Are there new approaches for diagnosis, therapy guidance and outcome prediction of sepsis?

Advancement in biomarker based effective diagnosis of neonatal sepsis

Neonatal sepsis is considered as alarming medical emergency and becomes the common global reason of neonatal mortality. Non-specific symptoms and limitations of conventional diagnostic methods for neonatal sepsis mandate fast and reliable method to diagnose disease for point of care application. Recently, disease specific biomarkers have gained interest for rapid diagnosis that led to the development of electrochemical biosensor with enhanced specificity, sensitivity, cost-effectiveness and user-friendliness. Other than conventional biomarker C-reactive protein to diagnose neonatal sepsis, several potential biomarkers including Procalcitonin (PCT), Serum amyloid A (SAA) and other candidates are extensively investigated. The present review provides insights on advancements and diagnostic abilities of protein and nucleotide based biomarkers with their incorporation in developing electrochemical biosensors by employing novel fabrication strategies. This review provides an overview of most promising biomarker and its capability for neonatal sepsis diagnosis to fulfil future demand to develop electrochemical biosensor for point-of-care applications.

Early Procalcitonin Assessment in the Emergency Department in Patients with Intra-Abdominal Infection: An Excess or a Need?

Background: Intra-abdominal infection (IAI) is a wide range of intra-abdominal disease. Management involves empirical therapy and source control. Procalcitonin (PCT) has been suggested to assist in defining individual infection status and delivering individualized therapy. The aim of this study was to investigate the effects on patient outcomes of an early procalcitonin (PCT) assessment (in the emergency department [ED]) in patients with IAI. Methods: This was a retrospective, mono-centric study evaluating consecutive patients admitted to the ED from 2015 to 2019 with diagnosis of IAI. According to whether there had been PCT determination in the ED, patients were divided into no ePCT determination (no-ePCT) and early PCT determination in the ED (ePCT). The primary endpoint was the intra-hospital mortality rate. Secondary endpoints were occurrence of major complications and length of hospital stay (LOS). The propensity score match (PSM) was generated using a logistic regression model on the baseline covariates considered to be potentially influencing the decision to determine PCT in the ED and confounding factors identified as significant at a preliminary statistical analysis with respect to in-hospital death. Results: A series of 3,429 patients were included. The ePCT group consisted to 768 (22.4%), whereas the no-ePCT group contained 2,661 patients (77.6%). When the PSM was matched to the two groups, no significant difference was observed. Considering patients with uncomplicated infections, the PCT determination was associated with a higher mortality rate. We found no significant differences regarding outcomes with the exception of LOS, which was slightly longer in the ePCT group. However, we observed a tendency toward a minor difference in the number of complications in the ePCT group, in particular a reduced rate of progression to sepsis. Conclusion: Early PCT determination could be irrelevant in IAIs. The PCT value may be cost-effective and possibly improve the prognosis in cIAIs. Further research is needed to understand the optimal use of PCT, including in combination with other emerging diagnostic tests.

A boosting inspired personalized threshold method for sepsis screening

Sepsis is one of the biggest risks to patient safety, with a natural mortality rate between 25% and 50%. It is difficult to diagnose, and no validated standard for diagnosis currently exists. A commonly used scoring criteria is the quick sequential organ failure assessment (qSOFA). It demonstrates very low specificity in ICU populations, however. We develop a method to personalize thresholds in qSOFA that incorporates easily to measure patient baseline characteristics. We compare the personalized threshold method to qSOFA, five previously published methods that obtain an optimal constant threshold for a single biomarker, and to the machine learning algorithms based on logistic regression and AdaBoosting using patient data in the MIMIC-III database. The personalized threshold method achieves higher accuracy than qSOFA and the five published methods and has comparable performance to machine learning methods. Personalized thresholds, however, are much easier to adopt in real-life monitoring than machine learning methods as they are computed once for a patient and used in the same way as qSOFA, whereas the machine learning methods are hard to implement and interpret.

Epidemiology of Community-Acquired Sepsis in Adult Patients: A Six Year Observational Study

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to an infection and it is a major cause of morbidity and mortality worldwide. The aim of this study is to describe epidemiology of community-acquired sepsis in the Intensive care unit (ICU) of the Macedonian tertiary care University Clinic for Infectious Diseases. A prospective observational study was conducted over a 6-year period from January, 2011 to December, 2016. All consecutive adults with community-acquired sepsis or septic shock were included in the study. Variables measured were incidence of sepsis, age, gender, comorbidities, season, source of infection, complications, interventions, severity indexes, length of stay, laboratory findings, blood cultures, 28-day and in hospital mortality. Of 1348 admissions, 277 (20.5%) had sepsis and septic shock. The most common chronic condition was heart failure (26.4%), and the most frequent site of infection was the respiratory tract (57.4%). Median Simplified Acute Physiology Score (SAPS II) was 50.0, and median Sequential Organ Failure Assessment (SOFA) score was 8.0. Blood cultures were positive in 22% of the cases. Gram-positive bacteria were isolated in 13% and Gram-negatives in 9.7% of patients with sepsis. The overall 28-day and in hospital mortality was 50.5% and 56.3% respectively. The presence of chronic heart failure, occurrence of ARDS, septic shock and the winter period may influence an unfavorable outcome. Mortality compared to previous years is unchanged but patients that we have been treating these last 6 years have had more severe illnesses. Better adherence to the Surviving Sepsis guidelines will reduce mortality in this group of severely ill patients.

Diagnostic Value of Procalcitonin for Bacterial Meningitis in Children: A Comparison Analysis Between Serum and Cerebrospinal Fluid Procalcitonin Levels

The aim of this study was to analyze and compare procalcitonin (PCT) levels in serum and cerebrospinal fluid (CSF) as tools for detecting bacterial meningitis (BM) in children. Serum and CSF PCT levels as well as albumin index (AI = CSF albumin/serum albumin × 1000) were measured from 29 BM, 25 viral meningitis (VM), and 47 non-meningitis patients. Differences between groups only for CSF PCT were significant. A stronger positive correlation between CSF PCT level and AI was observed in the BM patients ( R = 0.68, P < .001). As a predictor of BM, the area under the receiver operating characteristics curve for CSF PCT was greater than that of serum PCT (0.76 vs 0.67, P < .05) and a cutoff of ⩾0.085 ng/mL achieved 55.17% sensitivity and 95.83% specificity. High levels of CSF PCT may indicate loss of integrity of the blood-brain barrier; only CSF PCT has a diagnostic value for BM in children suspected meningitis.

Real-world use of procalcitonin and other biomarkers among sepsis hospitalizations in the United States: A retrospective, observational study

Background

Sepsis management guidelines endorse use of biomarkers to support clinical assessment and treatment decisions in septic patients. The impact of biomarkers on improving patient outcomes remains uncertain.

Methods

Retrospective observational study of adult sepsis discharges between January 1, 2012, and December 31, 2015, from Premier Healthcare Database hospitals. Sepsis was defined by an All Patients Refined Diagnosis-Related Group code of 720 (septicemia and disseminated infections). Use of four biomarker strategies was evaluated based on hospital records: (i) >1 procalcitonin (PCT), (ii) 1 PCT, (iii) no PCT but ≥1 C-reactive protein (CRP) and/or lactate and (iv) no sepsis biomarkers. Associations between biomarker use and clinical and cost outcomes were examined. The primary outcome was impact of biomarker strategy on hospital costs per day.

Results

Among 933,591 adult sepsis discharges during the study period, 731,392 (78%) had biomarker tests ordered. In multivariable analyses, discharges with >1 PCT had higher hospital costs per day ($1,904; 95% confidence interval [CI] $1,896–$1,911) compared with discharges with no sepsis biomarkers ($1,606; 95% CI $1,658–$1,664). Discharges with >1 PCT also had greater illness severity and antimicrobial exposure compared with other biomarker-use groups. The adjusted odds of dying during hospital stay compared with being discharged were significantly lower for sepsis discharges with >1 PCT (0.64; 95% CI 0.61–0.67) and 1 PCT (0.88; 95% CI 0.85–0.91) compared with no sepsis biomarker use. The proportion of discharges with ≥1 PCT increased almost six-fold during the study; use of other biomarkers remained constant.

Conclusions

Between 2012 and 2015, PCT use among sepsis discharges increased six-fold while lactate and CRP use remained unchanged. PCT use was associated with decreased odds of in-hospital mortality but increased hospital costs per day. Serial biomarker monitoring may be associated with improved patient outcomes in the most critically ill septic patients.

Heart-Rate Variability-More than Heart Beats?

Heart-rate variability (HRV) is frequently introduced as mirroring imbalances within the autonomous nerve system. Many investigations are based on the paradigm that increased sympathetic tone is associated with decreased parasympathetic tone and vice versa. But HRV is probably more than an indicator for probable disturbances in the autonomous system. Some perturbations trigger not reciprocal, but parallel changes of vagal and sympathetic nerve activity. HRV has also been considered as a surrogate parameter of the complex interaction between brain and cardiovascular system. Systems biology is an inter-disciplinary field of study focusing on complex interactions within biological systems like the cardiovascular system, with the help of computational models and time series analysis, beyond others. Time series are considered surrogates of the particular system, reflecting robustness or fragility. Increased variability is usually seen as associated with a good health condition, whereas lowered variability might signify pathological changes. This might explain why lower HRV parameters were related to decreased life expectancy in several studies. Newer integrating theories have been proposed. According to them, HRV reflects as much the state of the heart as the state of the brain. The polyvagal theory suggests that the physiological state dictates the range of behavior and psychological experience. Stressful events perpetuate the rhythms of autonomic states, and subsequently, behaviors. Reduced variability will according to this theory not only be a surrogate but represent a fundamental homeostasis mechanism in a pathological state. The neurovisceral integration model proposes that cardiac vagal tone, described in HRV beyond others as HF-index, can mirror the functional balance of the neural networks implicated in emotion-cognition interactions. Both recent models represent a more holistic approach to understanding the significance of HRV.

Identification of a panel of serum protein markers in early stage of sepsis and its validation in a cohort of patients

BACKGROUND

Sepsis is a life-threatening illness with a challenging diagnosis. Current serum biomarkers are not sensitive enough for diagnosis. With the aim of finding proteins associated with sepsis, serum protein profile was compared between patients and healthy donors and serum classical inflammatory proteins were analyzed in both groups.

METHODS

Serum protein profiles were characterized by two-dimensional electrophoresis (2DE). Identification of the proteins was carried out by mass spectrophotometry and their validation was performed by Enzyme-Linked-ImmunoSorbent Assay (ELISA) in a cohort of 85 patients and 67 healthy donors. Seven classical inflammatory proteins were analyzed in the same cohort by ELISA: interleukin-2 receptor α-chain (sCD25), scavenger receptor cysteine-rich-type-1 (sCD163), tumor-necrosis factor receptor superfamily-member-6 (sFas), hemeoxigenase-1 decycling (HO-1), interleukin-6 (IL-6), interleukin-18 (IL-18) and intercellular adhesion-molecule-1 (sICAM-1).

RESULTS

After 2DE, 20 significantly differently expressed spots were identified by mass spectrometry analysis, revealing deregulation of six different proteins upon sepsis and 50% were validated by ELISA: Antithrombin-III (AT-III), Clusterin (CLUS) and Serum amyloid A-1 (SAA-1). Serum concentration of AT-III and CLUS was significantly lower in patients' serum, whereas SAA-1 showed higher values in septic patients. Serum concentration of the seven inflammatory proteins was significantly increased in septic patients. Functional analysis of the ten deregulated proteins revealed an enrichment of proteins related mainly to the activation of the immune response.

CONCLUSION

We have identified a panel of ten potential sepsis marker proteins biologically connected and validated in a large number of patients, whose analysis could be considered as a complementary tool for the diagnosis of sepsis.

Validation of two multiplex platforms to quantify circulating markers of inflammation and endothelial injury in severe infection

Biomarkers can prognosticate outcome and enable risk-stratification. In severe infection, focusing on multiple markers reflecting pathophysiological mechanisms of organ injury could enhance management and pathway-directed therapeutics. Limited data exist on the performance of multiplex biomarker platforms. Our goal was to compare endothelial and immune activation biomarkers in severe pediatric infections using two multiplex platforms. Frozen plasma from 410 children presenting to the Jinja Regional Hospital in Uganda with suspected infection was used to measure biomarkers of endothelial (Angiopoietin-2, sFlt-1, sVCAM-1, sICAM-1) and immune (IL-6, IP-10, sTNFR-1, CHI3L1) activation. Two multiplex platforms (Luminex®, Ella^TM) based on monoclonal antibody sandwich immunoassays using biotin-streptavidin conjugate chemistry were selected with reagents from R&D Systems. The two platforms differed in ease and time of completion, number of samples per assay, and dynamic concentration range. Intra-assay variability assessed using a coefficient of variation (CV%) was 2.2–3.4 for Luminex® and 1.2–2.9 for Ella^TM. Correlations for biomarker concentrations within dynamic range of both platforms were best for IL-6 (ρ = 0.96, p<0.0001), IP-10 (ρ = 0.94, p<0.0001) and sFlt-1 (ρ = 0.94, p<0.0001). Agreement between concentrations obtained by both methods assessed by the Bland-Altman test varied, with best agreement for CHI3L1. Our data suggest that biomarkers of endothelial and immune activation can be readily measured with multiplex platforms. Luminex® and Ella^TM produced reliable results with excellent CV% values. The Ella^TM platform was more automated and completed in 75 minutes, potentially compatible with near-patient use. Trends in concentrations obtained by these methods were highly correlated, although absolute values varied, suggesting caution is required when comparing data from different multiplex platforms.

Could Biomarkers Direct Therapy for the Septic Patient?

Sepsis is a serious medical condition caused by a severe systemic inflammatory response to a bacterial, fungal, or viral infection that most commonly affects neonates and the elderly. Advances in understanding the pathophysiology of sepsis have resulted in guidelines for care that have helped reduce the risk of dying from sepsis for both children and older adults. Still, over the past three decades, a large number of clinical trials have been undertaken to evaluate pharmacological agents for sepsis. Unfortunately, all of these trials have failed, with the use of some agents even shown to be harmful. One key issue in these trials was the heterogeneity of the patient population that participated. What has emerged is the need to target therapeutic interventions to the specific patient's underlying pathophysiological processes, rather than looking for a universal therapy that would be effective in a "typical" septic patient, who does not exist. This review supports the concept that identification of the right biomarkers that can direct therapy and provide timely feedback on its effectiveness will enable critical care physicians to decrease mortality of patients with sepsis and improve the quality of life of survivors.

Heart Rate Variability in Porcine Progressive Peritonitis-Induced Sepsis

Accumulating evidence suggests that heart rate variability (HRV) alterations could serve as an indicator of sepsis progression and outcome, however, the relationships of HRV and major pathophysiological processes of sepsis remain unclear. Therefore, in this experimental study HRV was investigated in a clinically relevant long-term porcine model of severe sepsis/septic shock. HRV was analyzed by several methods and the parameters were correlated with pathophysiological processes of sepsis. In 16 anesthetized, mechanically ventilated, and instrumented domestic pigs of either gender, sepsis was induced by fecal peritonitis. Experimental subjects were screened up to the refractory shock development or death. ECG was continuously recorded throughout the experiment, afterwards RR intervals were detected and HRV parameters computed automatically using custom made measurement and analysis MATLAB routines. In all septic animals, progressive hyperdynamic septic shock developed. The statistical measures of HRV, geometrical measures of HRV and Poincaré plot analysis revealed a pronounced reduction of HRV that developed quickly upon the onset of sepsis and was maintained throughout the experiment. The frequency domain analysis demonstrated a decrease in the high frequency component and increase in the low frequency component together with an increase of the low/high frequency component ratio. The reduction of HRV parameters preceded sepsis-associated hemodynamic changes including heart rate increase or shock progression. In a clinically relevant porcine model of peritonitis-induced progressive septic shock, reduction of HRV parameters heralded sepsis development. HRV reduction was associated with a pronounced parasympathetic inhibition and a shift of sympathovagal balance. Early reduction of HRV may serve as a non-invasive and sensitive marker of systemic inflammatory syndrome, thereby widening the therapeutic window for early interventions.

MFHAS1 Is Associated with Sepsis and Stimulates TLR2/NF-κB Signaling Pathway Following Negative Regulation

Malignant fibrous histiocytoma amplified sequence 1 (MFHAS1) has a potential immunoregulatory role dependent on Toll-like receptors (TLRs). TLR2, associated with deleterious systemic inflammation, cardiac dysfunction, and acute kidney injury, acts synergistically in sepsis. The role of MFHAS1 in targeting TLR2 involved in sepsis has not been examined thus far. This study aimed to examine the relationship of MFHAS1 and sepsis, and the effect of MFHAS1 on the TLR2 signaling pathway. Blood samples were collected from eight sepsis patients after surgery and eight patients undergoing selective surgery to determine blood MFHAS1 levels. HEK 293 cells, RAW 264.7 macrophages and THP-1 monocytes were used to confirm the effect of MFHAS1 on TLR2 signaling pathway. Our study showed that blood MFHAS1 was significantly elevated in septic patients, and MFHAS1 was more increased in mononuclear cells from septic patients. Pam3CSK4 (TLR2 ligand) was found to induce MFHAS1 production in RAW 264.7 murine macrophages and THP-1 human monocytes in a time-dependent manner. MFHAS1 has dual effects on TLR2 signaling pathway and inflammation, i.e., inhibitory effect at 6 hours, and then stimulatory effect after 24 hours through the activation of TLR2/NF-κB signaling pathway, and MFHAS1 induced the phosphorylation of JNK and p38 after TLR2 stimulation.

Procalcitonin, MR-Proadrenomedullin, and Cytokines Measurement in Sepsis Diagnosis: Advantages from Test Combination

BACKGROUND

Elevated cytokines levels correlate with sepsis severity and mortality but their role in the diagnosis is controversial, whereas Procalcitonin (PCT) has been largely used. Recently, the mid-regional proadrenomedullin (MR-proADM) has been combined with PCT for diagnosis optimization. In this study the combined measurement of PCT, MR-proADM, and cytokines in patients with sepsis was evaluated.

METHODS

One hundred and four septic patients and 101 controls were enrolled. Receiver operating characteristic (ROC) analysis and multiple logistic regression were used to evaluate applicant markers for sepsis diagnosis. Markers with best Odds Ratio (OR) were combined, and the posttest probability and a composite score were computed.

RESULTS

Based upon ROC curves analysis, PCT, MR-proADM, IL-6, IL-10, TNF-α, and MCP-1 were considered applicant for sepsis diagnosis. Among these PCT, MR-proADM , IL-6, and TNF-α showed the best OR. A better posttest probability was found with the combination of PCT with MR-proADM and PCT with IL-6 or TNF-α compared to the single marker. A composite score of PCT, MR-proADM, and TNF-α showed the best ROC curve in the early diagnosis of sepsis.

CONCLUSION

The combination of PCT with other markers should expedite diagnosis and treatment of sepsis optimizing clinical management.

Mortality Prediction Model of Septic Shock Patients Based on Routinely Recorded Data

We studied the problem of mortality prediction in two datasets, the first composed of 23 septic shock patients and the second composed of 73 septic subjects selected from the public database MIMIC-II. For each patient we derived hemodynamic variables, laboratory results, and clinical information of the first 48 hours after shock onset and we performed univariate and multivariate analyses to predict mortality in the following 7 days. The results show interesting features that individually identify significant differences between survivors and nonsurvivors and features which gain importance only when considered together with the others in a multivariate regression model. This preliminary study on two small septic shock populations represents a novel contribution towards new personalized models for an integration of multiparameter patient information to improve critical care management of shock patients.