Procalcitonin is persistently increased among children with poor outcome from bacterial sepsis

The plasma proteome differentiates the multisystem inflammatory syndrome in children (MIS-C) from children with SARS-CoV-2 negative sepsis

BACKGROUND

The Multi-System Inflammatory Syndrome in Children (MIS-C) can develop several weeks after SARS-CoV-2 infection and requires a distinct treatment protocol. Distinguishing MIS-C from SARS-CoV-2 negative sepsis (SCNS) patients is important to quickly institute the correct therapies. We performed targeted proteomics and machine learning analysis to identify novel plasma proteins of MIS-C for early disease recognition.

METHODS

A case-control study comparing the expression of 2,870 unique blood proteins in MIS-C versus SCNS patients, measured using proximity extension assays. The 2,870 proteins were reduced in number with either feature selection alone or with a prior COMBAT-Seq batch effect adjustment. The leading proteins were correlated with demographic and clinical variables. Organ system and cell type expression patterns were analyzed with Natural Language Processing (NLP).

RESULTS

The cohorts were well-balanced for age and sex. Of the 2,870 unique blood proteins, 58 proteins were identified with feature selection (FDR-adjusted P < 0.005, P < 0.0001; accuracy = 0.96, AUC = 1.00, F1 = 0.95), and 15 proteins were identified with a COMBAT-Seq batch effect adjusted feature selection (FDR-adjusted P < 0.05, P < 0.0001; accuracy = 0.92, AUC = 1.00, F1 = 0.89). All of the latter 15 proteins were present in the former 58-protein model. Several proteins were correlated with illness severity scores, length of stay, and interventions (LTA4H, PTN, PPBP, and EGF; P < 0.001). NLP analysis highlighted the multi-system nature of MIS-C, with the 58-protein set expressed in all organ systems; the highest levels of expression were found in the digestive system. The cell types most involved included leukocytes not yet determined, lymphocytes, macrophages, and platelets.

CONCLUSIONS

The plasma proteome of MIS-C patients was distinct from that of SCNS. The key proteins demonstrated expression in all organ systems and most cell types. The unique proteomic signature identified in MIS-C patients could aid future diagnostic and therapeutic advancements, as well as predict hospital length of stays, interventions, and mortality risks.

Pediatric sepsis inflammatory blood biomarkers that correlate with clinical variables and severity of illness scores

BACKGROUND

Sepsis is a dysregulated systemic inflammatory response triggered by infection, resulting in organ dysfunction. A major challenge in clinical pediatrics is to identify sepsis early and then quickly intervene to reduce morbidity and mortality. As blood biomarkers hold promise as early sepsis diagnostic tools, we aimed to measure a large number of blood inflammatory biomarkers from pediatric sepsis patients to determine their predictive ability, as well as their correlations with clinical variables and illness severity scores.

METHODS

Pediatric patients that met sepsis criteria were enrolled, and clinical data and blood samples were collected. Fifty-eight inflammatory plasma biomarker concentrations were determined using immunoassays. The data were analyzed with both conventional statistics and machine learning.

RESULTS

Twenty sepsis patients were enrolled (median age 13 years), with infectious pathogens identified in 75%. Vasopressors were administered to 85% of patients, while 55% received invasive ventilation and 20% were ventilated non-invasively. A total of 24 inflammatory biomarkers were significantly different between sepsis patients and age/sex-matched healthy controls. Nine biomarkers (IL-6, IL-8, MCP-1, M-CSF, IL-1RA, hyaluronan, HSP70, MMP3, and MMP10) yielded AUC parameters > 0.9 (95% CIs: 0.837-1.000; p < 0.001). Boruta feature reduction yielded 6 critical biomarkers with their relative importance: IL-8 (12.2%), MCP-1 (11.6%), HSP70 (11.6%), hyaluronan (11.5%), M-CSF (11.5%), and IL-6 (11.5%); combinations of 2 biomarkers yielded AUC values of 1.00 (95% CI: 1.00-1.00; p < 0.001). Specific biomarkers strongly correlated with illness severity scoring, as well as other clinical variables. IL-3 specifically distinguished bacterial versus viral infection (p < 0.005).

CONCLUSIONS

Specific inflammatory biomarkers were identified as markers of pediatric sepsis and strongly correlated to both clinical variables and sepsis severity.

AACC Guidance Document on the Clinical Use of Procalcitonin

BACKGROUND

Procalcitonin (PCT), a peptide precursor of the hormone calcitonin, is a biomarker whose serum concentrations are elevated in response to systemic inflammation caused by bacterial infection and sepsis. Clinical adoption of PCT in the United States has only recently gained traction with an increasing number of Food and Drug Administration-approved assays and expanded indications for use. There is interest in the use of PCT as an outcomes predictor as well as an antibiotic stewardship tool. However, PCT has limitations in specificity, and conclusions surrounding its utility have been mixed. Further, there is a lack of consensus regarding appropriate timing of measurements and interpretation of results. There is also a lack of method harmonization for PCT assays, and questions remain regarding whether the same clinical decision points may be used across different methods.

CONTENT

This guidance document aims to address key questions related to the use of PCT to manage adult, pediatric, and neonatal patients with suspected sepsis and/or bacterial infections, particularly respiratory infections. The document explores the evidence for PCT utility for antimicrobial therapy decisions and outcomes prediction. Additionally, the document discusses analytical and preanalytical considerations for PCT analysis and confounding factors that may affect the interpretation of PCT results.

SUMMARY

While PCT has been studied widely in various clinical settings, there is considerable variability in study designs and study populations. Evidence to support the use of PCT to guide antibiotic cessation is compelling in the critically ill and in some lower respiratory tract infections but is lacking in other clinical scenarios, and evidence is also limited in the pediatric and neonatal populations. Interpretation of PCT results requires guidance from multidisciplinary care teams of clinicians, pharmacists, and clinical laboratorians.

Serum procalcitonin level is independently associated with mechanical ventilation and case-fatality in hospitalized COVID-19-positive US veterans-A potential marker for disease severity

The Coronavirus-19 disease (COVID-19) has claimed over 6.8 million lives since first being reported in late 2019. The virus that causes COVID-19 disease is highly contagious and spreads rapidly. To date, there are no approved prognostic tools that could predict why some patients develop severe or fatal disease outcomes. Early COVID-19 studies found an association between procalcitonin (PCT) and hospitalization or duration of mechanical ventilation and death but were limited by the cohort sizes. Therefore, this study was designed to confirm the associations of PCT with COVID-19 disease severity outcomes in a large cohort. For this retrospective data analysis study, 27,154 COVID-19-positive US veterans with post-infection PCT laboratory test data and their disease severity outcomes were accessed using the VA electronic healthcare data. Cox regression models were used to test the association between serum PCT levels and disease outcomes while controlling for demographics and relevant confounding variables. The models demonstrated increasing disease severity (ventilation and death) with increasing PCT levels. For PCT serum levels above 0.20 ng/ml, the unadjusted risk increased nearly 2.3-fold for mechanical ventilation (hazard ratio, HR, 2.26, 95%CI: 2.11-2.42) and in-hospital death (HR, 2.28, 95%CI: 2.16-2.41). Even when adjusted for demographics, diabetes, pneumonia, antibiotic use, white blood cell count, and serum C-reactive protein levels, the risks remained relatively high for mechanical ventilation (HR, 1.80, 95%CI: 1.67-1.94) and death (HR, 1.76, 95%CI: 1.66-1.87). These data suggest that higher PCT levels have independent associations with ventilation and in-hospital death in veterans with COVID-19 disease, validating previous findings. The data suggested that serum PCT level may be a promising prognostic tool for COVID-19 severity assessment and should be further evaluated in a prospective clinical trial.

Utility of specific laboratory biomarkers to predict severe sepsis in pediatric patients with SIRS

OBJECTIVE

To identify the association between readily available laboratory biomarkers and the development of severe sepsis in children presenting to the emergency department (ED) with systemic inflammatory response syndrome (SIRS).

METHODS

In this retrospective cohort study, ED patient encounters from June 2018 to June 2019 that triggered an automated sepsis alert based on SIRS criteria were analyzed. Encounters were included if the patient had any of the following laboratory tests sent within 6 h of ED arrival: C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), lactic acid, and procalcitonin. For each of the biomarkers, a receiver operating characteristic (ROC) curve was created for our primary outcome, severe sepsis within 24 h of ED disposition, and our secondary outcome, severe sepsis with a positive bacterial culture. For each ROC curve, we calculated the area under the curve (AUC) with 95% confidence intervals (95% CI) and created cutoff points to achieve 90% sensitivity and 90% sensitivity for the primary and secondary outcomes.

RESULTS

During the study period, 4349/61,195 (7.1%) encounters triggered an automated sepsis alert. Of those, 1207/4349 (27.8%) had one of the candidate biomarkers sent within 6 h of ED arrival and were included in the study. A total of 100/1207 (8.3%) met criteria for severe sepsis within 24 h of arrival, and 41/100 severe sepsis cases (41%) were deemed culture-positive. Procalcitonin had the highest AUC for identifying severe sepsis [0.62 (95% CI 0.52-0.73)] while ESR and CRP had the highest AUC for culture-positive sepsis [0.68 (95% CI 0.47-0.89) and 0.67 (95% CI 0.53-0.81), respectively]. At 90% sensitivity for detecting severe sepsis, all of the biomarker threshold values fell within that laboratory test's normal range. At 90% specificity for severe sepsis, threshold values were as follows: procalcitonin 2.72 ng/mL, CRP 16.79 mg/dL, ESR 79.5 mm/h and lactic acid 3.6 mmol/L.

CONCLUSION

Our data indicate that CRP, ESR, lactic acid, and procalcitonin elevations were all specific, but not sensitive, in identifying children in the ED with SIRS who go on to develop severe sepsis.

Clinical and laboratory predictors of 30-day mortality in severe acute malnourished children with severe pneumonia

OBJECTIVE

To determine the predictors of mortality within 30 days of hospital admission in a diarrhoeal disease hospital in Bangladesh.

METHODS

Cohort study of hospitalised children aged 0-59 months with severe acute malnutrition (SAM) and severe pneumonia in Dhaka Hospital, icddr,b, Bangladesh from April 2015 to March 2017. Those discharged were followed up, and survival status at 30 days from admission was determined. Children who died were compared with the survivors in terms of clinical and laboratory biomarkers. Multivariable logistic regression analysis was used for calculating adjusted odds ratio for death within 30 days of hospital admission.

RESULTS

We enrolled 191 children. Mortality within 30 days of admission was 6% (14/191). After adjusting for potential confounders (hypoxia, CRP and haematocrit) in logistic regression analysis, independent factors associated with death were female sex (aOR = 5.80, 95% CI: 1.34-25.19), LAZ <-4 (aOR = 6.51, 95% CI: 1.49-28.44) and Polymorphonuclear Leucocytes (PMNL) (>6.0 × 10⁹ /L) (aOR = 1.06, 95% CI: 1.01-1.11). Using sex, Z-score for length for age (LAZ), and PMNL percentage, we used random forest and linear regression models to achieve a cross-validated AUC of 0.83 (95% CI: 0.82, 0.84) for prediction of 30-day mortality.

CONCLUSIONS

The results of our data suggest that female sex, severe malnutrition (<-4 LAZ) and higher PMNL percentage were prone to be associated with 30-day mortality in children with severe pneumonia. Association of these factors may be used in clinical decision support for prompt identification and appropriate management for prevention of mortality in this population.

Utility of Procalcitonin as a Biomarker for Sepsis in Children

Sepsis is a complex process defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. It is associated with significant morbidity and mortality rates in both adults and children, and emphasis has been placed on its early recognition and prompt provision of antimicrobials. Owing to limitations of current diagnostic tests (i.e., poor sensitivity and delayed results), significant research has been conducted to identify sepsis biomarkers. Ideally, a biomarker could reliably and rapidly distinguish bacterial infection from other, noninfectious causes of systemic inflammatory illness. In doing so, a sepsis biomarker could be used for earlier identification of sepsis, risk stratification/prognostication, and/or guidance of antibiotic decision-making. In this minireview, we review one of the most common clinically used sepsis biomarkers, procalcitonin, and its roles in sepsis management in these three areas. We highlight key findings in the adult literature but focus the bulk of this review on pediatric sepsis. The challenges and limitations of procalcitonin measurement in sepsis are also discussed.

Toddalolactone Protects Lipopolysaccharide-Induced Sepsis and Attenuates Lipopolysaccharide-Induced Inflammatory Response by Modulating HMGB1-NF-κB Translocation

Toddalolactone (TA-8) is a main compound isolated from Toddalia asiatica (L.) Lam., and its anti-inflammatory activity and anti-inflammatory mechanism are less studied. In the present study, we investigated the anti-inflammatory effects of TA-8. Our experimental results showed that TA-8 inhibited the production of pro-inflammatory cytokines by both lipopolysaccharide (LPS)-activated RAW 264.7 cells and septic mice. Moreover, TA-8 suppressed the NF-κB transcriptional activity, reduced the nuclear translocation and phosphorylation of NF-κB, blocked the translocation of HMGB1 from the nucleus to cytosol, and decreased LPS-induced up-regulation of TLR4 and IKBKB expression, and decreased IκBα phosphorylation. In addition, the administration of TA-8 decreased LPS-induced liver damage markers (AST and ALT), attenuated infiltration of inflammatory cells and tissue damage of lung, liver, and kidney, and improved survival in septic mice. Taken together, these results suggested that toddalolactone protects LPS-induced sepsis and attenuates LPS-induced inflammatory response by modulating HMGB1-NF-κB translocation. TA-8 could potentially be a novel anti-inflammatory and immunosuppressive drug candidate in the treatment of sepsis and septic shock.

Diagnostic Challenges and Laboratory Considerations for Pediatric Sepsis

Background

Sepsis is a leading cause of death for children in the US and worldwide. There is a lack of consensus how sepsis is clinically defined, and sepsis definitions and diagnostic guidelines for the pediatric population have remained unchanged for more than a decade now. Current pediatric definitions are largely based on adult guidelines and expert opinion rather than evidence based on outcomes in the pediatric populations. Without a clear definition of sepsis, it is challenging to evaluate the performance of new laboratory tests on the diagnosis and management of sepsis.

Content

This review provides an overview of common etiologies of sepsis in pediatric populations, challenges in defining and diagnosing pediatric sepsis, and current laboratory tests used to identify and monitor sepsis. Strengths and limitations of emerging diagnostic strategies will also be discussed.

Summary

Currently there is no single biomarker that can accurately diagnose or predict sepsis. Current biomarkers such as C-reactive protein and lactate are neither sensitive nor specific for diagnosing sepsis. New biomarkers and rapid pathogen identification assays are much needed. Procalcitonin, although having some limitations, has emerged as a biomarker with demonstrated utility in management of sepsis in adults. Parallel studies analyzing the utility of procalcitonin in pediatric populations are lagging but have shown potential to affect sepsis care in pediatric populations. Multibiomarker approaches and stepwise algorithms show promise in the management of pediatric sepsis. However, a major hurdle is the lack of validated clinical criteria for classification of pediatric sepsis, which is necessary for the development of well-designed studies that can assess the clinical impact of these emerging biomarkers.

Procalcitonin Value Is an Early Prognostic Factor Related to Mortality in Admission to Pediatric Intensive Care Unit

Introduction

Procalcitonin (PCT) and C-reactive protein (CRP) are already known predictive markers in serious bacterial infections, and it is emphasized that these biomarkers can be used as a marker of increased mortality in critically ill patients. Herein, we aimed to evaluate the initial serum PCT and CRP levels on the outcome of patients in pediatric intensive care units (PICUs) and find out if these biomarkers can be used to predict mortality.

Materials and Methods

The relationship between the initial serum PCT and CRP levels and invasive mechanical ventilation (IMV) and noninvasive mechanical ventilation (NIV) support, inotropic drug need, acute renal kidney injury (AKI), continuous renal replacement therapy (CRRT), mortality, and hospitalization period was investigated retrospectively.

Results

In total, 418 suitable patients (226 males and 192 females) were included in the study. Age distributions of patients ranged from 1 month to 17 years. There was a statistically significant relationship between PCT levels in the first biochemical analysis performed during admission and MV support, inotropic drug use, mortality, ARF, hospitalization in the intensive care unit, CRRT and blood component transfusion. There was a statistically significant relationship between CRP levels and MV support, NIV, inotropic drug use, mortality, AKI, hospitalization in the intensive care unit, CRRT, and blood component transfusion.

Conclusion

We suggest that the initial PCT and CRP levels during admission can be used to predict the outcome of patients in PICU.

Relationship of Serum Procalcitonin, C-reactive Protein, and Lactic Acid to Organ Failure and Outcome in Critically Ill Pediatric Population

Objective:

To evaluate the clinical and prognostic utility of procalcitonin (PCT), C-reactive protein (CRP), and lactic acid in children admitted to the Pediatric Intensive Care Unit (PICU) of a university teaching hospital.

Materials and Methods:

Medical records of children (1 month–16 years) tested for serum PCT at the time of admission in the PICU of our hospital from July 1, 2013, to January 15, 2015, were reviewed. Within 24 h of admission, the Pediatric Risk of Mortality Score, blood cultures, white blood cell count, neutrophil counts, serum CRP, plasma lactic acid, and PCT were noted. Patient outcome was assessed at hospital discharge, and the patients were divided into nonsurvivors and survivors.

Results:

A total of 167 children being admitted to the PICU were enrolled. The median age of the study population was 3 years (0–16 years), with 58.6% being males. Nonsurvivors had significantly higher lactic acid (4.7 mmol/L [2.07–7.6]; P < 0.05) than that of the survivors (2 mmol/L [1.3–3]; P < 0.05). In addition, nonsurvivors (94.4%; P < 0.05) had greater incidence of multiple organ dysfunction syndrome (MODS) than that of the survivors (38.05%; P < 0.05). Binary logistic regression showed age, MODS, and lactic acid to be associated with mortality.

Conclusions:

This study found that in comparison to PCT and CRP, high plasma lactic acid levels are associated with the development of all-cause MODS and worse outcome in critically ill children admitted in PICU. Prediction of prognosis based on the lactic acid alone may contribute to improve patient management, but further studies are required to endorse our findings.

Cerebrospinal fluid procalcitonin as a biomarker of bacterial meningitis in neonates

OBJECTIVE

The objective of the study was to study the performance of cerebrospinal fluid (CSF) procalcitonin as a marker for bacterial meningitis in neonates, and to determine its optimal 'cutoff' in CSF that can be called significant for the diagnosis.

STUDY DESIGN

Neonates qualifying for lumbar puncture were prospectively studied. Procalcitonin and established CSF parameters were recorded.

RESULTS

At a cut-off value of 0.33 ng ml^-1, CSF procalcitonin had a sensitivity of 0.92, specificity of 0.87, with positive and negative likelihood ratios of 7.13 and 0.092, respectively. The area under the curve for different CSF parameters was: 0.926 (0.887 to 0.964) (P<0.001) for procalcitonin, 0.965 (0.956 to 0.974) for total leukocyte count, 0.961 (0.94 to 0.983) for neutrophil count, 0.874 (0.825 to 0.923) for protein, 0.946 (0.914 to 0.978) for sugar and 0.92 (0.955 to 0.992) for CSF:serum sugar ratio. The lumbar puncture was traumatic in 36 (21.4%) patients; out of these 15 (41.7%) had bacterial meningitis and 21 (58.3%) had no meningitis. In traumatic lumbar tap group, the median (IQR) CSF procalcitonin in patients with and without meningitis was 1.41 (0.32-3.42) ng/ml and 0.21(0.20-0.31) ng/ml respectively (p<0.05).

CONCLUSIONS

Procalcitonin measurement has diagnostic efficiency similar to the established CSF markers. Routine assessment of procalcitonin in clean non-contaminated CSF may not yield additional information, but it may have clinical utility in situations where diagnosis of meningitis is in dilemma, as in the case of blood contamination of CSF in traumatic lumbar punctures.

Use of biomarkers in pediatric sepsis: literature review

Despite advances in recent years, sepsis is still a leading cause of hospitalization and mortality in infants and children. The presence of biomarkers during the response to an infectious insult makes it possible to use such biomarkers in screening, diagnosis, prognosis (risk stratification), monitoring of therapeutic response, and rational use of antibiotics (for example, the determination of adequate treatment length). Studies of biomarkers in sepsis in children are still relatively scarce. This review addresses the use of biomarkers in sepsis in pediatric patients with emphasis on C-reactive protein, procalcitonin, interleukins 6, 8, and 18, human neutrophil gelatinase, and proadrenomedullin. Assessment of these biomarkers may be useful in the management of pediatric sepsis.

Changes in plasma protein levels as an early indication of a bloodstream infection

Blood culture is the primary diagnostic test performed in a suspicion of bloodstream infection to detect the presence of microorganisms and direct the treatment. However, blood culture is slow and time consuming method to detect blood stream infections or separate septic and/or bacteremic patients from others with less serious febrile disease. Plasma proteomics, despite its challenges, remains an important source for early biomarkers for systemic diseases and might show changes before direct evidence from bacteria can be obtained. We have performed a plasma proteomic analysis, simultaneously at the time of blood culture sampling from ten blood culture positive and ten blood culture negative patients, and quantified 172 proteins with two or more unique peptides. Principal components analysis, Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) and ROC curve analysis were performed to select protein(s) features which can classify the two groups of samples. We propose a number of candidates which qualify as potential biomarkers to select the blood culture positive cases from negative ones. Pathway analysis by two methods revealed complement activation, phagocytosis pathway and alterations in lipid metabolism as enriched pathways which are relevant for the condition. Data are available via ProteomeXchange with identifier PXD005022.

Emerging infection and sepsis biomarkers: will they change current therapies?

INTRODUCTION

Sepsis is a heterogeneous syndrome characterized by both immune hyperactivity and relative immune suppression. Biomarkers have the potential to improve recognition and management of sepsis through three main applications: diagnosis, monitoring response to treatment, and stratifying patients based on prognosis or underlying biological response.

AREAS COVERED

This review focuses on specific examples of well-studied, evidence-supported biomarkers, and discusses their role in clinical practice with special attention to antibiotic stewardship and cost-effectiveness. Biomarkers were selected based on availability of robust prospective trials and meta-analyses which supported their role as emerging tools to improve the clinical management of sepsis. Expert commentary: Great strides have been made in candidate sepsis biomarker discovery and testing, with the biomarkers in this review showing promise. Yet sepsis remains a dynamic illness with a great degree of biological heterogeneity - heterogeneity which may be further resolved by recently discovered gene expression-based endotypes in septic shock.

Procalcitonin: Is This the Promised Biomarker for Critically Ill Patients?

Objective Procalcitonin (PCT) has been increasingly used in the critical care setting to determine the presence of bacterial infection and also to guide antibiotic therapy. We reviewed PCT's physiologic role, as well as its clinical utility for the management of pediatric critically ill patients. Findings PCT is a precursor of the hormone calcitonin. Its production is induced by inflammatory conditions, especially bacterial infections. Literature shows that PCT is a moderately reliable diagnostic test for severe bacterial infection in children. Synthesis of available adult studies suggests that the use of PCT-based algorithms to support medical decision making reduces antibiotic exposure without compromising safety in critically ill patients. However, no study has addressed the usefulness and safety of PCT to guide antibiotic therapy in severely ill children. In pediatric patients with acute lower respiratory tract infections, the use of PCT-based algorithms also led to a safe decrease in antibiotic treatment duration. Conclusion PCT has demonstrated clinical utility in the pediatric critical care setting when used for the diagnosis of bacterial infections and to guide antibiotic use in children with acute lower respiratory tract infections. However, more research is needed in critically ill children to determine the utility of PCT-driven antibiotic therapy in this population.

Procalcitonin and community-acquired pneumonia (CAP) in children

The role of procalcitonin (PCT) as a biomarker for sepsis in adults is well documented, while its role in infections affecting neonatal children remains controversial. Among these infections, Community-Acquired pneumonia (CAP) has been studied extensively, because it's the second cause of death in children in developing countries, and one of the most frequent causes of hospitalization in industrialized countries. The PubMed database and the Cochrane Library were used to search for the following keywords: CAP, procalcitonin, and children. Thirteen articles were studied to determine the role of PCT in CAP management, specifically its usefulness for distinguishing pneumococcal infections from viral and unknown infections, for predicting severity and the correct antibiotic treatment. This paper focuses on the studies performed to identify the best inflammatory biomarker for CAP management. Although there is an increase in studies confirming the usefulness of PCT in CAP management in children, further studies are needed to have better understanding of its role for pediatric CAP management.

Efficacy of measuring procalcitonin levels in determination of prognosis and early diagnosis of bacterial resistance in sepsis

Background:

Rapid and proper diagnosis of sepsis is one of the daily challenges of emergency department (ED) and intensive care units. The general aim of the present study was to determine the efficacy of measuring procalcitonin levels in the early diagnosis of bacterial resistance to antibiotics administered empirically in patients with sepsis.

Materials and Methods:

The present cross-sectional study consisted of patients with clinical evidence of sepsis or systemic inflammatory response syndrome (SIRS), referring to the ED of a third-level hospital in Tehran, Iran in 2012. After collection of basic and clinical data of patients, venous blood samples were taken for routine laboratory tests and determination of procalcitonin serum levels at baseline and 6 and 24 hours after administration of the first dose of an empirical antibiotic. The subjects were divided into two groups of discharged and expired and then comparisons were made using t-test, Chi-squared test and Fisher's test. Specificity and sensitivity of procalcitonin were evaluated along with ROC curve.

Results:

In the present study, 170 patients with sepsis were included. Evaluation of serum levels of procalcitonin 24 hours after administration of antibiotics exhibited the best sensitivity and specificity for each patient's response to antibiotics. Use of the cutoff point of 6.5 mg/mL for procalcitonin can predict the disease outcome with sensitivity and specificity of 67% and 80%, respectively.

Conclusion:

It is suggested that procalcitonin be used for the diagnosis of sepsis or SIRS resulting from an infectious disease, for follow-up of treatment and for evaluation of response to treatment.

Use of procalcitonin for the prediction and treatment of acute bacterial infection in children

PURPOSE OF REVIEW

Procalcitonin (PCT) is increasingly utilized to determine the presence of infection or to guide antibiotic therapy. This review will highlight the diagnostic and prognostic utility of serum PCT in children.

RECENT FINDINGS

Recent studies endorse the use of serum PCT to detect invasive infection, to differentiate sepsis from noninfectious systemic inflammatory response syndrome, and to guide antibiotic therapy. Typical values for maximal sensitivity and specificity are less than 0.5  ng/ml for noninfectious inflammation and greater than 2.0  ng/ml for bacterial sepsis. PCT appears to be a reliable indicator of infection. PCT has performed better than C-reactive protein in some settings, though pediatric comparative data are lacking. PCT may aid in diagnosing infection in challenging patient populations such as those with sickle cell disease, congenital heart defects, neutropenia, and indwelling central venous catheters. Antibiotic therapy tailored to serial PCT measurements may shorten the antibiotic exposure without increasing treatment failure.

SUMMARY

PCT is a reliable serum marker for determining the presence or absence of invasive bacterial infection and response to antibiotic therapy. Tailoring antibiotics to PCT levels may reduce the duration of therapy without increasing treatment failure, but more research is needed in children.

Procalcitonin to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis

OBJECTIVE

The aim of this study was to conduct a preliminary analysis of serum procalcitonin (PCT) to predict bacterial coinfection in infants with acute bronchiolitis.

METHODS

Retrospective cohort chart review of 40 infants admitted with acute bronchiolitis to the pediatric intensive care unit. Logistic regression models were used to determine the association of PCT and white blood count with presence of bacterial coinfection defined by either positive culture or chest radiograph result.

RESULTS

Fifteen (38%) of 40 patients had a diagnosis of bacterial coinfection by positive culture (9/15) or chest radiograph (6/15). Procalcitonin (P < 0.0001) was significantly associated with bacterial coinfection. A cutoff value of 1.5 ng/mL had sensitivity of 0.80, specificity of 1.00, and area under the operating curve of 0.88. White blood count (P = 0.06) was borderline significant with sensitivity of 0.33, specificity of 0.96, and area under the operating curve of 0.67. Three of 15 patients were later found to have bacterial coinfection with initial PCT of less than 1.5 ng/mL. None had follow-up PCT measurements taken. Thirty-five of 40 were prescribed empiric antibiotic therapy, including 20 of 25 patients without evidence of bacterial coinfection. None had a PCT of greater than 1.5 ng/mL. If a PCT cutoff of greater than 1.5 ng/mL had been used, 57% fewer patients would have received antibiotics with a 45% reduction in antimicrobial charges.

CONCLUSIONS

An elevated PCT may assist clinicians in determining presence of bacterial coinfection at admission in infants with acute bronchiolitis. Implementation of a PCT cutoff of 1.5 ng/mL at admission may prevent unnecessary antibiotic use with associated cost savings. Serial PCT levels may increase sensitivity. Further validation is warranted.

Pro-adrenomedullin, pro-endothelin-1, procalcitonin, C-reactive protein and mortality risk in critically ill children: a prospective study

Introduction

We tested the hypothesis that higher mid-regional pro-adrenomedullin (MR-proADM), carboxy-terminal pro-endothelin-1 (CT-proET-1), procalcitonin (PCT) and C-reactive protein (CRP) plasma concentrations would be associated with increased prediction of mortality risk scores.

Methods

Prospective observational study set in two pediatric intensive care units (PICUs). Two-hundred-thirty-eight patients were included. MR-proADM, CT-proET-1, PCT and CRP levels were compared between children with PRISM III and PIM 2 > p75 (Group A; n = 33) and the rest (Group B; n = 205).

Results

Median (range) MR-proADM levels were 1.39 nmol/L (0.52–12.67) in group A versus 0.54 (0.15–3.85) in group B (P < 0.001). CT-proET-1 levels were 172 pmol/L (27–500) versus 58 (4–447) (P < 0.001). PCT levels were 7.77 ng/mL (0.34–552.00) versus 0.28 (0.02–107.00) (P < 0.001). CRP levels were 6.23 mg/dL (0.08-28.25) versus 1.30 mg/dL (0.00-42.09) (P = 0.210). The area under the ROC curve (AUC) for the differentiation of group A and B was 0.87 (95% CI:0.81–0.821) for MR-proADM, 0.86 (95% CI:0.79–0.92) for CT-proET-1 and 0.84 (95% CI:0.74–0.94) for PCT. A MR-proADM > 0.79 nmol/L had 93% sensitivity and 76% specificity to differentiate groups, whereas a CT-proET-1 > 123 pmol/L had 77% sensitivity and 84% specificity, and a PCT concentration > 2.05 ng/mL had 80% sensitivity and specificity.

Conclusions

In critically ill children, high levels of MR-proADM, CT-proET-1 and PCT were associated with increased prediction of mortality risk scores. MR-proADM, CT-proET-1 and PCT concentrations higher than 0.80 nmol/L, 123 pmol/L and 2 ng/mL, respectively, could be used by clinicians to identify critically ill children at higher prediction of risk death scores.

Procalcitonin in pediatrics

Over the past two decades, the body of literature on the clinical usefulness of procalcitonin (PCT) in adults has grown rapidly. Although this approach has led to increased insight, it has also prompted debate regarding its potential use in diagnosis and management of severe infection. Clinicians, however, are less familiar with the use of PCT in pediatric populations. In this review, we examine PCT as a marker of severe clinical pediatric conditions including its role in systemic inflammation, infection, and sepsis.

Biomarker response to drotrecogin alfa (activated) in children with severe sepsis: results from the RESOLVE clinical trial*

OBJECTIVE

REsearching severe Sepsis and Organ dysfunction in children: A gLobal perspective (RESOLVE), a phase III trial of drotrecogin alfa (activated) in pediatric severe sepsis, examined biomarker changes in inflammation and coagulation. This report describes biomarker profiles in early severe sepsis and the pharmacodynamic assessment of drotrecogin alfa (activated) in RESOLVE.

DESIGN

Serial measurements of interleukin-1β, interleukin-6, interleukin-8, interleukin-10, tissue necrosis factor-α, procalcitonin, D-dimer, and thrombin-antithrombin complex were performed at baseline and daily over the first five study days. Protein C levels were performed at baseline and at the end of the 96-hr study drug infusion. Analysis of variance-based log-transformed data compared the treatment groups for each measured variable.

SETTING

: One hundred four pediatric intensive care units in 18 countries.

PATIENTS

Four hundred seventy-seven children between 38 wks corrected gestational age and 17 yrs with sepsis-induced cardiovascular and respiratory dysfunction.

INTERVENTIONS

Drotrecogin alfa (activated).

MEASUREMENTS AND MAIN RESULTS

Pharmacodynamic activity of drotrecogin alfa (activated) compared with placebo was observed with reduction of D-dimer on day 1 (p < .01) and thrombin-antithrombin complex on days 1-4 (p < .05). There were no significant changes by treatment in multiple cytokines or procalcitonin. In the overall population, a median protein C difference was not observed (p > .05) with drotrecogin alfa (activated) administration compared with placebo, although a difference (median percentage change from baseline) in favor of drotrecogin alfa (activated) was observed in patients >1 yr old (p = .0449).

CONCLUSIONS

While children in the RESOLVE trial were similar to adults in that they showed a relationship between severity of coagulation and inflammation abnormalities and mortality, their pharmacodynamic response to drotrecogin alfa (activated) differed with respect to changes in protein C activity and systemic inflammation.

Evaluation of circulating soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) to predict risk profile, response to antimicrobial therapy, and development of complications in patients with chemotherapy-associated febrile neutropenia: a pilot study

The soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) is a useful marker of infection in patients with sepsis, but has not been adequately evaluated in patients with chemotherapy-associated febrile neutropenia (FN). The value of sTREM-1 in this setting has been tested in a retrospective, pilot study using stored serum from 48 cancer patients with documented FN. On presentation, patients were categorized according to the Talcott risk-index clinical score. Circulating soluble sTREM-1 was measured using an ELISA procedure, while procalcitonin (PCT) or interleukins 6 (IL-6) and 8 (IL-8), included for comparison, were measured using an immunoluminescence-based assay and Bio-Plex® suspension bead array system, respectively. Circulating concentrations of both sTREM-1 and PCT were significantly (P < 0.05) elevated in patients at high risk for complications or death, as predicted by the Talcott score and were significantly lower in patients who responded to empiric antimicrobial agents. Neither IL-6 nor IL-8 accurately predicted serious complications in patients with FN. These observations, albeit from a pilot study, demonstrate that sTREM-1 is indeed elevated in high-risk patients with FN and is potentially useful to predict their clinical course, either together with, or as an alternative to PCT.

Procalcitonin level as an aid for the diagnosis of bacterial infections following pediatric cardiac surgery

PURPOSE

The aim of the present study was to determine if blood procalcitonin can serve as an aid to differentiate between bacterial and nonbacterial cause of fever in children after cardiac surgery.

MATERIALS AND METHODS

A nested case-control study of children who underwent open cardiac surgery in critical care units of fourth-level pediatric hospital was performed. Blood samples for procalcitonin level were collected 1 day before operation; 1 hour postoperation; on postoperative days 1, 2, and 5; and on the day of fever, when it occurred.

RESULTS

Of 665 children who underwent cardiac bypass surgery, 126 had a febrile episode postoperatively, 47 children with a proven bacterial infection and 79 without bacterial infection. Among the 68 children in whom fever developed within the first 5 postoperative days, procalcitonin level at fever day was significantly higher in those with bacterial infection (n = 16) than in those without infection (n = 52). Similarly, among the 58 children in whom fever developed after day 5 postoperation, a significant difference was found in procalcitonin level at fever day between those with (n = 31) and without (n = 27) bacterial infection.

CONCLUSION

During the critical early and late periods after cardiac surgery in children, procalcitonin level may help to differentiate patients with bacterial infection from patients in whom the fever is secondary to nonbacterial infectious causes.

Biomarkers in the critically ill patient: procalcitonin

Infection and/or sepsis biomarkers should help to make the diagnosis and thus initiate therapy earlier, help to differentiate between infectious and sterile inflammation, allow the use of more-specific antimicrobials, shorten the time of antimicrobial use, and ideally identify distinct phenotypes that may benefit from specific adjunctive sepsis therapies. Procalcitonin (PCT) was proposed as a sepsis and infection marker more than 15 years ago. Meanwhile, PCT has been evaluated in various clinical settings. In this review the present use of PCT on the ICU and in critically ill patients is summarized, included it's role for diagnosis of severe sepsis and septic shock and antibiotic stewardship with PCT.

Preliminary evidence for leukocyte transcriptional signatures for pediatric ventilator-associated pneumonia

OBJECTIVE

Ventilator-associated pneumonia (VAP) is a significant contributor to intensive care unit (ICU) morbidity and mortality and presents a significant diagnostic challenge. Our hypothesis was that blood RNA expression profiles can be used to track the response to VAP in children, using the same methods that proved informational in adults.

DESIGN

A pilot, nonrandomized, repeated measures case-control study of changes in the abundance of total RNA in buffy coat and clinical scores for VAP.

SETTING

A large, multispecialty university-based pediatric ICU and cardiac ICU.

PATIENTS

Seven children requiring intubation and mechanical ventilation.

INTERVENTIONS

Blood samples were drawn at time of enrollment and every 48 hours for a maximum of 11 samples (21 days). Patients ranged in age from 1 to 18 months (mean 8 months). All patients survived to the end of the study. Of the 7 patients studied, 4 developed VAP.

MEASUREMENTS AND MAIN RESULTS

Statistical analysis of the Affymetrix Human Genome Focus GeneChip signal was conducted on normalized expression values of 8793 probe sets using analysis of variance (ANOVA) with a false discovery rate of 0.10. The expression patterns of 48 genes appeared to discriminate between the 2 classes of ventilated children: those with and those without pneumonia. Gene expression network analysis revealed several gene ontologies of interest, including cell proliferation, differentiation, growth, and apoptosis, as well as genes not previously implicated in sepsis.

CONCLUSIONS

These preliminary data are the first in critically ill children supporting the hypothesis that there is a detectable VAP signal in gene expression profiles. Larger studies are needed to validate these preliminary findings and test the diagnostic value of longitudinal changes in leukocyte RNA signatures.

Biomarker discovery and development in pediatric critical care medicine

OBJECTIVES

To frame the general process of biomarker discovery and development; and to describe a proposal for the development of a multibiomarker-based risk model for pediatric septic shock.

DATA SOURCE

Narrative literature review and author-generated data.

DATA SELECTION

Biomarkers can be grouped into four broad classes, based on the intended function: diagnostic, monitoring, surrogate, and stratification.

DATA EXTRACTION AND SYNTHESIS

Biomarker discovery and development requires a rigorous process, which is frequently not well followed in the critical care medicine literature. Very few biomarkers have successfully transitioned from the candidate stage to the true biomarker stage. There is great interest in developing diagnostic and stratification biomarkers for sepsis. Procalcitonin is currently the most promising diagnostic biomarker for sepsis. Recent evidence suggested that interleukin-8 can be used to stratify children with septic shock having a high likelihood of survival with standard care. Currently, there is a multi-institutional effort to develop a multibiomarker-based sepsis risk model intended to predict outcome and illness severity for individual children with septic shock.

CONCLUSIONS

Biomarker discovery and development are an important portion of the pediatric critical care medicine translational research agenda. This effort will require collaboration across multiple institutions and investigators. Rigorous conduct of biomarker-focused research holds the promise of transforming our ability to care for individual patients and our ability to conduct clinical trials in a more effective manner.

Biomarkers for pediatric sepsis and septic shock

Sepsis is a clinical syndrome defined by physiologic changes indicative of systemic inflammation, which are likely attributable to documented or suspected infection. Septic shock is the progression of those physiologic changes to the extent that delivery of oxygen and metabolic substrate to tissues is compromised. Biomarkers have the potential to diagnose, monitor, stratify and predict outcome in these syndromes. C-reactive protein is elevated in inflammatory and infectious conditions and has long been used as a biomarker indicating infection. Procalcitonin has more recently been shown to better distinguish infection from inflammation. Newer candidate biomarkers for infection include IL-18 and CD64. Lactate facilitates the diagnosis of septic shock and the monitoring of its progression. Multiple stratification biomarkers based on genome-wide expression profiling are under active investigation and present exciting future possibilities.

The era of molecular and other non-culture-based methods in diagnosis of sepsis

Sepsis, a leading cause of morbidity and mortality throughout the world, is a clinical syndrome with signs and symptoms relating to an infectious event and the consequent important inflammatory response. From a clinical point of view, sepsis is a continuous process ranging from systemic inflammatory response syndrome (SIRS) to multiple-organ-dysfunction syndrome (MODS). Blood cultures are the current "gold standard" for diagnosis, and they are based on the detection of viable microorganisms present in blood. However, on some occasions, blood cultures have intrinsic limitations in terms of sensitivity and rapidity, and it is not expected that these drawbacks will be overcome by significant improvements in the near future. For these principal reasons, other approaches are therefore needed in association with blood culture to improve the overall diagnostic yield for septic patients. These considerations have represented the rationale for the development of highly sensitive and fast laboratory methods. This review addresses non-culture-based techniques for the diagnosis of sepsis, including molecular and other non-culture-based methods. In particular, the potential clinical role for the sensitive and rapid detection of bacterial and fungal DNA in the development of new diagnostic algorithms is discussed.

Procalcitonin as a marker of severe bacterial infection in children in the emergency department

Procalcitonin, the prohormone of calcitonin, is a relatively new and innovative marker of bacterial infection that has multiple potential applications in the pediatric emergency department. In healthy individuals, circulating levels of procalcitonin are generally very low (<0.05 ng/mL), but in the setting of severe bacterial infection and sepsis, levels can increase by hundreds to thousands of fold within 4 to 6 hours. Although the exact physiologic function of procalcitonin has not been determined, the consistent response and rapid rise of this protein in the setting of severe bacterial infection make procalcitonin a very useful biomarker for invasive bacterial disease. In Europe, serum procalcitonin measurements are frequently used in the diagnosis and the management of patients in a variety of clinical settings. To date, the use of procalcitonin has been limited in the United States, but this valuable biomarker has many potential applications in both the pediatric emergency department and the intensive care unit. The intent of this article is to review the history of procalcitonin, describe the kinetics of the molecule in response to bacterial infection, describe the laboratory methods available for measuring procalcitonin, examine the main causes of procalcitonin elevation, and evaluate the potential applications of procalcitonin measurements in pediatric patients.

Biomarkers: diagnosis and risk assessment in sepsis

Prompt diagnosis, intervention, and risk assessment are critical in caring for septic patient but remain difficult with currently available methods. Biomarkers may become useful adjuncts to clinicians and ultimately serve as targets for future therapeutic trials in sepsis. The most relevant markers are reviewed in this article, including interleukin-6, C-reactive protein, procalcitonin, triggering receptor expressed on myeloid cells-1, and biomarker panels.

The pediatric multiple organ dysfunction syndrome

OBJECTIVES

To review the epidemiology of pediatric multiple organ dysfunction syndrome (MODS) and summarize current concepts regarding the pathophysiology of shock, organ dysfunction, and nosocomial infections in this population.

DATA SOURCE

A MEDLINE-based literature search using the keywords MODS and child, without any restriction to the idiom.

MAIN RESULTS

Critically ill children may frequently develop multisystemic manifestations during the course of severe infections, multiple trauma, surgery for congenital heart defects, or transplantations. Descriptive scores to estimate the severity of pediatric MODS have been validated. Young age and chronic health conditions have also been recognized as important contributors to the development of MODS. Unbalanced inflammatory processes and activation of coagulation may lead to the development of capillary leak and acute respiratory distress syndrome. Neuroendocrine and metabolic responses may result in insufficient adaptive immune response and the development of nosocomial infections, which may further threaten host homeostasis.

CONCLUSIONS

Over the last 20 yrs, there has been an increasing knowledge on the epidemiology of pediatric MODS and on the physiologic mechanisms involved in the genesis of organ dysfunction. Nevertheless, further studies are needed to more clearly evaluate what is the long-term outcome of pediatric MODS.

Procalcitonin in young febrile infants for the detection of serious bacterial infections

OBJECTIVES

The objectives of the study were (1) to study the test performance of procalcitonin for identifying serious bacterial infections in febrile infants <or=90 days of age without an identifiable bacterial source and (2) to determine an optimal cutoff value to identify infants at low risk for serious bacterial infections.

METHODS

A prospective observational study was performed with febrile infants <or=90 days of age presenting to an urban, pediatric, emergency department. Serum procalcitonin levels were measured by using an automated high-sensitivity assay. An optimal procalcitonin cutoff value was selected to maximize sensitivity and negative predictive value for the detection of serious bacterial infections. Infants were classified as having definite, possible, or no serious bacterial infections.

RESULTS

A total of 234 infants (median age: 51 days) were studied. Thirty infants (12.8%) had definite serious bacterial infections (bacteremia: n = 4; bacteremia with urinary tract infections: n = 2; urinary tract infections: n = 24), and 12 infants (5.1%) had possible serious bacterial infections (pneumonia: n = 5; urinary tract infections: n = 7). Mean procalcitonin levels for definite serious bacterial infections (2.21 +/- 3.9 ng/mL) and definite plus possible serious bacterial infections (2.48 +/- 4.6 ng/mL) were significantly higher than that for no serious bacterial infection (0.38 +/- 1.0 ng/mL). The area under the receiver operating characteristic curve was 0.82 for definite serious bacterial infections and 0.76 for definite and possible serious bacterial infections. For identifying definite and possible serious bacterial infections, a cutoff value of 0.12 ng/mL had sensitivity of 95.2%, specificity of 25.5%, negative predictive value of 96.1%, and negative likelihood ratio of 0.19; all cases of bacteremia were identified accurately with this cutoff value.

CONCLUSIONS

Procalcitonin has favorable test characteristics for detecting serious bacterial infections in young febrile infants. Procalcitonin measurements performed especially well in detecting the most serious occult infections.

Procalcitonin and C-reactive protein as markers of bacterial infection in critically ill children at onset of systemic inflammatory response syndrome

OBJECTIVE

To compare the accuracy of procalcitonin and C-reactive protein as diagnostic markers of bacterial infection in critically ill children at the onset of systemic inflammatory response syndrome (SIRS).

DESIGN

Prospective cohort study.

SETTING

Tertiary care, university-affiliated pediatric intensive care unit (PICU).

PATIENTS

Consecutive patients with SIRS.

INTERVENTIONS

From June to December 2002, all PICU patients were screened daily to include cases of SIRS. At inclusion (onset of SIRS), procalcitonin and C-reactive protein levels as well as an array of cultures were obtained. Diagnosis of bacterial infection was made a posteriori by an adjudicating process (consensus of experts unaware of the results of procalcitonin and C-reactive protein). Baseline and daily data on severity of illness, organ dysfunction, and outcome were collected.

MEASUREMENTS AND MAIN RESULTS

Sixty-four patients were included in the study and were a posteriori divided into the following groups: bacterial SIRS (n = 25) and nonbacterial SIRS (n = 39). Procalcitonin levels were significantly higher in patients with bacterial infection compared with patients without bacterial infection (p = .01). The area under the receiver operating characteristic curve for procalcitonin was greater than that for C-reactive protein (0.71 vs. 0.65, respectively). A positive procalcitonin level (>or=2.5 ng/mL), when added to bedside clinical judgment, increased the likelihood of bacterial infection from 39% to 92%, while a negative C-reactive protein level (<40 mg/L) decreased the probability of bacterial infection from 39% to 2%.

CONCLUSIONS

Procalcitonin is better than C-reactive protein for differentiating bacterial from nonbacterial SIRS in critically ill children, although the accuracy of both tests is moderate. Diagnostic accuracy could be enhanced by combining these tests with bedside clinical judgment.

Procalcitonin assay in systemic inflammation, infection, and sepsis: clinical utility and limitations

OBJECTIVE

The use of procalcitonin (ProCT) as a marker of several clinical conditions, in particular, systemic inflammation, infection, and sepsis, will be clarified, and its current limitations will be delineated. In particular, the need for a more sensitive assay will be emphasized. For these purposes, the medical literature comprising clinical studies pertaining to the measurement of serum ProCT in various clinical settings was examined.

DATA SOURCE AND SELECTION

A PubMed search (1965 through November 2007) was conducted, including manual cross-referencing. Pertinent complete publications were obtained using the MeSH terms procalcitonin, C-reactive protein, sepsis, and biological markers. Textbook chapters were also read and extracted.

DATA EXTRACTION AND SYNTHESIS

Available clinical and other patient data from these sources were reviewed, including any data relating to precipitating factors, clinical findings, associated illnesses, and patient outcome. Published data concerning sensitivity, specificity, and reproducibility of ProCT assays were reviewed.

CONCLUSIONS

Based on available data, the measurement of serum ProCT has definite utility as a marker of severe systemic inflammation, infection, and sepsis. However, publications concerning its diagnostic and prognostic utility are contradictory. In addition, patient characteristics and clinical settings vary markedly, and the data have been difficult to interpret and often extrapolated inappropriately to clinical usage. Furthermore, attempts at meta-analyses are greatly compromised by the divergent circumstances of reported studies and by the sparsity and different timing of the ProCT assays. Although a high ProCT commonly occurs in infection, it is also elevated in some noninfectious conditions. Thus, the test is not a specific indicator of either infection or sepsis. Moreover, in any individual patient, the precipitating cause of an illness, the clinical milieu, and complicating conditions may render tenuous any reliable estimations of severity or prognosis. It also is apparent that even a febrile septic patient with documented bacteremia may not necessarily have a serum ProCT that is elevated above the limit of functional sensitivity of the assay. In this regard, the most commonly applied assay (i.e., LUMItest) is insufficiently sensitive to detect potentially important mild elevations or trends. Clinical studies with a more sensitive ProCT assay that is capable of rapid and practicable day-to-day monitoring are needed and shortly may be available. In addition, investigations showing that ProCT and its related peptides may have mediator relevance point to the need for evaluating therapeutic countermeasures and studying the pathophysiologic effect of hyperprocalcitonemia in serious infection and sepsis.

Serum neutrophil gelatinase-associated lipocalin (NGAL) as a marker of acute kidney injury in critically ill children with septic shock

OBJECTIVE

To validate serum neutrophil gelatinase-associated lipocalin (NGAL) as an early biomarker for acute kidney injury in critically ill children with septic shock.

DESIGN

Observational cohort study.

SETTING

Fifteen North American pediatric intensive care units (PICUs).

PATIENTS

A total of 143 critically ill children with systemic inflammatory response syndrome (SIRS) or septic shock and 25 healthy controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serum NGAL was measured during the first 24 hrs of admission to the PICU. Acute kidney injury was defined as a blood urea nitrogen concentration >100 mg/dL, serum creatinine >2 mg/dL in the absence of preexisting renal disease, or the need for dialysis. There was a significant difference in serum NGAL between healthy children (median 80 ng/mL, interquartile ratio [IQR] 55.5-85.5 ng/mL), critically ill children with SIRS (median 107.5 ng/mL, IQR 89-178.5 ng/mL), and critically ill children with septic shock (median 302 ng/mL, IQR 151-570 ng/mL; p < .001). Acute kidney injury developed in 22 of 143 (15.4%) critically ill children. Serum NGAL was significantly increased in critically ill children with acute kidney injury (median 355 ng/mL, IQR 166-1322 ng/mL) compared with those without acute kidney injury (median 186 ng/mL, IQR 98-365 ng/mL; p = .009).

CONCLUSIONS

Serum NGAL is a highly sensitive but nonspecific predictor of acute kidney injury in critically ill children with septic shock. Further validation of serum NGAL as a biomarker of acute kidney injury in this population is warranted.

Procalcitonin Test in the Diagnosis of Bacteremia: A Meta-analysis

STUDY OBJECTIVE

We seek to evaluate the diagnostic performance of the procalcitonin test for the diagnosis of bacteremia in the emergency department (ED) population.

METHODS

We conducted a search of MEDLINE, bibliographies of previous systemic reviews, and pertinent national meeting research abstracts. We included studies that assessed the diagnostic accuracy of procalcitonin for bacteremia, with blood culture as the reference standard. We included prospective investigations of adults and children with suspected infection studied in the ED or at admission. Two authors independently extracted data and assessed study quality; consensus was reached by conference. The analysis was based on the I2 statistic for heterogeneity, unweighted summary receiver-operating characteristic curve, and random-effects pooled sensitivity and specificity across studies using the same test threshold.

RESULTS

The search yielded 348 publications and 1 unpublished study. Seventeen studies met the inclusion criteria and provided a sample of 2,008 subjects. There was a substantial degree of inconsistency (I2=64%). The unweighted summary receiver-operating characteristic curve provided the best overall estimate of test performance, with an area under the curve of 0.84 (95% confidence interval [CI] 0.75 to 0.90). Sensitivity analysis based on study quality did not significantly change the results. Subgroup analysis including only studies that used a test threshold of 0.5 or 0.4 ng/mL yielded pooled estimates for sensitivity and specificity of 76% (95% CI 0.66 to 0.84) and 70% (95% CI 0.60 to 0.79), respectively.

CONCLUSION

We found the diagnostic performance of the procalcitonin test for identifying bacteremia in ED patients to be moderate. Future research designed to determine the utility of the procalcitonin test as a diagnostic tool used in isolation for detecting bacteremia in ambulatory patients is needed before widespread clinical use.

Pediatric traumatic brain injury: past, present and future

Traumatic brain injury (TBI) is the leading cause of death and disability in children. Evidence-based guidelines for the management of this population are available; however, the data highlight significant deficiencies with few treatment standards or guidelines. Considering the limited availability of resources, it is necessary to define realistic goals. Attention should be given to injury prevention, developing standardized pediatric admission and outcome evaluations, increasing the utility and spectrum of physiological and biochemical testing, and defining the evolving role of imaging in TBI.

Procalcitonin in children with Escherichia coli O157:H7 associated hemolytic uremic syndrome

Shiga toxin producing Escherichia coli (STEC) are noninvasive enteric pathogens that may cause hemorrhagic colitis (HC) and diarrhea-associated hemolytic uremic syndrome (D+ HUS). We hypothesized that development of D+ HUS is associated with increased serum procalcitonin (PCT) levels. PCT was measured by an immunoluminometric assay in 113 patients. Concentrations of PCT were different in normal controls, disease control groups (rotavirus enteritis, HC due to non-STEC pathogens, chronic renal failure), and children with uncomplicated O157:H7 HC or D+ HUS. Children with D+ HUS showed higher PCT levels than those with uncomplicated O157:H7 HC, and increased concentrations were noted in cases requiring peritoneal dialysis. Severely increased concentrations were observed in children with D+ HUS on d 5 or 6 after the onset of enteritis, whereas serial measurements in those with uncomplicated O157:H7 HC remained within the normal range throughout the first week of illness. PCT was correlated with serum concentrations of lipopolysaccharide (LPS)-binding protein and serum levels of alanine aminotransferase. Using two separate sets of real-time PCR primers, we were unable to detect elevated PCT mRNA transcripts in nonadherent undifferentiated (monocytic) or differentiated (macrophage-like) THP-1 cells stimulated with purified Shiga toxin-1 and/or LPS. Our data show that serum levels of PCT are associated with the severity of illness in children with D+ HUS. Further studies are needed to determine the role of PCT in the pathogenesis of thrombotic microangiopathy associated to childhood D+ HUS.

Biomarkers of sepsis: clinically useful?

PURPOSE OF REVIEW

The purpose of this review is to indicate recent developments in biomarkers of sepsis and to evaluate their impact on clinical use. According to the 'surviving sepsis campaign,' diagnosis of sepsis and infection is urgent; early and specific treatment is most effective to reduce complications and to decrease mortality.

RECENT FINDINGS

A variety of biomarkers of sepsis is presently available. The diagnostic spectrum of the various markers, however, is different. Some primarily indicate severity of inflammation (e.g. interleukin-6), others respond to infection, but do not indicate the host response well (endotoxin, lipoprotein binding protein, triggering receptor on myeloid cells). There are new markers with limited clinical experience, for example triggering receptor on myeloid cells or mid-pro atrial natriuretic peptide (Seristra, Brahms AG, Hennigsdorf, Germany). Procalcitonin is a well-established biomarker of sepsis that fulfills several criteria of clinical needs: it responds both to infection and severity of inflammation and thus has an impact on therapy. Recent studies indicate that antibiotic treatment can also be guided by procalcitonin. Further indications, including diagnosis of invasive bacterial infections and diagnosis of sepsis in neonates and children have been reported recently.

SUMMARY

Recent data and cumulative analyses indicate that biomarkers of sepsis improve diagnosis of sepsis. However, only a few markers have impact on therapy and fulfill the clinical requirements. Procalcitonin is a well-established marker, indicating infection, sepsis, and progression to the more severe stages of the disease. Today, this biomarker should be in the diagnostic portfolio of an intensive care unit or emergency ward.

Procalcitonin does discriminate between sepsis and systemic inflammatory response syndrome

AIMS

To evaluate whether procalcitonin (PCT) and C reactive protein (CRP) are able to discriminate between sepsis and systemic inflammatory response syndrome (SIRS) in critically ill children.

METHODS

Prospective, observational study in a paediatric intensive care unit. Kinetics of PCT and CRP were studied in patients undergoing open heart surgery with cardiopulmonary bypass (CPB) (SIRS model; group I1) and patients with confirmed bacterial sepsis (group II).

RESULTS

In group I, PCT median concentration was 0.24 ng/ml (reference value <2.0 ng/ml). There was an increment of PCT concentrations which peaked immediately after CPB (median 0.58 ng/ml), then decreased to 0.47 ng/ml at 24 h; 0.33 ng/ml at 48 h, and 0.22 ng/ml at 72 h. CRP median concentrations remained high on POD1 (36.6 mg/l) and POD2 (13.0 mg/l). In group II, PCT concentrations were high at admission (median 9.15 ng/ml) and subsequently decreased in 11/14 patients who progressed favourably (median 0.31 ng/ml). CRP levels were high in only 11/14 patients at admission. CRP remained high in 13/14 patients at 24 h; in 12/14 at 48 h; and in 10/14 patients at 72 h. Median values were 95.0, 50.9, 86.0, and 20.3 mg/l, respectively. The area under the ROC curve was 0.99 for PCT and 0.54 for CRP. Cut off concentrations to differentiate SIRS from sepsis were >2 ng/ml for PCT and >79 mg/l for CRP.

CONCLUSION

PCT is able to differentiate between SIRS and sepsis while CRP is not. Moreover, unlike CRP, PCT concentrations varied with the evolution of sepsis.

Prognostic utility of the semi-quantitative procalcitonin test, neutrophil count and C-reactive protein in meningococcal infection in children

The aim was to determine whether semi-quantitative procalcitonin (PCT-Q) measurements on admission can identify the severity of meningococcal infection in children. A total of 65 children (mean age 2.4 years) with meningococcal disease were included in a prospective study. All patients were treated with antibiotics, rehydration, inotropic drugs and mechanical ventilation if presenting with shock or respiratory failure. On admission, blood was drawn for routine laboratory analyses including absolute neutrophil count (NC), C-reactive protein (CRP) and PCT-Q (immunochromatographic test). A total of 33 patients presented with septic shock on admission of whom 18 developed multiple organ dysfunction syndrome (MODS) and 9 died. Forty-three patients showed a very high PCT-Q level (>or=10 ng/ml), 12 showed values between 2-9.9 ng/ml and the remaining 10 patients showed PCT-Q levels<2 ng/ml. All patients with a PCT-Q level<10 ng/ml survived, whereas all those who developed MODS or died had PCT-Q levels>or=10 ng/ml. Receiver operator curve analysis showed that PCT-Q and NC had a high predictive value for MODS and death. PCT-Q showed a sensitivity of 100%, a negative predictive value of 100% and a negative likelihood ratio of 0.0 for MODS and death.

CONCLUSION

semi-quantitative procalcitonin levels under 10 ng/ml predict good outcome of children with meningococcal infection. It is a highly sensitive method to identify patients with an increased risk of multiple organ dysfunction syndrome or death.