Biomarkers of sepsis: time for a reappraisal

Multi-marker approach using C-reactive protein, procalcitonin, neutrophil CD64 index for the prognosis of sepsis in intensive care unit: a retrospective cohort study

Background

We aimed to explore the prognostic utilities of C-reactive protein (CRP), procalcitonin (PCT), neutrophil CD64 (nCD64) index, in combination or alone, in septic patients.

Methods

We retrospectively included 349 septic patients (based on Sepsis 3.0 definition). The primary outcome was 28-day all-cause mortality. Cox regression model, receiver-operating characteristic (ROC) curve, reclassification analysis, Kaplan–Meier survival curves were performed to evaluate the predictive efficacy of the above parameters.

Results

CRP, nCD64 index were independent predictors of 28-day mortality for sepsis in the Cox regression model [CRP, HR 1.004 (95% CI 1.002–1.006), P < 0.001; nCD64 index, HR 1.263 (95% CI 1.187–1.345, P < 0.001]. Area under the ROC curve (AUC) of CRP, PCT, nCD64 index, nCD64 index plus PCT, nCD64 index plus CRP, were 0.798 (95% CI 0.752–0.839), 0.833 (95% CI 0.790–0.871), 0.906 (95% CI 0.870–0.935), 0.910 (95% CI 0.875–0.938), 0.916 (95% CI 0.881–0.943), respectively. nCD64 plus CRP performed best in prediction, discrimination, and reclassification of the 28-day mortality risk in sepsis. The risk of 28-day mortality increased stepwise as the number of data exceeding optimal cut-off values increased.

Conclusions

nCD64 index combined with CRP was superior to CRP, PCT, nCD64 index and nCD64 index plus PCT in predicting 28-day mortality in sepsis. Multi-marker approach could improve the predictive accuracy and be beneficial for septic patients.

National Early Warning Score and New-Onset Atrial Fibrillation for Predicting In-Hospital Mortality or Transfer to the Intensive Care Unit in Emergency Department Patients with Suspected Bacterial Infections

Purpose

There are conflicting data regarding the role of the National Early Warning Score 2 (NEWS2) in predicting adverse outcomes in patients with infectious diseases. New-onset atrial fibrillation (NO-AF) has been suggested as a sepsis-defining sign of organ dysfunction. This study aimed to examine the prognostic accuracy of NEWS2 and whether NO-AF can provide prognostic information in emergency department (ED) patients with suspected bacterial infections.

Patients and Methods

Secondary analyses of data from a prospective observational cohort study of adults admitted in a 6-month period with suspected bacterial infections. We used the composite endpoint of in-hospital mortality or transfer to the intensive care unit as the primary outcome. The prognostic accuracy of NEWS2 and quick sequential organ failure assessment (qSOFA) and covariate-adjusted area under the receiver operating curves (AAUROC) were used to describe the performance of the scores. Logistic regression analysis was used to examine the association between NO-AF and the composite endpoint.

Results

A total of 2055 patients were included in this study. The composite endpoint was achieved in 198 (9.6%) patients. NO-AF was observed in 80 (3.9%) patients. The sensitivity and specificity for NEWS2 ≥5 were 70.2% (63.3-76.5) and 60.2% (57.9-62.4), respectively, and those for qSOFA ≥2 were 26.3% (20.3-33.0) and 91.0% (89.6-92.3), respectively. AAUROC for NEWS2 and qSOFA were 0.68 (0.65-0.73) and 0.63 (0.59-0.68), respectively. The adjusted odds ratio for achieving the composite endpoint in 48 patients with NO-AF who fulfilled the NEWS2 ≥5 criteria was 2.71 (1.35-5.44).

Conclusion

NEWS2 had higher sensitivity but lower specificity and better, albeit poor, discriminative ability to predict the composite endpoint compared to qSOFA. NO-AF can provide important prognostic information.

Bulk RNA Sequencing With Integrated Single-Cell RNA Sequencing Identifies BCL2A1 as a Potential Diagnostic and Prognostic Biomarker for Sepsis

Background

Sepsis is one of the leading causes of morbidity and mortality worldwide in the intensive care unit (ICU). The prognosis of the disease strongly depends on rapid diagnosis and appropriate treatment. Thus, some new and accurate sepsis-related biomarkers are pressing needed and their efficiency should be carefully demonstrated.

Methods

Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were applied to detect sepsis and monocyte/macrophage-related genes. Least absolute shrinkage and selection operator (LASSO) and random forest regression analyses were used in combination to screen out prognostic genes. Single-cell RNA sequence profiling was utilized to further verify the expression of these genes on a single cell level. Receiver operating characteristic (ROC) curve and decision curve analysis (DCA) were also applied to verify the diagnostic value of the target biomarkers.

Results

The intersections of the genes detected by differential expression and WGCNA analyses identified 141 overlapping candidate genes that were closely related to sepsis and macrophages. The LASSO and random forest regression analyses further screened out 17 prognostic genes. Single-cell RNA sequencing analysis detected that FCGR1A and BCL2A1 might be potential biomarkers for sepsis diagnosis and the diagnostic efficacy of BCL2A1 was further validated by ROC curve and DCA.

Conclusions

It was revealed that BCL2A1 had good diagnostic and prognostic value for sepsis, and that it can be applied as a potential and novel biomarker for the management of the disease.

The Diagnostic Value of Mitochondrial Mass of Peripheral T Lymphocytes in Early Sepsis

Background

Studies have shown that lymphocyte dysfunction can occur during the early stages of sepsis and that cell dysfunction is associated with mitochondrial dysfunction. Therefore, quantifying the mitochondrial function of lymphocytes in patients with sepsis could be valuable for the early diagnosis of sepsis.

Methods

Seventy-nine patients hospitalized from September 2020 to September 2021 with Sepsis-3 were retrospectively analyzed and subsequently compared with those without sepsis.

Results

Univariate analysis showed statistical differences between the data of the two groups regarding age, neutrophil/lymphocyte, procalcitonin (PCT), C-reactive protein, total bilirubin, serum creatinine, type B natriuretic peptide, albumin, prothrombin time, activated partial thromboplastin time, lactic acid, single-cell mitochondrial mass (SCMM)-CD3, SCMM-CD4, SCMM-CD8, and Acute Physiology and Chronic Health Evaluation II score (P < 0.05). Multivariate logistic regression analysis performed on the indicators mentioned above demonstrated a statistical difference in PCT, lactic acid, SCMM-CD4, and SCMM-CD8 levels between the two groups (P < 0.05). The receiver operating characteristic curves of five models were subsequently compared [area under the curve: 0.740 (PCT) vs. 0.933 (SCMM-CD4) vs. 0.881 (SCMM-CD8) vs. 0.961 (PCT + SCMM-CD4) vs. 0.915 (PCT+SCMM-CD8), P < 0.001].

Conclusion

SCMM-CD4 was shown to be a better diagnostic biomarker of early sepsis when compared with the traditional biomarker, PCT. Furthermore, the value of the combination of PCT and SCMM-CD4 in the diagnosis of early sepsis was better than that of SCMM-CD4 alone.

Evaluation of a Multivalent Transcriptomic Metric for Diagnosing Surgical Sepsis and Estimating Mortality Among Critically Ill Patients

Importance

Rapid and accurate discrimination of sepsis and its potential severity currently require multiple assays with slow processing times that are often inconclusive in discerning sepsis from sterile inflammation.

Objective

To analyze a whole-blood, multivalent, host-messenger RNA expression metric for estimating the likelihood of bacterial infection and 30-day mortality and compare performance of the metric with that of other diagnostic and prognostic biomarkers and clinical parameters.

Design, Setting, and Participants

This prospective diagnostic and prognostic study was performed in the surgical intensive care unit (ICU) of a single, academic health science center. The analysis included 200 critically ill adult patients admitted with suspected sepsis (cohort A) or those at high risk for developing sepsis (cohort B) between July 1, 2020, and July 30, 2021.

Exposures

Whole-blood sample measurements of a custom 29-messenger RNA transcriptomic metric classifier for likelihood of bacterial infection (IMX-BVN-3) or 30-day mortality (severity) (IMX-SEV-3) in a clinical-diagnostic laboratory setting using an analysis platform (510[k]-cleared nCounter FLEX; NanoString, Inc), compared with measurement of procalcitonin and interleukin 6 (IL-6) plasma levels, and maximum 24-hour sequential organ failure assessment (SOFA) scores.

Main Outcomes and Measures

Estimated sepsis and 30-day mortality performance.

Results

Among the 200 patients included (124 men [62.0%] and 76 women [38.0%]; median age, 62.5 [IQR, 47.0-72.0] years), the IMX-BVN-3 bacterial infection classifier had an area under the receiver operating characteristics curve (AUROC) of 0.84 (95% CI, 0.77-0.90) for discriminating bacterial infection at ICU admission, similar to procalcitonin (0.85 [95% CI, 0.79-0.90]; P = .79) and significantly better than IL-6 (0.67 [95% CI, 0.58-0.75]; P < .001). For estimating 30-day mortality, the IMX-SEV-3 metric had an AUROC of 0.81 (95% CI, 0.66-0.95), which was significantly better than IL-6 levels (0.57 [95% CI, 0.37-0.77]; P = .006), marginally better than procalcitonin levels (0.65 [95% CI, 0.50-0.79]; P = .06), and similar to the SOFA score (0.76 [95% CI, 0.62-0.91]; P = .48). Combining IMX-BVN-3 and IMX-SEV-3 with procalcitonin or IL-6 levels or SOFA scores did not significantly improve performance. Among patients with sepsis, IMX-BVN-3 scores decreased over time, reflecting the resolution of sepsis. In 11 individuals at high risk (cohort B) who subsequently developed sepsis during their hospital course, IMX-BVN-3 bacterial infection scores did not decline over time and peaked on the day of documented infection.

Conclusions and Relevance

In this diagnostic and prognostic study, a novel, multivalent, transcriptomic metric accurately estimated the presence of bacterial infection and risk for 30-day mortality in patients admitted to a surgical ICU. The performance of this single transcriptomic metric was equivalent to or better than multiple alternative diagnostic and prognostic metrics when measured at admission and provided additional information when measured over time.

The host response in different aetiologies of community-acquired pneumonia

BACKGROUND

Community-acquired pneumonia (CAP) can be caused by a variety of pathogens, of which Streptococcus pneumoniae, Influenza and currently SARS-CoV-2 are the most common. We sought to identify shared and pathogen-specific host response features by directly comparing different aetiologies of CAP.

METHODS

We measured 72 plasma biomarkers in a cohort of 265 patients hospitalized for CAP, all sampled within 48 hours of admission, and 28 age-and sex matched non-infectious controls. We stratified the biomarkers into several pathophysiological domains- antiviral response, vascular response and function, coagulation, systemic inflammation, and immune checkpoint markers. We directly compared CAP caused by SARS-CoV-2 (COVID-19, n=39), Streptococcus pneumoniae (CAP-strep, n=27), Influenza (CAP-flu, n=22) and other or unknown pathogens (CAP-other, n=177). We adjusted the comparisons for age, sex and disease severity scores.

FINDINGS

Biomarkers reflective of a stronger cell-mediated antiviral response clearly separated COVID-19 from other CAPs (most notably granzyme B). Biomarkers reflecting activation and function of the vasculature showed endothelial barrier integrity was least affected in COVID-19, while glycocalyx degradation and angiogenesis were enhanced relative to other CAPs. Notably, markers of coagulation activation, including D-dimer, were not different between the CAP groups. Ferritin was most increased in COVID-19, while other systemic inflammation biomarkers such as IL-6 and procalcitonin were highest in CAP-strep. Immune checkpoint markers showed distinctive patterns in viral and non-viral CAP, with highly elevated levels of Galectin-9 in COVID-19.

INTERPRETATION

Our investigation provides insight into shared and distinct pathophysiological mechanisms in different aetiologies of CAP, which may help guide new pathogen-specific therapeutic strategies.

FUNDING

This study was financially supported by the Dutch Research Council, the European Commission and the Netherlands Organization for Health Research and Development.

Cell-Free DNA as Biomarker for Sepsis by Integration of Microbial and Host Information

BACKGROUND

Cell-free DNA (cfDNA) is emerging as a biomarker for sepsis. Previous studies have been focused mainly on identifying blood infections or simply quantifying cfDNA. We propose that by characterizing multifaceted unexplored components, cfDNA could be more informative for assessing this complex syndrome.

METHODS

We explored multiple aspects of cfDNA in septic and nonseptic intensive care unit (ICU) patients by metagenomic sequencing, with longitudinal measurement and integrative assessment of plasma cfDNA quantity, human cfDNA fragmentation patterns, infecting pathogens, and overall microbial composition.

RESULTS

Septic patients had significantly increased cfDNA quantity and altered human cfDNA fragmentation pattern. Moreover, human cfDNA fragments appeared to comprise information about cellular oxidative stress and could indicate disease severity. Metagenomic sequencing was more sensitive than blood culture in detecting bacterial infections and allowed for simultaneous detection of viral pathogens. We found differences in microbial composition between septic and nonseptic patients and between survivors and nonsurvivors by 28-day mortality, both on the first day of ICU admission and across the study period. By integrating all the information into a machine learning model, we achieved improved performance in identifying sepsis and prediction of clinical outcome for ICU patients with areas under the curve of 0.992 (95% CI 0.969-1.000) and 0.802 (95% CI 0.605-0.999), respectively.

CONCLUSIONS

We were able to diagnose sepsis and predict mortality as soon as the first day of ICU admission by integrating multifaceted cfDNA information obtained in a single metagenomic assay; this approach could provide important advantages for clinical management and for improving outcomes in ICU patients.

Landscape of Metabolic Fingerprinting for Diagnosis and Risk Stratification of Sepsis

Background

Sepsis and septic shock, a subset of sepsis with higher risk stratification, are hallmarked by high mortality rates and necessitated early and accurate biomarkers.

Methods

Untargeted metabolomic analysis was performed to compare the metabolic features between the sepsis and control systemic inflammatory response syndrome (SIRS) groups in discovery cohort, and potential metabolic biomarkers were selected and quantified using multiple reaction monitoring based target metabolite detection method.

Results

Differentially expressed metabolites including 46 metabolites in positive electrospray ionization (ESI) ion mode, 22 metabolites in negative ESI ion mode, and 4 metabolites with dual mode between sepsis and SIRS were identified and revealed. Metabolites 5-Oxoproline, L-Kynurenine and Leukotriene D4 were selected based on least absolute shrinkage and selection operator regularization logistic regression and differential expressed between sepsis and septic shock group in the training and test cohorts. Respective risk scores for sepsis and septic shock based on a 3-metabolite fingerprint classifier were established to distinguish sepsis from SIRS, septic shock from sepsis. Significant relationship between developed sepsis risk scores, septic shock risk scores and Sequential (sepsis-related) Organ Failure Assessment (SOFA), procalcitonin (PCT) and lactic acid were observed.

Conclusions

Collectively, our findings demonstrated that the characteristics of plasma metabolites not only manifest phenotypic variation in sepsis onset and risk stratification of sepsis but also enable individualized treatment and improve current therapeutic strategies.

Copeptin: a neuroendocrine biomarker of COVID-19 severity

Aim: To investigate the change in a serum level of copeptin, a neuroendocrine biomarker, in differentiating grades of COVID-19 severity on admission time and to find its diagnostic potential. Materials & Methods: 160 COVID-19 patients were classified according to disease severity into 80 mild to moderate and 80 severe patients. Serum copeptin level was assessed by ELISA on their admission time. Besides, serum CRP, ferritin and D-dimer were estimated. Results: Severe COVID-19 patients showed higher serum copeptin level in comparison to mild to moderate cases, with diagnostic potential to distinguish disease severity with 93.33% sensitivity and 100% specificity at cutoff value >18.5 Pmol/l. Conclusion: Serum copeptin was remarkably increased with COVID-19 severity with reasonable differentiation potential for recently admitted patients.

Perspectives on the Immune System in Sepsis

Beyond the modifications shown by the biochemistry labs, profound and ample modifications are seen in septic patients at a molecular level stemming from DNA translation and gene expression, manifested as unique profiles of mRNA (messenger), as well as non-coding, functional RNAs: miRNA (micro) and lncRNAs (long non-coding). Counteracting these modifications requires treatment with pleiotropic molecules and/or combination of molecules and opens the possibility of future treatments with arrays of siRNAs and/or specific panels of small molecules tailored for each patient subpopulation.

Minimized Extracorporeal Circulation Is Associated with Reduced Plasma Levels of Free-Circulating Mitochondrial DNA Compared to Conventional Cardiopulmonary Bypass: A Secondary Analysis of an Exploratory, Prospective, Interventional Study

The use of minimized extracorporeal circulation (MiECC) during cardiac surgery is associated with a reduced inflammatory reaction compared to conventional cardiopulmonary bypass (cCPB). Since it is unknown if MiECC also reduces the amount of free-circulating mitochondrial DNA (mtDNA), this study aims to compare MiECC-induced mtDNA release to that of cCPB as well as to identify potential relations between the plasma levels of mtDNA and an adverse outcome. Overall, 45 patients undergoing cardiac surgery with either cCPB or MiECC were included in the study. MtDNA encoding for NADH dehydrogenase 1 was quantified with quantitative polymerase chain reaction. The plasma amount of mtDNA was significantly lower in patients undergoing cardiac surgery with MiECC compared to cCPB (MiECC: 161.8 (65.5−501.9); cCPB 190.8 (82−705.7); p < 0.001). Plasma levels of mtDNA showed comparable kinetics independently of the study group and peaked during CPB (MiECC preoperative: 68.2 (26.5−104.9); MiECC 60 min after start of CPB: 536.5 (215.7−919.6); cCPB preoperative: 152.5 (80.9−207.6); cCPB 60 min after start of CPB: 1818.0 (844.2−3932.2); all p < 0.001). Patients offering an mtDNA blood concentration of >650 copies/µL after the commencement of CPB had a 5-fold higher risk for postoperative atrial fibrillation independently of the type of cardiopulmonary bypass. An amount of mtDNA being higher than 650 copies/µL showed moderate predictive power (AUROC 0.71 (0.53−071)) for the identification of postoperative atrial fibrillation. In conclusion, plasma levels of mtDNA were lower in patients undergoing cardiac surgery with MiECC compared to cCPB. The amount of mtDNA at the beginning of the CPB was associated with postoperative atrial fibrillation independent of the type of cardiopulmonary bypass.

Pancreatic Stone Protein as a Biomarker for Sepsis at the Emergency Department of a Large Tertiary Hospital

Early recognition of sepsis is essential for improving outcomes and preventing complications such as organ failure, depression, and neurocognitive impairment. The emergency department (ED) plays a key role in the early identification of sepsis, but clinicians lack diagnostic tools. Potentially, biomarkers could be helpful in assisting clinicians in the ED, but no marker has yet been successfully implemented in daily practice with good clinical performance. Pancreatic stone protein (PSP) is a promising biomarker in the context of sepsis, but little is known about the diagnostic performance of PSP in the ED. We prospectively investigated the diagnostic value of PSP in such a population for patients suspected of infection. PSP was compared with currently used biomarkers, including white blood cell count (WBC) and C-reactive protein (CRP). Of the 156 patients included in this study, 74 (47.4%) were diagnosed with uncomplicated infection and 26 (16.7%) patients with sepsis, while 56 (35.9%) eventually had no infection. PSP was significantly higher for sepsis patients compared to patients with no sepsis. In multivariate regression, PSP was a significant predictor for sepsis, with an area under the curve (AUC) of 0.69. Positive and negative predictive values for this model were 100% and 84.4%, respectively. Altogether, these findings show that PSP, measured at the ED of a tertiary hospital, is associated with sepsis but lacks the diagnostic performance to be used as single marker.

Predictive Value of Procalcitonin and Neutrophil-to-Lymphocyte Ratio Variations for Bloodstream Infection with Septic Shock

BACKGROUND Little is known of neutrophil-to-lymphocyte ratio (NLR) variations in septic shock. Hence, the predictive value of procalcitonin (PCT) and NLR variations for septic shock in bloodstream infection were explored. MATERIAL AND METHODS We analyzed 146 patients with bloodstream infection admitted to the Intensive Care Unit (ICU) of the First Affiliated Hospital of Anhui Medical University from October 2016 to May 2020. PCT and NLR were evaluated at 0 and 48 h after admission, and their variations (ΔPCT and DNLR) were calculated. The patients were divided into a shock group (n=80) and a non-shock group (n=66) and a gram-positive cocci group (n=69) and a gram-negative bacilli group (n=77). The predictive value of ΔPCT and DNLR was compared among groups. RESULTS AUROC of NLR0h (0.756) higher than PCT0h (0.743).DPCT (0.561 vs 0.301) and ΔNLR (0.609 vs 0.361) were significantly higher in the shock group than in the non-shock group (P<0.05). No significant difference was seen in DPCT and DNLR in the gram-positive cocci infection group. However, the gram-negative bacilli infection group showed a significant difference in ΔPCT (0.606 vs 0.312) and ΔNLR (0.872 vs 0.508) between the shock and non-shock groups (P<0.05). ΔPCT+ΔNLR showed the best area under the curve (0.937), with a high sensitivity (78.80%) and specificity (90.80%), for predicting septic shock. CONCLUSIONS The prediction efficiency of initial NLR is higher than that of PCT. ΔPCT+ΔNLR best predicted septic shock in patients with bloodstream infections, with better accuracy for gram-negative infections.

The Potential Cost and Cost-Effectiveness Impact of Using a Machine Learning Algorithm for Early Detection of Sepsis in Intensive Care Units in Sweden

Background: Early diagnosis of sepsis has been shown to reduce treatment delays, increase appropriate care, and reduce mortality. The sepsis machine learning algorithm NAVOY® Sepsis, based on variables routinely collected at intensive care units (ICUs), has shown excellent predictive properties. However, the economic consequences of forecasting the onset of sepsis are unknown. Objectives: The potential cost and cost-effectiveness impact of a machine learning algorithm forecasting the onset of sepsis was estimated in an ICU setting. Methods: A health economic model has been developed to capture short-term and long-term consequences of sepsis. The model is based on findings from a randomized, prospective clinical evaluation of NAVOY® Sepsis and from literature sources. Modeling the relationship between time from sepsis onset to treatment and prevalence of septic shock and in-hospital mortality were of particular interest. The model base case assumes that the time to treatment coincides with the time to detection and that the algorithm predicts sepsis 3 hours prior to onset. Total costs include the costs of the prediction algorithm, days spent at the ICU and hospital ward, and long-term consequences. Costs are estimated for an average patient admitted to the ICU and for the healthcare system. The reference method is sepsis diagnosis in accordance with clinical practice. Results: In Sweden, the total cost per patient amounts to €16 436 and €16 512 for the algorithm and current practice arms, respectively, implying a potential cost saving per patient of €76. The largest cost saving is for the ICU stay, which is reduced by 0.16 days per patient (5860 ICU days for the healthcare sector) resulting in a cost saving of €1009 per ICU patient. Stochastic scenario analysis showed that NAVOY® Sepsis was a dominant treatment option in most scenarios and well below an established threshold of €20 000 per quality-adjusted life-year. A 3-hour faster detection implies a reduction in in-hospital mortality, resulting in 356 lives saved per year. Conclusions: A sepsis prediction algorithm such as NAVOY® Sepsis reduces the cost per ICU patient and will potentially have a substantial cost-saving and life-saving impact for ICU departments and the healthcare system.

Novel Damage Biomarkers of Sepsis-Related Acute Kidney Injury

Sepsis-related acute kidney injury (AKI) is one of the most common complications of sepsis at the intensive care unit (ICU) with more adverse mortality rates. The early diagnosis and reliable monitoring of sepsis-related AKI are essential in achieving a favorable outcome. Novel serum and urinary biomarkers could yield valuable information during this process. Regarding the widely used Kidney Disease Improving Global Outcomes (KDIGO) classifications, the diagnosis of AKI is still based on the increase of serum creatinine levels and the decrease of urine output; however, these parameters have limitations in reflecting the extent of kidney damage, therefore more sensitive and specific laboratory biomarkers are needed for the early diagnosis and prognosis of sepsis-related AKI. Regarding this, several serum parameters are discussed in this review including presepsin and the most important actin scavenger proteins (gelsolin, Gc-globulin) while other urinary markers are also examined including cell cycle arrest biomarkers, neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), Cystatin C and actin. Novel biomarkers of sepsis-related AKI could facilitate the early diagnosis and monitoring of sepsis-related AKI.

Coagulation factor protein abundance in the pre-septic state predicts coagulopathic activities that arise during late-stage murine sepsis

BACKGROUND

Although sepsis accounts for 1 in 5 deaths globally, few molecular therapies exist for this condition. The development of effective biomarkers and treatments for sepsis requires a more complete understanding of host responses and pathogenic mechanisms at early stages of disease to minimize host-driven pathology.

METHODS

An alternative to the current symptom-based approach used to diagnose sepsis is a precise assessment of blood proteomic changes during the onset and progression of Salmonella Typhimurium (ST) murine sepsis.

FINDINGS

A distinct pattern of coagulation factor protein abundance was identified in the pre-septic state- prior to overt disease symptoms or bacteremia- that was predictive of the dysregulation of fibrinolytic and anti-coagulant activities and resultant consumptive coagulopathy during ST murine sepsis. Moreover, the changes in protein abundance observed generally have the same directionality (increased or decreased abundance) reported for human sepsis. Significant overlap of ST coagulopathic activities was observed in Gram-negative Escherichia coli- but not in Gram-positive staphylococcal or pneumococcal murine sepsis models. Treatment with matrix metalloprotease inhibitors prevented aberrant inflammatory and coagulopathic activities post-ST infection and increased survival. Antibiotic treatment regimens initiated after specific changes arise in the plasma proteome post-ST infection were predictive of an increase in disease relapse and death after cessation of antibiotic treatment.

INTERPRETATION

Altered blood proteomics provides a platform to develop rapid and easy-to-perform tests to predict sepsis for early intervention via biomarker incorporation into existing blood tests prompted by patient presentation with general malaise, and to stratify Gram-negative and Gram-positive infections for appropriate treatment. Antibiotics are less effective in microbial clearance when initiated after the onset of altered blood proteomics as evidenced by increased disease relapse and death after termination of antibiotic therapy. Treatment failure is potentially due to altered bacterial / host-responses and associated increased host-driven pathology, providing insight into why delays in antibiotic administration in human sepsis are associated with increased risk for death. Delayed treatment may thus require prolonged therapy for microbial clearance despite the prevailing notion of antibiotic de-escalation and shortened courses of antibiotics to improve drug stewardship.

FUNDING

National Institutes of Health, U.S. Army.

Monocyte distribution width as part of a broad pragmatic sepsis screen in the emergency department

STUDY OBJECTIVE

Enhancement of a routine complete blood count (CBC) for detection of sepsis in the emergency department (ED) has pragmatic utility for early management. This study evaluated the performance of monocyte distribution width (MDW) alone and in combination with other routine CBC parameters as a screen for sepsis and septic shock in ED patients.

METHODS

A prospective cohort analysis of adult patients with a CBC collected at an urban ED from January 2020 through July 2021. The performance of MDW, white blood count (WBC) count, and neutrophil-to-lymphocyte-ratio (NLR) to detect sepsis and septic shock (Sepsis-3 Criteria) was evaluated using diagnostic performance measures.

RESULTS

The cohort included 7952 ED patients, with 180 meeting criteria for sepsis; 43 with septic shock and 137 without shock. MDW was highest for patients with septic shock (median 24.8 U, interquartile range [IQR] 22.0-28.1) and trended downward for patients with sepsis without shock (23.9 U, IQR 20.2-26.8), infection (20.4 U, IQR 18.2-23.3), then controls (18.6 U, IQR 17.1-20.4). In isolation, MDW detected sepsis and septic shock with an area under the receiver operator characteristic curve (AUC) of 0.80 (95% confidence interval [CI] 0.77-0.84) and 0.85 (95% CI 0.80-0 .91), respectively. Optimal performance was achieved in combination with WBC count and NLR for detection of sepsis (AUC 0.86, 95% CI 0.83-0.89) and septic shock (0.86, 95% CI 0.80-0.92).

CONCLUSION

A CBC differential panel that includes MDW demonstrated strong performance characteristics in a broad ED population suggesting pragmatic value as a rapid screen for sepsis and septic shock.

The prognostic value of N-terminal pro-brain natriuretic peptide (NT-proBNP) in major burn patients with sepsis

The aim is to examine the prognostic value of N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with major burns and sepsis. We collected the data of major burn patients who were admitted to our department. We compared the age, sex, burn area, burn depth, length of hospitalization, and mortality rate between the sepsis group and non-sepsis group and compared NT-proBNP, procalcitonin (PCT), platelet count, Sequential Organ Failure Assessment (SOFA) score, and quick SOFA (qSOFA) score between the survivors and nonsurvivors in the sepsis group. Receiver operating characteristic (ROC) curves were used in sepsis patients to evaluate the prognostic value of NT-proBNP, PCT, SOFA score, qSOFA score, et al.. Kaplan-Meier survival curves were used to compare the 90-day survival curves of patients. Logistic regression analysis was used to analyse the risk factors that affect the prognosis of sepsis patients. There were 90 major burn patients with sepsis and 114 major burn patients without sepsis. The mortality rate for the major burn sepsis group was significantly higher than that for the non-sepsis group. The NT-proBNP level in sepsis patients in the nonsurvivor group was 2900 pg/mL, which was significantly higher than that in patients in the survivor group. Survival analysis showed that the mean survival time for the NT-proBNP >2000 pg/mL group was 15.08 days. Multivariate regression analysis indicated that NT-proBNP was an independent risk factor for mortality in burn patients with sepsis. NT-proBNP can be used as a prognostic marker in patients with major burns and sepsis.

A Three-Protein Panel to Support the Diagnosis of Sepsis in Children

Sepsis is a syndrome without a standard validated diagnostic test. Early recognition is crucial. Serum proteome analysis in children with sepsis may identify new biomarkers. This study aimed to find suitable blood biomarkers for an early diagnosis of sepsis. An analytical observational case-control study was carried out in a single center. Children admitted to a Pediatric Intensive Care Unit with clinical diagnosed sepsis were eligible for study. A proteomic analysis conducted by mass spectrometry was performed. Forty patients with sepsis and 24 healthy donors were recruited. Proteomics results revealed 44 proteins differentially expressed between patients and healthy controls. Six proteins were selected to be validated: lactoferrin, serum amyloid-A1 (SAA-1), complement factor B, leucine-rich alpha-2 glycoprotein (LRG1), soluble interleukin-2 alpha chain receptor (sCD25) and soluble haptoglobin−hemoglobin receptor. Our results showed that sCD25, SAA-1, and LRG1 had high levels of specificity and sensitivity, as well as an excellent area under the ROC curve (>0.9). Our study provides a serum proteomic analysis that identifies new diagnostic biomarkers in sepsis. SAA-1, sCD25 and LRG1 were able to separate septic from healthy donor, so they could be used together with other clinical and analytical features to improve sepsis diagnosis in children.

Evaluation of the diagnostic and prognostic values of serum HSP90α in sepsis patients: a retrospective study

Background

Sepsis is a serious syndrome that is caused by immune responses dysfunction and leads to high mortality. The abilities of heat shock protein 90α (HSP90α) in assessing the diagnosis and prognosis in patients with sepsis remain ill-defined to date. We conducted a study to reveal the possible clinical applications of HSP90α as biomarker for the diagnosis and prognosis in patients with sepsis.

Methods

In total, 150 patients of sepsis, 110 patients without sepsis admitted to ICU and 110 healthy subjects were involved in this study. The serum HSP90α contents, sequential organ failure assessment (SOFA) scores, procalcitonin (PCT), and short-term survival status of the participants were measured and compared. Logistic and linear regression models adjusting for potential confounders were used to examine the association of HSP90α with sepsis survival. Moreover, serum IL-1β, IL-18, MIP-3α, and ENA-78 were also determined. Finally, Spearman correlation analysis was employed to reveal a possible mechanism that HSP90α contributed to the short-term deaths.

Results

Serum HSP90α levels in sepsis patients were higher than those in ICU controls and healthy controls (P < 0.001), and even increased in patients who died within 28 days (P < 0.001). Logistic and linear regression models identified HSP90α was an independent risk factors for sepsis mortality. Receiver operating characteristic (ROC) analysis displayed that HSP90α had a considerable predictive performance for sepsis outcome, with an area under curve (AUC) value up to 0.79. Survival analysis demonstrated that the mortality of sepsis individuals at 28 days was positively associated with HSP90α levels, especially the levels of HSP90α were greater than 120 ng/mL (P < 0.001). Moreover, among sepsis patients, those who died had notably elevated cytokines, IL-1β, IL-18, and chemokines, MIP-3α, ENA-78, relative to survivors. Further correlation analysis demonstrated that there was a nominally positive correlation between HSP90α and IL-1β, IL-18, and MIP-3α.

Conclusion

HSP90α is of favorable clinical significance in sepsis diagnosis and prognosis, laying a foundation for future clinical applications.

Value of CRP, PCT, and NLR in Prediction of Severity and Prognosis of Patients With Bloodstream Infections and Sepsis

Objective

To investigate the value of C-reactive protein (CRP), procalcitonin (PCT), and neutrophil to lymphocyte ratio (NLR) in assessing the severity of disease in patients with bloodstream infection and sepsis, and to analyze the relationship between the levels of three inflammatory factors and the prognosis of patients.

Methods

The clinical data of 146 patients with bloodstream infection and sepsis admitted to our intensive care unit (ICU) from October 2016 to May 2020 were retrospectively analyzed. The differences in the levels of inflammatory indicators such as CRP, PCT, and NLR within 24 h in patients with bloodstream infection sepsis with different conditions (critical group, non-critical group) and the correlation between these factors and the condition (acute physiology and chronic health evaluation II, APACHE II score) were analyzed. In addition, the prognosis of all patients within 28 days was counted, and the patients were divided into death and survival groups according to their mortality, and the risk factors affecting their death were analyzed by logistic regression, and the receiver operating characteristic (ROC) curve was used to analyze the value of the relevant indicators in assessing the prognosis of patients.

Results

The levels of NLR, CRP, PCT, total bilirubin (TBIL), glutamic oxaloacetic transaminase (AST), and serum creatinine (Scr) were significantly higher in the critically ill group than in the non-critically ill group, where correlation analysis revealed a positive correlation between CRP, PCT, and NLR and APACHE II scores (P < 0.05). Univariate logistic regression analysis revealed that CRP, PCT, NLR, and APACHE II scores were associated with patient prognosis (P < 0.05). Multi-factor logistic regression analysis found that PCT, NLR, and APACHE II scores were independent risk factors for patient mortality within 28 days (P < 0.05). ROC curve analysis found that PCT and NLR both had an AUC area > 0.7 in predicting patient death within 28 days (P < 0.05).

Conclusion

Inflammatory factors such as NLR, CRP, and PCT have important clinical applications in the assessment of the extent of disease and prognosis of patients with bloodstream infection and sepsis.

Biomarkers Predicting Tissue Pharmacokinetics of Antimicrobials in Sepsis: A Review

The pathophysiology of sepsis alters drug pharmacokinetics, resulting in inadequate drug exposure and target-site concentration. Suboptimal exposure leads to treatment failure and the development of antimicrobial resistance. Therefore, we seek to optimize antimicrobial therapy in sepsis by selecting the right drug and the correct dosage. A prerequisite for achieving this goal is characterization and understanding of the mechanisms of pharmacokinetic alterations. However, most infections take place not in blood but in different body compartments. Since tissue pharmacokinetic assessment is not feasible in daily practice, we need to tailor antibiotic treatment according to the specific patient’s pathophysiological processes. The complex pathophysiology of sepsis and the ineffectiveness of current targeted therapies suggest that treatments guided by biomarkers predicting target-site concentration could provide a new therapeutic strategy. Inflammation, endothelial and coagulation activation markers, and blood flow parameters might be indicators of impaired tissue distribution. Moreover, hepatic and renal dysfunction biomarkers can predict not only drug metabolism and clearance but also drug distribution. Identification of the right biomarkers can direct drug dosing and provide timely feedback on its effectiveness. Therefore, this might decrease antibiotic resistance and the mortality of critically ill patients. This article fills the literature gap by characterizing patient biomarkers that might be used to predict unbound plasma-to-tissue drug distribution in critically ill patients. Although all biomarkers must be clinically evaluated with the ultimate goal of combining them in a clinically feasible scoring system, we support the concept that the appropriate biomarkers could be used to direct targeted antibiotic dosing.

Combination of Prehospital NT-proBNP with qSOFA and NEWS to Predict Sepsis and Sepsis-Related Mortality

Background. The aim of this study was to assess the role of prehospital point-of-care N-terminal probrain natriuretic peptide to predict sepsis, septic shock, or in-hospital sepsis-related mortality. Methods. A prospective, emergency medical service-delivered, prognostic, cohort study of adults evacuated by ambulance and admitted to emergency department between January 2020 and May 2021. The discriminative power of the predictive variable was assessed through a prediction model trained using the derivation cohort and evaluated by the area under the curve of the receiver operating characteristic on the validation cohort. Results. A total of 1,360 patients were enrolled with medical disease in the study. The occurrence of sepsis, septic shock, and in-hospital sepsis-related mortality was 6.4% (67 cases), 4.2% (44 cases), and 6.1% (64 cases). Prehospital National Early Warning Score 2 had superior predictive validity than quick Sequential Organ Failure Assessment and N-terminal probrain natriuretic peptide for detecting sepsis and septic shock, but N-terminal probrain natriuretic peptide outperformed both scores in in-hospital sepsis-related mortality estimation. Application of N-terminal probrain natriuretic peptide to subgroups of the other two scores improved the identification of sepsis, septic shock, and sepsis-related mortality in the group of patients with low-risk scoring. Conclusions. The incorporation of N-terminal probrain natriuretic peptide in prehospital care combined with already existing scores could improve the identification of sepsis, septic shock, and sepsis-related mortality.

Pancreatic Stone Protein: Review of a New Biomarker in Sepsis

Sepsis is a life-threatening syndrome characterized by a dysregulated host response to an infection that may evolve rapidly into septic shock and multiple organ failure. Management of sepsis relies on the early recognition and diagnosis of infection and the providing of adequate and prompt antibiotic therapy and organ support. A novel protein biomarker, the pancreatic stone protein (PSP), has recently been studied as a biomarker of sepsis and the available evidence suggests that it has a higher diagnostic performance for the identification of infection than the most used available biomarkers and adds prognostic value. This review summarizes the clinical evidence available for PSP in the diagnosis and prognosis of sepsis.

A 2-year retrospective analysis of the prognostic value of MqSOFA compared to lactate, NEWS and qSOFA in patients with sepsis

Purpose

Sepsis is a life-threating organ dysfunction caused by a dysregulated host response to infection. Being a time-dependent condition, the present study aims to compare a recently established score, i.e., modified quick SOFA (MqSOFA), with other existing tools commonly applied to predict in-hospital mortality.

Methods

All cases of sepsis and septic shock consecutively observed at St. Anna University Hospital of Ferrara, Italy, from January 2017 to December 2018 were included in this study. Each patient was evaluated with MqSOFA, lactate assay, NEWS and qSOFA. Accurate statistical and logistic regression analyses were applied to our database.

Results

A total of 1001 consecutive patients with sepsis/septic shock were retrieved. Among them, 444 were excluded for incomplete details about vital parameters; thus, 556 patients were eligible for the study. Data analysis showed that MqSOFA, NEWS and lactate assay provided a better predictive ability than qSOFA in terms of in-hospital mortality (p < 0.001). Aetiology-based stratification in 5 subgroups demonstrated the superiority of NEWS vs. other tools in predicting fatal outcomes (p = 0.030 respiratory, p = 0.036 urinary, p = 0.044 abdominal, p = 0.047 miscellaneous and p = 0.041 for indeterminate causes). After Bonferroni’s correction, MqSOFA was superior to qSOFA over respiratory (p < 0.001) and urinary (p < 0.001) aetiologies. Age was an independent factor for negative outcomes (p < 0.001).

Conclusions

MqSOFA, NEWS and lactate assay better predicted in-hospital mortality compared to qSOFA. Since sepsis needs a time-dependent assessment, an easier and non-invasive score, i.e., MqSOFA, could be used to establish patients’ outcome in the emergency setting.

Antimicrobial Stewardship in the ICU

Increasing rates of infection and multidrug-resistant pathogens, along with a high use of antimicrobial therapy, make the intensive care unit (ICU) an ideal setting for implementing and supporting antimicrobial stewardship efforts. Overuse of antimicrobial agents is common in the ICU, as practitioners are challenged daily with achieving early, appropriate empiric antimicrobial therapy to improve patient outcomes. While early antimicrobial stewardship programs focused on the financial implications of antimicrobial overuse, current goals of stewardship programs align closely with those of critical care providers-to optimize patient outcomes, reduce development of resistance, and minimize adverse outcomes associated with antibiotic overuse and misuse such as acute kidney injury and Clostridioides difficile-associated disease. Significant opportunities exist in the ICU for critical care clinicians to support stewardship practices at the bedside, including thoughtful and restrained initiation of antimicrobial therapy, use of biomarkers in addition to rapid diagnostics, Staphylococcus aureus screening, and traditional microbiologic culture and susceptibilities to guide antibiotic de-escalation, and use of the shortest duration of therapy that is clinically appropriate. Integration of critical care practitioners into the initiatives of antimicrobial stewardship programs is key to their success. This review summarizes key components of antimicrobial stewardship programs and mechanisms for critical care practitioners to share the responsibility for antimicrobial stewardship.

Managing sepsis in the era of precision medicine: challenges and opportunities

INTRODUCTION

Precision medicine is a medical model in which decisions, practices, interventions and therapies are tailored to the individual patient based on their predicted response or risk of disease. Sepsis is a life-threatening condition characterized by immune system dysregulation whose pathophysiology remains incompletely understood. There is much hope that precision medicine can lead to better outcomes in patients with sepsis.

AREAS COVERED

In this review from a comprehensive literature search in PubMed for English-language studies conducted in adults, we highlight recent advances in the diagnosis and treatment of sepsis of bacterial origin in adults using precision medicine approaches including rapid diagnostic tests, predictive biomarkers, genomic methods, rapid antimicrobial susceptibility testing, and monitoring cell mediated immunity. Challenges and directions for future research are also discussed.

EXPERT OPINION

Current diagnostic testing in sepsis relies primarily on conventional cultures (e.g. blood cultures), which are time-consuming and may delay critical therapeutic decisions. Nonculture-based techniques including nucleic acid amplification technologies (NAAT), other molecular methods (biomarkers), and genomic sequencing offer promise to overcome some of the inherent limitations seen with culture-based techniques.

Investigating Morphological Changes of T-lymphocytes after Exposure with Bacterial Determinants for Early Detection of Septic Conditions

Sepsis is a leading cause of morbidity and mortality, annually affecting millions of people worldwide. Immediate treatment initiation is crucial to improve the outcome but despite great progress, early identification of septic patients remains a challenge. Recently, white blood cell morphology was proposed as a new biomarker for sepsis diagnosis. In this proof-of-concept study, we aimed to investigate the effect of different bacteria and their determinants on T-lymphocytes by digital holographic microscopy (DHM). We hypothesize that species- and strain-specific morphological changes occur, which may offer a new approach for early sepsis diagnosis and identification of the causative agent. Jurkat cells as a model system were exposed to different S. aureus or E. coli strains either using sterile determinants or living bacteria. Time-lapse DHM was applied to analyze cellular morphological changes. There were not only living bacteria but also membrane vesicles and sterile culture supernatant-induced changes of cell area, circularity, and mean phase contrast. Interestingly, different cellular responses occurred depending on both the species and strain of the causative bacteria. Our findings suggest that investigation of T-lymphocyte morphology might provide a promising tool for the early identification of bacterial infections and possibly discrimination between different causative agents. Distinguishing gram-positive from gram-negative infection would already offer a great benefit for the proper administration of antibiotics.

Diagnostic Potential of Plasma Extracellular Vesicle miR-483-3p and Let-7d-3p for Sepsis

Background: microRNAs (miRNAs) from circulating extracellular vesicles (EVs) have been reported as disease biomarkers. This study aimed to identify the diagnostic value of plasma EV-miRNAs in sepsis.

Methods: EVs were separated from the plasma of sepsis patients at admission and healthy controls. The expression of EV-miRNAs was evaluated by microarray and qRT-PCR.

Results: A preliminary miRNA microarray of plasma EVs from a discovery cohort of 3 sepsis patients at admission and three healthy controls identified 11 miRNAs with over 2-fold upregulation in sepsis group. Based on this finding, EV samples from a validation cohort of 37 sepsis patients at admission and 25 healthy controls were evaluated for the expression of the 6 miRNAs relating injury and inflammation via qRT-PCR. Elevated expression of miR-483-3p and let-7d-3p was validated in sepsis patients and corroborated in a mouse model of sepsis. miR-483-3p and let-7d-3p levels positively correlated with the disease severity. Additionally, a combination of miR-483-3p and let-7d-3p had diagnostic value for sepsis. Furthermore, bioinformatic analysis and experimental validation showed that miR-483-3p and let-7d-3p target pathways regulating immune response and endothelial function.

Conclusion: The present study reveals the potential role of plasma EV-miRNAs in the pathogenesis of sepsis and the utility of combining miR-483-3p and let-7d-3p as biomarkers for early sepsis diagnosis.

Association between oxidized nucleobases and mitochondrial DNA damage with long-term mortality in patients with sepsis

BACKGROUND

Sepsis not only leads to short-term mortality during hospitalization, but is also associated with increased mortality during long-term follow-up after hospital discharge. Metabolic stress during sepsis may cause oxidative damage to both nuclear and mitochondrial DNA (mtDNA) and RNA, which could affect long-term health and life span. Therefore, the aim of this study was to assess the association of sepsis with oxidized nucleobases and (mt)DNA damage and long-term all-cause mortality in septic patients.

METHODS

91 patients with sepsis who visited the emergency department (ED) of the University Medical Center Groningen between August 2012 and June 2013 were included. Urine and plasma were collected during the ED visit. Septic patients were matched with 91 healthy controls. Death rate was obtained until June 2020.The degree of oxidation of DNA, RNA and free nucleobases were assessed in urine by mass-spectrometry. Lipid peroxidation was assessed in plasma using a TBAR assay. Additionally, plasma levels of mtDNA and damage to mtDNA were determined by qPCR.

RESULTS

Sepsis patients denoted higher levels of oxidated DNA, RNA, free nucleobases and lipid peroxidation than controls (all p < 0.01). Further, sepsis patients displayed an increase in plasma mtDNA with an increase in mtDNA damage compared to matched controls (p < 0.01). Kaplan meier survival analyses revealed that high degrees of RNA- and nucleobase oxidation were associated with higher long-term all-cause mortality after sepsis (p < 0.01 and p = 0.01 respectively). Of these two, high RNA oxidation was associated with long-term all-cause mortality, independent of adjustment for age, medical history and sepsis severity (HR 1.29 [(1.17-1.41, 95% CI] p < 0.01).

CONCLUSIONS

Sepsis is accompanied with oxidation of nuclear and mitochondrial DNA and RNA, where RNA oxidation is an independent predictor of long-term all-cause mortality. In addition, sepsis causes mtDNA damage and an increase in cell free mtDNA in plasma.

Omics of endothelial cell dysfunction in sepsis

During sepsis, defined as life-threatening organ dysfunction due to dysregulated host response to infection, systemic inflammation activates endothelial cells and initiates a multifaceted cascade of pro-inflammatory signaling events, resulting in increased permeability and excessive recruitment of leukocytes. Vascular endothelial cells share many common properties but have organ-specific phenotypes with unique structure and function. Thus, therapies directed against endothelial cell phenotypes are needed to address organ-specific endothelial cell dysfunction. Omics allow for the study of expressed genes, proteins and/or metabolites in biological systems and provide insight on temporal and spatial evolution of signals during normal and diseased conditions. Proteomics quantifies protein expression, identifies protein-protein interactions and can reveal mechanistic changes in endothelial cells that would not be possible to study via reductionist methods alone. In this review, we provide an overview of how sepsis pathophysiology impacts omics with a focus on proteomic analysis of mouse endothelial cells during sepsis/inflammation and its relationship with the more clinically relevant omics of human endothelial cells. We discuss how omics has been used to define septic endotype signatures in different populations with a focus on proteomic analysis in organ-specific microvascular endothelial cells during sepsis or septic-like inflammation. We believe that studies defining septic endotypes based on proteomic expression in endothelial cell phenotypes are urgently needed to complement omic profiling of whole blood and better define sepsis subphenotypes. Lastly, we provide a discussion of how in silico modeling can be used to leverage the large volume of omics data to map response pathways in sepsis.

Biomarkers for sepsis: more than just fever and leukocytosis-a narrative review

A biomarker describes a measurable indicator of a patient's clinical condition that can be measured accurately and reproducibly. Biomarkers offer utility for diagnosis, prognosis, early disease recognition, risk stratification, appropriate treatment (theranostics), and trial enrichment for patients with sepsis or suspected sepsis. In this narrative review, we aim to answer the question, "Do biomarkers in patients with sepsis or septic shock predict mortality, multiple organ dysfunction syndrome (MODS), or organ dysfunction?" We also discuss the role of pro- and anti-inflammatory biomarkers and biomarkers associated with intestinal permeability, endothelial injury, organ dysfunction, blood-brain barrier (BBB) breakdown, brain injury, and short and long-term mortality. For sepsis, a range of biomarkers is identified, including fluid phase pattern recognition molecules (PRMs), complement system, cytokines, chemokines, damage-associated molecular patterns (DAMPs), non-coding RNAs, miRNAs, cell membrane receptors, cell proteins, metabolites, and soluble receptors. We also provide an overview of immune response biomarkers that can help identify or differentiate between systemic inflammatory response syndrome (SIRS), sepsis, septic shock, and sepsis-associated encephalopathy. However, significant work is needed to identify the optimal combinations of biomarkers that can augment diagnosis, treatment, and good patient outcomes.

Role of myeloid derived suppressor cells in sepsis

Sepsis is a serious and menacing organ dysfunction that occur due to dysregulated response of the host towards the infection. This organ dysfunction may lead to sepsis with intense cellular, metabolic and circulatory dysregulation, multiple organ failure and high mortality. Lymphopenia is observed in two-third of sepsis patients and a significant depletion of lymphocytes occurs in non-survivors compared to sepsis survivors. Myeloid derived suppressor cells (MDSCs) gave new insights into sepsis-associated lymphopenia. If MDSC expansion and its tissue-infiltration persist, it can induce significant pathophysiology including lymphopenia, host immunosuppression and immune-paralysis that contributes to worsened patient outcomes. This review focuses on MDSCs and its subsets, the role of MDSCs in infection, sepsis and septic shock.

The procalcitonin-to-cortisol ratio is a potential prognostic predictor in sepsis with abdominal source: a retrospective observational study

BACKGROUND

The aim of the study was to investigate the procalcitonin-to-cortisol ratio (P/C ratio) as a prognostic predictor among septic patients with abdominal source.

METHODS

We retrospectively enrolled 132 post-surgery patients between 18 and 90 years old with sepsis of the abdominal source. On the second day of sepsis onset, cortisol, procalcitonin (PCT), Acute Physiology and Chronic Health Evaluation (APACHE) II score, Sequential Organ Failure Assessment (SOFA) score, C-response protein (CRP), and other baseline characteristics were collected. In addition, the length of ICU stay, length of mechanical ventilation (MV) days, length of shock days, and 28-day mortality were also recorded. Univariate analysis was performed to screen potential risk factors. Stratified analysis was used to identify the interaction among the risk factors. Multivariate analysis was also utilized to demonstrate the relationship between the risk factors and mortality. The receiver operator characteristic (ROC) curve analysis was conducted to evaluate the risk factors. A restricted cubic spline (RCS) demonstrated the association between survival outcome and the P/C ratio variation.

RESULTS

A total of twenty-nine patients died, and 103 patients survived within 28 d. There were significant differences in cortisol, PCT, P/C ratio, interleukin (IL)-6, SOFA, and APACHE II scores between the survival and non-survival groups. No significant interaction was observed in the stratified analysis. Logistic regression analysis revealed that P/C ratio (P=0.033) was significantly related to 28-day mortality. Based on ROC curves, P/C ratio (AUC=0.919) had a higher AUC value than cortisol or PCT. RCS analysis depicted a positive relationship between survival possibility and P/C ratio decrement.

CONCLUSION

P/C ratio might be a potential prognostic predictor in septic patients with abdominal sources.

Source-specific host response and outcomes in critically ill patients with sepsis: a prospective cohort study

PURPOSE

There is limited knowledge on how the source of infection impacts the host response to sepsis. We aimed to compare the host response in sepsis patients with a single, known source at admission (< 24 h) to the intensive care unit.

METHODS

From the molecular diagnosis and risk stratification of sepsis (MARS) prospective cohort, we measured 16 plasma host response biomarkers reflective of key host response pathways in 621 sepsis patients. In a subgroup (n = 335), blood leukocyte transcriptomes were compared between the sources. Differences in clinical patient profiles and survival were compared in the whole sepsis cohort (n = 2019).

RESULTS

The plasma biomarker cohort was categorized into sepsis originating from the respiratory tract (n = 334, 53.8%), abdomen (n = 159, 25.6%), urinary tract (n = 44, 7.1%), cardiovascular (n = 41, 6.6%), central nervous system (CNS) (n = 18, 2.9%), or skin (n = 25, 4%). This analysis revealed stronger inflammatory and cytokine responses, loss of vascular integrity and coagulation activation in abdominal sepsis relative to respiratory. Endothelial cell activation was prominent in urinary, cardiovascular and skin infections, while CNS infection was associated with the least host response aberrations. The leukocyte transcriptional response showed the largest overlap between abdominal and pulmonary infections (76% in common); notable differences between the sources were detected regarding hemostasis, cytokine signaling, innate and adaptive immune, and metabolic transcriptional pathways. After adjustment for confounders, the source of infection remained an independent contributor to 30-day mortality (unadjusted p = 0.001, adjusted p = 0.028).

CONCLUSION

Sepsis heterogeneity is partly explained by source-specific host response dysregulations and should be considered when selecting patients for trials testing immune modulatory drugs.

Construction of a non-enzymatic electrochemical sensor based on graphitic carbon nitride nanosheets for sensitive detection of procalcitonin

In this study, we established a label free and ultrasensitive electrochemical sensor based on graphitic nitride nanosheets (g-C₃N₄ NS) for procalcitonin (PCT) detection. Firstly, an easy-to-prepare and well-conducting g-C₃N₄ NS was synthesized. Next the g-C₃N₄ NS was immobilized on the electrode surface by π–π stacking, and further used to anchor the specific recognition peptide (PP). The surface morphology and structure after g-C₃N₄ NS and PP modification was characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and electrochemistry. The sensing property of this sensor was evaluated by differential pulse voltammetry (DPV) and showed a detection sensitivity with a dynamic range from 0.15 to 11.7 fg mL⁻¹ with a low limit of detection (LOD) of 0.11 fg mL⁻¹. Besides, the electrochemical biosensor was successfully used to detect PCT in human serum samples, and the results suggest its potential use in clinical application.

A simple and ultra-sensitive electrochemical biosensor based on graphitic carbon nitride nanosheets (g-C₃N₄ NS) was developed for the detection of PCT. This sensor presented excellent sensing performance and demonstrates potential for clinical application.

A new indicator: The diagnostic value of CD8+T/B lymphocyte ratio in sepsis progression

Objective

To reveal the value of single lymphocyte subpopulation and their ratios in the progression of sepsis.

Methods

From January 2019 to March 2021, 39 sepsis patients, 16 septic shock patients, and 50 healthy volunteers were recruited in the Second Xiangya Hospital for this cross-sectional study. The absolute quantitation of CD4+T, CD8+T, B lymphocytes, and NK cells in peripheral blood were determined by flow cytometry. SPSS Software was used to analyze the results.

Results

On the whole, the numbers of lymphocytes in the sepsis group and in the septic shock group were lower than that in the healthy control group. Surprisingly, the percentage of CD8+T lymphocytes in the septic shock group was slightly higher than that in the sepsis group. The percentage of B lymphocytes in the sepsis group was higher than that in the healthy control group. The AUC of CD8+T/B was 0.724, with the sensitivity and specificity being 75.00% and 71.79%, respectively.

Conclusion

The immune expression pattern of patients with sepsis was not a simple decrease in the number of lymphocytes. The change in the ratios of lymphocyte subpopulation might be more meaningful along the development and progression of sepsis. The ratio of CD8+T/B could be used to diagnose the progression of sepsis and reduce the misdiagnosis rate to a certain extent.

Elevated Plasma Levels of Matrix Metalloproteinase-3 and Tissue-Inhibitor of Matrix Metalloproteinases-1 Associate With Organ Dysfunction and Mortality in Sepsis

BACKGROUND

Matrix Metalloproteinases (MMP) respond to tissue damage during sepsis. Higher plasma concentrations of MMPs and the tissue-inhibitor of matrix metalloproteinases (TIMP) have been reported in sepsis compared with healthy controls. The objective of this study was to examine if plasma levels of MMP-3, MMP-9, and TIMP-1 associate with mortality and organ dysfunction during sepsis.

METHODS

We conducted a prospective cohort study of critically ill patients with sepsis adjudicated per Sepsis-3 criteria at a tertiary academic medical center. We measured plasma concentrations of MMP-3, MMP-9, and TIMP-1 on intensive care unit admission. We phenotyped the subjects for shock, acute respiratory distress syndrome (ARDS), acute kidney injury (AKI), and mortality at 30 days. We used logistic regression to test the associations between the MMPs and TIMP-1 with shock, ARDS, AKI, and mortality.

RESULTS

Higher plasma TIMP-1 levels were associated with shock (odds ratio [OR] 1.51 per log increase [95% CI 1.25, 1.83]), ARDS (OR 1.24 [95% CI 1.05, 1.46]), AKI (OR 1.18 [95% CI 1.01, 1.38]), and mortality (OR 1.20 [95% CI 1.05, 1.46]. Higher plasma MMP-3 concentrations were associated with shock (OR 1.40 [95% CI 1.12, 1.75]) and mortality (OR 1.24 [95% CI 1.03, 1.48]) whereas MMP-9 levels were not associated with outcomes. Higher plasma TIMP-1 to MMP-3 ratios were associated with shock (OR 1.41 [95% CI 1.15, 1.72], P = 0.02).

CONCLUSION

Elevated plasma concentrations of TIMP-1 associate with organ dysfunction and mortality in sepsis. Higher plasma levels of MMP-3 associate with shock and mortality. Plasma MMP and TIMP-1 may warrant further investigation as emerging sepsis theragnostic biomarkers.

Immunomonitoring of Monocyte and Neutrophil Function in Critically Ill Patients: From Sepsis and/or Trauma to COVID-19

Immune cells and mediators play a crucial role in the critical care setting but are understudied. This review explores the concept of sepsis and/or injury-induced immunosuppression and immuno-inflammatory response in COVID-19 and reiterates the need for more accurate functional immunomonitoring of monocyte and neutrophil function in these critically ill patients. in addition, the feasibility of circulating and cell-surface immune biomarkers as predictors of infection and/or outcome in critically ill patients is explored. It is clear that, for critically ill, one size does not fit all and that immune phenotyping of critically ill patients may allow the development of a more personalized approach with tailored immunotherapy for the specific patient. In addition, at this point in time, caution is advised regarding the quality of evidence of some COVID-19 studies in the literature.

Rapid Detection of Sepsis: Recent Advances in Biomarker Sensing Platforms

Sepsis is a major cause of mortality among hospitalized patients worldwide. Rapid diagnosis is critical as early treatments have been demonstrated to improve survival. Despite the importance of early detection, current technologies and clinical methods are often insufficient due to their lack of the necessary speed, selectivity, or sensitivity. The development of rapid sensing platforms that target sepsis-related biomarkers could significantly improve the outcomes of patients. This Mini-Review focuses on the recent advances in rapid diagnosis of soluble biomarkers in blood with the emphasis on different configurations of point-of-care (POC) instruments. Specifically, it first describes the commonly targeted biomarkers and the mechanisms by which they are detected. Then, it highlights the recently developed sensors that aim to reduce the total time of diagnosis without sacrificing selectivity and limit of detection. These sensors are categorized based on their distinct sensing and transduction mechanisms. Finally, it concludes with a brief outlook over future developments of multiplexed sensors.

The immunology of sepsis

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to an infection. This recently implemented definition does not capture the heterogeneity or the underlying pathophysiology of the syndrome, which is characterized by concurrent unbalanced hyperinflammation and immune suppression. Here, we review current knowledge of aberrant immune responses during sepsis and recent initiatives to stratify patients with sepsis into subgroups that are more alike from a clinical and/or pathobiological perspective, which could be key for identification of patients who are more likely to benefit from specific immune interventions.

Diagnostic Challenges in Sepsis

Purpose of Review

Sepsis is a leading cause of death worldwide. Groundbreaking international collaborative efforts have culminated in the widely accepted surviving sepsis guidelines, with iterative improvements in management strategies and definitions providing important advances in care for patients. Key to the diagnosis of sepsis is identification of infection, and whilst the diagnostic criteria for sepsis is now clear, the diagnosis of infection remains a challenge and there is often discordance between clinician assessments for infection.

Recent Findings

We review the utility of common biochemical, microbiological and radiological tools employed by clinicians to diagnose infection and explore the difficulty of making a diagnosis of infection in severe inflammatory states through illustrative case reports. Finally, we discuss some of the novel and emerging approaches in diagnosis of infection and sepsis.

Summary

While prompt diagnosis and treatment of sepsis is essential to improve outcomes in sepsis, there remains no single tool to reliably identify or exclude infection. This contributes to unnecessary antimicrobial use that is harmful to individuals and populations. There is therefore a pressing need for novel solutions. Machine learning approaches using multiple diagnostic and clinical inputs may offer a potential solution but as yet these approaches remain experimental.

The pathophysiology of sepsis - 2021 update: Part 2, organ dysfunction and assessment

DISCLAIMER

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

This is the second article in a 2-part series discussing the pathophysiology of sepsis. Part 1 of the series reviewed the immunologic response and overlapping pathways of inflammation and coagulation that contribute to the widespread organ dysfunction. In this article (part 2), major organ systems and their dysfunction in sepsis are reviewed, with discussion of scoring systems used to identify patterns and abnormal vital signs and laboratory values associated with sepsis.

SUMMARY

Sepsis is a dysregulated host response to infection that produces significant morbidity, and patients with shock due to sepsis have circulatory and cellular and metabolic abnormalities that lead to a higher mortality. Cardiovascular dysfunction produces vasodilation, reduced cardiac output and hypotension/shock requiring fluids, vasopressors, and advanced hemodynamic monitoring. Respiratory dysfunction may require mechanical ventilation and attention to volume status. Renal dysfunction is a frequent manifestation of sepsis. Hematologic dysfunction produces low platelets and either elevation or reduction of leucocytes, so consideration of the neutrophil:lymphocyte ratio may be useful. Procoagulant and antifibrinolytic activity leads to coagulation that is stimulated by inflammation. Hepatic dysfunction manifest as elevated bilirubin is often a late finding in sepsis and may cause reductions in production of essential proteins. Neurologic dysfunction may result from local endothelial injury and systemic inflammation through activity of the vagus nerve.

CONCLUSION

Timely recognition and team response with efficient use of therapies can improve patient outcome, and pharmacists with a complete understanding of the pathophysiologic mechanisms and treatments are valuable members of that team.

Pentraxin-3 Is a Strong Biomarker of Sepsis Severity Identification and Predictor of 90-Day Mortality in Intensive Care Units via Sepsis 3.0 Definitions

BACKGROUND

Sepsis is the leading cause of mortality in intensive care units (ICUs). However, early diagnosis and prognosis of sepsis and septic shock are still a great challenge. Pentraxin-3 (PTX3) was shown to be associated with the severity and outcome of sepsis and septic shock. This study was carried out to investigate the diagnostic and prognostic value of PTX3 in patients with sepsis and septic shock based on Sepsis 3.0 definitions.

METHODS

In this single-center prospective observational study, all patients' serum was collected for biomarker measurements within 24 h after admission. Logistic and Cox regression analyses were used to identify the potential biomarkers of diagnosis, severity stratification, and prediction.

RESULTS

Serum levels of PTX3 were significantly increased on the first day of ICU admission, while septic shock patients had highest PTX3 levels than other groups. A combination between PTX3 and procalcitonin (PCT) could better discriminate sepsis and septic shock, and PTX3 was an independent predictor of mortality in sepsis and septic shock patients.

CONCLUSION

PTX3 may be a robust biomarker to classify the disease severity and predict the 90-day mortality of sepsis and septic shock based on the latest Sepsis 3.0 definitions.