Serum Calprotectin Expression as a Diagnostic Marker for Sepsis in Postoperative Intensive Care Unit Patients

Navigating the Modern Landscape of Sepsis: Advances in Diagnosis and Treatment

Sepsis poses a significant threat to human health due to its high morbidity and mortality rates worldwide. Traditional diagnostic methods for identifying sepsis or its causative organisms are time-consuming and contribute to a high mortality rate. Biomarkers have been developed to overcome these limitations and are currently used for sepsis diagnosis, prognosis prediction, and treatment response assessment. Over the past few decades, more than 250 biomarkers have been identified, a few of which have been used in clinical decision-making. Consistent with the limitations of diagnosing sepsis, there is currently no specific treatment for sepsis. Currently, the general treatment for sepsis is conservative and includes timely antibiotic use and hemodynamic support. When planning sepsis-specific treatment, it is important to select the most suitable patient, considering the heterogeneous nature of sepsis. This comprehensive review summarizes current and evolving biomarkers and therapeutic approaches for sepsis.

Plasma calprotectin as an indicator of need of transfer to intensive care in patients with suspected sepsis at the emergency department

BACKGROUND

Deciding whether to transfer patients with sepsis from the emergency department (ED) to intensive care units (ICUs) is challenging. We hypothesised that the new biomarker plasma calprotectin (p-calprotectin) could be used to aid the selection of patients for intensive care transfer, since it has been shown to be a promising tool for the determination of sepsis severity in critical care.

METHODS

This prospective study was performed on consecutive sepsis alert patients in the ED of Karolinska University Hospital Huddinge. The sepsis alert mandates clinical assessment and decisions regarding treatment, disposition, and level of care by physicians from the ED, the Department of Infectious Diseases, and the ICU. Blood sample analysis for C-reactive protein, procalcitonin, neutrophils, and lymphocytes was routinely performed. P-calprotectin was analysed from frozen plasma samples, using a specific turbidimetric assay.

RESULTS

Three-hundred fifty-one patients who triggered the sepsis alert were available for the study. Among 319 patients who were considered to have an infection, 66 patients (26%) were immediately transferred to the ICU or high-dependency unit (HDU), and 253 patients (74%) were transferred to ordinary wards. Median p-calprotectin was 2.2 mg/L (IQR 1.2-3.9 mg/L) for all patients with infection, it was 3.3 (IQR 1.6-5.2) for those transferred to ICU/HDU and 2.1 (IQR 1.1-3.5) for those transferred to ward units (p = 0.0001). Receiver operating characteristic curve analysis for transfer to the ICU/HDU showed superiority for p-calprotectin compared with procalcitonin and neutrophil-lymphocyte ratio, regarding both all sepsis alert cases and the patients with infection (p < 0.001 for all comparisons). The best p-calprotectin cut-off, 4.0 mg/L, showed a sensitivity of 42.5% and specificity of 83% for transfer to the ICU/HDU among patients with infection.

CONCLUSIONS

In sepsis alert patients, p-calprotectin was significantly elevated in patients who were subject to immediate ICU/HDU transfer after assessment by a multidisciplinary team. P-calprotectin was superior to traditional biomarkers in predicting the need for transfer to the ICU/HDU.

Calprotectin as a diagnostic marker for sepsis: A meta-analysis

Introduction

Sepsis is a life-threatening condition, and biomarkers are needed to diagnose sepsis fast and accurately. We aimed to perform this meta-analysis to investigate the diagnostic value of calprotectin on sepsis in critically ill patients.

Methods

The investigators searched MEDLINE, Embase, Web of Science and Cochrane Library. Studies were included if they assessed the diagnostic accuracy of serum calprotectin for sepsis in intensive care unit (ICU). We estimated its diagnostic value and explored the source of heterogeneity. The bivariate model and the hierarchical summary receiver operating characteristic (HSROC) curve were used in the meta-analysis.

Results

Six records assessing 821 patients were included in this meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio (PLR), and diagnostic odds ratio (DOR) were separately as 0.77, 0.85, 5.20, 0.27, respectively. The Fagan's nomogram showed post-test probabilities of 91% and 35% for positive and negative outcomes, respectively. Subgroup analysis indicated that sepsis definition could be a possible source of heterogeneity, but there's no sufficient data to investigate sepsis-3 definition. Sensitivity analysis suggested that two studies could affect the stability of pooled results.

Conclusion

On the basis of our meta-analysis, calprotectin is a helpful marker for early diagnosis of sepsis on ICU admission.

Elevated calprotectin levels are associated with mortality in patients with acute decompensation of liver cirrhosis

BACKGROUND

Acute decompensation (AD) of cirrhosis is related to systemic inflammation and elevated circulating cytokines. In this context, biomarkers of inflammation, such as calprotectin, may be of prognostic value.

AIM

To evaluate serum calprotectin levels in patients hospitalized for complications of cirrhosis.

METHODS

This is a prospective cohort study that included 200 subjects hospitalized for complications of cirrhosis, 20 outpatients with stable cirrhosis, and 20 healthy controls. Serum calprotectin was measured by enzyme-linked immunosorbant assay.

RESULTS

Calprotectin levels were higher among groups with cirrhosis when compared to healthy controls. Higher median calprotectin was related to Child-Pugh C, ascites, and hepatic encephalopathy. Higher calprotectin was related to acute-on-chronic liver failure (ACLF) and infection in the bivariate, but not in multivariate analysis. Calprotectin was not associated with survival among patients with ACLF; however, in patients with AD without ACLF, higher calprotectin was associated with a lower 30-d survival, even after adjustment for chronic liver failure-consortium (CLIF-C) AD score. A high-risk group (CLIF-C AD score ≥ 60 and calprotectin ≥ 580 ng/mL) was identified, which had a 30-d survival (27.3%) similar to that of patients with grade 3 ACLF (23.3%).

CONCLUSION

Serum calprotectin is associated with prognosis in patients with AD without ACLF and may be useful in clinical practice to early identify patients with a very low short-term survival.

Application of Biomarkers in the Diagnostic Distinction of Bacterial and Viral Infections

Infectious diseases, which pose a great threat worldwide, have a significant impact on public health and the world economy. It contributes to increased healthcare costs, unnecessary drug-related side effects, and increased antimicrobial resistance. It is not always easy to distinguish the etiological differentiation of diseases that can develop with bacteria and viruses. Therefore, one of the biggest challenges in medicine is how to correctly distinguish between the different causes of these infections and how to manage the patient. Because bacterial and viral infections often present similar symptoms. The real decision is whether the infection is caused by bacteria or viruses and whether to treat the patient with antibiotics. There are many different methodological approaches to diagnosing infections. Biomarkers have been used in the diagnosis of diseases and other conditions for many years. Biomarkers are molecules found in blood and body fluids in measurable amounts, which can evaluate biological and pathological processes. These key indicators can provide vital information in determining disease prognosis, predicting response to treatments, adverse events and drug interactions, and identifying key risks. An effective biomarker is extremely important for the early diagnosis of various diseases. The explosion of interest in biomarker research is driving the development of new predictive, diagnostic, and prognostic products in modern medical practice. The purpose of this review is to demonstrate the use and diagnostic potential of current and investigational biomarkers in the distinction between bacterial and viral infections.

Early kinetics of calprotectin in plasma following inguinal hernia surgery

Calprotectin is one of the most abundant proteins of neutrophil granulocytes. It is released upon neutrophil activation and is considered a sensitive and clinically useful marker for neutrophil-mediated inflammation, including bacterial infections. However, early kinetics of calprotectin activation following inflammatory activation has hitherto been unknown. The aim of the present study was to determine the early phase of the kinetics of calprotectin, in comparison with the inflammatory markers CRP, IL-6, TNF-α, and procalcitonin, in plasma following a standardized temporary mild inflammatory response, using uncomplicated inguinal hernia surgery as a model. The study cohort consisted of 17 adult patients (15 male and 2 female) undergoing elective surgery for hernia. Values of calprotectin increased significantly at 2 h following surgery, and continued to increase to reach the highest level at 24–36 h after surgery, values still not exceeding upper normal reference level. This contrasts to IL-6 and CRP, for which an elevation was found first later, 4 h and 24–36 h post-surgery, respectively, for IL-6, and CRP. No significant increase was seen for TNF-α, or procalcitonin. The data demonstrate a very rapid and significant but modest increase in calprotectin following induction of mild inflammation, supporting that calprotectin can be useful for early detection of inflammatory response.

Inflammation and Cell Death of the Innate and Adaptive Immune System during Sepsis

Sepsis is a life-threatening medical condition that occurs when the host has an uncontrolled or abnormal immune response to overwhelming infection. It is now widely accepted that sepsis occurs in two concurrent phases, which consist of an initial immune activation phase followed by a chronic immunosuppressive phase, leading to immune cell death. Depending on the severity of the disease and the pathogen involved, the hosts immune system may not fully recover, leading to ongoing complications proceeding the initial infection. As such, sepsis remains one of the leading causes of morbidity and mortality world-wide, with treatment options limited to general treatment in intensive care units (ICU). Lack of specific treatments available for sepsis is mostly due to our limited knowledge of the immuno-physiology associated with the disease. This review will provide a comprehensive overview of the mechanisms and cell types involved in eliciting infection-induced immune activation from both the innate and adaptive immune system during sepsis. In addition, the mechanisms leading to immune cell death following hyperactivation of immune cells will be explored. The evaluation and better understanding of the cellular and systemic responses leading to disease onset could eventuate into the development of much needed therapies to combat this unrelenting disease.

Plasma calprotectin as a biomarker of mortality at antiretroviral treatment initiation in advanced HIV - pilot study

Background: In advanced HIV, significant mortality occurs soon after starting antiretroviral treatment (ART) in low- and middle-incomes countries. Calprotectin is a biomarker of innate response to infection and inflammatory conditions. We examined the association between plasma calprotectin collected before ART treatment and mortality among individuals with advanced HIV.   Methods: We conducted a pilot case-cohort study among HIV infected adults and adolescents over 13 years old with CD4+ <100/mm3 at ART initiation at two Kenyan sites. Participants received three factorial randomised interventions in addition to ART within the REALITY trial (ISRCTN43622374). Calprotectin collected at baseline (before ART) and after 4 weeks of treatment was measured in archived plasma of those who died within 24 weeks (cases) and randomly selected participants who survived (non-cases). Association with mortality was assessed using Cox proportional hazards models with inverse sampling probability weights and adjusted for age, sex, site, BMI, viral load, randomised treatments, and clustered by CD4+ count (0-24, 25-49, and 50-99 cells/mm3).   Results: Baseline median (IQR) plasma calprotectin was 6.82 (2.65-12.5) µg/ml in cases (n=39) and 5.01 (1.92-11.5) µg/ml in non-cases (n=58). Baseline calprotectin was associated with age, neutrophil count and the presence of cough, but not other measured indicators of infection. In adjusted multivariable models, baseline calprotectin was associated with subsequent mortality: HR 1.64 (95% CI 1.11 - 2.42) and HR 2.77 (95% CI 1.58 - 4.88) for deaths during the first twenty-four and four weeks respectively. Calprotectin levels fell between baseline and 4 weeks among both cases and non-cases irrespective of randomised interventions.   Conclusions: Among individuals with advanced HIV starting ART in Kenya, plasma calprotectin may have potential as a biomarker of early mortality. Validation in larger studies, comparison with other biomarkers and investigation of the sources of infection and inflammation are warranted.

Association of Serum Calprotectin Concentrations with Mortality in Critically Ill and Septic Patients

Background: Calprotectin is present in the cytosol of neutrophil granulocytes and released upon activation. Fecal calprotectin is applied in the clinical management of inflammatory bowel disease whereas serum calprotectin has been discussed as a biomarker in inflammatory disorders. However, its long-term prognostic relevance in critical illness remains unclear. Our aim was to investigate serum calprotectin concentrations as a prognostic biomarker in critically ill and septic patients. Methods: Serum calprotectin concentrations were analyzed in 165 critically ill patients (108 with sepsis, 57 without sepsis) included in our observational study. Patients were enrolled upon admission to the medical intensive care unit (ICU) of the RWTH Aachen University Hospital. Calprotectin concentrations were compared to 24 healthy controls and correlated with clinical parameters, therapeutic interventions, and survival. Results: Serum calprotectin concentrations were significantly increased in ICU patients as well as in septic patients compared to respective controls (p < 0.001 for ICU patients and p = 0.001 for septic patients). Lower calprotectin concentrations were measured in patients with comorbidities i.e., coronary artery disease. Calprotectin concentrations strongly correlated with the C-reactive protein (p < 0.001) and were closely associated to parameters of mechanical ventilation (i.a. inspiratory oxygen fraction, FiO2; p < 0.001). The overall survival was significantly impaired in septic patients with high baseline calprotectin concentrations (p = 0.036). However, patients with increasing calprotectin serum concentrations within the first week of ICU admission showed an improved overall survival (p = 0.009). Conclusions: In summary, serum calprotectin concentrations are significantly increased in critically ill patients with sepsis. High calprotectin concentrations at ICU admission predict long-term mortality risk, whereas increasing calprotectin concentrations are associated with a favorable long-term outcome.

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.

Plasma calprotectin as a biomarker of mortality at antiretroviral treatment initiation in advanced HIV - pilot study

Background: In advanced HIV, significant mortality occurs soon after starting antiretroviral treatment (ART) in low- and middle-incomes countries. Calprotectin is a biomarker of innate response to infection and inflammatory conditions. We examined the association between plasma calprotectin at initiation of ART and mortality among individuals with advanced HIV. Methods: We conducted a pilot case-cohort study among HIV infected adults and children over 5 years old with CD4 + <100/mm 3 at ART initiation at two Kenyan sites. Participants received three factorial randomised interventions in addition to ART within the REALITY trial ( ISRCTN43622374). Calprotectin was measured by ELISA in archived plasma of those who died within 24 weeks (cases) and randomly selected participants who survived for 48 weeks (non-cases) for whom samples were available. Factors associated with baseline plasma calprotectin were investigated using linear regression. To test association with mortality, Cox proportional hazards models with inverse sampling probability weights and adjusted for age, sex, site, BMI, viral load, randomised treatments, and clustered by CD4 count were fitted. Results: Baseline median (IQR) plasma calprotectin was 6.82 (2.65-12.5) µg/ml in cases (n=39) and 5.01 (1.92-11.5) µg/ml in non-cases (n=58). Baseline calprotectin was associated with age, neutrophil count and the presence of cough, but not other measured indicators of infection. In adjusted multivariable models, baseline calprotectin was associated with subsequent mortality: HR 1.64 (95% CI 1.11 - 2.42) and HR 2.77 (95% CI 1.58 - 4.88) for deaths during the first twenty-four and four weeks respectively. Calprotectin levels fell between baseline and 4 weeks among both cases and non-cases irrespective of randomised interventions. Conclusion: Among individuals with advanced HIV starting ART in Kenya, plasma calprotectin may have potential as a biomarker of early mortality. Validation in larger studies, comparison with other biomarkers and investigation of the sources of infection and inflammation are warranted.

Calprotectin, a new biomarker for diagnosis of acute respiratory infections

Respiratory tract infections require early diagnosis and adequate treatment. With the antibiotic overuse and increment in antibiotic resistance there is an increased need to accurately distinguish between bacterial and viral infections. We investigated the diagnostic performance of calprotectin in respiratory tract infections and compared it with the performance of heparin binding protein (HBP) and procalcitonin (PCT). Biomarkers were analyzed in patients with viral respiratory infections and patients with bacterial pneumonia, mycoplasma pneumonia and streptococcal tonsillitis (n = 135). Results were compared with values obtained from 144 healthy controls. All biomarkers were elevated in bacterial and viral infections compared to healthy controls. Calprotectin was significantly increased in patients with bacterial infections; bacterial pneumonia, mycoplasma pneumonia and streptococcal tonsillitis compared with viral infections. PCT was significantly elevated in patients with bacterial pneumonia compared to viral infections but not in streptococcal tonsillitis or mycoplasma caused infections. HBP was not able to distinguish between bacterial and viral causes of infections. The overall clinical performance of calprotectin in the distinction between bacterial and viral respiratory infections, including mycoplasma was greater than performance of PCT and HBP. Rapid determination of calprotectin may improve the management of respiratory tract infections and allow more precise diagnosis and selective use of antibiotics.

An Update on Sepsis Biomarkers

Sepsis is a dysregulated systemic reaction to a common infection, that can cause life-threatening organ dysfunction. Over the last decade, the mortality rate of patients with sepsis has decreased as long as patients are treated according to the recommendations of the Surviving Sepsis Campaign, but is still unacceptably high. Patients at risk of sepsis should therefore be identified prior to the onset of organ dysfunction and this requires a rapid diagnosis and a prompt initiation of treatment. Unfortunately, there is no gold standard for the diagnosis of sepsis and traditional standard culture methods are time-consuming. Recently, in order to overcome these limitations, biomarkers which could help in predicting the diagnosis and prognosis of sepsis, as well as being useful for monitoring the response to treatments, have been identified. In addition, recent advances have led to the development of newly identified classes of biomarkers such as microRNAs, long-non-coding RNAs, and the human microbiome. This review focuses on the latest information on biomarkers that can be used to predict the diagnosis and prognosis of sepsis.

The time course of calprotectin liberation from human neutrophil granulocytes after Escherichia coli and endotoxin challenge

Plasma calprotectin has previously been reported as a biomarker for sepsis. The aim of the present study was to elucidate the kinetics of calprotectin release from neutrophils exposed to Escherichia coli and endotoxin. Whole blood samples were exposed to E. coli bacteria or endotoxin in vitro. Blood samples were collected after 0, 1, 2, 3 and 4 h and plasma calprotectin was analysed by particle enhanced turbidimetric immunoassay while TNF-α, IL-6, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) were analyzed by ELISA. When neutrophils were exposed to either E. coli or endotoxin, calprotectin levels began to increase within a couple of hours after the challenge. Calprotectin increases early in response to bacterial challenge. Given the logistic advantages of the calprotectin analysis, this may be of interest for early diagnosis of bacterial infections.

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.

Calprotectin and calgranulin C serum levels in bacterial sepsis

The aim of this study was to evaluate the serum levels of calprotectin and calgranulin C and routine biomarkers in patients with bacterial sepsis (BS). The initial serum concentrations of calprotectin and calgranulin C were significantly higher in patients with BS (n = 66) than in those with viral infections (n = 24) and the healthy controls (n = 26); the level of calprotectin was found to be the best predictor of BS, followed by the neutrophil-lymphocyte count ratio (NLCR) and the level of procalcitonin (PCT). The white blood cell (WBC) count and the NLCR rapidly returned to normal levels, whereas PCT levels normalized later and the increased levels of calprotectin, calgranulin C, and C-reactive protein persisted until the end of follow-up. Our results suggest that the serum levels of calprotectin are a reliable biomarker of BS and that the WBC count and the NLCR are rapid predictors of the efficacy of antimicrobial therapy.