studies on 4009 adults measuring 66 biomarkers. Study quality was limited by case-control design and study size; only 4 included studies had a prospective cohort design. IL-6 and IL-8 were the most studied biomarkers. We found plausible evidence to suggest that IL-8, IL-6, GRO-a, sTNF-1, sTNF-2 and MCR may benefit from more rigorous evaluation of their potential diagnostic value for UTI.

Conclusions

There is insufficient evidence to recommend the use of any novel biomarker for UTI diagnosis at present. Further evaluation of the more promising candidates, is needed before they can be recommended for clinical use.

Heparin-Binding Protein in Bronchoalveolar Lavage Fluid as a Biomarker for Discriminating Severe Bacterial and Viral Pneumonia in Critically Ill Children

Objective

This study is aimed at exploring the ability to use heparin-binding protein (HBP) in bronchoalveolar lavage fluid (BALF) to differentially diagnose bacterial infection from viral infection for severe community-acquired pneumonia (CAP) in critically ill children.

Methods

A total of 181 children with severe CAP admitted to the intensive care unit (ICU) were included in this study. BALF and blood samples were collected within the first 24 hours of admission. BALF HBP and interleukin-6 (IL-6) concentrations and neutrophil percentage (N%) as well as blood HBP, IL-6, procalcitonin (PCT), C-reactive protein, white blood cell concentrations and N% were measured.

Results

Of the enrolled children, 126 were confirmed to have bacterial pneumonia, and 55 were confirmed to have viral pneumonia. Blood HBP and PCT concentrations and N% and BALF HBP and IL-6 concentrations and N% were significantly higher in bacterial pneumonia than in viral pneumonia (P < 0.05). In the bacterial pneumonia group, HBP and IL-6 concentrations and N% in BALF samples were all significantly higher than those in blood samples (P < 0.001), and BALF HBP and IL-6 concentrations and N% were correlated with blood HBP and IL-6 concentrations and N%, respectively (r = 0.439, 0.250, and 0.235, P < 0.01). BALF N% and blood N% were both correlated with BALF HBP concentrations and blood HBP concentrations, respectively (r = 0.622 and 0.346, P < 0.001). ROC analysis revealed that BALF HBP showed the best ability to predict bacterial pneumonia, with an area under the curve of 0.994, a sensitivity of 95.24%, and a specificity of 100.00% at its optimal cutoff value of 74.05 ng/mL.

Conclusion

BALF HBP might be a promising biomarker for the early discrimination of bacterial infection from viral infection in critically ill children with severe CAP.

Heparin-binding protein-enhanced quick SOFA score improves mortality prediction in sepsis patients

Purpose

The Quick Sequential Organ Failure Assessment (qSOFA) score proposed by Sepsis-3 as a sepsis screening tool has shown suboptimal accuracy. Heparin-binding protein (HBP) has been shown to identify early sepsis with high accuracy. Herein, we aim to investigate whether or not HBP improves the model performance of qSOFA.

Methods

We conducted a multicenter prospective observational study of 794 adult patients who presented to the emergency department (ED) with presumed sepsis between 2018 and 2019. For each participant, serum HBP levels were measured and the hospital course was followed. The qSOFA score was used as the comparator. The data was split into a training dataset (n = 556) and a validation dataset (n = 238). The primary endpoint was 30-day all-cause mortality.

Results

Compared with survivors, non-survivors had significantly higher serum HBP levels (median: 71.5 ng/mL vs 209.5 ng/mL, p < 0.001). Serum level of HBP weakly correlated with qSOFA class (r² = 0.240, p < 0.001). Compared with the qSOFA model alone, the addition of admission HBP level to the qSOFA model significantly improved 30-day mortality discrimination (AUC, 0.70 vs. 0.80; P < 0.001), net reclassification improvement [26% (CI, 17–35%); P < 0.001], and integrated discrimination improvement [12% (CI, 9–14%); P < 0.001]. Addition of C-reactive protein (CRP) level or neutrophil-to-lymphocyte ratio (NLR) to qSOFA did not improve its performance. A web-based mortality risk prediction calculator was created to facilitate clinical implementation.

Conclusion

This study confirms the value of combining qSOFA and HBP in predicting sepsis mortality. The web calculator provides a user-friendly tool for clinical implementation. Further validation in different patient populations is needed before widespread application of this prediction model.

Antimicrobial peptides and proteins in human biological fluids

Antimicrobial peptides and proteins (AMPs) are endogenous compounds that have a direct antimicrobial effect on bacteria (e. g., by disrupting bacterial membranes), as well as on fungi and viruses. AMPs are the main component of the innate immunity of living organisms and are produced by both epithelial cells (skin cells, cells of respiratory tract, intestine, urinary and genital tracts) and cells of the immune system and are secreted into secretory fluids. AMPs can also act as chemoattractants for immunocompetent cells (neutrophils, monocytes, T lymphocytes, dendritic cells) in the inflammation site and affect the antigen presenting cells by modulating adaptive T cell immune responses. The representatives of the main 15 AMP classes, that we describe in this review, are the most studied group of the large pool of these compounds. We discuss their localization, expression, and concentration in various biofluids of humans under normal and pathological conditions.

Serum Interleukin-6 and Interleukin-8 are Sensitive Markers for Early Detection of Pyelonephritis and Its Prevention to Progression to Chronic Kidney Disease

Background:

Pyelonephritis is the most common bacterial infection in children that can cause renal failure if not diagnosed or treated early. We used serum biomarker interleukins (IL-6 and IL-8) and then confirmed the results by the findings dimercaptosuccinic acid (DMSA) scan to distinguish upper-tract infection from lower-tract infection.

Methods:

Serum IL-6 and IL-8 were measured in 57 children with newly diagnosed untreated urinary tract infection (UTI) documented by a positive urine culture. All children had a DMSA to determine whether serum IL6, IL-8 can be used as a marker to predict upper-tract from lower-tract infection. IL-6 and IL8 were determined by the enzyme link immunosorbent assay (ELISA) technique.

Results:

Of the 57 patients, 24 (42%) had renal parenchymal lesions on the DMSA scan. Patients with abnormal DMSA had significantly higher serum IL-6 and IL-8 compared with those with normal DMSA scan (187.1 ± 113.1 ng/mL vs. 396.1 ± 246.0 ng/mL, P = 0.005; and 165 ± 76.1 ng/mLvs. 190.8 ± 60.8 ng/mL, P = 0.026, respectively). Pyelonephritis was more frequent in children younger than 20 months old (n = 36, 63%, P < 0.005) and more prevalent in girls (n = 36, 63%, P = 0.005). Serum IL-6 had a sensitivity of 67.3% and a specificity of 63.0% and serum IL8 had a sensitivity of 80.1% and a specificity of 73.5% in the differential diagnosis of pyelonephritis and cystitis (P = 0.03).

Conclusions:

Serum levels of IL-6 and IL-8 are both sensitive biomarkers of UTI and can discriminate the upper from lower tract urinary infections. Determination of these biomarkers may help to identify patients with acute pyelonephritis and need for DMSA 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.

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.

Renal clearance of heparin-binding protein and elimination during renal replacement therapy: Studies in ICU patients and healthy volunteers

Background

Heparin-binding protein (HBP) is released by neutrophils upon activation, and elevated plasma levels are seen in inflammatory states like sepsis, shock, cardiac arrest, and burns. However, little is known about the elimination of HBP. We wanted to study renal clearance of HBP in healthy individuals and in burn patients in intensive care units (ICUs). We also wished to examine the levels of HBP in the effluent of renal replacement circuits in ICU patients undergoing continuous renal replacement therapy (CRRT).

Methods

We measured plasma and urine levels of HBP and urine flow rate in 8 healthy individuals and 20 patients in a burn ICU. In 32 patients on CRRT, we measured levels of HBP in plasma and in the effluent of the CRRT circuit.

Results

Renal clearance of HBP (median (IQR) ml/min) was 0.19 (0.08–0.33) in healthy individuals and 0.30 (0.01–1.04) in burn ICU patients. In ICU patients with cystatin C levels exceeding 1.44 mg/l, clearance was 0.45 (0.15–2.81), and in patients with cystatin C below 1.44 mg/l clearance was lower 0.28 (0.14–0.55) (p = 0.04). Starting CRRT did not significantly alter plasma levels of HBP (p = 0.14), and the median HBP level in the effluent on CRRT was 9.1 ng/ml (IQR 7.8–14.4 ng/ml).

Conclusion

In healthy individuals and critically ill burn patients, renal clearance of HBP is low. It is increased when renal function is impaired. Starting CRRT in critically ill patients does not alter plasma levels of HBP significantly, but HBP can be found in the effluent.

It seems unlikely that impaired kidney function needs to be considered when interpreting concentrations of HBP in previous studies. Starting CRRT does not appear to be an effective way of reducing HBP concentrations.

Evidence-Informed Practice: Diagnostic Questions in Urinary Tract Infections in the Elderly

Introduction

Routine interventions in the practice of medicine often lack definitive evidence or are based on evidence that is either not high quality or of only modest-to-marginal effect sizes. An abnormal urinalysis in an elderly patient presenting to the emergency department (ED) with non-specific symptoms represents one condition that requires an evidence-informed approach to diagnosis and management of either asymptomatic bacteriuria or urinary tract infection (UTI). The emergency provider often will not have access to urine cultures, and the risks associated with antibiotic use in the elderly are not without potentially significant side effects.

Methods

We performed a historical and clinical review of the growing body of literature suggesting measurable differences in the systemic immune response manifest among patients with asymptomatic pyuria and UTI, including increases in the pro-inflammatory cytokine interleukin-6 and the acute phase reactant procalcitonin.

Results

Serum procalcitonin, a peptide that undergoes proteolysis into calcitonin, has been demonstrated to quickly and reliably rise in patients with severe bacterial infections, and may serve as a potentially sensitive and specific marker for identification of bacterial illness.

Conclusion

In the absence of validated risk scores for diagnosing UTI in elderly patients presenting to the ED, there may be a role for the use of procalcitonin in this patient population.

Accuracy of heparin binding protein: as a new marker in prediction of acute bacterial meningitis

Background

Cerebrospinal fluid bacterial culture is the gold-standard for confirmation of acute bacterial meningitis, but many cases are not culture confirmed. Antibiotics reduce the chance of a microbiological diagnosis. Objective to evaluate efficacy of Heparin-binding protein in diagnosis of bacterial meningitis.

Patients

30 patients diagnosed with acute bacterial meningitis, 30 viral meningitis, and 30 subjects with normal CSF findings.

Design

Diagnosis was based on history, clinical criteria, CSF examination, latex agglutination & culture, and sensitivities and response to therapy. HBP was measured using enzyme-linked immunosorbent technique in both serum & CSF.

Results

Cerebrospinal fluid HBP levels averaged 0.82 ± 0.3 ng/mL in controls, 3.3 ± 1.7 ng/mL in viral and 174.8 ± 46.7 ng/mL in bacterial meningitis. Mean serum level was 0.84 ± 0.3 ng/mL in the controls, 3.7 ± 1.9 ng/mL in viral, and 192.2 ± 56.6 ng/mL in bacterial meningitis. Both HBP levels were significantly higher in patients with bacterial meningitis. Cut-offs of 56.7 ng/ml and 45.3 ng/ml in cerebrospinal fluid & serum showed 100% overall accuracy. Even in patients who received prior antibiotics, remained elevated.

Conclusion

Serum Heparin-binding protein serves as a non-invasive potential marker of acute bacterial meningitis even in partially treated cases.

Heparin-binding protein in sputum as a marker of pulmonary inflammation, lung function, and bacterial load in children with cystic fibrosis

Background

Cystic fibrosis (CF) is associated with bacterial pulmonary infections and neutrophil-dominated inflammation in the airways. The aim of this study was to evaluate the neutrophil-derived protein Heparin-binding protein (HBP) as a potential sputum marker of airway inflammation and bacterial load.

Methods

Nineteen CF patients, aged 6–18 years, were prospectively followed for 6 months with sputum sampling at every visit to the CF clinic. A total of 41 sputum samples were collected. Sputum-HBP was analysed with ELISA, neutrophil elastase activity with a chromogenic assay, and total bacterial load with RT-PCR of the 16 s rDNA gene. Data were compared to lung function parameters and airway symptoms.

Results

HBP and elastase correlated to a decrease in FEV₁%predicted compared to the patients´ individual baseline pulmonary function (∆FEV₁), but not to bacterial load. Area under the receiver operating characteristic curve values for the detection of > 10% decrease in ∆FEV₁ were 0.80 for HBP, 0.78 for elastase, and 0.54 for bacterial load.

Conclusions

Sputum HBP is a promising marker of airway inflammation and pulmonary function in children with CF.

Heparin-binding protein, lysozyme, and inflammatory cytokines in bronchoalveolar lavage fluid as diagnostic tools for pulmonary infection in lung transplanted patients

Pulmonary infection is a common complication after lung transplantation, and early detection is crucial for outcome. However, the condition can be clinically difficult to diagnose and to distinguish from rejection. The aim of this prospective study was to evaluate heparin-binding protein (HBP), lysozyme, and the cytokines interleukin (IL)-1β, IL-6, IL-8, IL-10 and tumor necrosis factor (TNF) in bronchoalveolar lavage fluid (BALF) as potential biomarkers for pulmonary infection in lung-transplanted patients. One hundred thirteen BALF samples from 29 lung transplant recipients were collected at routine scheduled bronchoscopies at 3 and 6 months, or on clinical indication. Samples were classified into no, possible, probable, or definite infection at the time of sampling. Rejection was defined by biopsy results. HBP, lysozyme, and cytokines were analyzed in BALF and correlated to likelihood of infection and rejection. All biomarkers were significantly increased in BALF during infection, whereas patients with rejection presented low levels that were comparable to noninfection samples. HBP, IL-1β, and IL-8 were the best diagnostic markers of infection with area under the receiver-operating characteristic curve values of 0.88, 0.91, and 0.90, respectively. In conclusion, HBP, IL-1β, and IL-8 could be useful diagnostic markers of pulmonary infection in lung-transplanted patients.

Symptomatic treatment of uncomplicated lower urinary tract infections in the ambulatory setting: randomised, double blind trial

Objective To investigate whether symptomatic treatment with non-steroidal anti-inflammatory drugs (NSAIDs) is non-inferior to antibiotics in the treatment of uncomplicated lower urinary tract infection (UTI) in women, thus offering an opportunity to reduce antibiotic use in ambulatory care.Design Randomised, double blind, non-inferiority trial.Setting 17 general practices in Switzerland.Participants 253 women with uncomplicated lower UTI were randomly assigned 1:1 to symptomatic treatment with the NSAID diclofenac (n=133) or antibiotic treatment with norfloxacin (n=120). The randomisation sequence was computer generated, stratified by practice, blocked, and concealed using sealed, sequentially numbered drug containers.Main outcome measures The primary outcome was resolution of symptoms at day 3 (72 hours after randomisation and 12 hours after intake of the last study drug). The prespecified principal secondary outcome was the use of any antibiotic (including norfloxacin and fosfomycin as trial drugs) up to day 30. Analysis was by intention to treat.Results 72/133 (54%) women assigned to diclofenac and 96/120 (80%) assigned to norfloxacin experienced symptom resolution at day 3 (risk difference 27%, 95% confidence interval 15% to 38%, P=0.98 for non-inferiority, P<0.001 for superiority). The median time until resolution of symptoms was four days in the diclofenac group and two days in the norfloxacin group. A total of 82 (62%) women in the diclofenac group and 118 (98%) in the norfloxacin group used antibiotics up to day 30 (risk difference 37%, 28% to 46%, P<0.001 for superiority). Six women in the diclofenac group (5%) but none in the norfloxacin group received a clinical diagnosis of pyelonephritis (P=0.03).Conclusion Diclofenac is inferior to norfloxacin for symptom relief of UTI and is likely to be associated with an increased risk of pyelonephritis, even though it reduces antibiotic use in women with uncomplicated lower UTI.Trial registration ClinicalTrials.gov NCT01039545.

Metabolic phenotyping in the mouse model of urinary tract infection shows that 3-hydroxybutyrate in plasma is associated with infection

Urinary tract infection is one of the most common bacterial infections worldwide. Current diagnosis of urinary tract infection chiefly relies on its clinical presentation, urine dipstick tests and urine culture. Small molecules found in bio-fluids related with both infection and recovery would facilitate diagnosis and management of UTI. Mass spectrometry-based fingerprinting of plasma and urine at 3 time points, pre-infection (t = -24h), infection (t = 24h) and post 3-day treatment (t = 112h), were acquired in the following four groups: mice which were healthy, infected but not treated, infected and treated with ciprofloxacin, and infected and treated with Relinqing^® granules (n = 6 per group). A metabolomics workflow including multivariate analysis and ROC regression was employed to select metabolic features that correlated with UTI and its treatment. Circa 4,000 molecular features were acquired for each sample. The small acid 3-hydroxybutyrate in plasma was found to be differentiated for urinary tract infection, with an area under the curve = 0.97 (95% confidence interval: 0.93–1.00, accuracy = 0.91, sensitivity = 0.92 and specificity = 0.91). The level of 3-hydroxybutyrate in plasma was depleted after infection with a fold change of -22 (q < 0.0001). Correlation between plasma 3-hydroxybutyrate and urine bacterial number in all groups and time points was r = -0.753 (p < 0.0001). The findings show that 3-hydroxybutyrate is depleted in blood and strongly associated with UTI at both infection and post-treatment stage in a UTI mouse model. Further work is envisaged to assess the clinical potential of blood tests to assist with UTI management.

Urine concentrations of human beta-defensins and ribonuclease 7 in urinary tract infection and asymptomatic bacteriuria

Antimicrobial peptides (AMPs) provide a first line of defense against bacterial infections. Here we report that urine levels of AMPs, locally produced in the urinary tract, are lower in individuals with asymptomatic bacteriuria (ABU) compared to patients with urinary tract infection (UTI).

New markers of urinary tract infection

Urinary tract infection (UTI) is the most common bacterial infection independent of age. It is also one of the most common causes of hospitalizations for infections among elderly people and the most common indication for antibiotic prescriptions in primary care. Both diagnostics and management of lower and upper urinary tract infections provide challenges in clinical practice due to their high prevalence and recurrence, and worldwide increase of antibiotic resistance. The clinical symptoms of UTI are often uncharacteristic or asymptomatic. The accurate diagnosis and early treatment are crucial due to risk of septicaemia and long-term consequences. Currently the diagnosis of urinary tract infection is based on the presence of clinical symptoms in combination with the results of nitrite strip test indicating the presence of bacteria in urine and semi-quantitative measurement of white blood cells count in urine. Although urine culture is the gold standard in UTI diagnostics it is both time-consuming and costly. Searching for novel biomarkers of UTI has attracted much attention in recent years. The article reviews several promising serum and urine biomarkers of UTI such as leukocyte esterase, C-reactive protein, procalcitonin, interleukins, elastase alpha (1)-proteinase inhibitor, lactofferin, secretory immunoglobulin A, heparin-binding protein, xanthine oxidase, myeloperoxidase, soluble triggering receptor expressed on myeloid cells-1, α-1 microglobulin (α1Mg) and tetrazolium nitroblue test (TNB).

Heparin-binding protein: a key player in the pathophysiology of organ dysfunction in sepsis

Infectious diseases remain a major health problem, and sepsis and other severe infectious diseases are common causes of morbidity and mortality. There is a need for clinical and laboratory tools to identify patients with severe infections early and to distinguish between bacterial and nonbacterial conditions. Heparin-binding protein (HBP), also known as azurocidin or cationic antimicrobial protein of 37 KDa, is a promising biomarker to distinguish between patients with these conditions. It is biologically plausible that HBP is an early and predictive biomarker because it is prefabricated and rapidly mobilized from migrating neutrophils in response to bacterial infections. HBP induces vascular leakage and oedema formation and has a pro-inflammatory effect on a variety of white blood cells and epithelial cells. The dysregulation of vascular barrier function and cellular inflammatory responses can then lead to organ dysfunction. Indeed, it has been shown that patients with sepsis express elevated levels of HBP in plasma several hours before they develop hypotension or organ dysfunction. HBP has a major role in the pathophysiology of severe bacterial infections and thus represents a potential diagnostic marker and a target for the treatment of sepsis.