Defining and Diagnosing Sepsis

TREM-1 as a Marker of Multiple Organ Failure in Cardiac Surgery

Systemic inflammatory response syndrome (SIRS) frequently accompanies early postoperative period after cardiac surgery and in some cases is complicated by multiple organ failure (MOF). Inherited variation in the innate immune response genes (e.g., TREM1) is among the major factors determining the development of SIRS and the risk of MOF. This research was aimed to study whether the polymorphisms within the TREM1 gene are associated with MOF after the coronary artery bypass graft (CABG) surgery. Here we enrolled 592 patients who underwent CABG surgery in the Research Institute for Complex Issues of Cardiovascular Diseases (Kemerovo, Russia) and documented 28 cases of MOF. Genotyping was performed by allele-specific PCR using TaqMan probes. In addition, we measured serum soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) using enzyme-linked immunosorbent assay. Five polymorphisms (rs1817537, rs2234246, rs3804277, rs7768162 andrs4711668) within the TREM1 gene were significantly associated with MOF. Patients with MOF had higher serum sTREM-1 as compared with those without MOF at both pre- and post-intervention stages. Serum sTREM-1 was associated with the rs1817537,rs2234246 and rs3804277 polymorphisms within the TREM1 gene. Minor alleles within the TREM1 gene define the level of serum sTREM-1 and are associated with MOF after CABG surgery.

Th17 cell plasticity towards a T-bet-dependent Th1 phenotype is required for bacterial control in Staphylococcus aureus infection

Staphylococcus aureus is frequently detected in patients with sepsis and thus represents a major health burden worldwide. CD4⁺ T helper cells are involved in the immune response to S. aureus by supporting antibody production and phagocytosis. In particular, Th1 and Th17 cells secreting IFN-γ and IL-17A, are involved in the control of systemic S. aureus infections in humans and mice.

To investigate the role of T cells in severe S. aureus infections, we established a mouse sepsis model in which the kidney was identified to be the organ with the highest bacterial load and abundance of Th17 cells. In this model, IL-17A but not IFN-γ was required for bacterial control. Using Il17aCre × R26YFP mice we could show that Th17 fate cells produce Th17 and Th1 cytokines, indicating a high degree of Th17 cell plasticity. Single cell RNA-sequencing of renal Th17 fate cells uncovered their heterogeneity and identified a cluster with a Th1 expression profile within the Th17 cell population, which was absent in mice with T-bet/Tbx21-deficiency in Th17 cells (Il17aCre x R26eYFP x Tbx21-flox). Blocking Th17 to Th1 transdifferentiation in Th17 fate cells in these mice resulted in increased S. aureus tissue loads.

In summary, we highlight the impact of Th17 cells in controlling systemic S. aureus infections and show that T-bet expression by Th17 cells is required for bacterial clearance. While targeting the Th17 cell immune response is an important therapeutic option in autoimmunity, silencing Th17 cells might have detrimental effects in bacterial infections.

Staphylococcus aureus is a commensal and opportunistic pathogen that is involved in a variety of diseases such as skin infection, food poisoning, endocarditis or pneumonia and sepsis. In particular, in patients with bacterial sepsis, S. aureus causes a high mortality. Despite progress in medical treatment in general, the survival rates of S. aureus sepsis did not improve in the last decades. The interaction between adaptive immune system and this pathogen is a topic of great interest. Infection of mice with S. aureus revealed the highest bacterial load and abundance of Th17 cells in the kidney. We could show prominent T-bet-dependent transdifferentiation of Th17 cells to highly effective anti-bacterial Th1 phenotypes in the kidney. Thus, T-bet is essential for the Th17 to Th1 transdifferentiation which is required for the control of bacterial infections. Targeting the plasticity of pro-inflammatory T cell subset is a promising therapeutic strategy to silence detrimental T cells in autoimmunity while augmenting anti-bacterial T cells in infection.

The Landscape of Featured Metabolism-Related Genes and Imbalanced Immune Cell Subsets in Sepsis

Sepsis is a heterogeneous disease state triggered by an uncontrolled inflammatory host response with high mortality and morbidity in severely ill patients. Unfortunately, the treatment effectiveness varies among sepsis patients and the underlying mechanisms have yet to be elucidated. The present aim is to explore featured metabolism-related genes that may become the biomarkers in patients with sepsis. In this study, differentially expressed genes (DEGs) between sepsis and non-sepsis in whole blood samples were identified using two previously published datasets (GSE95233 and GSE54514). A total of 66 common DEGs were determined, namely, 52 upregulated and 14 downregulated DEGs. The Gene Set Enrichment Analysis (GSEA) results indicated that these DEGs participated in several metabolic processes including carbohydrate derivative, lipid, organic acid synthesis oxidation reduction, and small-molecule biosynthesis in patients with sepsis. Subsequently, a total of 8 hub genes were screened in the module with the highest score from the Cytoscape plugin cytoHubba. Further study showed that these hub DEGs may be robust markers for sepsis with high area under receiver operating characteristic curve (AUROC). The diagnostic values of these hub genes were further validated in myocardial tissues of septic rats and normal controls by untargeted metabolomics analysis using liquid chromatography-mass spectrometry (LC-MS). Immune cell infiltration analysis revealed that different infiltration patterns were mainly characterized by B cells, T cells, NK cells, monocytes, macrophages, dendritics, eosinophils, and neutrophils between sepsis patients and normal controls. This study indicates that metabolic hub genes may be hopeful biomarkers for prognosis prediction and precise treatment in sepsis patients.

qSOFA is a useful prognostic factor for 30-day mortality in infected patients fulfilling the SIRS criteria for sepsis

INTRODUCTION

The "quick Sequential Organ Failure Assessment" (qSOFA) score is a bedside risk-stratification tool to predict the likelihood of organ dysfunction. This study evaluated the qSOFA score as a prognostic factor for 30-day mortality in emergency department (ED) patients with sepsis identified by the Systemic Inflammatory Response Syndrome (SIRS) criteria.

METHODS

A historical cohort study was conducted reviewing patients admitted to a single-center ED from November 1, 2013, to October 31, 2014. All patients with suspected or proven infections who fulfilled two or more SIRS criteria were included. Data of SIRS, qSOFA and baseline clinical data were obtained from triage forms and patient records.

RESULTS

A total of 434 patients with sepsis of any severity were included. A total of 73 (16.8%) had a qSOFA score of ≥2 and were more frequently transferred to the intensive care unit (ICU) (26.0 vs. 6.7%; 95% confidence interval (CI) of the difference 8.9-29.7%) and had increased 30-day mortality (32.9 vs. 9.1%, 95% CI of the difference 12.6-35.0%) compared to patients with a qSOFA score of <2. In an adjusted logistic regression model, a qSOFA score of ≥2 was independently associated with 30-day mortality (odds ratio 4.83; 95% CI 2.11-11.02).

CONCLUSION

Almost one third of the patients with a qSOFA score of ≥2 had died within 30 days and a qSOFA score of ≥2 was independently associated with mortality. This study indicated that qSOFA score of at least two could provide useful prognostic information for septic patients defined by the SIRS criteria.

Early Administration of Intravenous Fluids in Sepsis: Pros and Cons

Fluid resuscitation in the management of patients with sepsis and severe sepsis has been considered the standard of care for almost 2 decades. The rationale for fluid resuscitation is related to improvement in cardiac output and organ perfusion. Recent research evidence challenges the use of fluid resuscitation in patients diagnosed with sepsis. Research is needed to determine the timing of fluid administration, as well as the volume and type of fluid to achieve positive patient outcomes. This article discusses the pros and cons of early fluid administration in the management of patients with sepsis.

Emergency Department disposition decisions and associated mortality and costs in ICU patients with suspected infection

Background

Following emergency department (ED) assessment, patients with infection may be directly admitted to the intensive care unit (ICU) or alternatively admitted to hospital wards or sent home. Those admitted to the hospital wards or sent home may experience future deterioration necessitating ICU admission.

Methods

We used a prospectively collected registry from two hospitals within a single tertiary care hospital network between 2011 and 2014. Patient information, outcomes, and costs were stored in the hospital data warehouse. Patients were categorized into three groups: (1) admitted directly from the ED to the ICU; (2) initially admitted to the hospital wards, with ICU admission within 72 hours of initial presentation; or (3) sent home from the ED, with ICU admission within 72 hours of initial presentation. Using multivariable logistic regression, we sought to compare outcomes and total costs between groups. Total costs were evaluated using a generalized linear model.

Results

A total of 657 patients were included; of these, 338 (51.4%) were admitted directly from the ED to the ICU, 246 (37.4%) were initially admitted to the wards and then to the ICU, and 73 (11.1%) were initially sent home and then admitted to the ICU. In-hospital mortality was lowest among patients admitted directly to the ICU (29.5%), as compared with patients admitted to the ICU from wards (42.7%) or home (61.6%) (P < 0.001). As compared with direct ICU admission, disposition to the ward was associated with an adjusted OR of 1.75 (95% CI, 1.22–2.50; P < 0.01) for mortality, and disposition home was associated with an adjusted OR of 4.02 (95% CI, 2.32–6.98). Mean total costs were lowest among patients directly admitted to the ICU ($26,748), as compared with those admitted from the wards ($107,315) and those initially sent home ($71,492) (P < 0.001). Cost per survivor was lower among patients directly admitted to the ICU ($37,986) than either those initially admitted to the wards ($187,230) or those sent home ($186,390) (P < 0.001).

Conclusions

In comparison with direct admission to the ICU, patients with suspected infection admitted to the ICU who have previously been discharged home or admitted to the ward are associated with higher in-hospital mortality and costs.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2096-8) contains supplementary material, which is available to authorized users.

Helpful Only When Elevated: Initial Serum Lactate in Stable Emergency Department Patients with Sepsis Is Specific, but Not Sensitive for Future Deterioration

BACKGROUND

Early emergency department (ED) identification of septic patients at risk of deterioration is critical. Lactate is associated with 28-day mortality in admitted patients, but little evidence exists on its use in predicting short-term deterioration.

OBJECTIVE

Our aim was to determine the role of initial serum lactate for prediction of short-term deterioration in stable ED patients with suspected sepsis.

METHODS

We conducted a prospective cohort study of adult ED sepsis patients. Venous lactate was obtained within 2 h of ED arrival. Main outcome was subsequent deterioration (defined as any of the following: death, intensive care admission > 24 h, intubation, vasoactive medications for > 1 h, or noninvasive positive pressure ventilation for > 1 h) within 72 h. Patients meeting any endpoint within 1 h of arrival were excluded.

RESULTS

Nine hundred and eighty-five patients were enrolled, of whom 84 (8.5%) met the primary outcome of deterioration. Initial lactate ≥ 4.0 mmol/L had a specificity of 97% (95% confidence interval [CI] 94-100%), but a sensitivity of 27% (95% CI 18-37%) for predicting deterioration, with positive and negative likelihood ratios of 10.7 (95% CI 6.3-18.3) and 0.8 (95% CI 0.7-0.9), respectively. A lower threshold of lactate (≥2.0 mmol/L) had a sensitivity of 67% (95% CI 55-76%) and specificity of 66% (95% CI 63-69%), with corresponding positive and negative likelihood ratios of 2.0 (95% CI 1.7-2.3) and 0.5 (95% CI 0.4-0.7).

CONCLUSIONS

High ED lactate is predictive of subsequent deterioration from sepsis within 72 h, and may be useful in determining disposition, but low lactate is not effective in screening stable patients at risk of deterioration.

Metabolomics in Sepsis and Its Impact on Public Health

Sepsis, with its often devastating consequences for patients and their families, remains a major public health concern that poses an increasing financial burden. Early resuscitation together with the elucidation of the biological pathways and pathophysiological mechanisms with the use of "-omics" technologies have started changing the clinical and research landscape in sepsis. Metabolomics (i.e., the study of the metabolome), an "-omics" technology further down in the "-omics" cascade between the genome and the phenome, could be particularly fruitful in sepsis research with the potential to alter the clinical practice. Apart from its benefit for the individual patient, metabolomics has an impact on public health that extends beyond its applications in medicine. In this review, we present recent developments in metabolomics research in sepsis, with a focus on pneumonia, and we discuss the impact of metabolomics on public health, with a focus on free/libre open source software.

Maternal sepsis in the era of genomic medicine

PURPOSE

Maternal sepsis remains one of the leading causes of direct and indirect maternal mortality both in high- and low-income environments. In the last two decades, systems biology approaches, based on '-omics' technologies, have started revolutionizing the diagnosis and management of the septic syndrome. The scope of this narrative review is to present an overview of the basic '-omics' technologies, exemplified by cases relevant to maternal sepsis.

METHODS

Narrative review of the new '-omics' technologies based on a detailed review of the literature.

RESULTS

After presenting the main 'omics' technologies, we discuss their limitations and the need for integrated approaches that encompass research efforts across multiple '-omics' layers in the '-omics' cascade between the genome and the phenome.

CONCLUSIONS

Systems biology approaches are revolutionizing the research landscape in maternal sepsis. There is a need for increased awareness, from the side of health practitioners, as a requirement for the effective implementation of the new technologies in the research and clinical practice in maternal sepsis.

The role of propionic acid at diagnosis predicts mortality in patients with septic shock

PURPOSE

This study aims to assess the diagnostic and prognostic value of propionic acid in patients with septic shock on a medical intensive care unit (ICU).

METHODS

Serum propionic acid and clinical common cytokines levels were measured within 24h after the diagnosis of sepsis, and the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, Sequential Organ Failure Assessment (SOFA) score, and Mortality were recorded in ICU. A 28-day and 90-day follow-up was performed for all patients.

RESULTS

A total of 118 septic patients were enrolled in this study. The propionic acid was higher in patients with septic shock compared with sepsis. Multivariate logistic regression analysis showed that propionic acid was independent predictor of sepsis (odds ratio: 1.279; 95% confidence interval: 1.069-1.530; P=0.007) and septic shock (odds ratio: 1.859; 95% confidence interval: 1.342-2.576; P<0.001) and ICU mortality (odds ratio: 1.331; 95% confidence interval: 1.107-1.600; P=0.002), 28-day mortality (odds ratio: 1.259; 95% confidence interval: 1.046-1.514; P=0.015) and 90-day mortality (odds ratio: 1.304; 95% confidence interval: 1.092-1.558; P=0.003). The receiver operating characteristic curve (AUC) analysis showed the areas under of propionic acid on ICU admission day for predicting sepsis and septic shock were 0.773 and 0.85 respectively, the areas under of propionic acid for predicting ICU mortality, 28-d and 90-d mortality were 0.779, 0.739 and 0.809 respectively. Using a PA cutoff of 0.053 and 0.095 for predicting sepsis and septic shock respectively, the sensitivity was 97.62% and 85.5%, and the specificity was 58% and 83.5%, respectively. Using a PA cutoff of 0.139 for predicting ICU mortality, 28- and 90-day mortality, the sensitivity was 69.39%, 67.44% and 69.09% respectively, and the specificity was 78.26%, 73.33% and 82.54% respectively.

CONCLUSIONS

Propionic acid showed diagnostic capacity to diagnose septic shock and revealed prognostic information for mortality.