Lipopolysaccharide binding protein in a surgical intensive care unit: a marker of sepsis?

Lipopolysaccharide-binding protein in Crohn's disease patients: a promising noninvasive biomarker monitoring disease activity

BACKGROUND

Following STRIDE-II recommendations, the discovery of novel noninvasive biomarkers, beyond the use of C-reactive protein (CRP) and fecal calprotectin, remains a medical need to further improve the monitoring of patients with inflammatory bowel disease (IBD). This study aims to evaluate the potential of serum lipopolysaccharide-binding protein (LBP) in monitoring IBD activity.

METHODS

This retrospective cross-sectional study included 69 IBD patients (43 Crohn's disease and 26 ulcerative colitis) and 82 controls. Serum LBP levels were measured by ELISA. Clinical, biological and endoscopic parameters were analyzed for IBD patients with no reports of missing data. Statistical tests, including nonparametric tests and receiver operating characteristic (ROC) curve analysis, were used to evaluate the diagnostic accuracy of LBP.

RESULTS

IBD patients displayed a significantly higher LBP median [29.6 μg/ml (19.8-38.8) in Crohn's disease and 22.8 (13.7-38.8) in ulcerative colitis] than controls [5.8 (4.7-7.3), P  < 0.001] with little overlapping distributions. In Crohn's disease patients, LBP levels gradually increased with endoscopic activity scores demonstrating a 1.7-fold rise in active patients compared to remitter patients ( P  = 0.02). LBP level exhibited a positive correlation with CRP ( ρ  = 0.75, P  < 0.001) as well as fecal calprotectin ( ρ  = 0.42, P  < 0.01), both of which further increased when excluding cases that did not match endoscopic activity.

CONCLUSION

LBP might be a promising noninvasive biomarker for monitoring disease activity, especially in Crohn's disease patients. In clinical situations where current biomarkers lack sensitivity, LBP could be discriminative and help filling the gap for reliable therapeutic decisions.

Advances in sepsis biomarkers

Sepsis, a dysregulated host immune response to an infectious agent, significantly increases morbidity and mortality for hospitalized patients worldwide. This chapter reviews (1) the basic principles of infectious diseases, pathophysiology and current definition of sepsis, (2) established sepsis biomarkers such lactate, procalcitonin and C-reactive protein, (3) novel, newly regulatory-cleared/approved biomarkers, such as assays that evaluate white blood cell properties and immune response molecules, and (4) emerging biomarkers and biomarker panels to highlight future directions and opportunities in the diagnosis and management of sepsis.

Biomarkers for the Prediction and Judgement of Sepsis and Sepsis Complications: A Step towards precision medicine?

Sepsis and septic shock are a major public health concern and are still associated with high rates of morbidity and mortality. Whilst there is growing understanding of different phenotypes and endotypes of sepsis, all too often treatment strategies still only employ a “one-size-fits-all” approach. Biomarkers offer a unique opportunity to close this gap to more precise treatment approaches by providing insight into clinically hidden, yet complex, pathophysiology, or by individualizing treatment pathways. Predicting and evaluating systemic inflammation, sepsis or septic shock are essential to improve outcomes for these patients. Besides opportunities to improve patient care, employing biomarkers offers a unique opportunity to improve clinical research in patients with sepsis. The high rate of negative clinical trials in this field may partly be explained by a high degree of heterogeneity in patient cohorts and a lack of understanding of specific endotypes or phenotypes. Moving forward, biomarkers can support the selection of more homogeneous cohorts, thereby potentially improving study conditions of clinical trials. This may finally pave the way to a precision medicine approach to sepsis, septic shock and complication of sepsis in the future.

Biomarkers of sepsis in pigs, horses and cattle: from acute phase proteins to procalcitonin

Sepsis is a complex clinical syndrome triggered by an inflammatory host response to an infection. It is usually complicated to detect and diagnose, and has severe consequences in human and veterinary health, especially when treatment is not started early. Therefore, efforts to detect sepsis accurately are needed. In addition, its proper diagnosis could reduce the misuse of antibiotics, which is essential fighting against antimicrobial resistance. This case is a particular issue in farm animals, as antibiotics have been traditionally given massively, but now they are becoming increasingly restricted. When sepsis is suspected in animals, the most frequently used biomarkers are acute phase proteins such as C-reactive protein, serum amyloid A and haptoglobin, but their concentrations can increase in other inflammatory conditions. In human patients, the most promising biomarkers to detect sepsis are currently procalcitonin and presepsin, and there is a wide range of other biomarkers under study. However, there is little information on the application of these biomarkers in veterinary species. This review aims to describe the general concepts of sepsis and the current knowledge about the biomarkers of sepsis in pigs, horses, and cattle and to discuss possible advances in the field.

Lipopolysaccharide-Induced Transcriptional Changes in LBP-Deficient Rat and Its Possible Implications for Liver Dysregulation during Sepsis

Sepsis is an organ dysfunction caused by the dysregulated inflammatory response to infection. Lipopolysaccharide-binding protein (LBP) binds to lipopolysaccharide (LPS) and modulates the inflammatory response. A rare systematic study has been reported to detect the effect of LBP gene during LPS-induced sepsis. Herein, we explored the RNA sequencing technology to profile the transcriptomic changes in liver tissue between LBP-deficient rats and WT rats at multiple time points after LPS administration. We proceeded RNA sequencing of liver tissue to search differentially expressed genes (DEGs) and enriched biological processes and pathways between WT and LBP-deficient groups at 0 h, 6 h, and 24 h. In total, 168, 284, and 307 DEGs were identified at 0 h, 6 h, and 24 h, respectively, including Lrp5, Cyp7a1, Nfkbiz, Sigmar1, Fabp7, and Hao1, which are related to the inflammatory or lipid-related process. Functional enrichment analysis revealed that inflammatory response to LPS mediated by Ifng, Cxcl10, Serpine1, and Lbp was enhanced at 6 h, while lipid-related metabolism associated with C5, Cyp4a1, and Eci1 was enriched at 24 h after LPS administration in the WT samples. The inflammatory process was not found when the LBP gene was knocked out; lipid-related metabolic process and peroxisome proliferator-activated receptor (PPAR) signaling pathway mediated by Dhrs7b and Tysnd1 were significantly activated in LBP-deficient samples. Our study suggested that the invading LPS may interplay with LBP to activate the nuclear factor kappa B (NF-κB) signaling pathway and trigger uncontrolled inflammatory response. However, when inhibiting the activity of NF-κB, lipid-related metabolism would make bacteria removal via the effect on the PPAR signaling pathway in the absence of LBP gene. We also compared the serum lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) levels using the biochemistry analyzer and analyzed the expression of high mobility group box 1 (HMGB1) and cleaved-caspase 3 with immunohistochemistry, which further validated our conclusion.

Effects of Lipopolysaccharide-Binding Protein (LBP) Single Nucleotide Polymorphism (SNP) in Infections, Inflammatory Diseases, Metabolic Disorders and Cancers

Inflammation, which is induced by the immune response, is recognized as the driving factor in many diseases, including infections and inflammatory diseases, metabolic disorders and cancers. Genetic variations in pivotal genes associated with the immune response, particularly single nucleotide polymorphisms (SNPs), may account for predisposition and clinical outcome of diseases. Lipopolysaccharide (LPS)-binding protein (LBP) functions as an enhancer of the host response to LPS, the main component of the outer membrane of gram-native bacteria. Given the crucial role of LBP in inflammation, we will review the impact of SNPs in the LBP gene on infections and inflammatory diseases, metabolic disorders and cancers.

Neonatal sepsis at point of care

Sepsis, which includes infection followed by inflammation, is one of the leading causes of death among neonates worldwide. The major attribute of this disease process is dysregulated host response to infection leading to organ dysfunction and potentially death. A comprehensive understanding of the host response as well as the pathogen itself are important factors contributing to outcome. Early diagnosis is paramount, as it leads to accurate assessment and improved clinical management. Accordingly, a number of diagnostic platforms have been introduced to assess the presence of blood stream pathogens in septic neonates. Unfortunately, current point-of-care (POC) methods rely on a single parameter/biomarker and thus lack a comprehensive evaluation. The emerging field of biosensing has, however, resulted in the development of a wide range of analytical devices that may be useful at POC. This review discusses currently available methods to screen the inflammatory process in neonatal sepsis. We describe POC sensor-based methods for single platform multi-analyte detection and highlight the latest advances in this evolving technology. Finally, we critically evaluate the applicability of these POC devices clinically for early diagnosis of sepsis in neonates.

Biomarkers of sepsis: time for a reappraisal

INTRODUCTION

Sepsis biomarkers can have important diagnostic, therapeutic, and prognostic functions. In a previous review, we identified 3370 references reporting on 178 different biomarkers related to sepsis. In the present review, we evaluate the progress in the research of sepsis biomarkers.

METHODS

Using the same methodology as in our previous review, we searched the PubMed database from 2009 until September 2019 using the terms "Biomarker" AND "Sepsis." There were no restrictions by age or language, and all studies, clinical and experimental, were included.

RESULTS

We retrieved a total of 5367 new references since our previous review. We identified 258 biomarkers, 80 of which were new compared to our previous list. The majority of biomarkers have been evaluated in fewer than 5 studies, with 81 (31%) being assessed in just a single study. Apart from studies of C-reactive protein (CRP) or procalcitonin (PCT), only 26 biomarkers have been assessed in clinical studies with more than 300 participants. Forty biomarkers have been compared to PCT and/or CRP for their diagnostic value; 9 were shown to have a better diagnostic value for sepsis than either or both of these biomarkers. Forty-four biomarkers have been evaluated for a role in answering a specific clinical question rather than for their general diagnostic or prognostic properties in sepsis.

CONCLUSIONS

The number of biomarkers being identified is still increasing although at a slower rate than in the past. Most of the biomarkers have not been well-studied; in particular, the clinical role of these biomarkers needs to be better evaluated.

The History of Biomarkers: How Far Have We Come?

Sepsis is one of the oldest and most elusive syndromes in medicine that is still incompletely understood. Biomarkers may help to transform sepsis from a physiologic syndrome to a group of distinct biochemical disorders. This will help to differentiate between systemic inflammation of infectious and noninfectious origin and aid therapeutic decision making, hence improve the prognosis for patients, guide antimicrobial therapy, and foster the development of novel adjunctive sepsis therapies. To reach this goal requires increased systematic investigation that includes twenty-first century scientific approaches and technologies and appropriate clinical evaluation.

Plasma levels of C-reactive protein, matrix metalloproteinase-7 and lipopolysaccharide-binding protein distinguish active pulmonary or extrapulmonary tuberculosis from uninfected controls in children

The immune profile associated with distinct clinical forms of tuberculosis (TB) has been extensively described for adult populations. Nevertheless, studies describing immune determinants of pulmonary or extrapulmonary TB (PTB or EPTB, respectively) in children are scarce. Here, we retrospectively assessed plasma levels of several mediators of inflammation in age and sex-matched children from South India presenting with PTB (n = 14) or EPTB (n = 22) as well as uninfected healthy controls (n = 19) to identify biomarkers that could accurately distinguish different TB clinical forms. Furthermore, we performed exploratory analyses testing the influence of sex on the systemic inflammatory profile. The analyses identified a biosignature of 10 biomarkers capable of distinguishing the three clinical groups simultaneously. Machine-learning decision trees indicated that C-reactive protein (CRP), matrix metalloproteinase (MMP)-7 and lipopolysaccharide-binding protein (LBP) were the markers that, when combined, displayed the highest accuracy in identifying the clinical groups. Additional exploratory analyses suggested that the disease signatures were highly influenced by sex. Therefore, sex differentially impacted status of systemic inflammation, immune activation and tissue remodeling in children with distinct clinical forms of TB. Regardless of such nuances related to biological sex, MMP-7, CRP and LBP were strong discriminators of active TB and thus could be considered as biomarkers useful in discrimination different TB clinical forms. These observations have implications on our understanding of the immunopathology of both clinical forms of TB in pediatric patients. If validated by other studies in the future, the combination of identified biomarkers may help development of point-of-care diagnostic or prognostic tools.

Plasma interleukin-6 concentration for the diagnosis of sepsis in critically ill adults

BACKGROUND

The definition of sepsis has evolved over time, along with the clinical and scientific knowledge behind it. For years, sepsis was defined as a systemic inflammatory response syndrome (SIRS) in the presence of a documented or suspected infection. At present, sepsis is defined as a life-threatening organ dysfunction resulting from a dysregulated host response to infection. Even though sepsis is one of the leading causes of mortality in critically ill patients, and the World Health Organization (WHO) recognizes it as a healthcare priority, it still lacks an accurate diagnostic test. Determining the accuracy of interleukin-6 (IL-6) concentrations in plasma, which is proposed as a new biomarker for the diagnosis of sepsis, might be helpful to provide adequate and timely management of critically ill patients, and thus reduce the morbidity and mortality associated with this condition.

OBJECTIVES

To determine the diagnostic accuracy of plasma interleukin-6 (IL-6) concentration for the diagnosis of bacterial sepsis in critically ill adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, and Web of Science on 25 January 2019. We screened references in the included studies to identify additional studies. We did not apply any language restriction to the electronic searches.

SELECTION CRITERIA

We included diagnostic accuracy studies enrolling critically ill adults aged 18 years or older under suspicion of sepsis during their hospitalization, where IL-6 concentrations were evaluated by serological measurement.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the references to identify relevant studies and extracted data. We assessed the methodological quality of studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. We estimated a summary receiver operating characteristic (SROC) curve by fitting a hierarchical summary ROC (HSROC) non-linear mixed model. We explored sources of heterogeneity using the HSROC model parameters. We conducted all analyses in the SAS statistical software package and R software.

MAIN RESULTS

We included 23 studies (n = 4192) assessing the accuracy of IL-6 for the diagnosis of sepsis in critically ill adults. Twenty studies that were available as conference proceedings only are awaiting classification. The included participants were heterogeneous in terms of their distribution of age, gender, main diagnosis, setting, country, positivity threshold, sepsis criteria, year of publication, and origin of infection, among other factors. Prevalence of sepsis greatly varied across studies, ranging from 12% to 78%. We considered all studies to be at high risk of bias due to issues related to the index test domain in QUADAS-2. The SROC curve showed a great dispersion in individual studies accuracy estimates (21 studies, 3650 adult patients), therefore the considerable heterogeneity in the collected data prevented us from calculating formal accuracy estimates. Using a fixed prevalence of sepsis of 50% and a fixed specificity of 74%, we found a sensitivity of 66% (95% confidence interval 60 to 72). If we test a cohort 1000 adult patients under suspicion of sepsis with IL-6, we will find that 330 patients would receive appropriate and timely antibiotic therapy, while 130 patients would be wrongly considered to have sepsis. In addition, 370 out of 1000 patients would avoid unnecessary antibiotic therapy, and 170 patients would have been undiagnosed of sepsis. This numerical approach should be interpreted with caution due to the limitations described above.

AUTHORS' CONCLUSIONS

Our evidence assessment of plasma interleukin-6 concentrations for the diagnosis of sepsis in critically ill adults reveals several limitations. High heterogeneity of collected evidence regarding the main diagnosis, setting, country, positivity threshold, sepsis criteria, year of publication, and the origin of infection, among other factors, along with the potential number of misclassifications, remain significant constraints for its implementation. The 20 conference proceedings assessed as studies awaiting classification may alter the conclusions of the review once they are fully published and evaluated. Further studies about the accuracy of interleukin-6 for the diagnosis of sepsis in adults that apply rigorous methodology for conducting diagnostic test accuracy studies are needed. The conclusions of the review will likely change once the 20 studies pending publication are fully published and included.

Uso de procalcitonina como diagnóstico de sepsis o shock séptico: revisión sistemática y metaanálisis

Introducción: La procalcitonina (PCT) es una prohormona de la calcitonina, producida por las células C de la glándula tiroides y convertida intracelularmente por enzimas proteolíticas en la hormona activa. La producción de PCT durante procesos inflamatorios, está ligada a endotoxinas bacterianas y a citoquinas inflamatorias. La mortalidad por sepsis, depende en gran medida de la detección precoz y del inicio de una terapia adecuada, incluyendo la administración de antibióticos apropiados, sin embargo, no está claro si el rendimiento diagnóstico de la PCT en el contexto de la nueva definición de sepsis en el tercer consenso es igual que con la definición previa.Métodos: Se incluyeron estudios que describieran el uso de PCT dentro de las primeras 24 horas de admisión, como prueba diagnóstica de sepsis. Se realizó la búsqueda en las bases de datos de Medline (Pubmed) y Embase. La calidad metodológica se evaluó según la Colaboración Cochrane en el desarrollo de Revisiones Sistemáticas sobre Test de Análisis para la herramienta QUADAS-II. El sesgo de publicación fue estudiado con el Test de Asimetría de Deeks. Se usó el módulo de MIDAS de STATA 14 para el análisis univariado y la construcción de la Curva de ROC.Resultados: Se obtuvieron 2076 registros (783 de Medline y 1293 de Embase). De los 12 estudios seleccionados, se incluyeron un total de 1353 pacientes, con una prevalencia en los estudios revisados entre el 9% y 88%, con un promedio del 47%. La Sensibilidad agrupada fue 0,83% (IC95% (0,74-0,89)) y la Especificidad fue 0,84% (IC95%(0,76-0,89)). El área bajo la Curva fue 0,90 (IC95%(0,87-0,92)). La heterogeneidad entre los estudios es importante I2 88% (IC95%(77-100)). Existe un sesgo de publicación según el test de Deek, con resultado P=0,04. En el análisis sobre la Probabilidad Post test según el nomograma de Fagan, es del 56%, teniendo en cuenta una probabilidad pretest del 20% según el LR positivo 5.Conclusión: La PCT es una prueba diagnóstica con buen rendimiento para sepsis o shock séptico, en pacientes adultos, no gestantes. Aunque hay sesgo de publicación y una gran heterogeneidad en los resultados, la prueba se considera adecuada para el escenario de sepsis según las nuevas definiciones.

Lipids as Biomarkers of Cancer and Bacterial Infections

Lipids are ubiquitous molecules, known to play important roles in various cellular processes. Alterations to the lipidome can therefore be used as a read-out of the signs of disease, highlighting the importance to consider lipids as biomarkers in addition of nucleic acid and proteins. Lipids are among the primary structural and functional constituents of biological tissues, especially cell membranes. Along with membrane formation, lipids play also a crucial role in cell signalling, inflammation and energy storage. It was shown recently that lipid metabolism disorders play an important role in carcinogenesis and development. As well, the role of lipids in disease is particularly relevant for bacterial infections, during which several lipid bacterial virulence factors are recognized by the human innate immune response, such as lipopolysaccharide in Gram-negative bacteria, lipoteichoic acid in Gram-positive bacteria, and lipoglycans in mycobacteria. Compared to nucleic acids and proteins, a complete analysis of the lipidome, which is the comprehensive characterization of different lipid families, is usually very challenging due to the heterogeneity of lipid classes and their intrinsic physicoproperties caused by variations in the constituents of each class. Understanding the chemical diversity of lipids is therefore crucial to understanding their biological relevance and, as a consequence, their use as potential biomarkers for non-infectious and infectious diseases. This mini-review exposes the current knowledge and limitations of the use of lipids as biomarkers of the top global killers which are cancer and bacterial infections.

[Inflammatory markers in diagnosis and prognosis of abdominal sepsis]

For today, it is necessary to recognize, that treatment of patients with abdominal sepsis remains the basic problem in urgent surgery due to the invariably high mortality. Early diagnostics and targeted therapy are the key points for improving of sepsis outcome. At present, researchers around the world have proposed a large number of biological markers for diagnosing sepsis and predicting mortality. Ideally, doctors can use biomarkers for risk stratification, diagnosing, monitoring of treatment effectiveness and outcome prediction. The biomarker is a laboratory parameter that can be objectively measured and characterized as an indicator of normal and pathological biological processes. The article presents the modern concept of the sepsis pathogenesis for understanding the role of various biomarkers and inflammatory indicators in its development. We have analyzed literature data and summarized information on the possible use of biological markers and their combinations in the early detection of sepsis, for monitoring sepsis and predicting its outcome.

Companion and Point-of-Care Sensor System for Rapid Multiplexed Detection of a Panel of Infectious Disease Markers

A nanochannel-based electrochemical biosensor has been demonstrated for rapid and multiplexed detection of a panel of three biomarkers associated with rapid detection of sepsis. The label-free biosensor detected procalcitonin (PCT), lipoteichoic acid (LTA), and lipopolysaccharide (LPS) from human whole blood. The biosensor comprises a nanoporous nylon membrane integrated onto a microelectrode sensor platform for nanoconfinement effects. Charge perturbations due to biomarker binding are recorded as impedance changes using electrochemical impedance spectroscopy. The measured impedance change is used to quantitatively determine the concentration of the three biomarkers using antibody receptors from the tested sample. We were successful in detecting and quantifying the three biomarkers from whole blood. The limit of detection was 0.1 ng/mL for PCT and 1 µg/mL for LPS and LTA. The sensor was able to demonstrate a dynamic range of detection from 01.1 ng/mL to 10 µg/mL for PCT and from 1 µg/mL to 1000 µg/mL for LPS and LTA biomarkers. This novel technology has promising preliminary results toward the design of sensors for rapid and sensitive detection of the three panel biomarkers in whole blood toward diagnosis and classification of sepsis.

Biomarkers in Sepsis

A biomarker is a characteristic by which a (patho)physiologic process can be identified. Biomarkers can be of diagnostic value (to discriminate infection from noninfectious conditions or to determine the causative pathogen), of prognostic value (assigning risk profiles and predict outcome), and in the future may be of theranostic value (aid in selection and monitoring of therapy). Systems biology provides a promising tool for the discovery of novel biomarkers. Biomarkers can be the key to personalized targeted treatment in the future clinical management of sepsis.

Procalcitonin: a promising diagnostic marker for sepsis and antibiotic therapy

BACKGROUND

Sepsis is a global healthcare problem, characterized by whole body inflammation in response to microbial infection, which leads to organ dysfunction. It is becoming a frequent complication in hospitalized patients. Early and differential diagnosis of sepsis is needed critically to avoid unnecessary usage of antimicrobial agents and for proper antibiotic treatments through the screening of biomarkers that sustains with diagnostic significance.

MAIN BODY OF ABSTRACT

Current targeting conventional markers (C-reactive protein, white blood cell, tumour necrosis factor-α, interleukins, etc.) are non-specific for diagnosing sepsis. Procalcitonin (PCT), a member of the calcitonin super family could be a critical tool for the diagnosis of sepsis. But to distinguish between bacterial versus viral infections, procalcitonin alone may not be effective. Rapid elevation in the concentration of procalcitonin and other newly emerging biomarkers during an infection and its correlation with severity of illness makes it an ideal biomarker for bacterial infection. Beside this, the procalcitonin levels can be used for monitoring response to antimicrobial therapy, diagnosis of secondary inflammations, diagnosis of renal involvement in paediatric urinary tract infection, etc. The present article summarizes the relevance of procalcitonin in the diagnosis of sepsis and how it can be useful in determining the therapeutic approaches.

CONCLUSION

Further studies are needed to better understand the application of PCT in the diagnosis of sepsis, differentiating between microbial and non-microbial infection cases and determining the therapeutic approaches for sepsis.

Porcine CD14 gene silencing partially inhibited the bacterial immune response mediated by TLR4 signaling pathway

Cluster of differentiation antigen 14 (CD14) is the membrane receptor protein in Toll-like Receptor 4 (TLR4) signaling pathway, which plays an important regulation role in not only innate immune response but also adaptive immune response. In this study, the pig kidney epithelial cell (PK15) line with CD14 gene silencing mediated by lentivirus was established and cells of CD14-RNAi and NC group were exposed to three kinds of Escherichia coli (E. coli F18ab, E. coli F18ac and E. coli K88ac) and LPS. Then qPCR and western blot were used to detect expression levels of TLR4 signaling pathway-related genes. Finally, ELISA was used to detect the level of proinflammatory cytokines in the cell culture supernatant. The results showed that the expression level of TLR4 signaling pathway-related genes in the entire signal pathway had obvious increases when cells were exposed to the stimulation induced by E. coli and LPS. In addition, the expression levels of CD14-RNAi group were overall significantly lower than NC group (P<0.05 or P<0.01), which was the same with the release levels of proinflammatory cytokines. This study revealed that pig CD14 gene silencing partially inhibited immune response to E. coli F18 invasion mediated by TLR4 signaling pathway.

Diagnostic accuracy of procalcitonin, neutrophil-lymphocyte count ratio, C-reactive protein, and lactate in patients with suspected bacterial sepsis

Background

Early recognition is a key factor to achieve improved outcomes for septic patients. Combinations of biomarkers, as opposed to single ones, may improve timely diagnosis and survival. We investigated the performance characteristics of sepsis biomarkers, alone and in combination, for diagnosis of verified bacterial sepsis using Sepsis-2 and Sepsis-3 criteria, respectively.

Methods

Procalcitonin (PCT), neutrophil-lymphocyte count ratio (NLCR), C-reactive protein (CRP), and lactate were determined in a total of 1,572 episodes of adult patients admitted to the emergency department on suspicion of sepsis. All sampling were performed prior to antibiotic administration. Discriminant analysis was used to construct two composite biomarkers consisting of linear combinations of the investigated biomarkers, one including three selected biomarkers (i.e., NLCR, CRP, and lactate), and another including all four (i.e., PCT, NLCR, CRP, and lactate). The diagnostic performances of the composite biomarkers as well as the individual biomarkers were compared using the area under the receiver operating characteristic curve (AUC).

Results

For diagnosis of bacterial sepsis based on Sepsis-3 criteria, the AUC for PCT (0.68; 95% CI 0.65–0.71) was comparable to the AUCs for the both composite biomarkers. Using the Sepsis-2 criteria for bacterial sepsis diagnosis, the AUC for the NLCR (0.68; 95% CI 0.65–0.71) but not for the other single biomarkers, was equal to the AUCs for the both composite biomarkers. For diagnosis of severe bacterial sepsis or septic shock based on the Sepsis-2 criteria, the AUCs for both composite biomarkers were significantly greater than those of the single biomarkers (0.85; 95% CI 0.82–0.88 for the composite three-biomarker, and 0.86; 95% CI 0.83–0.89 for the composite four-biomarker).

Conclusions

Combinations of biomarkers can improve the diagnosis of verified bacterial sepsis in the most critically ill patients, but in less severe septic conditions either the NLCR or PCT alone exhibit equivalent performance.

Diagnostic accuracy of lipopolysaccharide-binding protein for sepsis in patients with suspected infection in the emergency department

Background Biomarkers can facilitate the diagnosis of sepsis, enabling early management and improving outcomes. Lipopolysaccharide-binding protein (LBP) has been reported as a biomarker for the detection of infection, but its diagnostic value is controversial. In this study, we assessed the diagnostic accuracy of LBP for sepsis in the emergency department (ED) patients, comparing it with more established biomarkers of sepsis, including procalcitonin (PCT) and C-reactive protein (CRP). Methods LBP and other sepsis biomarkers, including PCT and CRP, were measured on admission in 102 adult patients presenting with suspected infection . Classification of patients was performed using the recently updated definition for sepsis (Sepsis-3). The diagnostic accuracy of LBP, CRP and PCT for sepsis was evaluated by using receiver operating characteristic curve (ROC) analysis. Results A total of 49 patients were classified as having sepsis. In these patients, median (interquartile range) LBP (41.8 [41.1] µg/dL vs. 26.2 [25] µg/dL), CRP (240 [205] mg/L vs. 160 [148] mg/dL) and PCT (5.19 [13.68] µg/L vs. 0.39 [1.09] µg/L) were significantly higher than in patients classified as not having sepsis ( P < 0.001 for all three biomarkers). ROC curve analysis and area under curve (AUC) revealed a value of 0.701 for LBP, similar to CRP (0.707) and lower than that for PCT (0.844) ( P = 0.012). Conclusion In adult ED patients with suspected infection, the diagnostic accuracy for sepsis of LBP is similar to that of CRP but lower than that of PCT.

Companion and Point-of-Care Sensor System for Rapid Multiplexed Detection of a Panel of Infectious Disease Markers

A nanochannel-based electrochemical biosensor has been demonstrated for rapid and multiplexed detection of a panel of three biomarkers associated with rapid detection of sepsis. The label-free biosensor detected procalcitonin (PCT), lipoteichoic acid (LTA), and lipopolysaccharide (LPS) from human whole blood. The biosensor comprises a nanoporous nylon membrane integrated onto a microelectrode sensor platform for nanoconfinement effects. Charge perturbations due to biomarker binding are recorded as impedance changes using electrochemical impedance spectroscopy. The measured impedance change is used to quantitatively determine the concentration of the three biomarkers using antibody receptors from the tested sample. We were successful in detecting and quantifying the three biomarkers from whole blood. The limit of detection was 0.1 ng/mL for PCT and 1 µg/mL for LPS and LTA. The sensor was able to demonstrate a dynamic range of detection from 01.1 ng/mL to 10 µg/mL for PCT and from 1 µg/mL to 1000 µg/mL for LPS and LTA biomarkers. This novel technology has promising preliminary results toward the design of sensors for rapid and sensitive detection of the three panel biomarkers in whole blood toward diagnosis and classification of sepsis.

Antimicrobial Stewardship in the Management of Sepsis

Sepsis represents a unique clinical dilemma with regard to antimicrobial stewardship. The standard approach to suspected sepsis in the emergency department centers on fluid resuscitation and timely broad-spectrum antimicrobials. The lack of gold standard diagnostics and evolving definitions for sepsis introduce a significant degree of diagnostic uncertainty that may raise the potential for inappropriate antimicrobial prescribing. Intervention bundles that combine traditional quality improvement strategies with emerging electronic health record-based clinical decision support tools and rapid molecular diagnostics represent the most promising approach to enhancing antimicrobial stewardship in the management of suspected sepsis in the emergency department.

Biomarkers for diagnosis of sepsis in patients with systemic inflammatory response syndrome: a systematic review and meta-analysis

Background

Sepsis is one of the most common diseases that seriously threaten human health. Although a large number of markers related to sepsis have been reported in the last two decades, the diagnostic accuracy of these biomarkers remains unclear due to the lack of similar baselines among studies. Therefore, we conducted a large systematic review and meta-analysis to evaluate the diagnostic value of biomarkers from studies that included non-infectious systemic inflammatory response syndrome patients as a control group.

Methods

We searched Medline, Embase and the reference lists of identified studies beginning in April 2014. The last retrieval was updated in September 2016.

Results

Ultimately, 86 articles fulfilled the inclusion criteria. Sixty biomarkers and 10,438 subjects entered the final analysis. The areas under the receiver operating characteristic curves for the 7 most common biomarkers, including procalcitonin, C-reactive protein, interleukin 6, soluble triggering receptor expressed on myeloid cells-1, presepsin, lipopolysaccharide binding protein and CD64, were 0.85, 0.77, 0.79, 0.85, 0.88, 0.71 and 0.96, respectively. The remaining 53 biomarkers exhibited obvious variances in diagnostic value and methodological quality.

Conclusions

Although some biomarkers displayed moderate or above moderate diagnostic value for sepsis, the limitations of the methodological quality and sample size may weaken these findings. Currently, we still lack an ideal biomarker to aid in the diagnosis of sepsis. In the future, biomarkers with better diagnostic value as well as a combined diagnosis using multiple biomarkers are expected to solve the challenge of the diagnosis of sepsis.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-016-3591-5) contains supplementary material, which is available to authorized users.

Clinical Significance of Molecular Diagnostic Tools for Bacterial Bloodstream Infections: A Systematic Review

Bacterial bloodstream infection (bBSI) represents any form of invasiveness of the blood circulatory system caused by bacteria and can lead to death among critically ill patients. Thus, there is a need for rapid and accurate diagnosis and treatment of patients with septicemia. So far, different molecular diagnostic tools have been developed. The majority of these tools focus on amplification based techniques such as polymerase chain reaction (PCR) which allows the detection of nucleic acids (both DNA and small RNAs) that are specific to bacterial species and sequencing or nucleic acid hybridization that allows the detection of bacteria in order to reduce delay of appropriate antibiotic therapy. However, there is still a need to improve sensitivity of most molecular techniques to enhance their accuracy and allow exact and on time antibiotic therapy treatment. In this regard, we conducted a systematic review of the existing studies conducted in molecular diagnosis of bBSIs, with the main aim of reporting on clinical significance and benefits of molecular diagnosis to patients. We searched both Google Scholar and PubMed. In total, eighteen reviewed papers indicate that shift from conventional diagnostic methods to molecular tools is needed and would lead to accurate diagnosis and treatment of bBSI.

Role of interleukin-6 to differentiate sepsis from non-infectious systemic inflammatory response syndrome

Differentiating between sepsis and non-infectious systemic inflammatory response syndrome (SIRS) poses a great challenge. Several potential bloodstream biomarkers including Interleukin 6 (IL-6) have been investigated for their ability to diagnose sepsis. We conducted the present meta-analysis to evaluate the diagnostic quality of IL-6 in differentiating sepsis from non-infectious SIRS in adults. We also compared its accuracy with procalcitonin (PCT) and C-reactive protein (CRP). PubMed and EMBASE were systematically searched for studies published up to January 18, 2016. Twenty articles containing 22 studies and 2680 critically ill patients were included, of which, 21 studies also involved PCT and 14 involved CRP. Quantitative synthesis of studies showed that the pooled sensitivity/specificity of IL-6 and PCT were 0.68/0.73 and 0.78/0.67. The area under the curve (AUC) of IL-6, PCT and CPR for diagnosis of sepsis was 0.80, 0.83, and 0.71, respectively. This meta-analysis provides evidence that the IL-6 test has moderate diagnostic performance in differentiating sepsis from non-infectious SIRS in adults. IL-6 and PCT test has similar diagnostic value but higher than CRP. Considering its relatively high specificity, we recommend the use of IL-6 as a diagnostic aid to confirm infection rather than exclude infection in patients with SIRS.

Diagnostic Accuracy of Lipopolysaccharide-Binding Protein as Biomarker for Sepsis in Adult Patients: A Systematic Review and Meta-Analysis

INTRODUCTION

Lipopolysaccharide-binding protein (LBP) is widely reported as a biomarker to differentiate infected from non-infected patients. The diagnostic use of LBP for sepsis remains a matter of debate. We aimed to perform a systematic review and meta-analysis to assess the diagnostic accuracy of serum LBP for sepsis in adult patients.

METHODS

We performed a systematic review and meta-analysis to assess the accuracy of LBP for sepsis diagnosis. A systematic search in PubMed and EMBASE for studies that evaluated the diagnostic role of LBP for sepsis through December 2015 was conducted. We searched these databases for original, English language, research articles that studied the diagnostic accuracy between septic and non-septic adult patients. Sensitivity, specificity, and other measures of accuracy, such as diagnostic odds ratio (DOR) and area under the receiver operating characteristic curve (AUC) of LBP were pooled using the Hierarchical Summary Receiver Operating Characteristic (HSROC) method.

RESULTS

Our search returned 53 reports, of which 8 fulfilled the inclusion criteria, accounting for 1684 patients. The pooled sensitivity and specificity of LBP for diagnosis of sepsis by the HSROC method were 0.64 (95% CI: 0.56-0.72) and 0.63 (95% CI: 0.53-0.73), respectively. The value of the DOR was 3.0 (95% CI: 2.0-4.0) and the AUC was 0.68 (95% CI: 0.64-0.72). Meta-regression analysis revealed that cut-off values accounted for the heterogeneity of sensitivity and sample size (> = 150) accounted for the heterogeneity of specificity.

CONCLUSIONS

Based on the results of our meta-analysis, LBP had weak sensitivity and specificity in the detection of sepsis. LBP may not be practically recommended for clinical utilization as a single biomarker.

Prognostic Value and Daily Trend of Interleukin-6, Neutrophil CD64 Expression, C-Reactive Protein and Lipopolysaccharide-Binding Protein in Critically Ill Patients: Reliable Predictors of Outcome or Not?

Background

Severe sepsis and/or trauma complicated by multiple organ dysfunction syndrome are the leading causes of death in critically ill patients. The aim of this prospective single-centre study was to assess the prognostic value and daily trend of interleukin-6 (IL-6), neutrophil CD64 expression, C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP) regarding outcome in critically ill patients with severe trauma and/or severe sepsis. Outcome measure was hospital mortality.

Methods

One hundred and two critically ill patients admitted to the intensive care unit of a tertiary university hospital were enrolled in this prospective study. Blood samples were collected on admission (day 1), days 2 and 3.

Results

CD64 index was 1.6-fold higher on day 1 and 1.78-fold higher on day 2 in non-survivors (p<0.05). The area under the curve (AUC) for the CD64 index on day 1 for outcome was 0.727. At a cut-off level of 2.80 sensitivity was 75% and specificity was 65%. Patients with CD64 index level on day 1 higher than 2.80 had 2.4-fold higher probability of dying. Odds ratio is 2.40; 95% CI 0.60–9.67.

Conclusions

CD64 index on day 1 is a fairly good predictor of outcome. AUCs for IL-6, CRP and LBP were < 0.55, suggesting these biomarkers failed to predict outcome.

Sepsis biomarkers in neutropaenic systemic inflammatory response syndrome patients on standard care wards

BACKGROUND

Neutropaenic patients are at a high risk of contracting severe infections. In particular, in these patients, parameters with a high negative predictive value are desirable for excluding infection or bacteraemia. This study evaluated sepsis biomarkers in neutropaenic patients suffering from systemic inflammatory response syndrome (SIRS). Further, the predictive capacities of evaluated biomarkers in neutropaenic SIRS patients were compared to non-neutropaenic SIRS patients.

MATERIAL AND METHODS

In this prospective observational cohort study, patients with clinically suspected sepsis were screened. The predictive capacities of procalcitonin (PCT), C-reactive protein and lipopolysaccharide-binding protein (LBP) in neutropaenic SIRS patients were evaluated in terms of their potential to identify infection or bacteraemia and were compared to results for non-neutropaenic SIRS patients. To select an appropriate control cohort, propensity score matching was applied, balancing confounding factors between neutropaenic and non-neutropaenic SIRS patients.

RESULTS

Of 3370 prospectively screened patients with suspected infection, 51 patients suffered from neutropaenic SIRS. For the identification of infection, none of the assessed biomarkers presented a clinically relevant discriminatory potency. Lipopolysaccharide-binding protein and PCT demonstrated discriminatory capacity to discriminate between nonbacteraemic and bacteraemic SIRS in patients with neutropaenia [receiver-operating characteristics-area under the curves (ROC-AUCs): 0.860, 0.818]. In neutropaenic SIRS patients, LBP had a significantly better ROC-AUC than in a comparable non-neutropaenic patient cohort for identifying bacteraemia (P = 0.01).

CONCLUSION

In neutropaenic SIRS patients, none of the evaluated biomarkers was able to adequately identify infection. LBP and PCT presented a good performance in identifying bacteraemia. Therefore, these markers could be used for screening purposes to increase the pretest probability of blood culture analysis.

Clinical diagnosis of sepsis and the combined use of biomarkers and culture- and non-culture-based assays

Sepsis is among the most common causes of death in hospitalized patients, and early recognition followed by immediate initiation of therapy is an important concept to improve survival in these patients. According to the definition of sepsis, diagnosis of sepsis requires the recognition of the systemic inflammatory response syndrome (SIRS) caused by infection as well as recognition of possible infection-related organ dysfunctions for diagnosis of severe sepsis or septic shock. Both SIRS and organ dysfunctions may occur frequently in hospitalized patients for various reasons. However, the fast recognition of acute infection as a cause of SIRS and newly developed organ dysfunction may be a demanding task since culture-based results of microbiological samples will be available only days after onset of symptoms. Biomarkers and PCR-based pathogen detection may help the physician in differentiating SIRS from sepsis. Procalcitonin (PCT) is the best investigated biomarker for this purpose. Furthermore, the current data support the usage of PCT for guidance of antimicrobial therapy. C-reactive protein (CRP) may be used to monitor the course of infection but has only limited discriminative capabilities. Interleukin-6 is widely used for its fast response to the infectious stimulus, but conclusive data for the application of this biomarker are missing. None of the available biomarkers can by itself reliably differentiate SIRS from sepsis but can aid and shorten the decision process. PCR-based pathogen detection can theoretically shorten the recognition of the underlying pathogen to about 8 h. However, this technique is expensive and requires additional staff in the laboratory; controlled prospective studies are missing. Although current studies suggest that PCR-based pathogen detection may be useful to shorten time to adequate antimicrobial therapy and diagnose invasive Candida infections, no general recommendations about the application of PCR for the diagnosis of sepsis can be given.

Host response biomarkers in the diagnosis of sepsis: a general overview

Critically ill patients who display a systemic inflammatory response syndrome (SIRS) are prone to develop nosocomial infections. The challenge remains to distinguish as early as possible among SIRS patients those who are developing sepsis. Following a sterile insult, damage-associated molecular patterns (DAMPs) released by damaged tissues and necrotic cells initiate an inflammatory response close to that observed during sepsis. During sepsis, pathogen-associated molecular patterns (PAMPs) trigger the release of host mediators involved in innate immunity and inflammation through identical receptors as DAMPs. In both clinical settings, a compensatory anti-inflammatory response syndrome (CARS) is concomitantly initiated. The exacerbated production of pro- or anti-inflammatory mediators allows their detection in biological fluids and particularly within the bloodstream. Some of these mediators can be used as biomarkers to decipher among the patients those who developed sepsis, and eventually they can be used as prognosis markers. In addition to plasma biomarkers, the analysis of some surface markers on circulating leukocytes or the study of mRNA and miRNA can be helpful. While there is no magic marker, a combination of few biomarkers might offer a high accuracy for diagnosis.

[Use of biomarkers in sepsis. Update and perspectives]

Sepsis and related complications are a challenge for intensive care medicine. Despite many advances in antibiotic therapy sepsis remains one of the most common diseases of patients in intensive care units and is designated as the main cause of death in critically ill patients. Persisting sepsis leads to impaired immunity, resulting in immunosuppression. Unspecific predictive signs complicate an early diagnosis; however, an early initiation of adequate therapy is of crucial importance for the prognosis. Scoring systems can be applied for the initial evaluation but are controversially discussed concerning the monitoring of disease progression and therapy as well as outcome prediction. Biomarkers are considered as a complementary approach.

Sepsis biomarkers

Sepsis is the most frequent cause of death in non-coronary intensive care units (ICUs). In the past 10 years, progress has been made in the early identification of septic patients and in their treatment and these improvements in support and therapy mean that the mortality is gradually decreasing but it still remains unacceptably high. Leaving clinical diagnosis aside, the laboratory diagnostics represent a complex range of investigations that can place significant demands on the system given the speed of response required. There are hundreds of biomarkers which could be potentially used for diagnosis and prognosis in septic patients. The main attributes of successful markers would be high sensitivity, specificity, possibility of bed-side monitoring, and financial accessibility. Only a fraction is used in routine clinical practice because many lack sufficient sensitivity or specificity. The following review gives a short overview of the current epidemiology of sepsis, its pathogenesis and state-of-the-art knowledge on the use of specific biochemical, hematological and immunological parameters in its diagnostics. Prospective approaches towards discovery of new diagnostic biomarkers have been shortly mentioned.

Markers for sepsis diagnosis in the forensic setting: state of the art

Reliable diagnoses of sepsis remain challenging in forensic pathology routine despite improved methods of sample collection and extensive biochemical and immunohistochemical investigations. Macroscopic findings may be elusive and have an infectious or non-infectious origin. Blood culture results can be difficult to interpret due to postmortem contamination or bacterial translocation. Lastly, peripheral and cardiac blood may be unavailable during autopsy. Procalcitonin, C-reactive protein, and interleukin-6 can be measured in biological fluids collected during autopsy and may be used as in clinical practice for diagnostic purposes. However, concentrations of these parameters may be increased due to etiologies other than bacterial infections, indicating that a combination of biomarkers could more effectively discriminate non-infectious from infectious inflammations. In this article, we propose a review of the literature pertaining to the diagnostic performance of classical and novel biomarkers of inflammation and bacterial infection in the forensic setting.

Diagnostic and prognostic utility of soluble CD 14 subtype (presepsin) for severe sepsis and septic shock during the first week of intensive care treatment

Introduction

The aim of this study was to evaluate the diagnostic and prognostic value of presepsin in patients with severe sepsis and septic shock during the first week of ICU treatment.

Methods

In total, 116 patients with suspected severe sepsis or septic shock were included during the first 24 hours of ICU treatment. Blood samples for biomarker measurements of presepsin, procalcitonin (PCT), interleukin 6 (IL-6), C reactive protein (CRP) and white blood cells (WBC) were drawn at days 1, 3 and 8. All patients were followed up for six months. Biomarkers were tested for diagnosis of sepsis, severe sepsis, septic shock and for prognosis of 30-days and 6-months all-cause mortality at days 1, 3 and 8. Diagnostic and prognostic utilities were tested by determining diagnostic cutoff levels, goodness criteria, C-statistics and multivariable Cox regression models.

Results

Presepsin increased significantly from the lowest to most severe sepsis groups at days 1, 3 and 8 (test for linear trend P <0.03). Presepsin levels revealed valuable diagnostic capacity to diagnose severe sepsis and septic shock at days 1, 3 and 8 (range of diagnostic area under the curves (AUC) 0.72 to 0.84, P = 0.0001) compared to IL-6, PCT, CRP and WBC. Goodness criteria for diagnosis of sepsis severity were analyzed (≥sepsis, cutoff = 530 pg/ml; ≥severe sepsis, cutoff = 600 pg/ml; ≥septic shock, cutoff = 700 pg/ml; P <0.03). Presepsin levels revealed significant prognostic value for 30 days and 6 months all-cause mortality (presepsin: range of AUC 0.64 to 0.71, P <0.02). Patients with presepsin levels of the 4^th quartile were 5 to 7 times more likely to die after six months than patients with lower levels. The prognostic value for all-cause mortality of presepsin was comparable to that of IL-6 and better than that of PCT, CRP or WBC.

Conclusions

In patients with suspected severe sepsis and septic shock, precipices reveals valuable diagnostic capacity to differentiate sepsis severity compared to PCT, IL-6, CRP, WBC. Additionally, presepsin and IL-6 reveal prognostic value with respect to 30 days and 6 months all-cause mortality throughout the first week of ICU treatment.

Trial registration

ClinicalTrials.gov NCT01535534. Registered 14 February 2012.

[Prognostic value of lipopolysaccharide binding protein and procalcitonin in patients with severe sepsis and septic shock admitted to intensive care]

AIMS

1) To assess the prognostic value of levels on admission and serial measurements of lipopolysaccharide binding protein (LBP) and procalcitonin (PCT) in relation to in-hospital mortality; and 2) to determine whether the addition of these parameters to severity scores (APACHE II and SOFA) is able to improve prognostic accuracy.

DESIGN

A single-center, prospective observational study was carried out.

SETTING

Intensive Care unit of a university hospital.

PATIENTS

One hundred severe sepsis and septic shock patients were included.

DATA COLLECTED

Demographic data, APACHE II and SOFA scores, PCT and LBP levels on admission and after 48 hours, and in-hospital mortality.

RESULTS

The best area under the curve for predicting in-hospital mortality corresponded to APACHE II on admission and SOFA after 48 h (AUC ROC: 0.75 for both). PCT and LBP levels on admission and LBP clearance were not statistically different between in-hospital survivors and non-survivors. Only PCT clearance was higher among in-hospital survivors than in non-survivors (AUC ROC: 0.66). The combination of severity scores and PCT clearance did not result in superior areas under the curve.

CONCLUSIONS

LBP and PCT levels on admission and LBP clearance showed no prognostic value in severe sepsis and septic shock patients. Only PCT clearance was predictive of in-hospital mortality. The prognostic accuracy was significantly better for APACHE on admission and SOFA after 48 h than for any of the analyzed biomarkers, and the addition of PCT clearance did not improve their prognostic value.

Laboratory detection of sepsis: biomarkers and molecular approaches

Sepsis, severe sepsis, and septic shock cause significant morbidity and mortality worldwide. Rapid diagnosis and therapeutic interventions are desirable to improve the overall mortality in patients with sepsis. However, gold standard laboratory diagnostic methods for sepsis, pose a significant challenge to rapid diagnosis of sepsis by physicians and laboratories. This article discusses the usefulness and potential of biomarkers and molecular test methods for a more rapid clinical and laboratory diagnosis of sepsis. Because new technologies are quickly emerging, physicians and laboratories must appreciate the key factors and characteristics that affect the clinical usefulness and diagnostic accuracy of these test methodologies.

Biomarkers of sepsis

Sepsis remains a leading cause of death in critically ill patients, despite efforts to improve patient outcome. Thus far, no magic drugs exist for severe sepsis and septic shock. Instead, early diagnosis and prompt initial management such as early goal-directed therapy are key to improve sepsis outcome. For early detection of sepsis, biological markers (biomarkers) can help clinicians to distinguish infection from host response to inflammation. Ideally, biomarkers can be used for risk stratification, diagnosis, monitoring of treatment responses, and outcome prediction. More than 170 biomarkers have been identified as useful for evaluating sepsis, including C-reactive protein, procalcitonin, various cytokines, and cell surface markers. Recently, studies have reported on the usefulness of biomarker-guided antibiotic stewardships. However, the other side of these numerous biomarkers is that no novel single laboratory marker can diagnose, predict, and track the treatment of sepsis. The purpose of this review is to summarize several key biomarkers from recent sepsis studies.

Biomarkers for sepsis: a review with special attention to India

Sepsis is a serious infection and still a common cause of morbidity and mortality in resource-limited settings such as India. Even when microbiologic diagnostics are available, bacteremia is only identified in a proportion of patients who present with sepsis and bloodstream infections. Biomarkers have been used in a variety of disease processes and can help aid in diagnosing bacterial infections. There have been numerous biomarkers investigated to aid with diagnosis and prognostication in sepsis with the majority suffering from lack of sensitivity or specificity. Procalcitonin has been heralded as the biomarker that holds the most promise for bloodstream infections. Data are emerging in India, and in this review, we focus on the current data of biomarkers in sepsis with particular attention to how biomarkers could be used to augment diagnosis and treatment in India.

Rapid diagnosis of sepsis

Fast and appropriate therapy is the cornerstone in the therapy of sepsis. However, the discrimination of sepsis from non-infectious causes of inflammation may be difficult. Biomarkers have been suggested to aid physicians in this decision. There is currently no biochemical technique available which alone allows a rapid and reliable discrimination between sepsis and non-infectious inflammation. Procalcitonin (PCT) is currently the most investigated biomarker for this purpose. C-reactive protein and interleukin 6 perform inferior to PCT in most studies and their value in diagnosing sepsis is not defined. All biomarkers including PCT are also released after various non-infectious inflammatory impacts. This shortcoming needs to be taken into account when biomarkers are used to aid the physician in the diagnosis of sepsis. Polymerase chain reaction (PCR) based pathogen detection may improve time to adequate therapy but cannot rule out the presence of infection when negative.

Role of biomarkers in sepsis care

Sepsis is one of the leading causes of mortality and morbidity, even with the current availability of extended-spectrum antibiotics and advanced medical care. Biomarkers offer a tool in facilitating early diagnosis, in identifying patient populations at high risk of complications, and in monitoring progression of the disease, which are critical assessments for appropriate therapy and improvement in patient outcomes. Several biomarkers are already available for clinical use in sepsis; however, their effectiveness in many instances is limited by the lack of specificity and sensitivity to characterize the presence of an infection and the complexity of the inflammatory and immune processes and to stratify patients into homogenous groups for specific treatments. Current advances in molecular techniques have provided new tools facilitating the discovery of novel biomarkers, which can vary from metabolites and chemical products present in body fluids to genes and proteins in circulating blood cells. The purpose of this review was to examine the current status of sepsis biomarkers, with special emphasis on emerging markers, which are undergoing validation and may transition into clinical practice for their informative value in diagnosis, prognosis, or response to therapy. We will also discuss the new concept of combination biomarkers and biomarker risk models, their existing challenges, and their potential use in the daily management of patients with sepsis.

Infection surveillance in transsphenoidal pituitary surgery - comparison of lipopolysaccharide-binding-protein, interleukin 6, C-reactive protein, white blood cell count, erythrocyte sedimentation rate and body temperature

BACKGROUND

One of the major concerns in transsphenoidal surgery are infections because the approach to the pituitary includes a route of microbial colonization. To minimize the associated morbidity and mortality, a surveillance program is crucial to monitor for perioperative infections.

METHODS

For 1 year, we analysed body temperature (BT), erythrocyte sedimentation rate (ESR), white blood cell count (WBC), C-reactive protein (CRP), interleukin 6 (IL-6) and lipopolysaccharide-binding-protein (LBP) following elective transsphenoidal pituitary surgery. Samples were collected on admission, day 1, 3 and 7 as well as 3 months postoperatively.

RESULTS

In 116 patients, all data were available. No postoperative infections occurred within the first postoperative week. BT (37.6 ± 0.6, baseline 37.0 ± 0.5 °C), WBC (11,366 ± 2,541, baseline 6,861 ± 2,123/μl), CRP (25.3 ± 22.6, baseline 3.1 ± 6 mg/l), IL-6 (12 ± 13, baseline 2.7 ± 2.6 pg/ml), and LBP (11.3 ± 4.9, baseline 5.7 ± 2.7 μg/ml) peaked on day 1 postoperatively (each p = 0.001), while ESR peaked on day 3 (25 ± 16, baseline 13 ± 11 mm/h, p = 0.001). BT and IL-6 normalized by day 3 and CRP by day 7, while ESR (23 ± 16 mm/h, p = 0.001), WBC (7,807 ± 2,750/μl, p = 0.001) and LBP (7.3 ± 2.6 μg/ml, p = 0.028) were still increased by day 7.

CONCLUSION

The present study establishes normative values for an infection surveillance following transsphenoidal pituitary surgery. CRP, a convenient and reasonable priced parameter, is affected by the procedure for the first postoperative week. IL-6 is more robust and allows a close monitoring on the expense of additional pricing. ESR, WBC and LBP are sustained affected by surgery, and do not offer any advantage. Since no infections were observed, we were unable to calculate the respective sensitivity and specificity.

Biomarkers of sepsis

Sepsis is an unusual systemic reaction to what is sometimes an otherwise ordinary infection, and it probably represents a pattern of response by the immune system to injury. A hyper-inflammatory response is followed by an immunosuppressive phase during which multiple organ dysfunction is present and the patient is susceptible to nosocomial infection. Biomarkers to diagnose sepsis may allow early intervention which, although primarily supportive, can reduce the risk of death. Although lactate is currently the most commonly used biomarker to identify sepsis, other biomarkers may help to enhance lactate’s effectiveness; these include markers of the hyper-inflammatory phase of sepsis, such as pro-inflammatory cytokines and chemokines; proteins such as C-reactive protein and procalcitonin which are synthesized in response to infection and inflammation; and markers of neutrophil and monocyte activation. Recently, markers of the immunosuppressive phase of sepsis, such as anti-inflammatory cytokines, and alterations of the cell surface markers of monocytes and lymphocytes have been examined. Combinations of pro- and anti-inflammatory biomarkers in a multi-marker panel may help identify patients who are developing severe sepsis before organ dysfunction has advanced too far. Combined with innovative approaches to treatment that target the immunosuppressive phase, these biomarkers may help to reduce the mortality rate associated with severe sepsis which, despite advances in supportive measures, remains high.

CRISPLD2 is expressed at low levels during septic shock and is associated with procalcitonin

Introduction

Previous studies have shown that cysteine-rich secretory protein containing LCCL domain 2 (CRISPLD2) is a novel lipopolysaccharide (LPS)-binding protein, and the upregulation of CRISPLD2 expression protects mice against LPS-induced lethality. The aim of this study was to examine the expression of CRISPLD2 in patients with sepsis and characterize the association of this protein with procalcitonin.

Methods

The expression of CRISPLD2 was determined in100 healthy volunteers and 119 septic patients. According to the definition of sepsis, patients were divided into three groups sepsis, severe sepsis, and septic shock. The relationship between CRISPLD2 levels and procalcitonin was also examined and statistically analyzed.

Results

The CRISPLD2 levels in healthy individuals were 219.3±69.1 µg/ml. Patients with sepsis exhibited higher CRISPLD2 levels than observed in healthy individuals (p = 0.001), but CRISPLD2 expression was not upregulated in patients with septic shock. No significant differences were observed between the levels of CRISPLD2 in surviving and non-surviving spesis patients. CRISPLD2 levels were negatively correlated with procalcitonin levels(r = −0.334, p<0.001).

Conclusions

The present study is the first to demonstrate the decreased expression of CRISPLD2 in septic shock and its association with PCT in sepsis. Further studies are needed to clarify the potential association between CRISPLD2 expression and clinical outcomes to determine if it could be used as a novel sepsis biomarker.

Granulocyte colony stimulating factor induces lipopolysaccharide (LPS) sensitization via upregulation of LPS binding protein in rat

Liver is the main organ for lipopolysaccharide (LPS) clearance. Sensitization to LPS is associated with the upregulation of LPS-binding protein (LBP) in animal models. Therefore, we hypothesized that LBP could induce LPS sensitization through enhancing hepatic uptake of LPS. In this study, we examined the role of LBP in pathogenesis of LPS induced systemic inflammatory response syndrome (SIRS). LBP expression was upregulated after granulocyte colony stimulating (G-CSF) pretreatment. The effect of LBP was further confirmed by blockade of LBP using LBP blocking peptide--LBPK95A. After G-CSF pretreatment, upregulation of LBP was observed in bone marrow cells and liver. The G-CSF induced LBP upregulation caused LPS hypersensitization in rats as indicated by higher mortality and severer liver damage. Of note, LBP blockade increased the survival rate and attenuated the liver injury. The LBP induced LPS hypersensitization was associated with increased hepatic uptake of LPS and augmented hepatic expression of LPS receptors, such as toll-like receptor (TLR)-4. Furthermore, LBP mediated early neutrophil infiltration, which led to increased monocyte recruitment in liver after LPS administration. In conclusion, G-CSF induced LBP expression could serve as a new model for investigation of LPS sensitization. We demonstrated the crucial role of LBP upregulation in pathogenesis of LPS induced SIRS.

Procalcitonin as a diagnostic marker for sepsis: a systematic review and meta-analysis

BACKGROUND

Procalcitonin is a promising marker for identification of bacterial infections. We assessed the accuracy and clinical value of procalcitonin for diagnosis of sepsis in critically ill patients.

METHODS

We searched Medline, Embase, ISI Web of Knowledge, the Cochrane Library, Scopus, BioMed Central, and Science Direct, from inception to Feb 21, 2012, and reference lists of identified primary studies. We included articles written in English, German, or French that investigated procalcitonin for differentiation of septic patients--those with sepsis, severe sepsis, or septic shock--from those with a systemic inflammatory response syndrome of non-infectious origin. Studies of healthy people, patients without probable infection, and children younger than 28 days were excluded. Two independent investigators extracted patient and study characteristics; discrepancies were resolved by consensus. We calculated individual and pooled sensitivities and specificities. We used I(2) to test heterogeneity and investigated the source of heterogeneity by metaregression.

FINDINGS

Our search returned 3487 reports, of which 30 fulfilled the inclusion criteria, accounting for 3244 patients. Bivariate analysis yielded a mean sensitivity of 0 · 77 (95% CI 0 · 72-0 · 81) and specificity of 0 · 79 (95% CI 0 · 74-0 · 84). The area under the receiver operating characteristic curve was 0 · 85 (95% CI 0 · 81-0 · 88). The studies had substantial heterogeneity (I(2)=96%, 95% CI 94-99). None of the subgroups investigated--population, admission category, assay used, severity of disease, and description and masking of the reference standard--could account for the heterogeneity.

INTERPRETATION

Procalcitonin is a helpful biomarker for early diagnosis of sepsis in critically ill patients. Nevertheless, the results of the test must be interpreted carefully in the context of medical history, physical examination, and microbiological assessment.

FUNDING

Ministry of Education and Research, the Deutsche Forschungsgemeinschaft, Thuringian Ministry for Education, Science and Culture, the Thuringian Foundation for Technology, Innovation and Research, and the German Sepsis Society.

New approaches to sepsis: molecular diagnostics and biomarkers

Sepsis is among the most common causes of death in hospitals. It arises from the host response to infection. Currently, diagnosis relies on nonspecific physiological criteria and culture-based pathogen detection. This results in diagnostic uncertainty, therapeutic delays, the mis- and overuse of antibiotics, and the failure to identify patients who might benefit from immunomodulatory therapies. There is a need for new sepsis biomarkers that can aid in therapeutic decision making and add information about screening, diagnosis, risk stratification, and monitoring of the response to therapy. The host response involves hundreds of mediators and single molecules, many of which have been proposed as biomarkers. It is, however, unlikely that one single biomarker is able to satisfy all the needs and expectations for sepsis research and management. Among biomarkers that are measurable by assays approved for clinical use, procalcitonin (PCT) has shown some usefulness as an infection marker and for antibiotic stewardship. Other possible new approaches consist of molecular strategies to improve pathogen detection and molecular diagnostics and prognostics based on transcriptomic, proteomic, or metabolic profiling. Novel approaches to sepsis promise to transform sepsis from a physiologic syndrome into a group of distinct biochemical disorders and help in the development of better diagnostic tools and effective adjunctive sepsis therapies.