New concepts in the pathogenesis, diagnosis and treatment of bacteremia and sepsis

A Usefulness of Delta Neutrophil Index (DNI) for Prediction of 28 Day Mortality in Patients with Pneumonia-Induced Sepsis in the Intensive Care Unit

Background: The delta neutrophil index (DNI) represents the immature granulocyte fraction and is determined by subtracting the fraction of mature polymorphonuclear leucocytes from the sum of myeloperoxidase-reactive cells. The DNI has been proposed as a useful prognostic marker for sepsis. This study evaluated the clinical utility of DNI as a predictive marker in patients with pneumonia-induced sepsis in the intensive care unit (ICU). Methods: We conducted a retrospective study of pneumonia-induced sepsis in patients who were admitted to the Kangdong Sacred Heart Hospital's medical ICUs from July 2022 to March 2024. The DNI was measured on three consecutive days after ICU admission. The primary outcome of this study was a 28-day mortality. Results: A total of 227 patients with pneumonia-induced sepsis were included in this study. A 28-day mortality occurred 20.3% of the time in our study. In a univariate analysis, age (p = 0.05), lymphocyte (p = 0.02), DNI 1 (p = 0.01), DNI 2 (p = 0.00), DNI 3 (p = 0.00), and lactic acid (p = 0.00) were significantly associated with 28-day mortality. In a multivariable analysis, lactate (adj. OR: 0.86, 95% CI: 0.78-0.95, p = 0.002), and DNI 3 (adj. OR: 0.94, 95% CI: 0.89-0.99, p = 0.048) were significantly associated with 28-day mortality. In our study, the most appropriate cut-off values were DNI 1 (7.15), DNI 2 (8.9), and DNI 3 (2.6). Patients with higher DNI 3 (≥2.6) showed higher 28-day mortality than patients with lower DNI 3 values of <2.6 (67.4% vs. 32.6%; p < 0.001). However, those aged ≥70 did not show statistically significantly different DNI 1 values between the survivor and non- survivor groups. Conclusions: The DNI at 72 h after ICU admission is a promising predictive prognostic marker of 28-day mortality in patients with pneumonia-induced sepsis in the ICU. However, the interpretation of the DNI in sepsis patients aged 70 and older on the first day of hospitalization should be approached with caution.

Staphylococcus aureus in Inflammation and Pain: Update on Pathologic Mechanisms

Staphylococcus aureus (S. aureus) is a Gram-positive bacterium of significant clinical importance, known for its versatility and ability to cause a wide array of infections, such as osteoarticular, pulmonary, cardiovascular, device-related, and hospital-acquired infections. This review describes the most recent evidence of the pathogenic potential of S. aureus, which is commonly part of the human microbiota but can lead to severe infections. The prevalence of pathogenic S. aureus in hospital and community settings contributes to substantial morbidity and mortality, particularly in individuals with compromised immune systems. The immunopathogenesis of S. aureus infections involves intricate interactions with the host immune and non-immune cells, characterized by various virulence factors that facilitate adherence, invasion, and evasion of the host's defenses. This review highlights the complexity of S. aureus infections, ranging from mild to life-threatening conditions, and underscores the growing public health concern posed by multidrug-resistant strains, including methicillin-resistant S. aureus (MRSA). This article aims to provide an updated perspective on S. aureus-related infections, highlighting the main diseases linked to this pathogen, how the different cell types, virulence factors, and signaling molecules are involved in the immunopathogenesis, and the future perspectives to overcome the current challenges to treat the affected individuals.

Effects of β-Glucan Supplementation on LPS-Induced Endotoxemia in Horses

β-glucan is part of the cell wall of fungi and yeasts and has been known for decades to have immunomodulating effects on boosting immunity against various infections as a pathogen-associated molecular pattern that is able to modify biological responses. β-glucan has been used in rat models and in vitro studies involving sepsis and SIRS with good results, but this supplement has not been evaluated in the treatment of endotoxemia in horses. This study aims to evaluate the effects of preventive supplementation with β-glucan in horses submitted to endotoxemia by means of inflammatory response modulation. Eight healthy horses, both male and female, aged 18 ± 3 months, weighing 300 ± 100 kg of mixed breed, were randomly assigned to two groups of four animals, both of which were subjected to the induction of endotoxemia via the intravenous administration of E. coli lipopolysaccharides (0.1 µg/kg). For 30 days before the induction of endotoxemia, horses in the β-glucan group (GB) received 10 mg/kg/day of β-glucan orally, and horses in the control group (GC) received 10 mg/kg/day of 0.9% sodium chloride orally. The horses were submitted to physical exams, including a hematological, serum biochemistry, and peritoneal fluid evaluation, and the serum quantification of cytokines TNF-α, IL-6, IL-8, and IL-10. For statistical analysis, the normality of residues and homogeneity of variances were verified; then, the variables were analyzed as repeated measures over time, checking the effect of treatment, time, and the interaction between time and treatment. Finally, the averages were compared using Tukey's test at a significance level of 5%. Horses from both experimental groups presented clinical signs and hematological changes in endotoxemia, including an increase in heart rate and body temperature, neutrophilic leukopenia, an increase in serum bilirubin, glucose, lactate, and an increase in TNF-α, IL-6, and IL-10. Hepatic and renal function were not compromised by β-glucan supplementation. GB presented higher mean values of the serum total protein, globulins, and IL-8 compared to that observed in GC. In the peritoneal fluid, horses from GB presented a lower mean concentration of neutrophils and a higher mean concentration of macrophages compared to the GC. It was concluded that preventive supplementation of β-glucan for thirty days modulated the immune response, as evidenced by increasing serum total proteins, globulins, IL-8, and changes in the type of peritoneal inflammatory cells, without effectively attenuating clinical signs of endotoxemia in horses. Considering the safety of β-glucan in this study, the results suggest the potential clinical implication of β-glucan for prophylactic use in horse endotoxemia.

Explainable machine learning using perioperative serial laboratory results to predict postoperative mortality in patients with peritonitis-induced sepsis

Purpose

Sepsis is one of the most common causes of death after surgery. Several conventional scoring systems have been developed to predict the outcome of sepsis; however, their predictive power is insufficient. The present study applies explainable machine-learning algorithms to improve the accuracy of predicting postoperative mortality in patients with sepsis caused by peritonitis.

Methods

We performed a retrospective analysis of data from demographic, clinical, and laboratory analyses, including the delta neutrophil index (DNI), WBC and neutrophil counts, and CRP level. Laboratory data were measured before surgery, 12-36 hours after surgery, and 60-84 hours after surgery. The primary study output was the probability of mortality. The areas under the receiver operating characteristic curves (AUCs) of several machine-learning algorithms using the Sequential Organ Failure Assessment (SOFA) and Simplified Acute Physiology Score (SAPS) 3 models were compared. 'SHapley Additive exPlanations' values were used to indicate the direction of the relationship between a variable and mortality.

Results

The CatBoost model yielded the highest AUC (0.933) for mortality compared to SAPS3 and SOFA (0.860 and 0.867, respectively). Increased DNI on day 3, septic shock, use of norepinephrine therapy, and increased international normalized ratio on day 3 had the greatest impact on the model's prediction of mortality.

Conclusion

Machine-learning algorithms increase the accuracy of predicting postoperative mortality in patients with sepsis caused by peritonitis.

Predictors of bacteremia in febrile infants under 3 months old in the pediatric emergency department

INTRODUCTION

Fever may serve as the primary indicator of underlying infection in children admitted to the pediatric emergency department (PED), especially in high-risk young infants. This study aimed to identify early clinical factors that could help predict bacteremia in young febrile infants.

METHODS

The study included infants under 90 days of age who were admitted to the PED due to fever. Patients were divided into two groups based on the presence or absence of bacteremia and further divided into three age groups: (1) less than 30 days, (2) 30 to 59 days, and (3) 60 to 90 days. Several clinical and laboratory variables were analyzed, and logistic regression and receiver operating characteristic (ROC) analyses were used to identify potential risk factors associated with bacteremia in young febrile infants.

RESULTS

A total of 498 febrile infants were included, of whom 6.4% were diagnosed with bacteremia. The bacteremia group had a higher body temperature (BT) at triage, especially in neonates, higher pulse rates at triage, longer fever subsidence time, longer hospital stays, higher neutrophil counts, and higher C-reactive protein (CRP) levels than those of the non-bacteremia group. ROC analysis showed that the best cut-off values for predicting bacteremia in infants with pyrexia were a BT of 38.7 °C, neutrophil count of 57.9%, and CRP concentration of 53.8 mg/L.

CONCLUSIONS

A higher BT at triage, increased total neutrophil count, and elevated CRP levels may be useful for identifying bacteremia in young febrile infants admitted to the PED.

Nanomedicine: New Frontiers in Fighting Microbial Infections

Microbes have dominated life on Earth for the past two billion years, despite facing a variety of obstacles. In the 20th century, antibiotics and immunizations brought about these changes. Since then, microorganisms have acquired resistance, and various infectious diseases have been able to avoid being treated with traditionally developed vaccines. Antibiotic resistance and pathogenicity have surpassed antibiotic discovery in terms of importance over the course of the past few decades. These shifts have resulted in tremendous economic and health repercussions across the board for all socioeconomic levels; thus, we require ground-breaking innovations to effectively manage microbial infections and to provide long-term solutions. The pharmaceutical and biotechnology sectors have been radically altered as a result of nanomedicine, and this trend is now spreading to the antibacterial research community. Here, we examine the role that nanomedicine plays in the prevention of microbial infections, including topics such as diagnosis, antimicrobial therapy, pharmaceutical administration, and immunizations, as well as the opportunities and challenges that lie ahead.

Transmission of gram-negative antibiotic-resistant bacteria following differing exposure to antibiotic-resistance reservoirs in a rural community: a modelling study for bloodstream infections

Exposure to community reservoirs of gram-negative antibiotic-resistant bacteria (GN-ARB) genes poses substantial health risks to individuals, complicating potential infections. Transmission networks and population dynamics remain unclear, particularly in resource-poor communities. We use a dynamic compartment model to assess GN-ARB transmission quantitatively, including the susceptible, colonised, infected, and removed populations at the community-hospital interface. We used two side streams to distinguish between individuals at high- and low-risk exposure to community ARB reservoirs. The model was calibrated using data from a cross-sectional cohort study (N = 357) in Chile and supplemented by existing literature. Most individuals acquired ARB from the community reservoirs (98%) rather than the hospital. High exposure to GN-ARB reservoirs was associated with 17% and 16% greater prevalence for GN-ARB carriage in the hospital and community settings, respectively. The higher exposure has led to 16% more infections and attributed mortality. Our results highlight the need for early-stage identification and testing capability of bloodstream infections caused by GN-ARB through a faster response at the community level, where most GN-ARB are likely to be acquired. Increasing treatment rates for individuals colonised or infected by GN-ARB and controlling the exposure to antibiotic consumption and GN-ARB reservoirs, is crucial to curve GN-ABR transmission.

Atractylenolide III alleviates sepsis-mediated lung injury via inhibition of FoxO1 and VNN1 protein

PURPOSE

To evaluate the influence of atractylenolide (Atr) III on sepsis-induced lung damage.

METHODS

We constructed a mouse sepsis model through cecal ligation and puncture. These mice were allocated to the normal, sepsis, sepsis + Atr III-L (2 mg/kg), as well as Atr III-H (8 mg/kg) group. Lung injury and pulmonary fibrosis were accessed via hematoxylin-eosin (HE) and Masson's staining. We used terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and flow cytometry for detecting sepsis-induced lung cell apoptosis. The contents of the inflammatory cytokines in lung tissue were measured via enzyme-linked immunosorbent assay (ELISA).

RESULTS

Atr III-H did not only reduce sepsis-induced lung injury and apoptosis level, but also curbed the secretion of inflammatory factors. Atr III-H substantially ameliorated lung function and raised Bcl-2 expression. Atr III-H eased the pulmonary fibrosis damage and Bax, caspase-3, Vanin-1 (VNN1), as well as Forkhead Box Protein O1 (FoxO1) expression.

CONCLUSIONS

Atr III alleviates sepsis-mediated lung injury via inhibition of FoxO1 and VNN1 protein.

Bacteria and Host Interplay in Staphylococcus aureus Septic Arthritis and Sepsis

Staphylococcus aureus (S. aureus) infections are a major healthcare challenge and new treatment alternatives are needed. S. aureus septic arthritis, a debilitating joint disease, causes permanent joint dysfunction in almost 50% of the patients. S. aureus bacteremia is associated with higher mortalities than bacteremia caused by most other microbes and can develop to severe sepsis and death. The key to new therapies is understanding the interplay between bacterial virulence factors and host immune response, which decides the disease outcome. S. aureus produces numerous virulence factors that facilitate bacterial dissemination, invasion into joint cavity, and cause septic arthritis. Monocytes, activated by several components of S. aureus such as lipoproteins, are responsible for bone destructions. In S. aureus sepsis, cytokine storm induced by S. aureus components leads to the hyperinflammatory status, DIC, multiple organ failure, and later death. The immune suppressive therapies at the very early time point might be protective. However, the timing of treatment is crucial, as late treatment may aggravate the immune paralysis and lead to uncontrolled infection and death.

Albumin-to-Fibrinogen Ratio Independently Predicts 28-Day Mortality in Patients with Peritonitis-Induced Sepsis

Background

This study is aimed at investigating whether albumin-to-fibrinogen ratio (AFR) could independently predict the prognosis in patients with peritonitis-induced sepsis.

Methods

A total of 246 eligible patients who were scheduled to undergo surgical treatment for peritonitis-induced sepsis were enrolled in this study. The primary observational endpoint was 28-day hospital mortality. Cox proportional hazards regression analysis with the Wald test was performed to identify prognostic factors for 28-day mortality in septic patients. Receiver operating characteristic (ROC) and Kaplan-Meier curve analyses were carried out to evaluate the association of baseline AFR and prognosis in septic patients.

Results

Of all the cohort study participants, there were 59 nonsurvivors with a 28-day mortality of 24.0% (59/246). Baseline AFR (hazard ratio (HR): 0.67, 95% confidence interval (CI): 0.42-0.93, P = 0.018) and the presence of septic shock (HR: 2.43, 95% CI: 1.42-3.91, P = 0.021) were two independent prognostic factors for 28-day mortality in patients with peritonitis-induced sepsis by multivariate Cox analysis. Baseline AFR was a significant predictor for 28-day mortality with an area under the curve (AUC) of 0.751, a cut-off value of 8.85, a sensitivity of 66.10%, and a specificity of 70.05%, respectively (95% CI: 0.688-0.813, P < 0.001). A low baseline AFR level (≤8.85) was significantly associated with a lower overall survival rate in septic patients by Kaplan-Meier curve analysis with log-rank test (P = 0.004).

Conclusions

This study indicates that AFR independently predicts 28-day mortality in patients with peritonitis-induced sepsis.

Nano-Based Drug Delivery or Targeting to Eradicate Bacteria for Infection Mitigation: A Review of Recent Advances

Pathogenic bacteria infection is a major public health problem due to the high morbidity and mortality rates, as well as the increased expenditure on patient management. Although there are several options for antimicrobial therapy, their efficacy is limited because of the occurrence of drug-resistant bacteria. Many conventional antibiotics have failed to show significant amelioration in overall survival of infectious patients. Nanomedicine for delivering antibiotics provides an opportunity to improve the efficiency of the antibacterial regimen. Nanosystems used for antibiotic delivery and targeting to infection sites render some benefits over conventional formulations, including increased solubility, enhanced stability, improved epithelium permeability and bioavailability, prolonged antibiotic half-life, tissue targeting, and minimal adverse effects. The nanocarriers' sophisticated material engineering tailors the controllable physicochemical properties of the nanoparticles for bacterial targeting through passive or active targeting. In this review, we highlight the recent progress on the development of antibacterial nanoparticles loaded with antibiotics. We systematically introduce the concepts and amelioration mechanisms of the nanomedical techniques for bacterial eradication. Passive targeting by modulating the nanoparticle structure and the physicochemical properties is an option for efficient drug delivery to the bacteria. In addition, active targeting, such as magnetic hyperthermia induced by iron oxide nanoparticles, is another efficient way to deliver the drugs to the targeted site. The nanoparticles are also designed to respond to the change in environment pH or enzymes to trigger the release of the antibiotics. This article offers an overview of the benefits of antibacterial nanosystems for treating infectious diseases.

Vitamin lipid nanoparticles enable adoptive macrophage transfer for the treatment of multidrug-resistant bacterial sepsis

Sepsis, a condition caused by severe infections, affects more than 30 million people worldwide every year and remains the leading cause of death in hospitals^1,2. Moreover, antimicrobial resistance has become an additional challenge in the treatment of sepsis³, and thus, alternative therapeutic approaches are urgently needed^2,3. Here, we show that adoptive transfer of macrophages containing antimicrobial peptides linked to cathepsin B in the lysosomes (MACs) can be applied for the treatment of multidrug-resistant bacteria-induced sepsis in mice with immunosuppression. The MACs are constructed by transfection of vitamin C lipid nanoparticles that deliver antimicrobial peptide and cathepsin B (AMP-CatB) mRNA. The vitamin C lipid nanoparticles allow the specific accumulation of AMP-CatB in macrophage lysosomes, which is the key location for bactericidal activities. Our results demonstrate that adoptive MAC transfer leads to the elimination of multidrug-resistant bacteria, including Staphylococcus aureus and Escherichia coli, leading to the complete recovery of immunocompromised septic mice. Our work provides an alternative strategy for overcoming multidrug-resistant bacteria-induced sepsis and opens up possibilities for the development of nanoparticle-enabled cell therapy for infectious diseases.

Real-Time Monitoring of Bacteria Clearance From Blood in a Murine Model

Bloodstream infections, especially those that are antibiotic resistant, pose a significant challenge to health care leading to increased hospitalization time and patient mortality. There are different facets to this problem that make these diseases difficult to treat, such as the difficulty to detect bacteria in the blood and the poorly understood mechanism of bacterial invasion into and out of the circulatory system. However, little progress has been made in developing techniques to study bacteria dynamics in the bloodstream. Here, we present a new approach using an in vivo flow cytometry platform for real-time, noninvasive, label-free, and quantitative monitoring of the lifespan of green fluorescent protein-expressing Staphylococcus aureus and Pseudomonas aeruginosa in a murine model. We report a relatively fast average rate of clearance for S. aureus (k = 0.37 ± 0.09 min^-1 , half-life ~1.9 min) and a slower rate for P. aeruginosa (k = 0.07 ± 0.02 min^-1 , half-life ~9.6 min). We also observed what appears to be two stages of clearance for S. aureus, while P. aeruginosa appeared only to have a single stage of clearance. Our results demonstrate that an advanced research tool can be used for studying the dynamics of bacteria cells directly in the bloodstream, providing insight into the progression of infectious diseases in circulation. © 2019 International Society for Advancement of Cytometry.

Comparative-effectiveness of ceftaroline and daptomycin as first-line MRSA therapy for patients with sepsis admitted to hospitals in the United States Veterans Health Care System

Objectives: This study compared hospital readmission and mortality for patients with sepsis who received ceftaroline or daptomycin as first-line MRSA therapy.Methods: This retrospective comparative-effectiveness study included adults ≥18 years old hospitalized in the United States Veterans Health Care System with sepsis between 10/1/2010-9/30/2014, who received ceftaroline or daptomycin within 14 days of hospital admission as the first antibiotic effective against methicillin resistant Staphylococcus aureus (MRSA). Patients with pneumonia, and those who received both study drugs, were excluded. Baseline characteristics were compared using Chi-square, Fischer's exact, Student's t, and Wilcoxon Rank Sum tests. Patient outcomes were compared with multivariable logistic regression models.Results: 409 patients were included (ceftaroline = 67, daptomycin = 342). Ceftaroline patients were older, less likely to be Black, more likely to have diabetes with complications, and had higher Charlson comorbidity scores. Median (interquartile range) time from admission to drug initiation was 1 (0-1) day for ceftaroline and 1 (1-3) day for daptomycin (p = 0.01). Unadjusted hospital readmission rates for ceftaroline and daptomycin, respectively, were: 30-day (25%/37%, p = 0.06), 60-day (27%/44%, p = 0.008), and 90-day (28%/46%, p = 0.01). Unadjusted mortality rates were: in-hospital (7%/12%, p = 0.4), 30-day (3%/9%, p = 0.1), 60-day (6%/12%, p = 0.2), and 90-day (7%/15%, p = 0.1). In multivariable models with all divergent baseline characteristics included as covariates, patients treated with ceftaroline were less likely to experience (OR, 95% CI): 30/60/90-day hospital readmission (0.54, 0.29-0.98; 0.42, 0.23-0.76; 0.42, 0.23-0.75) and 30/60/90-day mortality (0.23, 0.04-0.82; 0.34, 0.10-0.93; 0.34, 0.11-0.86).Conclusion: In patients with sepsis, ceftaroline was associated with fewer hospital readmissions and lower mortality as compared to daptomycin. Prospective investigations in larger, more generalized cohorts are needed to examine outcomes with specific MRSA therapies.

APRIL and sTACI could be predictors of multiorgan dysfunction syndrome in sepsis

Although the role of B cells in sepsis immunoregulation has become an interesting topic, there is lack of data on the role of B cell function regulators in prediction of multiorgan dysfunction syndrome (MODS). The aim of this study was to evaluate the prognostic value of A Proliferation Inducing Ligand (APRIL) and soluble Transmembrane Activator and CAML Interactor Protein (sTACI), the main B cell function regulators, in prediction of MODS development within the first 48 h after admission to intensive care unit, among septic patients. We included 112 patients with sepsis, treated at Clinic for Infectious Diseases and Emergency Center, Clinical Center of Vojvodina, Novi Sad, Serbia. Plasma concentrations of APRIL and sTACI were determined at the admission and potential development of MODS was confirmed in the first 48 h. Concentrations of APRIL (p = 0.003) and sTACI (p<0.001) were higher in patients who developed MODS (n = 30). ROC curve analysis showed that AUC for sTACI (AUC = 0.764) was greater than that for procalcitonin (AUC = 0.719) and APRIL (AUC = 0.673) in MODS development prediction. Multivariate regression analysis showed that sTACI, as an anti-inflammatory biomarker stimulating the apoptosis of B cells, was the only independent predictor of MODS, beside SOFA score. Elevated level of sTACI could be the alarm for the increased B cell apoptosis and development of immune paralysis. Including these biomarkers into predictive scores specific for septic patients may potentially improve their sensitivity and specificity. Measurement of their concentrations dynamics could contribute to better assessment of sepsis evolution and timely introduction of immunomodulatory therapy.

The role of TNF-α superfamily members in immunopathogenesis of sepsis

BACKGROUND

Members of TNFα superfamily, A proliferation inducing ligand (APRIL), B-cell activating factor (BAFF) and Transmembrane activator and calcium cyclophylin interactor (TACI) are main regulators of B-cell function. The aim of this study was to evaluate concentrations of APRIL, BAFF and soluble TACI (sTACI) receptor in septic patients compared to healthy controls and compare concentrations of these biomarkers depending on sepsis severity and outcome.

MATERIALS AND METHODS

A total of 115 septic patients and 30 healthy volunteers were included and concentrations of APRIL, BAFF and sTACI were determined in all subjects at the admission (ELISA R&D Systems tests). Concentrations of these biomarkers in function of sepsis severity (sepsis n = 94 and septic shock n = 21) and outcome (lethal n = 40, recovery n = 75) were tested, as well as correlations with APACHE II and SOFA scores, immunoglobulins, complement, PCT and CRP concentrations.

RESULTS

Concentrations of all three biomarkers were significantly increased in septic patients compared to controls (AUC_APRIL = 0.982, AUC_BAFF = 0.873, AUC_sTACI = 0.683). Higher concentrations of APRIL and sTACI (p = 0.033, p = 0.037), and lower concentrations of BAFF (p = 0.005) were observed in patients with septic shock compared to sepsis. BAFF concentrations correlated positively with IgM, C3 and C4 levels. sTACI and APRIL were shown to be predictors of lethal outcome (p = 0.003, p = 0.049).

CONCLUSIONS

Concentrations of observedTNFα superfamily members are significantly increased in septic patients, confirming their role in sepsis pathogenesis.Higher concentrations of anti-inflammatory sTACI receptor correlated with severity of sepsis and poorer prognosis, thus potentially indicating domination of anti-inflammatory response in septic patients with worse outcome.

High Circulating Caspase-Cleaved Keratin 18 Fragments (M30) Indicate Short-Term Mortality in Critically Ill Patients

Caspase-cleaved fragments of the intermediate filament protein keratin 18 (cytokeratin-18 (CK18)) can be detected in serum as M30 levels and may serve as a circulating biomarker indicating apoptosis of epithelial and parenchymal cells. In order to evaluate M30 as a biomarker in critical illness, we analyzed circulating M30 levels in 243 critically ill patients (156 with sepsis, 87 without sepsis) at admission to the medical intensive care unit (ICU), in comparison to healthy controls (n = 32). M30 levels were significantly elevated in ICU patients compared with healthy controls. Circulating M30 was closely associated with disease severity but did not differ between patients with sepsis and ICU patients without sepsis. M30 serum levels were correlated with biomarkers of inflammation, cell injury, renal failure, and liver failure in critically ill patients. Patients that died at the ICU showed increased M30 levels at admission, compared with surviving patients. A similar trend was observed for the overall survival. Regression analyses confirmed that M30 levels are associated with mortality, and patients with M30 levels above 250.8 U/L displayed an excessive short-term mortality. Thus, our data support the utility of circulating levels of the apoptosis-related keratin fragment M30 as a prognostic biomarker at ICU admission.

In vivo and in vitro anti-sepsis effects of physcion 8-O-β-glucopyranoside extracted from Rumex japonicus

The present study was designed to investigate the anti-sepsis effects of physcion 8-O-β-glucopyranoside (POG) isolated from Rumex japonicas and explore its possible pharmacological mechanisms. POG was extracted from R. japonicas by bioactivity-guided isolation with the anti-sepsis agents. Survival analysis in septic mouse induced by LPS and heat-killed Escherichia coli were used to evaluate the protective effect of POG (40 mg·kg^-1, i.p.) on sepsis. Cytokines including TNF-α, IL-1β and IL-6 in RAW 264.7 cells induced by LPS (100 ng·mL^-1) were determined by ELISA. In addition, the proteins expressions of TLR2 and TLR4 were determined by Western blotting assay. Our results demonstrated that POG (40 mg·kg^-1, i.p.) possessed significant protective activity on the endotoxemic mice. The POG treatment (20, 40, and 80 μg·mL^-1) significantly decreased the TNF-α, IL-1β and IL-6 induced by LPS (P < 0.01) in a concentration-dependent manner. Furthermore, the TLR4 and TLR2 proteins were also down-regulated by POG at 20 (P < 0.01), 40 (P < 0.01), and 80 μg·mL^-1 (P < 0.01). The present study demonstrated that the POG extracted from R. japonicas possessed significant anti-sepsis effect on endotoxemic mice, and can be developed as a novel drug for treating sepsis in the future.

Early immune anergy towards recall antigens and mitogens in patients at onset of septic shock

The pathology of sepsis is typically characterized by an infection and excessive initial inflammation including a cytokine storm, followed by a state of immune suppression or paralysis. This classical view of a two peak kinetic immune response is currently controversially discussed. This study was a sub-study of the randomized clinical Trial SISPCT registered with www.clinicaltrials.gov (NCT00832039, Registration date: 29/01/2009). Blood samples from 76 patients with severe sepsis and septic shock were incubated for 48 h at 37 °C in vitro with bacterial or fungal recall-antigens or specific mitogen antigens within 24 hours of sepsis onset. Recall-antigen stimulation led to a severe dampening of normal cytokine release. This immunologic anergy was similarly observed after mitogen stimulation. Moreover, patients under hydrocortisone therapy or with lowered arterial oxygen tension had further reductions in cytokine levels upon B- and T-cell mitogen stimulation. This investigation reveals an early onset of immunoparalysis during sepsis. This immune incompetence in mounting an adequate response to further infections includes previously sensitized pathogens, as seen with recall-antigens. Also, the immune-suppressive role of hydrocortisone and low PaO2 is highlighted. Aside from early broad-spectrum antimicrobial therapy, our findings reinforce the need for maximal immunological support and protection against further infections at the onset of sepsis.

The delta neutrophil index is a prognostic factor for postoperative mortality in patients with sepsis caused by peritonitis

Introduction

The delta neutrophil index (DNI) represents the fraction of circulating immature granulocytes and is a marker of infection and sepsis. Our objective was to evaluate the usefulness of DNI for predicting in-hospital mortality within 30 days after surgery in patients with sepsis caused by peritonitis by means of comparing DNI, white blood cell (WBC) count, neutrophil percentage, and C-reactive protein (CRP) before and after surgery.

Materials and methods

We performed a retrospective analysis of demographic, clinical, and laboratory data. DNI, WBC count, neutrophil percentage, and CRP were measured before surgery, and at 12–36 h (day 1) and 60–84 h (day 3) after surgery.

Results

There were 116 (73.7%) survivors and 44 (26.3%) non-survivors. The rates of septic shock, norepinephrine administration, renal replacement, mechanical ventilator therapy, and reoperation, the Simplified Acute Physiology Score-3 (SAPS3), and the Sepsis-related Organ Failure Assessment (SOFA) score were greater in non-survivors. DNI on day 3 was better than the other laboratory variables for predicting mortality. DNI was correlated with the SAPS3 (r = .46, p = .00) and SOFA score (r = .45, p = .00). The optimal cut-off DNI for predicting mortality was 7.8% (sensitivity: 77.3%; specificity: 95.9%). In receiver-operating characteristic curve analysis, DNI on day 3 was the best indicator of mortality (area under the curve: .880; 95% confidence interval: .80–.96).

Conclusions

Our results indicate that DNI is better than other laboratory variables for predicting postoperative mortality in patients with sepsis caused by peritonitis. DNI > 7.8% on day 3 was a reliable predictor of postoperative mortality.

Use of presepsin and procalcitonin for prediction of SeptiFast results in critically ill patients

PURPOSE

There is a need for identification of marker that could lead physicians to take the right step towards laboratory techniques for documentation of infection. The aim of this study was to investigate whether presepsin and procalcitonin (PCT) levels in patients with suspected sepsis could predict blood culture (BC) and SeptiFast (SF) results.

MATERIAL AND METHODS

100 patients were included in our study. PCT, C-reactive protein (CRP), and presepsin levels were determined. Differences between groups of patients were assessed by Mann-Whitney U test. Categorical variables were compared using chi-square test. Receiver operating characteristic (ROC) curves were plotted to determine predictive values of biomarkers for prediction of positive SF results.

RESULTS

PCT (70.9±106.36 vs. 16.35±26.79) and presepsin (4899.73±5207.81 vs. 1751.59±2830.62) were significantly higher in patients with positive SF in contrast to patients with negative SF. There was no significant difference between patients who had positive and negative BC for PCT and presepsin values. PCT and presepsin showed a similar performance in predicting positive SF results with AUC of 0.75 for PCT and 0.73 for presepsin.

CONCLUSION

Presepsin can serve as good predictor of bacteremia detected by SF and it should be included with PCT in protocols for sepsis diagnosing.

Long Pentraxin 3 as a Predictive Marker of Mortality in Severe Septic Patients Who Received Successful Early Goal-Directed Therapy

PURPOSE

Pentraxin 3 (PTX3) has been suggested to be a prognostic marker of mortality in severe sepsis. Currently, there are limited data on biomarkers including PTX3 that can be used to predict mortality in severe sepsis patients who have undergone successful initial resuscitation through early goal-directed therapy (EGDT).

MATERIALS AND METHODS

A prospective cohort study was conducted among 83 severe sepsis patients with fulfillment of all EGDT components and the achievement of final goal. Plasma PTX3 levels were measured by sandwich ELISA on hospital day (HD) 0, 3, and 7. The data for procalcitonin, C-reactive protein and delta neutrophil index were collected by electric medical record. The primary outcome was 28-day all-cause mortality.

RESULTS

28-day all-cause mortality was 19.3% and the median (interquartile range) APHCH II score of total patients was 16 (13-19). The non-survivors (n=16) had significantly higher PTX3 level at HD 0 [201.4 (56.9-268.6) ng/mL vs. 36.5 (13.7-145.3) ng/mL, p=0.008]. PTX3 had largest AUC(ROC) value for the prediction of mortality among PTX3, procalcitonin, delta neutrophil index, CRP and APACHE II/SOFA sore at HD 0 [0.819, 95% confidence interval (CI) 0.677-0.961, p=0.008]. The most valid cut-off level of PTX3 at HD 0 was 140.28 ng/mL (sensitivity 66.7%, specificity 73.8%). The PTX3 and procalcitonin at HD 0 showed strong correlation (r=0.675, p<0.001). However, PTX3 at HD 0 was the only independent predictive marker in Cox's proportional hazards model (≥140 ng/mL; hazard rate 7.16, 95% CI 2.46-15.85, p=0.001).

CONCLUSION

PTX3 at HD 0 could be a powerful predictive biomarker of 28-day all-cause mortality in severe septic patients who have undergone successful EGDT.

Higher serum caspase-cleaved cytokeratin-18 levels during the first week of sepsis diagnosis in non-survivor patients

Background:

Caspase-cleaved cytokeratin (CCCK)-18 is a protein released into the blood during apoptosis. Higher circulating CCCK-18 concentrations have been found in non-survivor than in survivor septic patients at moment of sepsis diagnosis. The following questions arise now: (1) How are serum CCCK-18 levels during the first week of sepsis? (2) Is there an association between sepsis severity and mortality and serum CCCK-18 levels during the first week? The aims of this study were to answer these questions.

Methods:

Multicenter study with 321 severe septic patients from eight Spanish intensive care units. We determined serum concentration of CCCK-18, tumor necrosis factor (TNF)-α, and interleukin (IL)-10 during the first week. Our end-point study was 30-day mortality.

Results:

Non-survivor (n=108) compared to survivor patients (n=213) showed higher serum CCCK-18 levels at days 1, 4 and 8 (p<0.001). ROC curve analyses showed that serum CCCK-18 levels at days 1 (AUC=0.77; 95% CI=0.72–0.82), 4 (AUC=0.81; 95% CI=0.76–0.85) and 8 (AUC=0.83; 95% CI=0.78–0.88) could predict mortality at 30 days (p<0.001). Logistic regression analyses showed that serum CCCK-18 levels at days 1 (OR=4.367; 95% CI=2.491–7.659), 4 (OR=10.137; 95% CI=4.741–21.678) and 8 (OR=8.781; 95% CI=3.626–21.268) were associated with 30-day mortality (p<0.001). We found a positive correlation between CCCK-18, SOFA, and lactic acid at days 1, 4 and 8.

Conclusions:

Non-survivor septic patients showed persistently during the first week higher serum CCCK-18 levels than survivor patients, and there is an association between sepsis severity and mortality and serum CCCK-18 levels during the first week.

Staphylococcus epidermidis as a cause of bacteremia

Staphylococcus epidermidis is a biofilm-producing commensal organism found ubiquitously on human skin and mucous membranes, as well as on animals and in the environment. Biofilm formation enables this organism to evade the host immune system. Colonization of percutaneous devices or implanted medical devices allows bacteria access to the bloodstream. Isolation of this organism from blood cultures may represent either contamination during the blood collection procedure or true bacteremia. S. epidermidis bloodstream infections may be indolent compared with other bacteria. Isolation of S. epidermidis from a blood culture may present a management quandary for clinicians. Over-treatment may lead to patient harm and increases in healthcare costs. There are numerous reports indicating the difficulty of predicting clinical infection in patients with positive blood cultures with this organism. No reliable phenotypic or genotypic algorithms currently exist to predict the pathogenicity of a S. epidermidis bloodstream infection. This review will discuss the latest advances in identification methods, global population structure, pathogenicity, biofilm formation, antimicrobial resistance and clinical significance of the detection of S. epidermidis in blood cultures. Previous studies that have attempted to discriminate between invasive and contaminating strains of S. epidermidis in blood cultures will be analyzed.

Protective effects of caffeoylxanthiazonoside isolated from fruits of Xanthium strumarium on sepsis mice

CONTEXT

The fruit of Xanthium strumarium L. (Asteraceae) has been used for the treatment of various inflammatory diseases.

OBJECTIVE

This study investigates the protective effect of caffeoylxanthiazonoside (CYXD) isolated from fruits of X. strumarium on sepsis mice in vitro and in vivo.

MATERIALS AND METHODS

Cecal ligation and puncture (CLP) operation was used to establish the sepsis mice model, and sham mice were also performed. CYXD was administered by intraperitoneal injection (10, 20, and 40 mg/kg/d), then the survival rate was measured in 96 h. Additionally, sepsis mice were induced by injection LPS (2 mg/kg); CYXD was administered by intraperitoneal injection (10, 20, and 40 mg/kg/d), then mice were sacrificed, and serum levels of TNF-α and IL-6 were determined by ELISA assay. Furthermore, the ability of CYXD to neutralize LPS was measured by using the LAL test, and expressions of TNF-α, IL-6 were determined by using real-time fluorogenic PCR.

RESULTS

Results indicated that CYXD significantly elevated survival rates of sepsis mice induced by CLP (p < 0.05) with survival rates of 35%, 45%, and 65%. Furthermore, the LPS level was decreased obviously by CYXD (1, 2, and 4 mg/L) (p < 0.05). Additionally, CYXD (10, 20, and 40 mg/kg) can not only significantly decrease TNF-α and IL-6 levels induced by LPS in mice's serum (p < 0.05), but also inhibit mRNA expressions of TNF-α and IL-6 induced by LPS in RAW 264.7 cells at doses of 20, 40, and 80 μg/mL (p < 0.05).

CONCLUSION

Our study demonstrated that CYXD has significant protective effects on sepsis mice.

The protective effect of atractylenolide I on systemic inflammation in the mouse model of sepsis created by cecal ligation and puncture

CONTEXT

Atractylenolide I (AT-I), an active compound isolated from Atractylodes macrocephala Koidz (Compositae), shows several pharmacological activities.

OBJECTIVE

Our present study is designed to investigate the protective effect of AT-I on systemic inflammation in the mouse model of sepsis created by cecal ligation and puncture (CLP), and explore the possible mechanism.

MATERIALS AND METHODS

Sepsis mouse model was established by CLP, and the tested dosages of AT-I were 10, 20, and 40 mg/kg (ip). Pro-inflammatory cytokines in serum (TNF-α, IL-1β and IL-6) were determined by the ELISA method; serum lipopolysaccharide (LPS) level was measured by the Limulus Amebocyte Lysate (LAL) test; white blood cells (WBC) were counted by Blood cell analyzer; contents of alanine transaminase (ALT), aspartate transarninase (AST), creatinine (Cre), and blood urea nitrogen (BUN) in serum were determined by automatic biochemistry analyzer. For survival rate tests, CLP mice were observed within 7 days, and body temperature was measured at 0, 4, 8, 12, 24, 48 and 72 h after surgery.

RESULTS

Our results indicated that AT-I significantly increased the survival rate of mice with sepsis (p < 0.05), whereas the WBCs and levels of LPS, pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), ALT, AST, Cre, and BUN decreased significantly after treatment with AT-I (p < 0.05).

CONCLUSION

In conclusion, the AT-I ameliorates sepsis syndrome by reduction of pro-inflammatory cytokines and LPS, and provides an improvement in liver and kidney functions.

Novel integrated and portable endotoxin detection system based on an electrochemical biosensor

This paper describes the design, implementation and validation of a sensitive and integral technology solution for endotoxin detection.

Engineered liposomes sequester bacterial exotoxins and protect from severe invasive infections in mice

Gram-positive bacterial pathogens that secrete cytotoxic pore-forming toxins, such as Staphylococcus aureus and Streptococcus pneumoniae, cause a substantial burden of disease. Inspired by the principles that govern natural toxin-host interactions, we have engineered artificial liposomes that are tailored to effectively compete with host cells for toxin binding. Liposome-bound toxins are unable to lyse mammalian cells in vitro. We use these artificial liposomes as decoy targets to sequester bacterial toxins that are produced during active infection in vivo. Administration of artificial liposomes within 10 h after infection rescues mice from septicemia caused by S. aureus and S. pneumoniae, whereas untreated mice die within 24-33 h. Furthermore, liposomes protect mice against invasive pneumococcal pneumonia. Composed exclusively of naturally occurring lipids, tailored liposomes are not bactericidal and could be used therapeutically either alone or in conjunction with antibiotics to combat bacterial infections and to minimize toxin-induced tissue damage that occurs during bacterial clearance.

Serum levels of caspase-cleaved cytokeratin-18 and mortality are associated in severe septic patients: pilot study

OBJECTIVE

Apoptosis is increased in sepsis. Cytokeratin 18 (CK-18), a protein of the intermediate filament group present in most epithelial and parenchymal cells, is cleaved by the action of caspases and released into the blood as caspase-cleaved CK (CCCK)-18 during apoptosis. Circulating levels of CCCK-18 have scarcely been explored in septic patients. In one study with 101 severe septic patients, the authors reported higher serum CCCK-18 levels in non-survivors than in survivors; however, the sample size was too small to demonstrate an association between serum CCCK-18 levels and early mortality and whether they could be used as a biomarker to predict outcomes in septic patients. Thus, these were the objectives of this study with a large series of patients.

METHODS

We performed a prospective, multicenter, observational study in six Spanish Intensive Care Units with 224 severe septic patients. Blood samples were collected at the time that severe sepsis was diagnosed to determine serum levels of CCCK-18, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6 and IL-10. The end point was 30-day mortality.

RESULTS

Non-surviving patients (n = 80) showed higher serum CCCK-18 levels (P<0.001) than survivors (n = 144). Multiple logistic regression analysis showed that serum CCCK-18 levels>391 u/L were associated with 30-day survival (Odds ratio = 2.687; 95% confidence interval = 1.449-4.983; P = 0.002), controlling for SOFA score, serum lactic acid levels and age. Kaplan-Meier survival analysis showed that the risk of death in septic patients with serum CCCK-18 levels >391 u/L was higher than in patients with lower values (Hazard Ratio = 3.1; 95% CI = 1.96-4.84; P<0.001). Serum CCCK-18 levels were positively associated with serum levels of IL-6 and lactic acid, and with SOFA and APACHE scores.

CONCLUSIONS

The major novel finding of our study, the largest cohort of septic patients providing data on circulating CCCK-18 levels, was that serum CCCK-18 levels are associated with mortality in severe septic patients.

Redox state of pentraxin 3 as a novel biomarker for resolution of inflammation and survival in sepsis

In an endotoxaemic mouse model of sepsis, a tissue-based proteomics approach for biomarker discovery identified long pentraxin 3 (PTX3) as the lead candidate for inflamed myocardium. When the redox-sensitive oligomerization state of PTX3 was further investigated, PTX3 accumulated as an octamer as a result of disulfide-bond formation in heart, kidney, and lung—common organ dysfunctions seen in patients with sepsis. Oligomeric moieties of PTX3 were also detectable in circulation. The oligomerization state of PTX3 was quantified over the first 11 days in critically ill adult patients with sepsis. On admission day, there was no difference in the oligomerization state of PTX3 between survivors and non-survivors. From day 2 onward, the conversion of octameric to monomeric PTX3 was consistently associated with a greater survival after 28 days of follow-up. For example, by day 2 post-admission, octameric PTX3 was barely detectable in survivors, but it still constituted more than half of the total PTX3 in non-survivors (p < 0.001). Monomeric PTX3 was inversely associated with cardiac damage markers NT-proBNP and high-sensitivity troponin I and T. Relative to the conventional measurements of total PTX3 or NT-proBNP, the oligomerization of PTX3 was a superior predictor of disease outcome.

Mesenchymal stem cells decrease splenocytes apoptosis in a sepsis experimental model

OBJECTIVE AND DESIGN

Mesenchymal stem cells (MSCs) are potent modulators of immune responses. Sepsis is the association of a systemic inflammatory response with an infection. The aim of this study was to test the ability of MSCs derived from adipose tissue, which have immunomodulatory effects, and to inhibit the septic process in an experimental model of mice.

METHODS

Three experimental groups (male C57BL/6 mice) were formed for the test: control group, untreated septic group and septic group treated with MSCs (1 × 10(6) cells/animal).

RESULTS

In the control group, there were no deaths; in the untreated septic group, the mortality rate was 100 % within 26 h; in the septic group treated with MSCs, the mortality rate reached 40 % within 26 h. The group treated with MSCs was able to reduce the markers of tissue damage in the liver and pancreas. The treated group had a reduction of inflammatory markers. Furthermore, the MSCs-treated group was able to inhibit the increase of apoptosis in splenocytes observed in the untreated septic group.

CONCLUSIONS

Our data showed that MSCs ameliorated the immune response with decrease of inflammatory cytokines and increase anti-inflammatory IL-10; moreover, inhibited splenocytes apoptosis and, consequently, inhibited tissue damage during sepsis.

Delta neutrophil index as a prognostic marker of early mortality in gram negative bacteremia

BACKGROUND

Sepsis is a syndrome that results in high morbidity and mortality. We investigated the delta neutrophil index (DN) as a predictive marker of early mortality in patients with gram-negative bacteremia.

MATERIALS AND METHODS

We conducted a retrospective study at a tertiary referral hospital in South Korea from November 2010 to March 2011. The DN was measured at onset of bacteremia and 24 hours and 72 hours later. The DN was calculated using an automatic hematology analyzer. Factors associated with 10-day mortality were assessed using logistic regression.

RESULTS

A total of 172 patients with gram-negative bacteremia were included in the analysis; of these, 17 patients died within 10 days of bacteremia onset. In multivariate analysis, Sequental organ failure assessment scores (odds ratio [OR]: 2.24, 95% confidence interval [CI]: 1.31 to 3.84; P = 0.003), DN-day 1 ≥ 7.6% (OR: 305.18, 95% CI: 1.73 to 53983.52; P = 0.030) and DN-day 3 ≥ DN-day 1 (OR: 77.77, 95% CI: 1.90 to 3188.05; P = 0.022) were independent factors associated with early mortality in gram-negative bacteremia. Of four multivariate models developed and tested using various factors, the model using both DN-day 1 ≥ 7.6% and DN-day 3 ≥ DN-day 1 was most predictive early mortality.

CONCLUSIONS

DN may be a useful marker of early mortality in patients with gram-negative bacteremia. We found both DN-day 1 and DN trend to be significantly associated with early mortality.

Evaluation of MolYsis™ Complete5 DNA extraction method for detecting Staphylococcus aureus DNA from whole blood in a sepsis model using PCR/pyrosequencing

Bacterial bloodstream infections (BSI) and ensuing sepsis are important causes of morbidity and mortality. Early diagnosis and rapid treatment with appropriate antibiotics are vital for improving outcome. Nucleic acid amplification of bacteria directly from whole blood has the potential of providing a faster means of diagnosing BSI than automated blood culture. However, effective DNA extraction of commonly low levels of bacterial target from whole blood is critical for this approach to be successful. This study compared the Molzyme MolYsis™ Complete5 DNA extraction method to a previously described organic bead-based method for use with whole blood. A well-characterized Staphylococcus aureus-induced pneumonia model of sepsis in canines was used to provide clinically relevant whole blood samples. DNA extracts were assessed for purity and concentration and analyzed for bacterial rRNA gene targets using PCR and sequence-based identification. Both extraction methods yielded relatively pure DNA with median A260/280 absorbance ratios of 1.71 (MolYsis™) and 1.97 (bead-based). The organic bead-based extraction method yielded significantly higher average DNA concentrations (P<0.05) at each time point throughout the experiment, closely correlating with changes observed in white blood cell (WBC) concentrations during this same time period, while DNA concentrations of the MolYsis™ extracts closely mirrored quantitative blood culture results. Overall, S. aureus DNA was detected from whole blood samples in 70.7% (58/82) of MolYsis™ DNA extracts, and in 59.8% (49/82) of organic bead-based extracts, with peak detection rates seen at 48h for both MolYsis™ (87.0%) and organic bead-based (82.6%) methods. In summary, the MolYsis™ Complete5 DNA extraction kit proved to be the more effective method for isolating bacterial DNA directly from extracts made from whole blood.

Bloodstream infection in patients with end-stage renal disease in a teaching hospital in central-western Brazil

INTRODUCTION

Vascular access in patients undergoing hemodialysis is considered a critical determinant of bloodstream infection (BSI) and is associated with high morbidity and mortality. The purpose of this study was to investigate the occurrence of BSI in patients with end-stage renal disease using central venous catheters for hemodialysis.

METHODS

A cohort study was conducted in a public teaching hospital in central-western Brazil from April 2010 to December 2011. For every patient, we noted the presence of hyperemia/exudation upon catheter insertion, as well as fever, shivering, and chills during hemodialysis.

RESULTS

Fifty-nine patients were evaluated. Thirty-fi ve (59.3%) patients started dialysis due to urgency, 37 (62.7%) had BSI, and 12 (20%) died. Hyperemia at the catheter insertion site (64.9%) was a significant clinical manifestation in patients with BSI. Statistical analysis revealed 1.7 times more cases of BSI in patients with hypoalbuminemia compared with patients with normal albumin levels. The principal infective agents identified in blood cultures and catheter-tip cultures were Staphylococcus species (24 cases), non-fermentative Gram-negative bacilli (7 cases of Stenotrophomonas maltophilia and 5 cases of Chryseobacterium indologenes), and Candida species (6). Among the Staphylococci identified, 77.7% were methicillin-resistant, coagulase-negative Staphylococci. Of the bacteria isolated, the most resistant were Chryseobacterium indologenes and Acinetobacter baumannii.

CONCLUSIONS

Blood culture was demonstrated to be an important diagnostic test and identified over 50% of positive BSI cases. The high frequency of BSI and the isolation of multiresistant bacteria were disturbing findings. Staphylococcus aureus was the most frequently isolated microorganism, although Gram-negative bacteria predominated overall. These results highlight the importance of infection prevention and control measures in dialysis units.

TAT-SNAP-23 treatment inhibits the priming of neutrophil functions contributing to shock and/or sepsis-induced extra-pulmonary acute lung injury

Respiratory burst function of neutrophils is thought to play a pivotal role in the development of pathologies such as indirect (extra-pulmonary) acute lung injury (iALI), as well as sepsis. The current study was conducted to determine the effect of an HIV transactivator of transcription (TAT)-fusion protein containing a soluble N-ethylmaleimide-sensitive factor attachment protein receptor domain from synaptosome-associated protein-23 (SNAP-23) on the shock/sepsis- and sepsis-enhanced neutrophil burst capacity using the clinical relevant two-hit iALI mouse model and the classical cecal ligation and puncture (CLP) septic model. TAT-SNAP-23 significantly decreased the blood neutrophil respiratory burst in vitro, and also in vivo in CLP and hemorrhaged mice. We found that the neutrophil influx to the lung tissue, as measured by myeloperoxidase levels and neutrophil-specific esterase(+) cells, was also decreased in the TAT-SNAP-23-treated group. Consistent with this, treatment of TAT-SNAP-23 significantly reduced the disruption of lung tissue architecture and protein concentration of bronchoalveolar lavage fluid in iALI mice compared with vehicle-treated iALI mice. In addition, although TAT-SNAP-23 did not alter the extent of local cytokine/chemokine expression, the in vitro migration capacity of neutrophils was blunted from septic and hemorrhagic mice. These data support our hypothesis that TAT-SNAP-23 reduces neutrophil dysfunction in iALI and sepsis by inhibiting neutrophil respiratory burst.

Biomarkers predicting sepsis in polytrauma patients: Current evidence

INTRODUCTION

Major trauma still represents one of the leading causes of death in the first four decades of life. Septic complications represent the predominant causes of late death (45% of overall mortality) in polytrauma patients. The ability of clinicians to early differentiate between systemic inflammatory response syndrome (SIRS) and sepsis is demonstrated to improve clinical outcome and mortality. The identification of an "ideal" biomarker able to early recognize incoming septic complications in trauma patients is still a challenge for researchers.

AIM

To evaluate the existing evidence regarding the role of biomarkers to predict or facilitate early diagnosis of sepsis in trauma patients, trying to compile some recommendations for the clinical setting.

METHODS

An Internet-based search of the MEDLINE, EMBASE and Cochrane Library databases was performed using the search terms: "Biomarkers", "Sepsis" and "Trauma" in various combinations. The methodological quality of the included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies Checklist (QUADAS). After data extraction, the level of evidence available for each bio-marker was rated and presented using the "best-evidence synthesis" method, in line with the US Agency for Healthcare Research and Quality.

RESULTS

Thirty studies were eligible for the final analysis: 13 case-control studies and 17 cohort studies. The "strong evidence" available demonstrated the potential use of procalcitonin as an early indicator of post-traumatic septic complications and reported the inability of c-reactive protein (CRP) to specifically identify infective complications. Moderate, conflicting and limited evidence are available for the other 31 biomarkers.

CONCLUSION

Several biomarkers have been evaluated for predicting or making early diagnosis of sepsis in trauma patients. Current evidence does not support the use of a single biomarker in diagnosing sepsis. However, procalcitonin trend was found to be useful in early identification of post-traumatic septic course and its use is suggested (Recommendation Grade: B) in clinical practice.

Comparison of PCR and conventional blood culture to analyze blood from dogs with suspected sepsis

Sepsis carries a poor prognosis in critically ill dogs. PCR-based diagnostics could be more sensitive for detecting bacteremia than conventional blood culture, allowing earlier initiation of appropriate therapy. Molecular techniques have been considered as ancillary tools for detecting bacteremia and identifying pathogens in humans and in dogs with bacterial endocarditis. This study compared PCR analysis and blood culture for detecting bacteremia in six dogs with suspected sepsis and six healthy control dogs. One blood culture from a dog with suspected sepsis was positive but none from the healthy controls. PCR was negative for extracts from all dogs. This pilot study does not support the hypothesis that culture-independent PCR-based techniques used directly on small samples of blood are useful for diagnosing bacteremia in dogs with suspected sepsis.

Verigene® gram-positive blood culture nucleic acid test

Bloodstream infections (BSIs) are a major cause of morbidity and mortality worldwide, and impose considerable costs on healthcare systems. A key predictor of clinical outcomes in patients with BSIs is the early initiation of appropriate targeted antimicrobial therapy. However, with conventional blood culture methods, the gold standard, there is a significant time delay of approximately 2-3 days before clinical results are available, with many patients receiving inappropriate and/or unnecessary antimicrobial therapy in the interim. During the past two decades, the use of in vitro assays that utilize nucleic acid amplification-based detection of pathogen-associated molecular patterns has led to a significant reduction in the time (hours vs. days with blood culture) to detection and identification of several of the causative pathogens of BSIs and, potentially, earlier initiation of targeted antimicrobial therapy. This review focuses on the properties and clinical use of one of these molecular diagnostic assays, the Verigene(®) Gram-Positive Blood Culture Nucleic Acid Test (BC-GP), which detects many of the potentially pathogenic Gram-positive bacteria associated with BSIs, including Staphylococcus spp., Streptococcus spp., Listeria spp., and Enterococcus spp., and specific resistance markers (mecA, vanA, and vanB). Based on more than 1,600 samples, there was a high degree of agreement between BC-GP test results and those obtained using conventional blood culture and assay methods, irrespective of whether samples were fresh or frozen, and a high degree of agreement for identification of mecA-mediated meticillin resistance in S. aureus and S. epidermidis organisms and vanA- or vanB-mediated vancomycin resistance in E. faecalis and E. faecium organisms.

The complex pathogenesis of bacteremia: from antimicrobial clearance mechanisms to the genetic background of the host

Bacteremia develops when bacteria manage to escape the host immune mechanisms or when the otherwise well-orchestrated immune response fails to control bacterial spread due to inherent or acquired immune defects that are associated with susceptibility to infection. The pathogenesis of bacteremia has some characteristic features that are influenced by the genetic signature of the host. In this review, the host defense mechanisms that help prevent bacteremia will be described and the populations who are at risk because of congenital or acquired deficiencies in such mechanisms will be defined. A special mention will be made to novel insights regarding host immune defense against the most commonly isolated organisms from patients with community-acquired bloodstream infections.

Heterogeneity among septic shock patients in a set of immunoregulatory markers

Immune activation is a regular feature of sepsis, but the incidence and nature of the ensuing inflammation-resolving and immunosuppressive component is less well understood. In this study, we compared immunoregulatory markers on blood leukocytes from patients with Gram-negative or Gram-positive sepsis or septic shock, and compared this to blood from patients with severe virosis or healthy controls. To this end, blood from 32 patients with sepsis, including ten cases with shock, and 12 patients with severe virosis were analysed by flow cytometry for the expression levels of monocyte HLA-DR, CD11c, CD14 and CD40, and for frequencies of CD163⁺-suppressive monocytes, HLA-DR⁺ or CD40⁺-activated T cells and Tregs. Plasma cytokine levels were analysed as a functional measurement. Signs of immunosuppression dominated in the septic shock and Gram-positive sepsis groups, whereas monocyte activation was common in Gram-negative sepsis patients without shock. However, the main finding was the large inter-individual variation of immune activation and immunosuppression, with no correlation to prognosis among the shock patients. The pronounced inter-individual variation in the analysed monocyte and lymphocyte markers forms a strong argument that, when immunomodulatory treatment is considered in a sepsis patient, it should be personalised and guided by a detailed immune status assessment.

Assessment of a semi-automated protocol for multiplex analysis of sepsis-causing bacteria with spiked whole blood samples

Sepsis is associated with high morbidity and mortality rates worldwide. Rapid and reliable diagnostic methods are needed for efficient and evidence-based treatment of septic patients. Recently, new molecular tools have emerged to complement the conventional culture-based diagnostic methods. In this study, we used spiked whole blood samples to evaluate together two ready-to-use molecular solutions for the detection of sepsis-causing bacteria. We spiked whole blood with bacterial species relevant in sepsis and extracted bacterial DNA with the NorDiag Arrow device, using the SelectNA Blood pathogen DNA isolation kit. DNA extracts were analyzed by the polymerase chain reaction (PCR)- and microarray-based Prove-it™ Bone and Joint assay, resulting in correctly identified bacterial species with detection limits of 11-600 colony-forming unit/mL (CFU/mL). To understand the recovery losses of bacterial DNA during the sample preparation step and the capability of the PCR- and microarray-based platform to respond to the sensitivity requirements, we also determined the analytical sensitivity of the PCR and microarray platform to be 1-21 genome equivalents for the tested bacterial species. In addition, the inclusivity of the Prove-it™ Bone and Joint assay was demonstrated with methicillin-resistant Staphylococcus aureus (MRSA) clones carrying SCCmec types I, II, IV, or V and a nontypable SCCmec type. The proof-of-concept for accurate multiplex pathogen and antibacterial resistance marker detection from spiked whole blood samples was demonstrated by the selective bacterial DNA extraction method combined with the high-throughput PCR- and microarray-based platform. Further investigations are needed to study the promising potential of the concept for sensitive, semi-automated identification of sepsis-causing pathogens directly from whole blood.

Sulfatide attenuates experimental Staphylococcus aureus sepsis through a CD1d-dependent pathway

Natural killer T (NKT) lymphocytes are implicated in the early response to microbial infection. Further, sulfatide, a myelin self-glycosphingolipid, activates a type II NKT cell subset and can modulate disease in murine models. We examined the role of NKT cells and the effect of sulfatide treatment in a murine model of Staphylococcus aureus sepsis. The lack of CD1d-restricted NKT cells did not alter survival after a lethal inoculum of S. aureus. In contrast, sulfatide treatment significantly improved the survival rate of mice with S. aureus sepsis, accompanied by decreased levels of tumor necrosis factor alpha and interleukin-6 in the blood. The protective effect of sulfatide treatment depended on CD1d but not on type I NKT cells, suggesting that activation of type II NKT cells by sulfatide has beneficial effects on the outcome of S. aureus sepsis in this model.

Propionibacterium acnes-killed attenuates the inflammatory response and protects mice from sepsis by modulating inflammatory factors

Background

Sepsis is a systemic inflammation associated with infection caused by pathogenic micro-organisms with high mortality rates.

Objective

In this study, we investigated the protective effect of Propionibacterium acnes-killed against polymicrobial sepsis induced by cecal ligation and puncture.

Methods

The mice were treated by intramuscular route in 1, 3, 5, and 7 days before the cecal ligation and puncture induction. The control group animals received vehicle (saline solution 0.9%) and the animals of the treated group received the P. acnes-killed (0.4 mg/animal). After anesthesia, midline laparotomy was performed with exposure of cecum followed by ligature and one transverse perforation of the same, with a 18 G needle, for induction of lethal sepsis. After surgery, the cecum of the animals was replaced into the peritoneal cavity, and it was closed with a 4.0 nylon suture. The survival of animals subjected to lethal sepsis was evaluated after cecal ligation and puncture induction. Six hours after the induction of sepsis, neutrophil migration, the number of bacteria, TNF-α, MCP-1, IL-6, and IL-10 were performed in the peritoneal lavage.

Results

Prophylactic treatment with P. acnes-killed increased the survival of the animals, followed by a significant decrease in the TNF-α, IL-10, and MCP-1 levels, 6 h after cecal ligation and puncture. Furthermore, P. acnes-killed administration reduced the number of bacteria in the peritoneal cavity with increased migration of leukocytes, especially neutrophils.

Conclusion

P. acnes-killed promoted increased survival rate of animals with sepsis, in part attributed to its immunomodulatory properties against pathogenic microorganisms, as well as better control of infection by reducing bacterial counts.