Septic Shock Sera Containing Circulating Histones Induce Dendritic Cell–Regulated Necrosis in Fatal Septic Shock Patients

Objectives: Innate immune system alterations, including dendritic cell loss, have been reproducibly observed in patients with septic shock and correlated to adverse outcomes or nosocomial infections. The goal of this study is to better understand the mechanisms behind this observation in order to better assess septic shock pathogenesis.Design: Prospective, controlled experimental study. Setting: Research laboratory at an academic medical center. Subjects: The study enrolled 71 patients, 49 with septic shock and 22 with cardiogenic shock. Seventeen healthy controls served as reference. In vitro monocyte-derived dendritic cells were generated from healthy volunteers. Interventions: Sera were assessed for their ability to promote in vitro dendritic cell death through flow cytometry detection in each group of patients. The percentage of apoptotic or necrotic dendritic cells was evaluated by annexin-V and propidium iodide staining. Measurements and Main Results: We observed that only patients with septic shock and not patients with pure cardiogenic shock were characterized by a rapid and profound loss of circulating dendritic cells. In vitro analysis revealed that sera from patients with septic shock induced higher dendritic cell death compared to normal sera or cardiogenic shock (p < 0.005). Sera from surviving patients induced dendritic cell death through a caspase-dependent apoptotic pathway, whereas sera from nonsurviving patients induced dendritic cell-regulated necrosis. Dendritic cell necrosis was not due to necroptosis but was dependent of the presence of circulating histone. The toxicity of histones toward dendritic cell could be prevented by recombinant human activated protein C. Finally, we observed a direct correlation between the levels of circulating histones in patients and the ability of the sera to promote dendritic cell-regulated necrosis. Conclusions: The study demonstrates a differential mechanism of dendritic cell death in patients with septic shock that is dependent on the severity of the disease

Depletion of Dendritic Cells Enhances Innate Anti-Bacterial Host Defense through Modulation of Phagocyte Homeostasis

Dendritic cells (DCs) as professional antigen-presenting cells play an important role in the initiation and modulation of the adaptive immune response. However, their role in the innate immune response against bacterial infections is not completely defined. Here we have analyzed the role of DCs and their impact on the innate anti-bacterial host defense in an experimental infection model of Yersinia enterocolitica (Ye). We used CD11c-diphtheria toxin (DT) mice to deplete DCs prior to severe infection with Ye. DC depletion significantly increased animal survival after Ye infection. The bacterial load in the spleen of DC-depleted mice was significantly lower than that of control mice throughout the infection. DC depletion was accompanied by an increase in the serum levels of CXCL1, G-CSF, IL-1α, and CCL2 and an increase in the numbers of splenic phagocytes. Functionally, splenocytes from DC-depleted mice exhibited an increased bacterial killing capacity compared to splenocytes from control mice. Cellular studies further showed that this was due to an increased production of reactive oxygen species (ROS) by neutrophils. Adoptive transfer of neutrophils from DC-depleted mice into control mice prior to Ye infection reduced the bacterial load to the level of Ye-infected DC-depleted mice, suggesting that the increased number of phagocytes with additional ROS production account for the decreased bacterial load. Furthermore, after incubation with serum from DC-depleted mice splenocytes from control mice increased their bacterial killing capacity, most likely due to enhanced ROS production by neutrophils, indicating that serum factors from DC-depleted mice account for this effect. In summary, we could show that DC depletion triggers phagocyte accumulation in the spleen and enhances their anti-bacterial killing capacity upon bacterial infection

A performance assessment framework for hospitals: the WHO regional office for Europe PATH project

Objective. The World Health Organization (WHO) Regional Office for Europe launched in 2003 a project aiming to develop and disseminate a flexible and comprehensive tool for the assessment of hospital performance and referred to as the performance assessment tool for quality improvement in hospitals (PATH). This project aims at supporting hospitals in assessing their performance, questioning their own results, and translating them into actions for improvement, by providing hospitals with tools for performance assessment and by enabling collegial support and networking among participating hospitals. Methods. PATH was developed through a series of four workshops gathering experts representing most valuable experiences on hospital performance assessment worldwide. An extensive review of the literature on hospital performance projects was carried out, more than 100 performance indicators were scrutinized, and a survey was carried out in 20 European countries. Results. Six dimensions were identified for assessing hospital performance: clinical effectiveness, safety, patient centredness, production efficiency, staff orientation and responsive governance. The following outcomes were achieved: (i) definition of the concepts and identification of key dimensions of hospital performance; (ii) design of the architecture of PATH to enhance evidence-based management and quality improvement through performance assessment; (iii) selection of a core and a tailored set of performance indicators with detailed operational definitions; (iv) identification of trade-offs between indicators; (v) elaboration of descriptive sheets for each indicator to support hospitals in interpreting their results; (vi) design of a balanced dashboard; and (vii) strategies for implementation of the PATH framework. Conclusion. PATH is currently being pilot implemented in eight countries to refine its framework before further expansio

Mildiou et oïdium de la vigne pour des décisions coordonnées

National audienceDans le but d'aider les viticulteurs à diminuer le nombre de leurs traitements fongicides contre l'oïdium et le mildiou (réduction d'usage des pesticides) sans prendre de risque pour la quantité ni la qualité de la vendange, un nouvel outil nommé Mildium a été élaboré grâce au soutien de l'ANR et diverses collaborations. Mildium est un processus opérationnel de décision (POD) ; il stipule comment sont ordonnées dans le temps les prises d'information et les décisions, avec deux principes : - limiter le nombre d'observations au vignoble, coûteuses en temps, en choisissant bien le moment de les réaliser ; - coordonner les décisions concernant le mildiou et l'oïdium pour limiter le nombre de passages. L'article explique sa conception, ses principes et son contenu, et raconte les étapes de sa formalisation et de ses premières validations réalisées en Aquitaine de 2005 à 2008 inclus et élargies au Languedoc-Roussillon en 2008. Il évoque les résultats, très encourageants, et le travail restant à fournir

Mildiou et oïdium de la vigne pour des décisions coordonnées

National audienceDans le but d'aider les viticulteurs à diminuer le nombre de leurs traitements fongicides contre l'oïdium et le mildiou (réduction d'usage des pesticides) sans prendre de risque pour la quantité ni la qualité de la vendange, un nouvel outil nommé Mildium a été élaboré grâce au soutien de l'ANR et diverses collaborations. Mildium est un processus opérationnel de décision (POD) ; il stipule comment sont ordonnées dans le temps les prises d'information et les décisions, avec deux principes : - limiter le nombre d'observations au vignoble, coûteuses en temps, en choisissant bien le moment de les réaliser ; - coordonner les décisions concernant le mildiou et l'oïdium pour limiter le nombre de passages. L'article explique sa conception, ses principes et son contenu, et raconte les étapes de sa formalisation et de ses premières validations réalisées en Aquitaine de 2005 à 2008 inclus et élargies au Languedoc-Roussillon en 2008. Il évoque les résultats, très encourageants, et le travail restant à fournir

Real-Time Antimicrobial Susceptibility Assay of Planktonic and Biofilm Bacteria by Isothermal Microcalorimetry

Most antimicrobials currently used in the clinical practice are tested as growth inhibitors against free-floating microorganisms in a liquid suspension, rather than against sessile cells constituting biofilms. Hence, reliable, fast, and reproducible methods for assessing biofilm susceptibility to antimicrobials are strongly needed. Isothermal microcalorimetry (IMC) is a nondestructive sensitive technique that allows for the real-time monitoring of microbial viability in the presence or absence of antimicrobial compounds. Therefore, the efficacy of specific antimicrobials, alone or in combination, may be promptly validated supporting the development of new drugs and avoiding the administration of ineffective therapies. Furthermore, the susceptibility of both planktonic and biofilm cells to antimicrobials can be conveniently assessed without the need for elaborated staining procedures and under nontoxic working conditions. Quantitative data regarding the antimicrobial effect against different strains might be collected by monitoring the microbial cell replication, and, more importantly, a dose-dependent activity can be efficiently detected by measuring the delay and decrease in the heat flow peak of the treated samples. A limitation of IMC for anti-biofilm susceptibility test is the inability to directly quantify the non-replicating cells in the biofilm or the total biomass. However, as IMC is a nondestructive method, the samples can be also analyzed by using different techniques, acquiring more information complementary to calorimetric data. IMC finds application also for the investigation of antibiotic eluting kinetics from different biomaterials, as well as for studying bacteriophages activity against planktonic and biofilm bacteria. Thus, the wide applicability of this ultra-sensitive and automated technique provides a further advance in the field of clinical microbiology and biomedical sciences

Quantification of vital adherent Streptococcus sanguinis cells on protein-coated titanium after disinfectant treatment

The quantification of vital adherent bacteria is challenging, especially when efficacy of antimicrobial agents is to be evaluated. In this study three different methods were compared in order to quantify vital adherent Streptococcus sanguinis cells after exposure to disinfectants. An anaerobic flow chamber model accomplished initial adhesion of S. sanguinis on protein-coated titanium. Effects of chlorhexidine, Betadine®, Octenidol®, and ProntOral® were assessed by quantifying vital cells using Live/Dead BacLight?, conventional culturing and isothermal microcalorimetry (IMC). Results were analysed by Kruskal-Wallis one-way analysis of variance. Live/dead staining revealed highest vital cell counts (P > 0.05) and demonstrated dose-dependent effect for all disinfectants. Microcalorimetry showed time-delayed heat flow peaks that were proportioned to the remaining number of viable cells. Over 48 h there was no difference in total heat between treated and untreated samples (P < 0.05), indicating equivalent numbers of bacteria were created and disinfectants delayed growth but did not eliminate it. In conclusion, contrary to culturing, live/dead staining enables detection of cells that may be viable but non-cultivable. Microcalorimetry allows unique evaluation of relative disinfectant effects by quantifying differences in time delay of regrowth of remaining vital cells