Biomarkers for Sepsis: What Is and What Might Be?

Beyond the Horizon: A Comprehensive Review of Contemporary Strategies in Sepsis Management Encompassing Predictors, Diagnostic Tools, and Therapeutic Advances

This comprehensive review offers a detailed exposition of contemporary strategies in sepsis management, encompassing predictors, diagnostic tools, and therapeutic advances. The analysis elucidates the dynamic nature of sepsis, emphasizing the crucial role of early detection and intervention. The multifaceted strategies advocate for a holistic and personalized approach to sepsis care from traditional clinical methodologies to cutting-edge technologies. The implications for clinical practice underscore clinicians' need to adapt to evolving definitions, integrate advanced diagnostic tools, and embrace precision medicine. Integrating artificial intelligence and telemedicine necessitates a commitment to training and optimization. Judicious antibiotic use and recognition of global health disparities emphasize the importance of a collaborative, global effort in sepsis care. Looking ahead, recommendations for future research underscore priorities such as longitudinal studies on biomarkers, precision medicine trials, implementation science in technology, global health interventions, and innovative antibiotic stewardship strategies. These research priorities aim to contribute to transformative advancements in sepsis management, ultimately enhancing patient outcomes and reducing the global impact of this critical syndrome.

A 29-mRNA host-response classifier identifies bacterial infections following liver transplantation - a pilot study

PURPOSE

Infections are common complications in patients following liver transplantation (LTX). The early diagnosis and prognosis of these infections is an unmet medical need even when using routine biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT). Therefore, new approaches are necessary.

METHODS

In a prospective, observational pilot study, we monitored 30 consecutive patients daily between days 0 and 13 following LTX using the 29-mRNA host classifier IMX-BVN-3b that determine the likelihood of bacterial infections and viral infections. True infection status was determined using clinical adjudication. Results were compared to the accuracy of CRP and PCT for patients with and without bacterial infection due to clinical adjudication.

RESULTS

Clinical adjudication confirmed bacterial infections in 10 and fungal infections in 2 patients. 20 patients stayed non-infected until day 13 post-LTX. IMX-BVN-3b bacterial scores were increased directly following LTX and decreased until day four in all patients. Bacterial IMX-BVN-3b scores detected bacterial infections in 9 out of 10 patients. PCT concentrations did not differ between patients with or without bacterial, whereas CRP was elevated in all patients with significantly higher levels in patients with bacterial infections.

CONCLUSION

The 29-mRNA host classifier IMX-BVN-3b identified bacterial infections in post-LTX patients and did so earlier than routine biomarkers. While our pilot study holds promise future studies will determine whether these classifiers may help to identify post-LTX infections earlier and improve patient management.

CLINICAL TRIAL NOTATION

German Clinical Trials Register: DRKS00023236, Registered 07 October 2020, https://drks.de/search/en/trial/DRKS00023236.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Microfluidic systems for infectious disease diagnostics

Microorganisms, encompassing both uni- and multicellular entities, exhibit remarkable diversity as omnipresent life forms in nature. They play a pivotal role by supplying essential components for sustaining biological processes across diverse ecosystems, including higher host organisms. The complex interactions within the human gut microbiota are crucial for metabolic functions, immune responses, and biochemical signalling, particularly through the gut-brain axis. Viruses also play important roles in biological processes, for example by increasing genetic diversity through horizontal gene transfer when replicating inside living cells. On the other hand, infection of the human body by microbiological agents may lead to severe physiological disorders and diseases. Infectious diseases pose a significant burden on global healthcare systems, characterized by substantial variations in the epidemiological landscape. Fast spreading antibiotic resistance or uncontrolled outbreaks of communicable diseases are major challenges at present. Furthermore, delivering field-proven point-of-care diagnostic tools to the most severely affected populations in low-resource settings is particularly important and challenging. New paradigms and technological approaches enabling rapid and informed disease management need to be implemented. In this respect, infectious disease diagnostics taking advantage of microfluidic systems combined with integrated biosensor-based pathogen detection offers a host of innovative and promising solutions. In this review, we aim to outline recent activities and progress in the development of microfluidic diagnostic tools. Our literature research mainly covers the last 5 years. We will follow a classification scheme based on the human body systems primarily involved at the clinical level or on specific pathogen transmission modes. Important diseases, such as tuberculosis and malaria, will be addressed more extensively.

Platelet P2Y12 signalling pathway in the dysregulated immune response during sepsis

Sepsis is a complicated pathological condition in response to severe infection. It is characterized by a strong systemic inflammatory response, where multiple components of the immune system are involved. Currently, there is no treatment for sepsis. Blood platelets are known for their role in haemostasis, but they also participate in inflammation through cell-cell interaction and the secretion of inflammatory mediators. Interestingly, an increase in platelet activation, secretion, and aggregation with other immune cells (such as monocytes, T-lymphocytes and neutrophils) has been detected in septic patients. Therefore, antiplatelet therapy in terms of P2Y12 antagonists has been evaluated as a possible treatment for sepis. It was found that blocking P2Y12 receptors decreased platelet marker expression and limited attachment to immune cells in some studies, but not in others. This review addresses the role of platelets in sepsis and discusses whether antagonizing P2Y12 signalling pathways can alter the disease outcome. Challenges in studying P2Y12 antagonists in sepsis also are discussed. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Microbiological Profiles and Inflammatory Biomarkers of Bacteremia in Children in a Teaching Hospital in Kuwait: An 8-Year Retrospective Study

OBJECTIVES

The objectives of this study were to determine the bacterial profiles and prevalence of antibiotic resistance patterns of bacteria causing bacteremia in febrile children and to compare levels of inflammatory markers between children with and without bacteremia in Kuwait from 2015 to 2022.

MATERIALS AND METHODS

Isolates from all episodes of significant bacteremia (n = 96) during the study period were recorded and evaluated. Microorganisms were identified using standard microbiological methods. Antimicrobial susceptibility testing was carried out using the VITEK2 system and Etest method. Extended-spectrum β-lactamase (ESBL) production by Enterobacterales was detected by the double-disk diffusion method and VITEK2 system. Patient age, gender, and inflammatory markers were collected at admission and compared between patients with and without bacteremia.

RESULTS

A majority of the patients were infants (37, 40%) and newborns (13, 14%). The main ports of entry were the lower respiratory tract, the genitourinary tract, and the gastrointestinal tract. Streptococcus pneumoniae was the most common pathogen (16, 16.7%) followed by Escherichia coli (12, 12.5%), Staphylococcus aureus (10, 10.4%), and Streptococcus agalactiae (9, 9.4%). High rates of resistance to ampicillin, cefuroxime, ciprofloxacin, and trimethoprim-sulfamethoxazole were observed among the Enterobacterales. The prevalence of ESBL-producing E. coli and K. pneumoniae were 45% and 29%, respectively. The prevalence of methicillin-resistant S. aureus was 30%. Patients with bacteremia had significantly higher white blood cell (WBC) counts, absolute neutrophil count (ANC), C-reactive protein (CRP), and neutrophil-lymphocyte ratio (NLR).

CONCLUSION

Continuous surveillance of the prevalence and antimicrobial susceptibility patterns of blood isolates is imperative for the formulation of antibiotic policy. WBC, ANC, CRP, and NLR could be valuable indicators of bacteremia in febrile children.

Quick Sequential Organ Failure Assessment Score, Lactate, and Neutrophil-Lymphocyte Ratio Help in Diagnosis and Mortality Prediction during Golden Hour of Sepsis in Emergency Department

Introduction

Sepsis is a life-threatening condition with a very narrow golden period in which confirmatory diagnosis may change the outcome dramatically. No confirmatory biomarker is available till date for early diagnosis of sepsis. This study aimed to evaluate the combined and independent role of quick sequential organ failure assessment (qSOFA) score, lactate, and neutrophil-lymphocyte ratio (NLR) in diagnosis and mortality prediction in early sepsis.

Methods

This was a hospital-based, single-center, prospective cohort study conducted in a tertiary care institute, Karnataka, India. Three hundred adult sepsis patients were recruited during 10-month period, and demographic data, qSOFA score, lactate, NLR, and culture samples were collected in ED within 1 h of admission. Outcome groups (survivor and nonsurvivor) were statistically analyzed with relative frequencies (%), median, mean ± standard deviation with 95% confidence interval (CI), univariate, bivariate, and multivariate logistic regression analysis, and Receiver -operating characteristic curve (ROC) curve to test the predictive ability of initial levels of three biomarkers.

Results

Sepsis was more prevalent among middle-aged male patients. Male gender (odds ratio [OR], 6.9; 95% CI: 1.61-30.1), qSOFA (OR, 154; 95% CI: 15-1565), and lactate (OR, 1.36; 95% CI: 22-833) show 97% (area under the curve) predictive accuracy of the model for sepsis on bivariate and multivariate logistic regression analysis. A significant rise in NLR was a poor outcome indicator on univariate analysis (P = 0.773).

Conclusion

All three biomarkers are good outcome predictors whereas qSOFA and lactate have diagnostic significance in early sepsis. These markers can be used for patient triaging, minimizing culture report dependence for treatment and ultimately the outcome.

Decoding Sepsis-Induced Disseminated Intravascular Coagulation: A Comprehensive Review of Existing and Emerging Therapies

Disseminated intravascular coagulation (DIC) is a recurrent complication of sepsis. Since DIC not only promotes organ dysfunction but also represents a strong prognostic factor, it is important to diagnose DIC as early as possible. When coagulation is activated, fibrinolysis is inhibited, blood thinners are consumed, and a condition is created that promotes blood clotting, making it more difficult for the body to remove fibrin or prevent it from being deposited in the blood vessels. This leads to microvascular thrombosis, which plays a role in organ dysfunction. Despite efforts to understand the underlying mechanisms of sepsis-induced DIC, healthcare providers worldwide still face challenges in effectively treating this condition. In this review, we provide an in-depth analysis of the available strategies for sepsis-induced DIC, considering their effectiveness, limitations, and potential for future advances. Corticosteroids (CS), recombinant thrombomodulin (rTM), vitamin C, fibrinolytic therapy, and platelet transfusion are among the treatments discussed in the review. In addition, we are specifically addressing immunomodulatory therapy (IMT) by investigating treatments such as granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon gamma (IFN-γ), and mesenchymal stem cell therapy (MSC). Finally, we also examined how these therapies might affect COVID-19 cases, which often present with sepsis-induced DIC. The review suggests that targeted experiments with randomization are needed to verify the effectiveness of these treatments and to discover novel approaches to treat sepsis-induced DIC. By increasing our knowledge of sepsis-induced DIC, we can develop targeted treatments that have the potential to save lives and improve outcomes.

The value of plasma presepsin as a diagnostic and prognostic biomarker for sepsis in Southern China

BACKGROUND

Presepsin is a soluble CD14 subtype that has been considered as a novel marker for patients with sepsis. This study explored the clinical value of presepsin for sepsis in Southern China, and further established models for diagnosis and prognosis of sepsis through using machine learning (ML), by combining presepsin and other laboratory parameters.

METHODS

269 subjects (105 infected patients, 164 sepsis and septic shock) and 198 healthy controls were enrolled. Laboratory parameters (hematological parameters, coagulation parameters, liver function indices, renal function indices, and inflammatory markers) were collected. Plasma presepsin was tested by chemiluminescence enzyme immunoassay. ML of DxAI™ Research platform was used to establish diagnostic and prognostic models. Sensitivity, specificity, and other performance indicators were used to evaluate the performance of each model.

RESULTS

The level of presepsin was obviously increased in sepsis and sepsis shock, compared with that of infected and healthy group (all P < 0.0001). Presepsin concentration was positively correlated with positive blood culture and 30-day mortality in sepsis and septic shock patients. Through ROC curve analysis, Hb, UREA, APTT, CRP, PCT, and presepsin were incorporated into machine learning to construct diagnosis models. Ada Boost model had the best diagnostic efficiency (AUC: 0.94 (95% CI 0.919-0.968) in the training set and AUC: 0.86 (95% CI 0.813-0.900) in validation set). Furthermore, AST, APTT, UREA, PCT, and presepsin were included in the prognosis ML models, and the Bernoulli NB model had greater predictive ability for 30-day mortality risk of sepsis (AUC: 0.706), which was higher than that of PCT (AUC: 0.617) and presepsin (AUC: 0.634) alone.

CONCLUSION

Machine-learning model based on presepsin and routinely laboratory parameters showed good performance of diagnostic and prognostic ability for sepsis patients.

Metabolomics Study Revealing Purines as Potential Diagnostic Biomarkers of Acute Respiratory Distress Syndrome in Patients with Community─Acquired Pneumonia

Community-acquired pneumonia (CAP) is a significant threat to human health and the leading cause of acute respiratory distress syndrome (ARDS). We aimed to reveal the metabolic profiling whether can be used for assessing CAP with or without ARDS (nARDS) and therapeutic effects on CAP patients after treatment. Urine samples were collected at the onset and recovery periods, and metabolomics was employed to identify robust biomarkers. 19 metabolites were significantly changed in the ARDS relative to nARDS, mainly involving purines and fatty acids. After treatment, 7 metabolites in the nARDS and 14 in the ARDS were found to be significantly dysregulated, including fatty acids and amino acids. In the validation cohort, we observed that the biomarker panel consisted of N2,N2-dimethylguanosine, 1-methyladenosine, 3-methylguanine, 1-methyladenosine, and uric acid exhibited better AUCs of 0.900 than pneumonia severity index and acute physiology and chronic health evaluation II (APACHE II) scores between the ARDS and nARDS. Combining L-phenylalanine, phytosphingosine, and N-acetylaspartylglutamate as biomarkers for discriminating the nARDS and ARDS patients after treatment exhibited good AUCs of 0.811 and 0.821, respectively. The metabolic pathway and defined biomarkers may serve as crucial indicators for predicting the development of ARDS in CAP patients and for assessing therapeutic effects.

Rapid, High-Throughput Single-Cell Multiplex In Situ Tagging (MIST) Analysis of Immunological Disease with Machine Learning

The cascade of immune responses involves activation of diverse immune cells and release of a large amount of cytokines, which leads to either normal, balanced inflammation or hyperinflammatory responses and even organ damage by sepsis. Conventional diagnosis of immunological disorders based on multiple cytokines in the blood serum has varied accuracy, and it is difficult to distinguish normal inflammation from sepsis. Herein, we present an approach to detect immunological disorders through rapid, ultrahigh-multiplex analysis of T cells using single-cell multiplex in situ tagging (scMIST) technology. scMIST permits simultaneous detection of 46 markers and cytokines from single cells without the assistance of special instruments. A cecal ligation and puncture sepsis model was built to supply T cells from two groups of mice that survived the surgery or died after 1 day. The scMIST assays have captured the T cell features and the dynamics over the course of recovery. Compared with cytokines in the peripheral blood, T cell markers show different dynamics and cytokine levels. We have applied a random forest machine learning model to single T cells from two groups of mice. Through training, the model has been able to predict the group of mice through T cell classification and majority rule with 94% accuracy. Our approach pioneers the direction of single-cell omics and could be widely applicable to human diseases.

A Host-Directed Approach to the Detection of Infection in Hard-to-Heal Wounds

Wound infection is traditionally defined primarily by visual clinical signs, and secondarily by microbiological analysis of wound samples. However, these approaches have serious limitations in determining wound infection status, particularly in early phases or complex, chronic, hard-to-heal wounds. Early or predictive patient-derived biomarkers of wound infection would enable more timely and appropriate intervention. The observation that immune activation is one of the earliest responses to pathogen activity suggests that immune markers may indicate wound infection earlier and more reliably than by investigating potential pathogens themselves. One of the earliest immune responses is that of the innate immune cells (neutrophils) that are recruited to sites of infection by signals associated with cell damage. During acute infection, the neutrophils produce oxygen radicals and enzymes that either directly or indirectly destroy invading pathogens. These granular enzymes vary with cell type but include elastase, myeloperoxidase, lysozyme, and cathepsin G. Various clinical studies have demonstrated that collectively, these enzymes, are sensitive and reliable markers of both early-onset phases and established infections. The detection of innate immune cell enzymes in hard-to-heal wounds at point of care offers a new, simple, and effective approach to determining wound infection status and may offer significant advantages over uncertainties associated with clinical judgement, and the questionable value of wound microbiology. Additionally, by facilitating the detection of early wound infection, prompt, local wound hygiene interventions will likely enhance infection resolution and wound healing, reduce the requirement for systemic antibiotic therapy, and support antimicrobial stewardship initiatives in wound care.

Concurrent Change in Serum Cholinesterase Activity and Midregional-Proadrennomedullin Level Could Predict Patient Outcome following Liver Transplantation

Background: After liver transplantation (LTX), patients are susceptible to opportunistic infections resulting in reduced outcomes within the early post-transplantation period. The postoperative monitoring of LTX patients has gained much importance in recent years. However, reliable plasmatic markers predicting 90-day outcomes are still lacking. Methods: In the post hoc analysis of a prospective, observational study, butyrylcholinesterase (BChE), mid-regional proadrenomedullin (MR-proADM), as well as conventional inflammatory markers (procalcitonin, C-reactive protein) were evaluated in 93 patients at seven consecutive timepoints within the first 28 days following LTX. Results: Persistently reduced activity of BChE and elevated MR-proADM levels indicated reduced 90-day survival following LTX. Furthermore, reduced BChE and increased MR-proADM activity could indicate early post-transplantation bacterial infections, whereas conventional inflammatory biomarkers showed no diagnostic efficacy within the observation period. Conclusion: Concurrent assessment of BChE and MR-proADM activity might serve as a bedside diagnostic tool for early bacterial infections following liver transplantation. Thus, a combined utilization of the two biomarkers may be a useful tool in the risk evaluation of patients following liver transplantation.

Bioelectronic Sensor with Magnetic Modulation to Quantify Phagocytic Activity of Blood Cells Employing Machine Learning

Microbial infections result in activating an immune response in the human body, which triggers inflammatory pathways resulting in recognition and subsequent killing of the pathogens. Quantifying the blood cells' natural ability to kill pathogens, i.e., phagocytosis, is critical to demonstrating the effectiveness of an individual's response in combating pathogens. Current laboratory processes and equipment that can be used to monitor phagocytic activity are costly and time-consuming and require significant technical expertise to run such assays. Here, we design and develop a novel biosensing platform capable of quantifying the phagocytic ability of blood cells. The sensor design is composed of electronic sensing and magnetic modulation sub-systems that work in conjunction to monitor phagocytic activity in microfluidic channels. The phagocytes internalize the IgG-coated magnetic beads, and when infused into the sensor, their speed will be modulated using the quadrupole magnetic field configuration as they pass through microfluidic channels where microfabricated electrodes are placed. The electronic sensor will generate the voltage pulse for each passage of the phagocyte, whose distinct features are correlative to the phagocytic activity. We experimentally tested this device using 17 blood samples collected from patients at Robert Wood Johnson Medical Hospital. Further, we developed artificial neural networks (ANN) to improve the accuracy of the phagocytic activity detection. ANN model detected the phagocytic activity with 88.2% accuracy. This novel sensing platform can potentially be used to triage high risk patients and develop personalized theranostics for the septic patients in the future.

COVID-19, what could sepsis, severe acute pancreatitis, gender differences, and aging teach us?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a potentially life-threatening disease, defined as Coronavirus Disease 19 (COVID-19). The most common signs and symptoms of this pathological condition include cough, fever, shortness of breath, and sudden onset of anosmia, ageusia, or dysgeusia. The course of COVID-19 is mild or moderate in more than 80% of cases, but it is severe or critical in about 14% and 5% of infected subjects respectively, with a significant risk of mortality. SARS-CoV-2 related infection is characterized by some pathogenetic events, resembling those detectable in other pathological conditions, such as sepsis and severe acute pancreatitis. All these syndromes are characterized by some similar features, including the coexistence of an exuberant inflammatory- as well as an anti-inflammatory-response with immune depression. Based on current knowledge concerning the onset and the development of acute pancreatitis and sepsis, we have considered these syndromes as a very interesting paradigm for improving our understanding of pathogenetic events detectable in patients with COVID-19. The aim of our review is: 1)to examine the pathogenetic mechanisms acting during the emergence of inflammatory and anti-inflammatory processes in human pathology; 2)to examine inflammatory and anti-inflammatory events in sepsis, acute pancreatitis, and SARS-CoV-2 infection and clinical manifestations detectable in patients suffering from these syndromes also according to the age and gender of these individuals; as well as to analyze the possible common and different features among these pathological conditions; 3)to obtain insights into our knowledge concerning COVID-19 pathogenesis. This approach may improve the management of patients suffering from this disease and it may suggest more effective diagnostic approaches and schedules of therapy, depending on the different phases and/or on the severity of SARS-CoV-2 infection.

A panel of urine-derived biomarkers to identify sepsis and distinguish it from systemic inflammatory response syndrome

Sepsis is a potentially fatal condition caused by infection. It is frequently difficult to distinguish sepsis from systemic inflammatory response syndrome (SIRS), often resulting in poor prognoses and the misuse of antibiotics. Hence, highly sensitive and specific biomarkers are needed to differentiate sepsis from SIRS. Urine samples were collected and segregated by group (a sepsis group, a SIRS group, and a healthy control group). iTRAQ was used to identify the differentially expressed proteins among the three groups. The identified proteins were measured by ELISA in urine samples. Finally, all the acquired data were analyzed in SPSS. C-reactive protein, leucine-rich alpha glycoprotein-1 and serum amyloid A (SAA) protein were differentially expressed among the three groups. The adjusted median concentrations of urinary C-reactive protein were 1337.6, 358.7, and 2.4 in the sepsis, SIRS, and healthy control groups, respectively. The urinary leucine-rich alpha glycoprotein-1 levels in these three groups were 1614.4, 644.5, and 13.6, respectively, and the levels of SAA were 6.3, 2.9, and 0.07, respectively. For all three of these measures, the sepsis group had higher levels than the SIRS group (P < 0.001), and the SIRS group had higher levels than the healthy control group. When combined, the three biomarkers had a sensitivity of 0.906 and a specificity of 0.896 in distinguishing sepsis from SIRS. Urinary C-reactive protein, urinary leucine-rich alpha glycoprotein-1 and urinary SAA have diagnostic value in cases of sepsis. This initial study suggests the possibility of improved differential diagnosis between sepsis and systemic inflammatory response syndrome; additional confirmation is necessary to corroborate the findings.

Evaluation of sTREM1 and suPAR Biomarkers as Diagnostic and Prognostic Predictors in Sepsis Patients

Background

The purpose of this study was to explore the diagnostic role of sTREM1 in the diagnosis of sepsis and in differentiating between sepsis and systemic inflammatory response syndrome (SIRS). We also aimed to assess the prognostic value of suPAR in comparison to sequential organ-failure assessment (SOFA), acute physiology and chronic health evaluation (APACHE) II scores, and 28-day mortality.

Methods

This was a cross-sectional study conducted in the Medical Microbiology and Immunology Department and Central Research Laboratory, Faculty of Medicine, Sohag University from June 2019 to January 2021. The study population was classified into two groups: SIRS (no evidence of infection) and sepsis (with SIRS and evidence of infection). Patients were rated on the SOFA and APACHE II scoring systems at admission and after 7 days. Serum levels of sTREM1 and suPAR were measured by ELISA at the same time points.

Results

CRP and sTREM1 values were significantly higher in the sepsis group than the SIRS group on both days (P<0.0001). The area under the curve (AUC) for CRP was 0.87 on the first day and 0.97 on the seventh, while the AUC for sTREM1 was 1.00 and 0.93 on the first and seventh days, respectively. The sensitivity of sTREM1 was 100% and specificity 84% at a cutoff of 49 pg/mL. There was a significantly positive correlation between CRP and sTREM1 values (P<0.0001). On the seventh day, nonsurvivors had significantly higher serum levels of suPAR (median 4.9 ng/mL) than survivors (median 2.9 ng/mL; P<0.0001). Nonsurvivors also had significantly higher SOFA and APACHE II scores than survivors (P<0.0001 and P<0.0001, respectively).

Conclusion

sTREM1 can be used as a good indicator for diagnosing sepsis in intensive care–unit patients. suPAR can also be used as a predictor of bad prognosis and poor survival at 7 days following admission.

Diagnostic and prognostic accuracy of Protein C in adult patients with sepsis: protocol for a systematic review and meta-analysis

INTRODUCTION

Sepsis is a dysregulated host response to infection characterised by activation of proinflammatory and procoagulant mechanisms. Protein C (PC)'s activity as an anticoagulant and antiinflammatory molecule makes it an appealing target for sepsis biomarker studies. To date, there has been no systematic review of PC as a sepsis biomarker.

OBJECTIVES

To evaluate the diagnostic accuracy and prognostic strength of PC as a biomarker for adult sepsis.

METHODS AND ANALYSIS

Medline, Embase, Cochrane Library, PubMed and Cumulative Index to Nursing and Allied Health Literature (CINAHL) will be searched from inception through 20 January 2021 for prospective observational studies that evaluate the use of PC as a diagnostic or prognostic biomarker for adult sepsis. Title and abstract screening, full-text screening and data extraction will be conducted in duplicate. Risk of bias will be assessed using the Quality Assessment of Diagnostic Accuracy Studies and Quality in Prognostic Studies tools. If sufficient data are available, a meta-analysis will be conducted. The standardised mean difference and 95% CI will be calculated for prognostic and diagnostic studies. If possible, a hierarchical summary receiver operator characteristic curve will be generated to assess overall prognostic and diagnostic biomarker accuracy. I² statistics will be used to assess heterogeneity. Sensitivity analysis will be performed by removing studies with a high risk of bias and re-examining the meta-analysis results.

ETHICS AND DISSEMINATION

Given this is a systematic review and meta-analysis, there is no requirement for ethics approval. Findings will be disseminated through a peer-reviewed publication and social media.

PROSPERO REGISTRATION NUMBER

CRD42021229786.

Factors Influencing the Prognosis of Patients with Intra-Abdominal Infection and Its Value in Assessing Prognosis

Purpose

To explore the distribution of pathogenic bacteria in patients with intra-abdominal infection, to clarify the independent factors that affect the prognosis of patients with intra-abdominal infection and its evaluation value for prognosis.

Patients and Methods

The pathogens, underlying diseases, and related clinical data of patients with intra-abdominal infection from January 2012 to December 2019 in our hospital were retrospectively collected and the APACHE II score was calculated. The patients were divided into survival group and death group according to the prognosis, and the index between the two groups was compared. Spearman correlation analysis was used to evaluate the correlation between each index and prognosis, multivariate logistic regression analysis was used to screen the independent prognostic factors.

Results

Spearman correlation analysis showed that ALB level was negatively correlated with prognosis, age and APACHE II score were positively correlated with prognosis. Logistic regression analysis showed that age, ALB level, and APACHE II score were independent prognostic factors. The formula of age combined ALB level and APACHE II score was Y = X1-3.6X2 + 6.5X3 (X1 was the age, X2 was the ALB level and X3 was the APACHE II score), Y was positively correlated with poor prognosis, and the optimal cutoff value was Y = 40.96.

Conclusion

Age, ALB level, and APACHE II score are independent factors that influencing the prognosis of patients with intra-abdominal infection, and the combination of age, ALB level, and APACHE II score can better assess the prognosis of patients with intra-abdominal infection.

Point-of-critical-care diagnostics for sepsis enabled by multiplexed micro and nanosensing technologies

Sepsis is responsible for the highest economic and mortality burden in critical care settings around the world, prompting the World Health Organization in 2018 to designate it as a global health priority. Despite its high universal prevalence and mortality rate, a disproportionately low amount of sponsored research funding is directed toward diagnosis and treatment of sepsis, when early treatment has been shown to significantly improve survival. Additionally, current technologies and methods are inadequate to provide an accurate and timely diagnosis of septic patients in multiple clinical environments. For improved patient outcomes, a comprehensive immunological evaluation is critical which is comprised of both traditional testing and quantifying recently proposed biomarkers for sepsis. There is an urgent need to develop novel point-of-care, low-cost systems which can accurately stratify patients. These point-of-critical-care sensors should adopt a multiplexed approach utilizing multimodal sensing for heterogenous biomarker detection. For effective multiplexing, the sensors must satisfy criteria including rapid sample to result delivery, low sample volumes for clinical sample sparring, and reduced costs per test. A compendium of currently developed multiplexed micro and nano (M/N)-based diagnostic technologies for potential applications toward sepsis are presented. We have also explored the various biomarkers targeted for sepsis including immune cell morphology changes, circulating proteins, small molecules, and presence of infectious pathogens. An overview of different M/N detection mechanisms are also provided, along with recent advances in related nanotechnologies which have shown improved patient outcomes and perspectives on what future successful technologies may encompass. This article is categorized under: Diagnostic Tools > Biosensing.

Recent advances in biomedical, biosensor and clinical measurement devices for use in humans and the potential application of these technologies for the study of physiology and disease in wild animals

The goal of achieving enhanced diagnosis and continuous monitoring of human health has led to a vibrant, dynamic and well-funded field of research in medical sensing and biosensor technologies. The field has many sub-disciplines which focus on different aspects of sensor science; engaging engineers, chemists, biochemists and clinicians, often in interdisciplinary teams. The trends which dominate include the efforts to develop effective point of care tests and implantable/wearable technologies for early diagnosis and continuous monitoring. This review will outline the current state of the art in a number of relevant fields, including device engineering, chemistry, nanoscience and biomolecular detection, and suggest how these advances might be employed to develop effective systems for measuring physiology, detecting infection and monitoring biomarker status in wild animals. Special consideration is also given to the emerging threat of antimicrobial resistance and in the light of the current SARS-CoV-2 outbreak, zoonotic infections. Both of these areas involve significant crossover between animal and human health and are therefore well placed to seed technological developments with applicability to both human and animal health and, more generally, the reviewed technologies have significant potential to find use in the measurement of physiology in wild animals. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

Presepsin as Early Marker of Sepsis in Emergency Department: A Narrative Review

The diagnosis and treatment of sepsis have always been a challenge for the physician, especially in critical care setting such as emergency department (ED), and currently sepsis remains one of the major causes of mortality. Although the traditional definition of sepsis based on systemic inflammatory response syndrome (SIRS) criteria changed in 2016, replaced by the new criteria of SEPSIS-3 based on organ failure evaluation, early identification and consequent early appropriated therapy remain the primary goal of sepsis treatment. Unfortunately, currently there is a lack of a foolproof system for making early sepsis diagnosis because conventional diagnostic tools like cultures take a long time and are often burdened with false negatives, while molecular techniques require specific equipment and have high costs. In this context, biomarkers, such as C-Reactive Protein (CRP) and Procalcitonin (PCT), are very useful tools to distinguish between normal and pathological conditions, graduate the disease severity, guide treatment, monitor therapeutic responses and predict prognosis. Among the new emerging biomarkers of sepsis, Presepsin (P-SEP) appears to be the most promising. Several studies have shown that P-SEP plasma levels increase during bacterial sepsis and decline in response to appropriate therapy, with sensitivity and specificity values comparable to those of PCT. In neonatal sepsis, P-SEP compared to PCT has been shown to be more effective in diagnosing and guiding therapy. Since in sepsis the P-SEP plasma levels increase before those of PCT and since the current methods available allow measurement of P-SEP plasma levels within 17 min, P-SEP appears a sepsis biomarker particularly suited to the emergency department and critical care.

Emerging therapeutic targets for sepsis

Introduction: Sepsis is characterized by a dysregulated host response to infection. Sepsis-associated morbidity/mortality demands concerted research efforts toward therapeutic interventions which are reliable, broadly effective, and etiologically based. More intensive and extensive investigations on alterations in cellular signaling pathways, gene targeting as a means of modifying the characteristic hyper and/or hypo-immune responses, prevention through optimization of the microbiome, and the molecular pathways underlying the septic immune response could improve outcomes.] Areas covered: The authors discuss key experimental mammalian models and clinical trials. They provide an evaluation of evolving therapeutics in sepsis and how they have built upon past and current treatments. Relevant literature was derived from a PubMed search spanning 1987-2020.Expert opinion: Given the complex nature of sepsis and the elicited immune response, it is not surprising that a single cure-all therapeutic intervention, which is capable of effectively and reliably improving patient outcomes has failed to emerge. Innovative approaches seek to address not only the disease process but modify underlying patient factors. A true improvement in sepsis-associated morbidity/mortality will require a combination of unique therapeutic modalities.

Identification of S1PR3 gene signature involved in survival of sepsis patients

BACKGROUND

Sepsis is a life-threatening complication of infection that rapidly triggers tissue damage in multiple organ systems and leads to multi-organ deterioration. Up to date, prognostic biomarkers still have limitations in predicting the survival of patients with sepsis. We need to discover more prognostic biomarkers to improve the sensitivity and specificity of the prognosis of sepsis patients. Sphingosine-1-phosphate (S1P) receptor 3 (S1PR3), as one of the S1P receptors, is a prospective prognostic biomarker regulating sepsis-relevant events, including compromised vascular integrity, antigen presentation, and cytokine secretion. Until now, no S1PR3-related prognostic gene signatures for sepsis patients have been found.

METHODS

This study intends to obtain an S1PR3-associated gene signature from whole blood samples to be utilized as a probable prognostic tool for patients with sepsis.

RESULTS

We obtained an 18-gene S1PR3-related molecular signature (S3MS) from the intersection of S1PR3-associated genes and survival-associated genes. Numerous important immunity pathways that regulate the progression of sepsis are enriched among our 18 genes. Significantly, S3MS functions greatly in both the discovery and validation cohort. Furthermore, we demonstrated that S3MS obtains significantly better classification performance than random 18-gene signatures.

CONCLUSIONS

Our results confirm the key role of S1PR3-associated genes in the development of sepsis, which will be a potential prognostic biomarker for patients with sepsis. Our results also focus on the classification performance of our S3MS as biomarkers for sepsis, which could also provide an early warning system for patients with sepsis.

Functionalization of hybrid surface microparticles for in vitro cellular antigen classification

Hybrid material surfaces on microparticles are emerging as vehicles for many biomedical multiplexing applications. Functionalization of these hybrid surface microparticles to biomolecules presents unique challenges related to optimization of surface chemistries including uniformity, repeatability, and sample sparring. Hybrid interfaces between microlevel surfaces and individual biomolecules will provide different microenvironments impacting the surface functionalization optimization and efficiency. Here, we propose and validate the first demonstration of streptavidin adsorption-based antibody functionalization on unmodified, hybrid surface microparticles for in vitro analysis. We test this analytical technique and fabricate hybrid surface microparticles with a polystyrene core and aluminum oxide semi-coating. Additionally, we optimize the streptavidin-biotin functionalization chemistry in both assay implementation and sample sparring via analytical mass balances for these microparticles and subsequently conjugate anti-human CD11b antibodies. Result confirmation and characterization occurs from ultraviolet protein absorbance and ImageJ processing of fluorescence microscopy images. Additionally, we design and implement the multi-sectional imaging (MSI) approach to support functionalization uniformity on the hybrid surface microparticles. Finally, as a proof-of-concept performance, we validate anti-CD11b antibodies functionalization by visualizing hybrid surface microparticles conjugate to human neutrophils isolated from blood samples collected from potentially septic patients. Our study introduces and defines a category of functionalization for hybrid surface microparticles with the intent of minuscule sample volumes, low cost, and low environmental impact to be used for many cellular or proteomic in vitro multiplexing applications in the future. Graphical abstract.

Current Evidence and Limitation of Biomarkers for Detecting Sepsis and Systemic Infection

Sepsis was recently redefined as a life-threatening disease involving organ dysfunction caused by a dysregulated host response to infection. Biomarkers play an important role in early detection, diagnosis, and prognostication. We reviewed six promising biomarkers for detecting sepsis and systemic infection, including C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), CD64, presepsin, and sTREM-1. Among the recent studies, we found the following risks of bias: only a few studies adopted the random or consecutive sampling strategy; extensive case-control analysis, which worsened the over-estimated performance; most of the studies used post hoc cutoff values; and heterogeneity with respect to the inclusion criteria, small sample sizes, and different quantitative synthesis methods applied in meta-analyses. We recommend that CD64 and presepsin should be considered as the most promising biomarkers for diagnosing sepsis. Future studies should enroll a larger sample size with a cohort rather than a case-control study design. A random or consecutive study design with a pre-specified laboratory threshold, consistent sampling timing, and an updated definition of sepsis will also increase the reliability of the studies. Further investigations of appropriate specimens, testing assays, and cutoff levels for specific biomarkers are also warranted.

Delta-like Canonical Notch Ligand 1 in Patients Following Liver Transplantation-A Secondary Analysis of a Prospective Cohort Study

Opportunistic bacterial infections are dreaded risks in patients following liver transplantation (LTX), even though patients receive an antibiotic prophylaxis. The timely recognition of such an infection may be delayed, as culture-based diagnostic methods are linked with a relevant gap in performance. We measured plasma concentrations of Delta-like canonical Notch ligand 1 (DLL1) in 93 adult patients at seven consecutive time points after liver transplantation and correlated the results to the occurrence of culture-proven bacterial infection or a complicated clinical course (composite endpoint of two or more complications: graft rejection or failure, acute kidney failure, acute lung injury, or 90-day mortality). Patients exhibited elevated plasma concentrations after liver transplantation over the whole 28 d observation time. Patients with bacterial infection showed increased DLL1 levels compared to patients without infection. Persistent elevated levels of DLL1 on day 7 and afterward following LTX were able to indicate patients at risk for a complicated course. Plasma levels of DLL1 following LTX may be useful to support an earlier detection of bacterial infections in combination with C-reactive protein (CRP) and procalcitonin (PCT), or they may lead to risk stratification of patients as a single marker for post-operative complications. (Clinical Trial Notation. German Clinical Trials Register: DRKS00005480).

Efficient Early Diagnosis of Sepsis Using Whole-Blood PCR-Reverse Blot Hybridization Assay Depending on Serum Procalcitonin Levels

Sepsis is one of the medical emergencies, and its early detection, within the first hours of development, and proper management improve outcomes. Molecular diagnostic assays using whole blood collected from patients with suspected sepsis have been developed, but the decision making is difficult because of the possibility of false positives, due to contamination. Here, we evaluated the performance of the reverse blot hybridization assay (REBA) Sepsis-ID test for the detection of sepsis-causing microorganisms using whole-blood samples. In addition, the concentrations of C-reactive protein (CRP) and procalcitonin (PCT) were determined to evaluate whether these biomarkers can provide criteria for performing REBA Sepsis-ID in clinical settings. For this study, EDTA-anticoagulated whole blood was simultaneously collected for REBA Sepsis-ID and blood culture from 440 patients with suspected sepsis, from January to October 2015. In addition, CRP and PCT concentrations were measured in 227 patients. The overall positive rates of REBA Sepsis-ID and blood culture were 16.6% (73/440) and 13.9% (61/440), respectively. The pathogen-positive rates of REBA Sepsis-ID and blood culture were 9.8% (43/440) and 9.5% (42/440), respectively. The areas under the receiver operating characteristic (AUROC) curves of PCT and CRP for predicting pathogen-positive results of REBA Sepsis-ID were 0.72 and 0.69, respectively. The PCT concentrations in the group of patients aged ≥50 years were significantly higher than those in the group aged <50 years. After adjusting for age, the PCT AUROC value was 0.77 for predicting pathogen-positive results of REBA Sepsis-ID. The optimal cutoff values of PCT concentrations for subsequent application of REBA Sepsis-ID were 0.12 ng/mL in all patients and 0.22 ng/mL in patients aged ≥50 years. Our observations showed that REBA Sepsis-ID using whole blood was advantageous for the early detection of sepsis-causing microorganisms, and the PCT concentration could be used to determine the necessity of using REBA Sepsis-ID in clinical settings. The application of REBA Sepsis-ID using whole blood, based on the PCT concentration, may contribute to a highly efficient detection of sepsis-causing microorganisms.

The soluble tumor necrosis factor receptor 1 as a potential early diagnostic and prognostic markers in intensive care unit patients with severe infections

Introduction

Substantial causes of high mortality (30-50%) of people with severe infections treated in intensive care units (ICUs) are still inadequately known in terms of mechanisms and insufficient diagnostic tools for immune responses in sepsis.

Material and methods

The aim of this study was to establish a practical value of determining the concentration of chosen proteins (by ELISA) in peripheral blood as potential in early diagnostics of severe infections, paying special attention to their prognostic values.

Results

In 163 patients treated in ICUs, changes were assessed in the concentration of chosen proteins relating to the TLR4 receptor signalling pathway, including its effectors of pro- and anti-inflammatory cytokines (IL-1Ra, TNF-α, sTNFR1, IL-6, IL-10, sTLR4, MyD88, TNFAIP3/A20, HSP70, and HMGB1). In the analysis of changes in the process of immune response in severely ill patients with and without infections, a significantly higher concentration of sTNFR1 was observed in patients with infections than those who deceased. In the ROC curves tests, it was noted that an assessment of the concentration of sTNFR1 proteins (AUC = 0.686 and cut-off point = 24.841 pg/ml) was a particularly efficient tool, with prognostic significance in patients with infections.

Conclusions

In other patients treated in an ICU, the efficiency of determining IL-6 (AUC = 0.736) was confirmed and at the same time, the effectiveness of this cytokine in predicting death in cases with infections was excluded. The results of the present study are encouraging, suggesting the benefits of undertaking multi-center clinical trials, which consider monitoring sTNFR1 in different groups of patients with infections treated in intensive care units.

Recombinant Human Proteoglycan-4 Mediates Interleukin-6 Response in Both Human and Mouse Endothelial Cells Induced Into a Sepsis Phenotype

OBJECTIVES

Sepsis is a leading cause of death in the United States. Putative targets to prevent systemic inflammatory response syndrome include antagonism of toll-like receptors 2 and 4 and CD44 receptors in vascular endothelial cells. Proteoglycan-4 is a mucinous glycoprotein that interacts with CD44 and toll-like receptor 4 resulting in a blockade of the NOD-like receptor pyrin domain-containing-3 pathway. We hypothesized that endothelial cells induced into a sepsis phenotype would have less interleukin-6 expression after recombinant human proteoglycan 4 treatment in vitro.

DESIGN

Enzyme-linked immunosorbent assay and reverse transcriptase-quantitative polymerase chain reaction to measure interleukin-6 protein and gene expression.

SETTING

Research laboratory.

SUBJECTS

Human umbilical vascular endothelial cells, human lung microvascular endothelial cells, and transgenic mouse (wild type) (Cd44 +/+/Prg4 +/+), Cd44 -/- (Cd44 tm1Hbg Prg4 +/+), Prg4 GT/GT (Cd44 +/+ Prg4 tm2Mawa/J), and double knockout (Cd44 tm1Hbg Prg4 tm2Mawa/J) lung microvascular endothelial cells.

INTERVENTIONS

Cells were treated with 100 or 250 ng/mL lipopolysaccharide-Escherichia coli K12 and subsequently treated with recombinant human proteoglycan 4 after 30 minutes. Interleukin-6 levels in conditioned media were measured via enzyme-linked immunosorbent assay and gene expression was measured via reverse transcriptase-quantitative polymerase chain reaction with ΔΔ-Ct analysis. Additionally, human umbilical vascular endothelial cells and human lung microvascular endothelial cells were treated with 1:10 diluted plasma from 15 patients with sepsis in culture media. After 30 minutes, either 50 or 100 µg/mL recombinant human proteoglycan 4 was administered. Interleukin-6 protein and gene expression were assayed. Proteoglycan 4 levels were also compared between control and sepsis patient plasma.

MEASUREMENTS AND MAIN RESULTS

Human umbilical vascular endothelial cell, human lung microvascular endothelial cell, and mouse lung microvascular endothelial cell treated with lipopolysaccharide had significantly increased interleukin-6 protein compared with controls. Recombinant human proteoglycan-4 significantly reduced interleukin-6 in human and mouse endothelial cells. Interleukin-6 gene expression was significantly increased after lipopolysaccharide treatment compared with controls. This response was reversed by 50 or 100 µg/mL recombinant human proteoglycan-4 in 80% of sepsis samples in human umbilical vascular endothelial cells and in 60-73% in human lung microvascular endothelial cells. In Cd44 -/- genotypes of the mouse lung microvascular endothelial cells, recombinant human proteoglycan-4 significantly reduced interleukin-6 protein levels after lipopolysaccharide treatment, indicating that Cd44 is not needed for recombinant human proteoglycan-4 to have an effect in a toll-like receptor 4 agonist inflammation model. Patient sepsis samples had higher plasma levels of native proteoglycan-4 than controls.

INTERPRETATION AND CONCLUSIONS

Recombinant human proteoglycan-4 is a potential adjunct therapy for sepsis patients and warrants future in vivo model studies.

New markers for sepsis caused by Pseudomonas aeruginosa during burn infection

INTRODUCTION

Sepsis is a leading cause of mortality in burn patients. One of the major causes of sepsis in burn patients is Pseudomonas aeruginosa. We hypothesized that during dissemination from infected burn wounds and subsequent sepsis, P. aeruginosa affects the metabolome of the blood resulting in changes to specific metabolites that would serve as biomarkers for early diagnosis of sepsis caused by P. aeruginosa.

OBJECTIVES

To identify specific biomarkers in the blood after sepsis caused by P. aeruginosa infection of burns.

METHODS

Gas chromatography with time-of-flight mass spectrometry was used to compare the serum metabolome of mice that were thermally injured and infected with P. aeruginosa (B-I) to that of mice that were neither injured nor infected, mice that were injured but not infected, and mice that were infected but not injured.

RESULTS

Serum levels of 19 metabolites were significantly increased in the B-I group compared to controls while levels of eight metabolites were significantly decreased. Thymidine, thymine, uridine, and uracil (related to pyrimidine metabolism), malate and succinate (a possible sign of imbalance in the tricarboxylic acid cycle), 5-oxoproline (related to glutamine and glutathione metabolism), and trans-4-hydroxyproline (a major component of the protein collagen) were increased. Products of amino acid metabolism were significantly decreased in the B-I group, including methionine, tyrosine, indole-3-acetate, and indole-3-propionate.

CONCLUSION

In all, 26 metabolites were identified, including a unique combination of five metabolites (trans-4-hydroxyproline, 5-oxoproline, glycerol-3-galactoside, indole-3-acetate, and indole-3-propionate) that could serve as a set of biomarkers for early diagnosis of sepsis caused by P. aeruginosa in burn patients.

Part II: Minimum Quality Threshold in Preclinical Sepsis Studies (MQTiPSS) for Types of Infections and Organ Dysfunction Endpoints

Although the clinical definitions of sepsis and recommended treatments are regularly updated, a systematic review has not been done for preclinical models. To address this deficit, a Wiggers-Bernard Conference on preclinical sepsis modeling reviewed the 260 most highly cited papers between 2003 and 2012 using sepsis models to create a series of recommendations. This Part II report provides recommendations for the types of infections and documentation of organ injury in preclinical sepsis models. Concerning the types of infections, the review showed that the cecal ligation and puncture model was used for 44% of the studies while 40% injected endotoxin. Recommendation #8 (numbered sequentially from Part I): endotoxin injection should not be considered as a model of sepsis; live bacteria or fungal strains derived from clinical isolates are more appropriate. Recommendation #9: microorganisms should replicate those typically found in human sepsis. Sepsis-3 states that sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection, but the review of the papers showed limited attempts to document organ dysfunction. Recommendation #10: organ dysfunction definitions should be used in preclinical models. Recommendation #11: not all activities in an organ/system need to be abnormal to verify organ dysfunction. Recommendation #12: organ dysfunction should be measured in an objective manner using reproducible scoring systems. Recommendation #13: not all experiments must measure all parameters of organ dysfunction, but investigators should attempt to fully capture as much information as possible. These recommendations are proposed as "best practices" for animal models of sepsis.

Cannabis Sativa Revisited-Crosstalk between microRNA Expression, Inflammation, Oxidative Stress, and Endocannabinoid Response System in Critically Ill Patients with Sepsis

Critically ill patients with sepsis require a multidisciplinary approach, as this situation implies multiorgan distress, with most of the bodily biochemical and cellular systems being affected by the condition. Moreover, sepsis is characterized by a multitude of biochemical interactions and by dynamic changes of the immune system. At the moment, there is a gap in our understanding of the cellular, genetic, and molecular mechanisms involved in sepsis. One of the systems intensely studied in recent years is the endocannabinoid signaling pathway, as light was shed over a series of important interactions of cannabinoid receptors with biochemical pathways, specifically for sepsis. Furthermore, a series of important implications on inflammation and the immune system that are induced by the activity of cannabinoid receptors stimulated by the delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) have been noticed. One of the most important is their ability to reduce the biosynthesis of pro-inflammatory mediators and the modulation of immune mechanisms. Different studies have reported that cannabinoids can reduce oxidative stress at mitochondrial and cellular levels. The aim of this review paper was to present, in detail, the important mechanisms modulated by the endocannabinoid signaling pathway, as well as of the molecular and cellular links it has with sepsis. At the same time, we wish to present the possible implications of cannabinoids in the most important biological pathways involved in sepsis, such as inflammation, redox activity, immune system, and epigenetic expression.

Check Point Inhibitors and Their Role in Immunosuppression in Sepsis

Checkpoint regulators are a group of membrane-bound receptors or ligands expressed on immune cells to regulate the immune cell response to antigen presentation and other immune stimuli, such as cytokines, chemokines, and complement. In the context of profound immune activation, such as sepsis, the immune system can be rendered anergic by these receptors to prevent excessive inflammation and tissue damage. If this septic immunosuppression is prolonged, the host is unable to mount the appropriate immune response to a secondary insult or infection. This article describes the manner in which major regulators in the B7-CD28 family and their ligands mediate immunosuppression in sepsis.

Infection-induced innate antimicrobial response disorders: from signaling pathways and their modulation to selected biomarkers

Severe infections are a major public health problem responsible for about 40-65% of hospitalizations in intensive care units (ICU). The high mortality (30-50%) of persons diagnosed with severe infection is caused by largely unknown mechanisms of sepsis-induced immune system response. Severe infections with dynamic progress are accompanied with SIRS (systemic inflammatory reaction syndrome) and CARS (compensatory anti-inflammatory response syndrome), and require a biological treatment appropriate to the phase of immune response. The mechanisms responsible for severe infection related to immune system response particularly attract extensive interest of non-specific defense mechanisms, including signaling pathways of Toll-like receptors (mainly TLR4 and TLR2) that recognize distinct pathogen-associated molecular patterns (PAMP) and play a critical role in innate immune response. There are attempts of treatment, followed by blocking ligand binding with TLR or modulation of intracellular signaling pathways, to inhibit signal transduction. Moreover, researches regarding new and more efficient diagnostics biomarkers were mostly focused on indicators related to innate response to infection as well as connections of pro-inflammatory response with anti-inflammatory response.According to these studies, in case of ICU septic patients with high-risk of mortality, the solution for the problem will require mainly early immune and genetic diagnostics (e.g. cytokines, microRNA, cluster of differentiation-64 [CD64], triggering receptor expressed on myeloid cells-1 [TREM-1], and high mobility group box 1 protein [HMGB1]).

Lubricin as a Therapeutic and Potential Biomarker in Sepsis

Proteoglycan 4 (or lubricin), a mucin-like glycoprotein, was originally classified as a lubricating substance within diarthrodial joints. More recently, lubricin has been found in other tissues and has been implicated in 2 inflammatory pathways within the cell, via the Toll-like receptors (TLRs) and CD44. Lubricin is an antagonist of TLR2 and TLR4, and appears to enter cells via the CD44 receptor. Because of lubricin's action on these receptors, downstream processes of inflammation are halted, thereby preventing release of cytokines (a hallmark of inflammation and sepsis) from the cell, indicating lubricin's role as a biomarker and possible therapeutic for sepsis.

Diagnostic and prognostic value of interleukin-6, pentraxin 3, and procalcitonin levels among sepsis and septic shock patients: a prospective controlled study according to the Sepsis-3 definitions

Background

This study investigated the clinical value of interleukin-6 (IL-6), pentraxin 3 (PTX3), and procalcitonin (PCT) in patients with sepsis and septic shock diagnosed according to the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3).

Methods

Serum levels of IL-6, PTX3, and PCT were measured in 142 enrolled subjects (51 with sepsis, 46 with septic shock, and 45 as controls). Follow-up IL-6 and PTX3 levels were measured in patients with initial septic shock within 24 h of hospital discharge. Optimal cut-off values were determined for sepsis and septic shock, and prognostic values were evaluated.

Results

Serum IL-6 levels could discriminate sepsis (area under the curve [AUC], 0.83–0.94, P <  0.001; cut-off value, 52.60 pg/mL, 80.4% sensitivity, 88.9% specificity) from controls and could distinguish septic shock (AUC, 0.71–0.89; cut-off value, 348.92 pg/mL, 76.1% sensitivity, 78.4% specificity) from sepsis. Twenty-eight-day mortality was significantly higher in the group with high IL-6 (≥ 348.92 pg/mL) than in the group with low IL-6 (< 348.92 pg/mL) (P = 0.008). IL-6 was an independent risk factor for 28-day mortality among overall patients (hazard ratio, 1.0004; 95% confidence interval, 1.0003–1.0005; p = 0.024). In septic shock patients, both the initial and follow-up PTX3 levels were consistently significantly higher in patients who died than in those who recovered (initial p = 0.004; follow-up P <  0.001).

Conclusions

The diagnostic and prognostic value of IL-6 was superior to those of PTX3 and PCT for sepsis and septic shock.

Is Infrared Spectroscopy Ready for the Clinic?

Fourier transform-infrared spectroscopy (FT-IR) represents an attractive molecular diagnostic modality for translation to the clinic, where comprehensive chemical profiling of biological samples may revolutionize a myriad of pathways in clinical settings. Principally, FT-IR provides a rapid, cost-effective platform to obtain a molecular fingerprint of clinical samples based on vibrational transitions of chemical bonds upon interaction with infrared light. To date, considerable research activities have demonstrated competitive to superior performance of FT-IR strategies in comparison to conventional techniques, with particular promise for earlier, accessible disease diagnostics, thereby improving patient outcomes. However, amidst the changing healthcare landscape in times of aging populations and increased prevalence of cancer and chronic disease, routine adoption of FT-IR within clinical laboratories has remained elusive. Hence, this perspective shall outline the significant clinical potential of FT-IR diagnostics and subsequently address current barriers to translation from the perspective of all stakeholders, in the context of biofluid, histopathology, cytology, microbiology, and biomarker discovery frameworks. Thereafter, future perspectives of FT-IR for healthcare will be discussed, with consideration of recent technological advances that may facilitate future clinical translation.

Association mapping in biomedical time series via statistically significant shapelet mining

Motivation

Most modern intensive care units record the physiological and vital signs of patients. These data can be used to extract signatures, commonly known as biomarkers, that help physicians understand the biological complexity of many syndromes. However, most biological biomarkers suffer from either poor predictive performance or weak explanatory power. Recent developments in time series classification focus on discovering shapelets, i.e. subsequences that are most predictive in terms of class membership. Shapelets have the advantage of combining a high predictive performance with an interpretable component-their shape. Currently, most shapelet discovery methods do not rely on statistical tests to verify the significance of individual shapelets. Therefore, identifying associations between the shapelets of physiological biomarkers and patients that exhibit certain phenotypes of interest enables the discovery and subsequent ranking of physiological signatures that are interpretable, statistically validated and accurate predictors of clinical endpoints.

Results

We present a novel and scalable method for scanning time series and identifying discriminative patterns that are statistically significant. The significance of a shapelet is evaluated while considering the problem of multiple hypothesis testing and mitigating it by efficiently pruning untestable shapelet candidates with Tarone's method. We demonstrate the utility of our method by discovering patterns in three of a patient's vital signs: heart rate, respiratory rate and systolic blood pressure that are indicators of the severity of a future sepsis event, i.e. an inflammatory response to an infective agent that can lead to organ failure and death, if not treated in time.

Availability and implementation

We make our method and the scripts that are required to reproduce the experiments publicly available at https://github.com/BorgwardtLab/S3M.

Supplementary information

Supplementary data are available at Bioinformatics online.

Host-Derived Delta-Like Canonical Notch Ligand 1 as a Novel Diagnostic Biomarker for Bacterial Sepsis-Results From a Combinational Secondary Analysis

Background: Sepsis is a life-threatening syndrome, resulting from a dysbalanced host response to infection. However, especially the early, pro-inflammatory immune response in sepsis is similar to other inflammatory conditions without infectious cause, e.g., trauma or surgery. This aspect challenges the value of current biomarkers for diagnosis, as these are often broadly induced. We earlier identified Delta-like Protein 1 (DLL1), a canonical Notch ligand, to be released from monocytes upon bacterial stimulation. Considering the importance of monocytes in the pathophysiology of sepsis, we hypothesized that this mechanism might occur also in the clinical setting and DLL1 might serve as a biomarker of life-threatening bacterial infection.

Methods: We combined samples from three different studies, including subgroups of patients with sepsis (n = 80), surgical patients (n = 50), trauma patients (n = 36), as well as healthy controls (n = 50). We assessed plasma concentrations of DLL1 using ELISA. We performed Area-under-receiver-operator-curve (AUROC) analysis to evaluate the diagnostic performance of DLL1 compared to leucocytes, C-reactive protein (CRP), and procalcitonin (PCT).

Results: Plasma concentrations of DLL1 were strongly elevated already at sepsis onset and maintained elevated until day 7. In contrast, neither surgical patients nor patients after severe trauma presented with elevated levels, while conventional biomarkers of inflammation (e.g., leucocytes and CRP), responded. AUROC analysis revealed a cut-off of 30 ng/ml associated with the best diagnostic performance, yielding a superior accuracy of 91% for DLL1, compared to 75, 79, and 81% for CRP, leucocytes, and PCT.

Conclusion: DLL1 is a novel host-derived biomarker for the diagnosis of sepsis with a better performance compared to established ones, most likely due to its high robustness in non-infectious inflammatory responses.

Clinical Trial Registration:POCSEP-Trial DRKS00008090; MIRSI DRKS00005463; SPRINT DRKS00010991.

Risk stratification and prognostic evaluation of endothelial cell-specific molecule1, von Willebrand factor, and a disintegrin-like and metalloprotease with thrombospondin type 1 motif for sepsis in the emergency department: An observational study

This study evaluated endothelial cell-specific molecule1 (endocan), von Willebrand factor (vWF), and A disintegrin-like and metalloprotease with thrombospondin type 1 motif (ADAMTS-13), alone or in combination, in the risk stratification and prognosis prediction of patients with sepsis. Clinical data of 301 patients were prospectively analyzed, and divided into systemic inflammatory reaction syndrome, sepsis, severe sepsis, and septic shock groups. A total of 40 healthy individuals were studied as the control group. Endocan, vWF, ADAMTS-13, vWF/ADAMTS-13, and procalcitonin levels were measured, and Acute Physiology and Chronic Health Evaluation (APACHE II) score, Mortality in Emergency Department Sepsis (MEDS) score as well as Sequential Organ Failure Assessment (SOFA) score were calculated. The all-cause death or survival of each patient was recorded during the 28-day follow-up. The endocan, vWF, and vWF/ADAMTS-13 levels significantly increased in patients and were positively correlated with disease severity. On the first day of admission, MEDS score, ADAMTS-13, and vWF/AMAMTS-13 ratio were independent predictors for 28-day mortality from sepsis. Moreover, the combination of vWF/ADAMTS-13 ratio with MEDS score improved the accuracy in predicting the 28-day mortality from sepsis. On day 5, endocan, vWF, ADAMTS-13, and vWF/ADAMTS-13 ratio were independent predictors for the 28-day mortality from sepsis, while the combined use of endocan and vWF/ADAMTS-13 ratio improved the prognostic value of individual indicators. Endocan, vWF, ADAMTS-13, and vWF/ADAMTS-13 ratio are valuable in the risk stratification and prognostic evaluation of sepsis as novel biomarkers.

The Long Pentraxin PTX3 as a Humoral Innate Immunity Functional Player and Biomarker of Infections and Sepsis

The first line of defense in innate immunity is provided by cellular and humoral mediators. Pentraxins are a superfamily of phylogenetically conserved humoral mediators of innate immunity. PTX3, the first long pentraxin identified, is a soluble pattern recognition molecule rapidly produced by several cell types in response to primary pro-inflammatory signals and microbial recognition. PTX3 acts as an important mediator of innate immunity against pathogens of fungal, bacterial and viral origin, and as a regulator of inflammation, by modulating complement activation and cell extravasation, and facilitating pathogen recognition by myeloid cells. In sepsis, PTX3 plasma levels are associated with severity of the condition, patient survival, and response to therapy. In combination with other established biomarkers, PTX3 could improve stratification of sepsis patients and thus, complement the system of classification and monitoring of this disease.

Markers of Inflammation and Infection in Sepsis and Disseminated Intravascular Coagulation

Sepsis is a severe systemic inflammatory response to infection that manifests with widespread inflammation as well as endothelial and coagulation dysfunction that may lead to hypotension, organ failure, shock, and death. Disseminated intravascular coagulation (DIC) is a complication of sepsis involving systemic activation of the fibrinolytic and coagulation pathways that can lead to multi-organ dysfunction, thrombosis, and bleeding, with a 2-fold increase in mortality. This study demonstrates the diagnostic and prognostic value of profiling various biomarkers of inflammation and infection in patients with sepsis-associated DIC to assess the severity of illness. Deidentified samples were obtained from adult patients with sepsis and suspected DIC. Platelet count, prothrombin time, D-dimer, and fibrinogen levels were used to assign International Society of Thrombosis and Hemostasis DIC scores to plasma samples from 103 patients with sepsis and suspected DIC. Using commercially available enzyme-linked immunosorbent assay, chromogenic assay, and RANDOX Biochip methods, levels of procalcitonin (PCT), extracellular nucleosomes, interleukin (IL) 6, IL-8, IL-10, and tumor necrosis factor α (TNFα) were measured in patients with sepsis and DIC and compared to levels in healthy individuals. Elevated levels of PCT, IL-6, IL-8, IL-10, and TNFα were observed in most patients with sepsis and DIC. Additionally, the levels of these markers show significant positive correlations with each other and with DIC score. Currently, no single biomarker can effectively diagnose DIC in patients with sepsis. This study lays the groundwork for the development of a diagnostic algorithm using several markers of inflammation and infection and DIC score as parameters in assessing severity of sepsis-associated coagulopathy in a clinical setting.

Diagnostic and predictive performance of biomarkers in patients with sepsis in an intensive care unit

Objective

This study was performed to compare the predictive performance of serum procalcitonin (PCT), N-terminal brain natriuretic propeptide (NT-proBNP), interleukin-6 (IL-6), prothrombin time (PT), thrombin time (TT), and Sequential Organ Failure Assessment (SOFA) score in the intensive care unit (ICU).

Methods

This retrospective cohort study enrolled 150 patients with sepsis and septic shock and 30 control patients without sepsis. Each patient was followed until death or 28 days. Correlations between variables were assessed with Spearman’s rho test. The Kruskal–Wallis and Mann–Whitney U tests were used for between-group comparisons.

Results

Receiver operating characteristic curve analysis of the SOFA score, PCT, NT-proBNP, IL-6, PT, and TT showed an area under the curve of 0.872, 0.732, 0.711, 0.706, 0.806, and 0.691, respectively, for diagnosing sepsis. Binary logistic regression demonstrated that the SOFA score was an independent predictor of 28-day mortality and septic shock. The correlation coefficient (r) between SOFA and PCT, NT-proBNP and SOFA, IL-6 and SOFA, PT and SOFA, and TT and SOFA was 0.79, 0.52, 0.57, 0.56, and 0.58, respectively.

Conclusion

While the SOFA score is the gold standard, analysis of multiple biomarkers could increase the performance capacity for diagnosis and prognosis in patients with sepsis in the ICU.

Reduction in the IL-6 level at 24 h after admission to the intensive care unit is a survival predictor for Vietnamese patients with sepsis and septic shock: a prospective study

Background

Sepsis and septic shock are common problems in intensive care units (ICUs). The mortality of patients with sepsis or septic shock is high. We investigated if reduction in the serum concentration of the cytokines tumor necrosis factor α, interleukin (IL)-6 and IL-10, and the rate of change in the IL-6 level at 24 h after ICU admission were survival predictors for patients with sepsis and septic shock in a Vietnamese population.

Methods

This was a prospective study conducted at an ICU in Cho Ray Hospital, Vietnam, from October 2014 to October 2016. Patients diagnosed with sepsis or septic shock using validated international guidelines were enrolled. Plasma samples were collected upon (T₀) and 24 h after (T₂₄) ICU admission for measurement of cytokine concentrations. Blood tests were done to detect organ dysfunction. The duration of ICU stays, hospital stay, APACHE II and SOFA scores, and the in-hospital mortality were compared between survival and non-survival groups. Univariate logistic regression and multivariate analysis were done to determine the association between survival and IL-6 reduction at 24 h after ICU admission.

Results

A total of 123 patients were enrolled. The concentration (in pg/mL) of IL-6 at T_o was 413.3 in survivors and 530.0 in non- survivors. At T₂₄, the IL-6 level was 65.4 for survivors and 286.9 for non-survivors. The survival rate was 39.0%. At T₂₄, the concentrations of IL-6 and the reduction in IL-6 level were predictors of survival in patients with sepsis and septic shock. We found a significant association between IL-6 reduction and survival at ≥86% with Odds Ratio (OR) 5.67, 95% Confidence Interval (CI); 1.27–25.3, compared with an increase in the IL-6 rate of change.

Conclusions

Our findings suggested that a reduction in the IL-6 level of ≥86% at 24 h from ICU admission is a survival predictor for patients with sepsis and septic shock in our population.

A computational analysis of dynamic, multi-organ inflammatory crosstalk induced by endotoxin in mice

Bacterial lipopolysaccharide (LPS) induces an acute inflammatory response across multiple organs, primarily via Toll-like receptor 4 (TLR4). We sought to define novel aspects of the complex spatiotemporal dynamics of LPS-induced inflammation using computational modeling, with a special focus on the timing of pathological systemic spillover. An analysis of principal drivers of LPS-induced inflammation in the heart, gut, lung, liver, spleen, and kidney to assess organ-specific dynamics, as well as in the plasma (as an assessment of systemic spillover), was carried out using data on 20 protein-level inflammatory mediators measured over 0-48h in both C57BL/6 and TLR4-null mice. Using a suite of computational techniques, including a time-interval variant of Principal Component Analysis, we confirm key roles for cytokines such as tumor necrosis factor-α and interleukin-17A, define a temporal hierarchy of organ-localized inflammation, and infer the point at which organ-localized inflammation spills over systemically. Thus, by employing a systems biology approach, we obtain a novel perspective on the time- and organ-specific components in the propagation of acute systemic inflammation.

Gram-negative bacterial lipopolysaccharide (LPS) is both a central mediator of sepsis and a canonical inducer of acute inflammation via Toll-like receptor 4 (TLR4). Sepsis involves the systemic spillover of inflammation that normally remains localized in individual organs. The goal of this study was to gain insights into 1) early vs. later drivers of LPS-induced inflammation in various compartments, and 2) the systemic spillover from affected organs vs. local production of inflammatory mediators in the blood. This study involved a large number of data points on the dynamics of inflammatory mediators at the protein level, data-driven computational modeling of principal characteristics and cross-correlations, and validation of key hypotheses. In addition to verifying key mechanisms in LPS/TLR4-driven acute inflammation, this approach yielded key insights into the progression of inflammation across tissues, and also suggested the presence of TLR4-independent pathways (especially in the gut). This is, to our knowledge, the first study examining the dynamic evolution of some key inflammatory mediators and their interactions with each other in both the systemic circulation and within a number of targeted parenchymal organs in mice.

Paving the way for precision medicine v2.0 in intensive care by profiling necroinflammation in biofluids

Current clinical diagnosis is typically based on a combination of approaches including clinical examination of the patient, clinical experience, physiologic and/or genetic parameters, high-tech diagnostic medical imaging, and an extended list of laboratory values mostly determined in biofluids such as blood and urine. One could consider this as precision medicine v1.0. However, recent advances in technology and better understanding of molecular mechanisms underlying disease will allow us to better characterize patients in the future. These improvements will enable us to distinguish patients who have similar clinical presentations but different cellular and molecular responses. Treatments will be able to be chosen more “precisely”, resulting in more appropriate therapy, precision medicine v2.0. In this review, we will reflect on the potential added value of recent advances in technology and a better molecular understanding of necrosis and inflammation for improving diagnosis and treatment of critically ill patients. We give a brief overview on the mutual interplay between necrosis and inflammation, which are two crucial detrimental factors in organ and/or systemic dysfunction. One of the challenges for the future will thus be the cellular and molecular profiling of necroinflammation in biofluids. The huge amount of data generated by profiling biomolecules and single cells through, for example, different omic-approaches is needed for data mining methods to allow patient-clustering and identify novel biomarkers. The real-time monitoring of biomarkers will allow continuous (re)evaluation of treatment strategies using machine learning models. Ultimately, we may be able to offer precision therapies specifically designed to target the molecular set-up of an individual patient, as has begun to be done in cancer therapeutics.

Critical care mostly implies life-threatening situations involving systemic infection, inflammation and necrosis. Biofluids are an easily accessible source of liquid biopsies that can be used to monitor the evolution of the patient’s critical illness. The cellular and molecular profiling of necrosis and inflammation in biofluids using cutting-edge technologies such as realtime immunodiagnostics, next-generation sequencing and mass spectrometry will pave the way for precision medicine v2.0 in critical care. This is needed for data mining approaches to allow patientclustering, identify novel biomarkers and develop novel intervention strategies controlling necrosis and inflammation. The real-time monitoring of biomarkers will allow continued (re)evaluation of treatment strategies using machine learning models.

MALDI-TOF MS monitoring of PBMC activation status in sepsis

Background

MALDI-TOF mass spectrometry (MS) on whole cells enables the detection of different cell types and cell activation. Here, we wondered whether this approach would be useful to investigate the host response in sepsis.

Methods

Peripheral blood mononuclear cells (PBMCs) from patients with severe sepsis and healthy donors were analyzed with MALDI-TOF MS. PBMCs from healthy donors were also stimulated with lipopolysaccharide, peptidoglycan, CpG oligonucleotides, polyinosinic polycytidylic acid, and with heat-inactivated bacteria. Averaged spectra of PBMCs stimulated in vitro by different agonists were generated from the database using the Biotyper software and matching scores between each spectrum from patients and averaged spectra from the database were calculated.

Results

We show that the MALDI-TOF MS signature of PBMCs from septic patients was specific, compared with healthy controls. As the fingerprints observed in patients may be related to PBMC activation, PBMCs from healthy controls were stimulated with cytokines, soluble Pathogen-Associated Molecular Patterns (PAMPs) and heat-killed bacteria, and we created a database of reference spectra. The MALDI-TOF MS profiles of PBMCs from septic patients were then compared with the database. No differences were found between patients with documented infection (n = 6) and those without bacteriological documentation (n = 6). The spectra of PBMCs from septic patients matched with those of interferon-γ- and interleukin-10-stimulated PBMCs, confirming that sepsis is characterized by both inflammatory and immunoregulatory features. Interestingly, the spectra of PBMCs from septic patients without documented infection matched with the reference spectrum of PBMCs stimulated by CpG oligonucleotides, suggesting a bacterial etiology in these patients.

Conclusions

Despite the limits of this preliminary study, these results indicate that the monitoring of functional status of PBMCs in peripheral blood by whole cell MALDI-TOF MS could provide unique opportunities to assess disease progression or resolution in clinical settings.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3266-7) contains supplementary material, which is available to authorized users.