Gram-negative versus Gram-positive bacteremia: what is more alarmin(g)?

Thromboelastometry-Based Profiling of Haemostatic Alterations in Neonatal Sepsis by Causative Pathogens

Background: Neonatal sepsis is a serious condition with high mortality, especially in premature and low-birth-weight neonates. This study aims to examine whether the haemostatic profile of neonates with sepsis defers depending on the type of bacteria (Gram-positive or Gram-negative), by using the method of Rotational Thromboelastometry (ROTEM). Methods: This single-centre prospective cohort study was conducted on 128 neonates with sepsis, including 95 cases caused by Gram-negative pathogens and 33 cases caused by Gram-positive bacteria. All participants were hospitalised in the Neonatal Intensive Care Unit (NICU). ROTEM parameters were compared between neonates with Gram-positive and Gram-negative infections. Results: The ROTEM parameters were found to be significantly different between neonates suffering from Gram-positive versus Gram-negative infections, with Gram-positive pathogens associated with an increased clotting potential compared to Gram-negative pathogens. This is reflected in the higher ROTEM values such as A10, α-angle, and MCF in the EXTEM and INTEM assays. Multivariant analysis showed that Gram-positive infections were linked to increased clot thickness at 10 min (coefficient: 8.9, CI: 2.8-15.0, p = 0.004), higher maximum clot stability (coefficient: 10.4, CI: 4.3-16.6, p = 0.001), and a bigger α-angle (coefficient: 8.0, CI: 2.7-13.2, p = 0.003). Similar findings were observed in the INTEM assay parameters. Conclusions: Neonatal sepsis caused by Gram-positive bacteria leads to a hypercoagulable haemostatic state, whereas neonates with sepsis caused by Gram-negative bacteria exhibit a more hypocoagulable profile and a higher incidence of haemorrhagic episodes. These findings provide valuable insights into the haemostatic disorders associated with sepsis, and may aid in developing an individualised approach for the treatment of those disorders, dependent on and adapted for the specific type of causative organism.

Comparative Analysis of Bacteremic and Non-bacteremic Sepsis: A Retrospective Study

INTRODUCTION

Sepsis remains a prevalent critical illness encountered in emergency departments and intensive care units (ICU), with culture-negative sepsis constituting 30-60% of cases. The effect of culture type on treatment and outcomes remains unclear, and conflicting evidence exists regarding disparities between Gram-positive and Gram-negative infections.

OBJECTIVE

To further describe and compare characteristics and outcomes of culture-positive versus culture-negative sepsis.

DESIGN, SETTING AND PARTICIPANTS

This retrospective cohort study included 1375 patients admitted to the ICU of a single tertiary care hospital between 2016 and 2019 with a diagnosis of sepsis or septic shock. Patients who did not meet the screening criteria, lacked drawn or documented cultures, or had documented non-bacterial infections, were excluded.

MAIN OUTCOMES AND MEASURES

The primary outcome was disease severity and secondary outcomes included in-hospital mortality and duration of hospital and ICU stay. The principal and secondary exposure variables were blood culture status (positive vs. negative) and Gram staining (positive vs. negative), respectively.

RESULTS

Overall, 943 patients (68.5%) were culture-negative and 432 (31.5%) were culture-positive. Gram-positive bacteria were isolated from 178 patients, Gram-negative bacteria from 199 patients, and both from 55 patients. Culture-positive patients demonstrated an almost two-fold higher likelihood of requiring vasopressors (adjusted odds ratio (OR): 1.98), a higher incidence of stress-dose steroid administration (adjusted OR, 1.68), and higher resuscitative fluid administration at six and 72 hours than culture-negative patients. No significant between-group differences emerged in the ICU or hospital length of stay, or mortality. No significant variations were observed when comparing Gram-positive and Gram-negative bacteremia.

CONCLUSION

Although significant differences in illness severity existed between blood culture-negative and blood culture-positive patients with sepsis, patient-oriented secondary outcomes did not exhibit significant between-group differences. These results indicate that clinicians should not be reassured by the lack of proven bacteremia in patients with suspected sepsis, given similar outcomes.

Rapid Antimicrobial Susceptibility Testing Using the MicroScan System: Performance Evaluation of a 4-Hour Bacterial Cultivation From Positive Blood Cultures

A reliable and above all, rapid antimicrobial susceptibility test (AST) is required for the diganostics of blood stream infections (BSI). In this study, resistance testing using DxM MicroScan WalkAway (MicroScan) from a 4-h subculture is compared with the standard overnight culture (18-24 h). Randomly selected positive blood cultures (PBC, n = 102) with gram-negative bacteria were included in the study. PBC were sub-cultured onto appropriate agar plates and AST by MicroScan was performed after 4 h of incubation and repeated after incubation for 18-24 h as standard. In a total of 1909 drug-strain pairs, the 4-h subculture approach showed a very high essential agreement (EA) (98.6%) and categorical agreement (CA) (97.1%) compared with the standard. The incidence of minor error (mE), major error (ME), very major error (VME), and adjusted very major error (aVME) was 1.1%, 0.4%, 12.9%, and 5.3%, respectively. In summary, the use of 4-h subcultures for resistance testing with the MicroScan offers a very reliable and easy to realize time saving when testing positive blood cultures with gram-negative bacteria.

Impact of the COVID-19 Pandemic on the Epidemiology of Bloodstream Infections in Hospitalized Patients-Experience from a 4th Military Clinical Hospital in Poland

Bloodstream infections (BSIs) are associated with high mortality and inappropriate or delayed antimicrobial therapy. The purpose of this study was to investigate the impact of the COVID-19 pandemic on the epidemiology of BSIs in hospitalized patients. The research aimed to compare the incidence of BSIs and blood culture results in patients hospitalized before and during the COVID-19 pandemic.

METHODS

Retrospective and prospective data were collected from blood cultures obtained from 4289 patients hospitalized between June 2018 and July 2022. Two groups of patients were distinguished: those with BSIs admitted during the pre-COVID-19 period and those admitted during the COVID-19 surge. Demographic and clinical data, blood cytology, and biochemistry results were analyzed, and the usefulness of PCT was assessed in patients with COVID-19.

RESULTS

The study showed a significant increase in the incidence of BSIs during the pandemic compared to the pre-COVID-19 period. Positive blood cultures were obtained in 20% of patients hospitalized during the pandemic (vs. 16% in the pre-COVID-19 period). The incidence of BSIs increased from 1.13 to 2.05 cases per 1000 patient days during COVID-19, and blood culture contamination was more frequently observed. The mortality rate was higher for patients hospitalized during the COVID-19 pandemic. An increased frequency of MDRO isolation was observed in the COVID-19 period.

CONCLUSIONS

The incidence of BSIs increased and the mortality rate was higher in the COVID-19 period compared to the pre-COVID-19 period. The study showed limited usefulness of procalcitonin in patients with COVID-19, likely due to the administered immunosuppressive therapy.

Risk Factors and Outcome Analysis of Gram-Positive Bacteremia in Critically Ill Patients

Introduction Bloodstream infection (BSI) is a common problem for patients in the intensive care unit (ICU). Nearly 60% of primary bloodstream infections are caused by Gram-positive cocci. Gram-positive bacteria gain access to the bloodstream through invasive procedures and various patient care equipment like catheters, intravenous lines, and mechanical ventilators. S. aureus is considered to be the major cause of septicemia. Knowledge of healthcare-associated infections and the antimicrobial susceptibility patterns of the isolates are crucial in guiding empirical treatment. Methods This prospective observational study was conducted in Medical ICU, Dayanand Medical College & Hospital, Ludhiana over a period of one year (December 2015 to November 2016). Patients whose blood cultures tested positive for Gram-positive bacteria were included in the study. This study was carried out to assess the implications and risk factors for nosocomial BSI and several factors, including the age of the patient, the severity of illness, the presence of catheters, and the microorganisms causing the BSI to independently predict mortality. Chief complaints and risk factors were evaluated. APACHE-II scores were calculated for all patients and outcomes were analyzed. Results In our study, the mean age of patients was 50.93±14.09 years. Central line insertion was found as the most common risk factor (58.7%). A statistically significant correlation was obtained between APACHE-II scores and the presence of risk factors i.e. central line insertion (p-value=0.010) and diabetes mellitus (p-value=0.003). The most common Gram-positive pathogen isolated by blood culture was methicillin-sensitive S. aureus (44.2%). For management, the majority of the patients were prescribed teicoplanin (58.7%). The 28-day overall mortality rate in our study was 52.9%. Conclusion We conclude that independent risk factors like diabetes mellitus, central line insertion, and acute pancreatitis in adult patients with Gram-positive bacteremia were associated with higher mortality. We have also concluded that the administration of early appropriate antibiotics improves patient outcomes.

Mortality and Sequential Organ Failure Assessment Score in Patients With Suspected Sepsis: The Impact of Acute and Preexisting Organ Failures and Infection Likelihood

The Sequential Organ Failure Assessment (SOFA) was chosen in the definition of sepsis due to superior validity in predicting mortality. However, few studies have assessed the contributions of acute versus chronic organ failures to SOFA for mortality prediction.

OBJECTIVES

The main objective in this study was to assess the relative importance of chronic and acute organ failures in mortality prediction in patients with suspected sepsis at hospital admission. We also evaluated how the presence of infection influenced the ability of SOFA to predict 30-day mortality.

DESIGN SETTING AND PARTICIPANTS

Single-center prospective cohort study including 1,313 adult patients with suspected sepsis in rapid response teams in the emergency department.

MAIN OUTCOMES AND MEASURES

The main outcome was 30-day mortality. We measured the maximum total SOFA score during admission (SOFATotal), whereas preexisting chronic organ failure SOFA (SOFAChronic) score was assessed by chart review, allowing calculation of the corresponding acute SOFA (SOFAAcute) score. Likelihood of infection was determined post hoc as "No infection" or "Infection."

RESULTS

SOFAAcute and SOFAChronic were both associated with 30-day mortality, adjusted for age and sex (adjusted odds ratios [AORs], 1.3; 95% CI, 1.3-14 and 1.3; 1.2-1.7), respectively. Presence of infection was associated with lower 30-day mortality (AOR, 0.4; 95% CI, 0.2-0.6), even when corrected for SOFA. In "No infection" patients, SOFAAcute was not associated with mortality (AOR, 1.1; 95% CI, 1.0-1.2), and in this subgroup, neither SOFAAcute greater than or equal to 2 (relative risk [RR], 1.1; 95% CI, 0.6-1.8) nor SOFATotal greater than or equal to 2 (RR, 3.6; 95% CI, 0.9-14.1) was associated with higher mortality.

CONCLUSIONS AND RELEVANCE

Chronic and acute organ failures were equally associated with 30-day mortality in suspected sepsis. A substantial part of the total SOFA score was due to chronic organ failure, calling for caution when using total SOFA in defining sepsis and as an outcome in intervention studies. SOFA's mortality prediction ability was highly dependent on actual presence of infection.

Sepsis among Neonates in a Ghanaian Tertiary Military Hospital: Culture Results and Turnaround Times

In this study, we described the bacterial profile, antibiotic resistance pattern, and laboratory result turnaround time (TAT) in neonates with suspected sepsis from a tertiary-level, military hospital in Accra, Ghana (2017-2020). This was a cross-sectional study using secondary data from electronic medical records. Of 471 neonates clinically diagnosed with suspected sepsis in whom blood samples were collected, the median TAT from culture request to report was three days for neonates who were culture-positive and five days for neonates who were culture-negative. There were 241 (51%) neonates discharged before the receipt of culture reports, and of them, 37 (15%) were culture-positive. Of 471 neonates, twenty-nine percent (n = 139) were bacteriologically confirmed, of whom 61% (n = 85) had late-onset sepsis. Gram-positive bacterial infection (89%, n = 124) was the most common cause of culture-positive neonatal sepsis. The most frequent Gram-positive pathogen was coagulase-negative Staphylococcus (55%, n = 68) followed by Staphylococcus aureus (36%, n = 45), of which one in two were multidrug resistant. The reasons for large numbers being discharged before the receipt of culture reports need to be further explored. There is a need for improved infection prevention and control, along with ongoing local antimicrobial resistance surveillance and antibiotic stewardship to guide future empirical treatment.

Routine laboratory biomarkers used to predict Gram-positive or Gram-negative bacteria involved in bloodstream infections

This study evaluated routine laboratory biomarkers (RLB) to predict the infectious bacterial group, Gram-positive (GP) or Gram-negative (GN) associated with bloodstream infection (BSI) before the result of blood culture (BC). A total of 13,574 BC of 6787 patients (217 BSI-GP and 238 BSI-GN) and 68 different RLB from these were analyzed. The logistic regression model was built considering BSI-GP or BSI-GN as response variable and RLB as covariates. After four filters applied total of 320 patients and 16 RLB remained in the Complete-Model-CM, and 4 RLB in the Reduced-Model-RM (RLB p > 0.05 excluded). In the RM, only platelets, creatinine, mean corpuscular hemoglobin and erythrocytes were used. The reproductivity of both models were applied to a test bank of 2019. The new model presented values to predict BSI-GN of the area under the curve (AUC) of 0.72 and 0.69 for CM and RM, respectively; with sensitivity of 0.62 and 0.61 (CM and RM) and specificity of 0.67 for both. These data confirm the discriminatory capacity of the new models for BSI-GN (p = 0.64). AUC of 0.69 using only 4 RLB, associated with the patient's clinical data could be useful for better targeted antimicrobial therapy in BSI.

Clinical Characteristics of Patients with Pyogenic Vertebral Osteomyelitis and Concurrent Infections and Their Clinical Outcomes

Patients with pyogenic vertebral osteomyelitis (PVO) often develop concurrent infections, and a significant number of these patients show rapid deterioration in their medical condition, leading to mortality without PVO-related structural instability or neurological deficits. To improve clinical outcomes, we investigated the clinical presentation and treatment outcomes of patients with PVO and concurrent infections. This study included 695 patients with PVO, of which 175 (25%) had concurrent infections and 520 (75%) did not. The clinical characteristics of the two groups were compared, and multivariable analysis was performed to identify the association between concurrent infections and clinical outcomes. Patients with concurrent infections were older and had more comorbidities than those without. Moreover, there were significant intergroup differences in the anatomical involvement of PVO, and patients with concurrent infections had a higher number of regions involved more frequently than those without concurrent infections (15% vs. 6%). In contrast, patients with concurrent infections showed a lower degree of focal invasiveness, including a lower incidence of posterior abscess (47% vs. 59%; p = 0.008) and fewer neurological impairments according to the American Spinal Injury Association grade (p < 0.001) than those without concurrent infections. The causative organisms also differed significantly between the two groups, and patients with concurrent infections had a greater proportion of Gram-negative infections (31% vs. 16%, respectively) and a smaller proportion of methicillin-resistant S. aureus infections than those without concurrent infections (6% vs. 24%). Consequently, their clinical outcomes were significantly different, and patients with concurrent infections showed lower recurrence and higher mortality rates. We investigated the 1-year recurrence and mortality rates and their 95% confidence intervals according to the types of concurrent infections and their time of diagnosis and found variations in these parameters. Our results, based on a large number of patients, can be practically used as a reasonable reference to warn clinicians of the clinical risks of concurrent infections in patients with PVO and to help predict their clinical outcomes.

Inhibition of Bruton's Tyrosine Kinase Protects Against Burn Sepsis-Induced Intestinal Injury

This study aimed to investigate the role and molecular mechanisms of Bruton's tyrosine kinase (BTK), a member of the Tec family in burn sepsis-induced intestinal injury. Eighty C57BL/6 mice were randomly divided into four groups: the sham group, the burn group, the burn + sepsis group, and the burn + sepsis + LFM-A13 (a selective BTK inhibitor) group. The dynamic expression profiles of BTK and p-BTK in the intestine were measured by Western blot analysis. Intestinal histopathological changes and cellular apoptosis were determined. Inflammatory cytokines in serum and intestinal tissue were examined through enzyme-linked immunosorbent assay. Myeloperoxidase (MPO) activity was determined via a colorimetric assay. Intestinal p-BTK expression in the burn+sepsis group was significantly increased compared with that in the sham and burn groups. In the burn + sepsis group, the p-BTK expression level increased over time, peaked at 12, and then decreased at 24 h. LFM-A13 administration significantly inhibited p-BTK expression in the intestine. In contrast to the sham and burn groups, the burn + sepsis group exhibited obvious histopathological changes, which gradually aggravated over time. LFM-A13 also reduced the histopathological changes and cellular apoptosis in intestinal tissues, inhibited the inflammatory cytokines IL-4, IL-6, and TNF-α in serum and intestinal tissues, and significantly inhibited the increase in intestinal MPO activity induced by burn sepsis. BTK activation is one important aspect of the signaling event that may mediate the release of the anti-inflammatory cytokine IL-4 and the pro-inflammatory cytokines IL-6 and TNF-α; oxidative stress; and intestinal cell apoptosis. Thus, it contributes to burn sepsis-induced intestinal injury.

The Impact of Estrogens and Their Receptors on Immunity and Inflammation during Infection

Simple Summary

Human health is significantly affected by microbial infections. One of the largest determinants of the outcomes of such infections is the host immune response. Too weak of a response can lead to enhanced spread by the pathogen, while an overstimulated response can lead to immune-induced tissue damage. Thus, to effectively treat infected individuals, it is critical to understand the regulators that control inflammatory responses. Recently, it has become widely accepted that estrogens, a class of sex hormones, are capable of dramatically altering the responses of host cells to microbes. In this review, we discuss how estrogens change the host immune response, as well as how these changes can alter the outcome of the infection for the individual.

Abstract

Sex hormones, such as estrogen and testosterone, are steroid compounds with well-characterized effects on the coordination and development of vertebrate reproductive systems. Since their discovery, however, it has become clear that these “sex hormones” also regulate/influence a broad range of biological functions. In this review, we will summarize some current findings on how estrogens interact with and regulate inflammation and immunity. Specifically, we will focus on describing the mechanisms by which estrogens alter immune pathway activation, the impact of these changes during infection and the development of long-term immunity, and how different types of estrogens and their respective concentrations mediate these outcomes.

Bacteriological Profile and Predictors of Death Among Neonates With Blood Culture-Proven Sepsis in a National Hospital in Tanzania-A Retrospective Cohort Study

BACKGROUND

Neonatal sepsis is still a major cause of death and morbidity in newborns all over the world. Despite substantial developments in diagnosis, treatments, and prevention strategies, sepsis remains a common problem in clinical practice, particularly in low-resource countries.

METHODS

A retrospective cohort study of 238 neonates with positive blood culture-proven sepsis (in Muhimbili National Hospital) was conducted from January 2019 to December 2020. The outcomes of hospitalization were survival and death.

RESULTS

In total, 45.4% mortality resulted from 238 neonates who had sepsis exclusively based on blood culture positivity. A significant association was found between very low birth weight (VLBW), hyperglycemia, mechanical ventilation, and high neonatal mortality. Among the different clinical presentations of neonatal sepsis, lethargy, vomiting, and respiratory distress were found to be frequently associated with neonatal mortality. Furthermore, sepsis with Gram-negative bacteria and early-onset sepsis were also associated with high neonatal mortality. Of the 108 neonatal deaths, the largest proportion (40%) was observed with Staphylococcus aureus, and the remaining 38% was caused by Klebsiella, 14% by Escherichia coli, 5% by Pseudomonas, 4% by Acinetobacter, and 2% by Streptococcus. No neonatal deaths from Serratia infection were observed. The overall resistance of isolated organisms to the recommended first-line antibiotics was 84% for ampicillin and 71.3% for gentamicin. The resistance pattern for the recommended second-line antibiotics was 76.2% for ceftriaxone, 35.9% for vancomycin, and 17.5% for amikacin.

CONCLUSION

VLBW, early-onset sepsis, clinical and laboratory parameters like lethargy, vomiting, and hyperglycemia, sepsis with Gram-negative bacteria, and being on mechanical ventilation are strong predictors of death in neonatal sepsis. In addition, this study discovered extraordinarily high resistance to conventional antibiotics. These findings give light on the crucial aspects to consider in preventing this disease and poor outcomes.

Clinical Characteristics and Predictive Factors of Invasive Fungal Disease in Pediatric Oncology Patients with Febrile Neutropenia in a Country with Limited Resources

Background

The most common complication among pediatric oncology patients is febrile neutropenia (FN). Invasive fungal disease (IFD) is suspected when fever persists >4–7 days after empirical antibiotics. Its clinical characteristics and predictive factors associated with IFD among pediatric oncology patients with FN were thus explored.

Methods

Pediatric oncology patients with FN between January 1, 2012 and December 31, 2016 were enrolled in this study. Clinical characteristics, including laboratory investigations, treatment modalities, and final outcomes of IFD were retrospectively reviewed and analyzed.

Results

In all, 73 patients with 180 episodes of confirmed diagnosis of FN were studied. Median age at diagnosis was 6.2 years, with equal sex distribution. The most common diagnosis was acute lymphoblastic leukemia (n=91, 51%), followed by acute myeloid leukemia (n=47, 26%), Burkitt’s lymphoma (n=7, 4%) and neuroblastoma (n=7, 4%). Median absolute neutrophil count at FN diagnosis was 0 (0–806) cells/mm³. IFD was diagnosed for 25 (14%) episodes. Mortality rates for FN and IFD were 4% and 20%, respectively. Respiratory compromise, oxygen requirement, hypotension, prolonged hospitalization, duration of fever and neutropenia, bacteremia, bacteriuria, funguria, abnormal liver-function results, and prolonged broad-spectrum antibiotic administration were factors associated with IFD (P<0.05). Prolonged duration between initiation of fever and antifungal administration for nearly 10 days was an independent factor in prediction of IFD occurrence (P=0.014).

Conclusion

Respiratory compromise, oxygen requirement, hypotension, prolonged hospitalization, duration of fever and neutropenia, bacteremia, bacteriuria, funguria, abnormal liver-function results and prolonged broad-spectrum antibiotic administration were factors associated with IFD. Duration between initiation of fever and antifungal administration of nearly 10 days were considered a risk factors of IFD among patients with FN.

IRB Reference Number

IRBRTA 825/2560.

Hyper-Activation of Endogenous GLP-1 System to Gram-negative Sepsis Is Associated With Early Innate Immune Response and Modulated by Diabetes

BACKGROUND

Culture-positive gram-negative sepsis induces greater magnitude of early innate immunity /inflammatory response compared with culture-negative sepsis. We previously demonstrated increased activation of anti-inflammatory Glucagon Like Peptide-1 (GLP-1) hormone in initial phase of sepsis more pronounced in diabetes patients. However, whether GLP-1 system is hyperactivated during the early innate immune response to gram-negative sepsis and modulated by diabetes remains unknown.

OBJECTIVES

Total and active GLP-1, soluble Dipeptidyl peptidase 4 (sDPP-4) enzyme, and innate immunity markers presepsin (sCD14) and procalcitonin (PCT) in plasma were determined by ELISA on admission and after 2 to 4 days in 37 adult patients with and without type 2 diabetes and gram-negative or culture-negative sepsis of different severity.

RESULTS

Severe but not non-severe sepsis was associated with markedly increased GLP-1 system response, which correlated with PCT and the organ dysfunction marker lactate. Culture-positive gram-negative bacteria but not culture-negative sepsis induced hyper-activation of GLP-1 system, which correlated with increased innate immune markers sCD14, PCT, and lactate. GLP-1 inhibitory enzyme sDPP-4 was down regulated by sepsis and correlated negatively with sCD14 in gram-negative sepsis. Diabetic patients demonstrated increased GLP-1 response but significantly weaker innate immune response to severe and gram-negative sepsis.

CONCLUSIONS

Early stage of gram-negative sepsis is characterized by endogenous GLP-1 system hyperactivity associated with over activation of innate immune response and organ dysfunction, which are modulated by diabetes. Total GLP-1 may be novel marker for rapid diagnosis of gram-negative sepsis and its severity.

Culture-Negative Mycotic Aortic Aneurysms Probably Have a Less Severe Clinical Nature Than Culture-Positive Counterparts

BACKGROUND

Mycotic aortic aneurysm constitutes a potentially devastating disease that necessitates prompt suspicion and diagnosis. There is no exact consensus for treatment, but removal of infected tissues and prolonged use of antimicrobials based on the identified causative microorganisms seem widely acceptable and have been similarly practiced worldwide. However, some patients still show no identified microorganisms. In this study, we sought to determine whether there are any clinical significance or differences of note in culture-negative mycotic aortic aneurysms.

METHODS

Between October 2003 and August 2018, 71 patients were identified as treated for mycotic aortic aneurysms at a single tertiary institution. Review of medical records and imaging studies were completed to collect the following information: demographics, previous medical/surgical history regarding potential infection sources, laboratory and radiologic findings, clinical presentations, treatment method, and morbidity and mortality rates. For analysis, patients were categorized into two groups: the blood and/or tissue culture-positive (CP) group and the blood and/or tissue culture-negative (CN) group. The latter was further divided as CN with identified microorganism by molecular biologic methods [CN(+)] and CN with no identified microorganism [CN(-)].

RESULTS

More patients in the CP group were symptomatic than were in the CN(+) group (100% vs. 80%; P = 0.034). However, identification of causative microorganisms did not result in a difference in symptom status upon comparing the [CP + CN(+)] and [CN(-)] groups. Inflammatory markers were the most elevated in the CP group and least elevated in the CN(-) group. The aneurysm growth rate seemed slower in the CN(-) group than in the CN(+) and CP groups (1.3 vs. 3.4 vs. 9 mm/month respectively). Aneurysm rupture at initial presentation was more prevalent in the CP group (33.3%). ¹⁸F-Fluorodeoxyglucose-positron emission tomography showed increased uptake regardless of whether or not the microorganisms were identified. Early mortality and disease-specific mortality rates during the follow-up period were higher in the CP group but without statistical significance.

CONCLUSIONS

Compared with the CP group, the CN groups appeared clinically less severe, and also exhibited a relatively less devastating course as exhibited by the slower aneurysm expansion rate and smaller number of ruptured aneurysms at the initial presentation.

Development and Validation of a Machine Learning Model to Estimate Bacterial Sepsis Among Immunocompromised Recipients of Stem Cell Transplant

IMPORTANCE

Sepsis disproportionately affects recipients of allogeneic hematopoietic cell transplant (allo-HCT), and timely detection is crucial. However, the atypical presentation of sepsis within this population makes detection challenging, and existing clinical sepsis tools have limited prognostic value among this high-risk population.

OBJECTIVE

To develop a full risk factor (demographic, transplant, clinical, and laboratory factors) and clinical factor-specific automated bacterial sepsis decision support tool for recipients of allo-HCT with potential bloodstream infections (PBIs).

DESIGN, SETTING, AND PARTICIPANTS

This prognostic study used data from adult recipients of allo-HCT transplanted at the Fred Hutchinson Cancer Research Center, Seattle, Washington, between June 2010 and June 2019 randomly divided into 70% modeling and 30% validation data sets. Tools were developed using the area under the curve (AUC) optimized SuperLearner, and their performance was compared with existing clinical sepsis tools: National Early Warning Score (NEWS), quick Sequential Organ Failure Assessment (qSOFA), and Systemic Inflammatory Response Syndrome (SIRS), using the validation data set. Data were analyzed between January and October of 2020.

MAIN OUTCOMES AND MEASURES

The primary outcome was high-sepsis risk bacteremia (culture confirmed gram-negative species, Staphylococcus aureus, or Streptococcus spp bacteremia), and the secondary outcomes were 10- and 28-day mortality. Tool discrimination and calibration were examined using accuracy metrics and expected vs observed probabilities.

RESULTS

Between June 2010 and June 2019, 1943 recipients of allo-HCT received their first transplant, and 1594 recipients (median [interquartile range] age at transplant, 54 [43-63] years; 911 [57.2%] men; 1242 individuals [77.9%] identifying as White) experienced at least 1 PBI. Of 8131 observed PBIs, 238 (2.9%) were high-sepsis risk bacteremia. Compared with high-sepsis risk bacteremia, the full decision support tool had the highest AUC (0.85; 95% CI, 0.81-0.89), followed by the clinical factor-specific tool (0.72; 95% CI, 0.66-0.78). SIRS had the highest AUC of existing tools (0.64; 95% CI, 0.57-0.71). The full decision support tool had the highest AUCs for PBIs identified in inpatient (0.82; 95% CI, 0.76-0.89) and outpatient (0.82; 95% CI, 0.75-0.89) settings and for 10-day (0.85; 95% CI, 0.79-0.91) and 28-day (0.80; 95% CI, 0.75-0.84) mortality.

CONCLUSIONS AND RELEVANCE

These findings suggest that compared with existing tools and the clinical factor-specific tool, the full decision support tool had superior prognostic accuracy for the primary (high-sepsis risk bacteremia) and secondary (short-term mortality) outcomes in inpatient and outpatient settings. If used at the time of culture collection, the full decision support tool may inform more timely sepsis detection among recipients of allo-HCT.

Emerging therapeutic targets for sepsis

Introduction: Sepsis is characterized by a dysregulated host response to infection. Sepsis-associated morbidity/mortality demands concerted research efforts toward therapeutic interventions which are reliable, broadly effective, and etiologically based. More intensive and extensive investigations on alterations in cellular signaling pathways, gene targeting as a means of modifying the characteristic hyper and/or hypo-immune responses, prevention through optimization of the microbiome, and the molecular pathways underlying the septic immune response could improve outcomes.] Areas covered: The authors discuss key experimental mammalian models and clinical trials. They provide an evaluation of evolving therapeutics in sepsis and how they have built upon past and current treatments. Relevant literature was derived from a PubMed search spanning 1987-2020.Expert opinion: Given the complex nature of sepsis and the elicited immune response, it is not surprising that a single cure-all therapeutic intervention, which is capable of effectively and reliably improving patient outcomes has failed to emerge. Innovative approaches seek to address not only the disease process but modify underlying patient factors. A true improvement in sepsis-associated morbidity/mortality will require a combination of unique therapeutic modalities.

Coexistence of Pseudomonas aeruginosa With Candida albicans Enhances Biofilm Thickness Through Alginate-Related Extracellular Matrix but Is Attenuated by N-acetyl-l-cysteine

Bacteria and Candidaalbicans are prominent gut microbiota, and the translocation of these organisms into blood circulation might induce mixed-organism biofilms, which warrants the exploration of mixed- versus single-organism biofilms in vitro and in vivo. In single-organism biofilms, Acinetobacter baumannii and Pseudomonas aeruginosa (PA) produced the least and the most prominent biofilms, respectively. C. albicans with P. aeruginosa (PA+CA) induced the highest biofilms among mixed-organism groups as determined by crystal violet straining. The sessile form of PA+CA induced higher macrophage responses than sessile PA, which supports enhanced immune activation toward mixed-organism biofilms. In addition, Candida incubated in pre-formed Pseudomonas biofilms (PA>CA) produced even higher biofilms than PA+CA (simultaneous incubation of both organisms) as determined by fluorescent staining on biofilm matrix (AF647 color). Despite the initially lower bacteria during preparation, bacterial burdens by culture in mixed-organism biofilms (PA+CA and PA>CA) were not different from biofilms of PA alone, supporting Candida-enhanced Pseudomonas growth. Moreover, proteomic analysis in PA>CA biofilms demonstrated high AlgU and mucA with low mucB when compared with PA alone or PA+CA, implying an alginate-related mucoid phenotype in PA>CA biofilms. Furthermore, mice with PA>CA biofilms demonstrated higher bacteremia with more severe sepsis compared with mice with PA+CA biofilms. This is possibly due to the different structures. Interestingly, l-cysteine, a biofilm matrix inhibitor, attenuated mixed-organism biofilms both in vitro and in mice. In conclusion, Candida enhanced Pseudomonas alginate–related biofilm production, and Candida presentation in pre-formed Pseudomonas biofilms might alter biofilm structures that affect clinical manifestations but was attenuated by l-cysteine.

Vancomycin-loaded nanoparticles against vancomycin intermediate and methicillin resistant Staphylococcus aureus strains

Bacterial infections represent one of the leading causes of mortality in the world. Among causative pathogens, S. aureus is prominently known as the underlying cause of many multidrug resistant infections that are often treated with the first-line choice antibiotic vancomycin (VCM). Loading antibiotics into polymeric nanoparticles (Np) displays promise as an alternative method to deliver therapy due to the greater access and accumulation of the antibiotic at the site of the infection as well as reducing toxicity, irritation and degradation. The aim of this work was to prepare, characterize and evaluate VCM-loaded nanoparticles (VNp) for use against S. aureus strains. Moreover, conjugation of Nps with holo-transferrin (h-Tf) was investigated as an approach for improving targeted drug delivery. VNp were prepared by double emulsion solvent evaporation method using PLGA and PVA or DMAB as surfactants. The particles were characterized for size distribution, Zeta Potential, morphology by transmission electron microscopy, encapsulation yield and protein conjugation efficiency. Process yield and drug loading were also investigated along with an in vitro evaluation of VNp antimicrobial effects against S. aureus strains. Results showed that Np were spontaneously formed with a mean diameter lower than 300 nm in a narrow size distribution that presented a spherical shape. The bioconjugation with h-Tf did not appear to increase the antimicrobial effect of VNp. However, non-bioconjugated Np presented a minimal inhibitory concentration lower than free VCM against a MRSA (Methicillin-resistant S. aureus) strain, and slightly higher against a VISA (VCM intermediate S. aureus) strain. VNp without h-Tf showed potential to assist in the development of new therapies against S. aureus infections.

Diminished HIV Infection of Target CD4+ T Cells in a Toll-Like Receptor 4 Stimulated in vitro Model

Genital inflammation is associated with increased HIV acquisition risk. Induction of an inflammatory response can occur through the recognition of pathogenic or commensal microbes by Toll-like receptors (TLRs) on various immune cells. We used a in vitro peripheral blood mononuclear cell (PBMC) system to understand the contribution of TLR stimulation in inducing inflammation and the activation of target T cells, and its effect on HIV susceptibility. PBMCs were stimulated with TLR agonists LPS (TLR4), R848 (TLR7/8), and Pam3CSK4 (TLR1/2), and then infected with HIV NL4-3 AD8. Multiplexed ELISA was used to measure 28 cytokines in cell culture supernatants. Flow cytometry was used to measure the activation state (CD38 and HLA-DR), and CCR5 expression on CD4+ and CD8+ T cells. Although TLR agonists induced higher cytokine and chemokine secretion, they did not significantly activate CD4+ and CD8+ T cells and showed decreased CCR5 expression relative to the unstimulated control. Despite several classes of inflammatory cytokines and chemokines being upregulated by TLR agonists, CD4+ T cells were significantly less infectable by HIV after TLR4-stimulation than the unstimulated control. These data demonstrate that the inflammatory effects that occur in the presence TLR agonist stimulations do not necessarily translate to the activation of T cells. Most importantly, the finding that TLR4-stimulation reduces rather than increases susceptibility of CD4+ T cells to HIV infection in this in vitro system strongly suggests that the increased chemokine and possible antiviral factor expression induced by these TLR agonists play a powerful although complex role in determining HIV infection risk.

The state of the immune system in abdominal sepsis

AIM

To evaluate the prognostic value of cytokine profile, phagocytosis activity indices, endotoxin concentration and activity in blood in gram-negative sepsis.

MATERIALS AND METHODS

78 patients with abdominal sepsis were included in a one-center prospective cohort study, of them 45 died. All the patients were evaluated for the concentration of circulating cytokines (TNF-α, IFN-γ, IL-6, IL-8, IL-10), cellular molecules (CD3, CD45RO, CD95 and HLA-DR), bactericidal and phagocytic activity of neutrophils and endotoxin (lipopolysaccharide) level in peripheral blood.

RESULTS

The concentrations of all cytokines were slightly lower in the survivors. Significant differences were noted for TNF-α (p=0.001), IL-6 (p=0.001), and IL-8 (p=0.007). The expression of HLA-DR molecules was slightly higher (p=0.055), and CD95 was lower (p=0.146) in survivors than in the dead. However, the differences have not reached the required level of statistical significance. The phagocytic (p&lt;0.001) and bactericidal activity (р=0.002 for stimulated activity and p=0.001 for spontaneous activity) of neutrophils is significantly different. In survived patients, we noted large values of stimulated bactericidal activity and phagocytic index than the dead. Level of spontaneous activity in survivors was lower. In subsequently deceased patients, the level of endotoxin load was higher than in the surviving patients: level of lipopolysaccharide concentration (p=0.002), endotoxin activity (p=0.032) and neutrophils activity (p=0.028).

CONCLUSION

Evaluation of cytokine levels is informative, but due to the high spread of indicators in different patients, should be carried out in the dynamics. The most informative prognostic parameters in sepsis are the concentration and activity of lipopolysaccharides (endotoxin), phagocytic and bactericidal activity of neutrophils. The EAA (endotoxin activity assay) assessment should be conducted in conjunction with the neutrophil &quot;response&quot; assessment.

Abdominal Sepsis: An Update

Despite the significant development and advancement in antibiotic therapy, life-threatening complication of infective diseases cause hundreds of thousands of deaths world. This paper updates some of the issues regarding the etiology and treatment of abdominal sepsis and summaries the latest guidelines as recommended by the Intra-abdominal Infection (IAI) Consensus (2017). Prognostic scores are currently used to assess the course of peritonitis. Irrespective of the initial cause, there are several measures universally accepted as contributing to an improved survival rate, with the early recognition of IAI being the critical matter in this respect. Immediate correction of fluid balance should be undertaken with the use of vasoactive agents being prescribed, if necessary, to augment and assist fluid resuscitation. The WISS study showed that mortality was significantly affected by sepsis irrespective of any medical and surgical measures. A significant issue is the prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in the clinical setting, and the reported prevalence of ESBLs intra-abdominal infections has steadily increased in Asia. Europe, Latin America, Middle East, North America, and South Pacific. Abdominal cavity pathology is second only to sepsis occurring in a pulmonary site. Following IAI (2017) guidelines, antibiotic therapy should be initiated as soon as possible after a diagnosis has been verified.

Prognostic value of pneumococcal urinary antigen test in community-acquired pneumonia

Background

The pneumococcal urinary antigen test (UAT) has been known to improve sensitivity and specificity for the diagnosis of pneumococcal pneumonia. Associations of UAT results with prognosis in community acquired pneumonia (CAP) are not known. We hypothesized that positive UAT is associated with a good prognosis, and incorporation of UAT into CRB65 would improve its prognostic performance.

Methods

In this registry-based retrospective study, we analyzed CAP patients over a 10-year period beginning in April 2008. Patients who had UAT results were included in multivariable extended Cox-regression analyses to determine the association between UAT positivity and 30-day mortality. UAT results were incorporated for patients with a CRB65 score of 1 by subtracting 1 from the scoring system if the test was positive. The performance of the modified scoring systems was assessed with area under the receiver operating characteristic (AUROC) curves.

Results

Among 5145 CAP patients, total 2280 patients had UAT results and were included in analyses. A positive UAT result was associated with a good prognosis after a week of hospitalization (aHR, 0.14; p = 0.007). After modification of CRB65 using UAT results, positive and negative predictive values for 30-day mortality were increased from 7.7 to 8.3 (p<0.001) and 98.9 to 99.1 (p = 0.010). The AUROC increased from 0.73 to 0.75 (p<0.001).

Conclusions

Positive results on UAT could be considered as a good prognostic factor in CAP. UAT could be used as a useful tool in deciding whether to refer patients to the hospital, especially in moderate CAP with a CRB score of 1.

Tamarixetin Exhibits Anti-inflammatory Activity and Prevents Bacterial Sepsis by Increasing IL-10 Production

Sepsis is a systemic inflammatory response to pathogenic infection that currently has no specific pharmaceutical interventions. Instead, antibiotics administration is considered the best available option, despite increasing drug resistance. Alternative strategies are therefore urgently required to prevent sepsis and strengthen the host immune system. One such option is tamarixetin (4'- O-methylquercetin), a naturally occurring flavonoid derivative of quercetin that protects against inflammation. The purpose of this study was to determine whether the anti-inflammatory effects of tamarixetin protect against the specific inflammatory conditions induced in lipopolysaccharide (LPS) or Escherichia coli K1 models of sepsis. Our study showed that tamarixetin reduced the secretion of various inflammatory cytokines by dendritic cells after activation with LPS. It also promoted the secretion of the anti-inflammatory cytokine interleukin (IL)-10 and specifically increased the population of IL-10-secreting immune cells in LPS-activated splenocytes. Tamarixetin showed general anti-inflammatory effects in mouse models of bacterial sepsis and decreased bacteria abundance and endotoxin levels. We therefore conclude that tamarixetin has superior anti-inflammatory properties than quercetin during bacterial sepsis. This effect is associated with an increased population of IL-10-secreting immune cells and suggests that tamarixetin could serve as a specific pharmaceutical option to prevent bacterial sepsis.

Development of a zebrafish sepsis model for high-throughput drug discovery

Sepsis is a leading cause of death worldwide. Current treatment modalities remain largely supportive. Intervention strategies focused on inhibiting specific mediators of the inflammatory host response have been largely unsuccessful, a consequence of an inadequate understanding of the complexity and heterogeneity of the innate immune response. Moreover, the conventional drug development pipeline is time consuming and expensive and the low success rates associated with cell-based screens underline the need for whole organism screening strategies, especially for complex pathological processes. Here, we established an LPS-induced zebrafish endotoxemia model, which exhibits the major hallmarks of human sepsis including, edema and tissue/organ damage, increased vascular permeability and vascular leakage accompanied by an altered expression of cellular junction proteins, increased cytokine expression, immune cell activation and ROS production, reduced circulation and increased platelet aggregation. We tested the suitability of the model for phenotype-based drug screening using three primary readouts: mortality, vascular leakage, and ROS production. Preliminary screening identified fasudil, a drug known to protect against vascular leakage in murine models, as a lead hit thereby validating the utility of our model for sepsis drug screens. This zebrafish sepsis model has the potential to rapidly analyze sepsis associated pathologies and cellular processes in the whole organism, as well as to screen and validate large numbers of compounds that can modify sepsis pathology in vivo.

Bacteria and their cell wall components uniformly co-activate interleukin-17-producing thymocytes

Interleukin (IL)-17-producing T cells play a critical role in the immune response against microbial pathogens. Traditionally, experimental studies have focused upon understanding the activity of IL-17-producing T cells which differentiate from naive T cells in the peripheral immune system. However, we have demonstrated previously that IL-17-producing T cells are also present in the thymus of naive wild-type mice and can be co-activated there by microbial stimuli. Other studies have supported the concept that IL-17-producing thymocytes have a specific role in the immediate defence against microbial pathogens, which is independent from the development of an adaptive immune response. Given an important role of the thymus in systemic bacterial infection and sepsis, in this study we investigate the effect of a broad spectrum of bacteria and cell wall components on thymocyte cytokine production. Surprisingly, we find that all types of bacteria investigated (including non-pathogenic species) uniformly activate IL-17-producing thymocytes upon α-CD3 stimulation. In contrast, there is a heterogeneous effect on IL-6 and interferon (IFN)-γ-production with Gram-negative bacteria inducing far higher frequencies of IL-6- and IFN-γ-producing thymocytes than Gram-positive bacteria. We conclude that IL-17-producing thymocytes constitute a 'first line of recognition', but not a 'first line of defence' against bacteria in general. Their activity might lead to immune activation, but not necessarily to a pathological inflammatory disease condition. The difference between these two states might be determined by other immunological effector molecules, such as IL-6 and IFN-γ.

Utility of qualitative C- reactive protein assay and white blood cells counts in the diagnosis of neonatal septicaemia at Bugando Medical Centre, Tanzania

Background

Neonatal septicaemia diagnosis based on clinical features alone is non-specific leading to the initiation of unnecessary antibiotic treatment posing a danger of increased antibiotic resistance. In the present study the utility of serial qualitative C-reactive protein (CRP) assay and white blood cells count (WBC) in the diagnosis of neonatal septicaemia was investigated using blood culture as gold standard.

Methods

A total of 305 neonates admitted at Bugando Medical Centre (BMC) neonatal units between September 2013 and April 2014 were enrolled. Demographic and clinical data were collected using standardized data collection tool. Blood specimens were collected for blood culture, WBC count and qualitative CRP assay.

Results

Of 305 neonates; 224 (73.4%) were ≤ 72 hrs of age and 91(29.8%) had low birth weight. The positive CRP assay was observed in 67 (22.0%), 80 (26.2%) and 88 (28.9%) of neonates on day 1, 2 and 3 respectively; with any CRP positive occurred in 104 (34.1%) of neonates. The sensitivities of CRP assay in the diagnosis of septicaemia using culture as gold standard on day 1, 2, 3 and any positive were 40.4%, 53.2%, 54.8% and 62.9% respectively. While specificities were 82.7%, 80.7%, 77.8% and 73.3% respectively. Higher sensitivity of 75% was observed when CRP was used to diagnose gram negative septicaemia compared to 50% that was observed in the diagnosis of gram positive septicaemia. WBC count of ≥13 × 10⁹ /L had sensitivity and specificity of 64.5% and 66.7% respectively with area under the curve of 0.694. When the any positive CRP and WBC of ≥13 × 10⁹ /L were used the sensitivity increased to 90.3% with specificity of 50%. Neonates with septicaemia due to gram negative bacteria were significantly found to have higher rates of positive CRP than neonates with gram positive septicaemia and with negative culture (p < 0.001, OR 8.2, 95 CI; 2.9-26).

Conclusion

In place where blood culture is limited neonates having clinical features of neonatal sepsis with positive qualitative CRP assay and increased WBC should urgently be initiated on appropriate sepsis management in order to reduce morbidity and mortality associated with neonatal sepsis.

Interleukin-6 in sepsis and capillary leakage syndrome

Bacterial sepsis is one of the most frequent and dreaded causes of death in intensive care units. According to the current understanding of sepsis, bacterial components activate innate immune responses via pattern-recognition receptors that stimulate signaling pathways, thereby leading to activation of NF-κB and the release of cytokines, alarming the organism and coordinating appropriate defense mechanisms. The resulting "cytokine storm" not only restricts bacterial invasion; it also harms the host by triggering a hemodynamic collapse with a drop in blood pressure, which could lead to death. One of the cytokines released during sepsis is interleukin-6 (IL-6). Originally described as a B-cell-stimulating factor, this cytokine has since been shown to have multiple additional functions. Interestingly, there is emerging evidence of IL-6 trans-signaling in the pathogenesis of sepsis. We review recent findings and discuss whether therapeutic interference with IL-6 trans-signaling may be beneficial in this important clinical scenario.

Physiopathology of shock

Shock syndromes are of three types: cardiogenic, hemorrhagic and inflammatory. Hemorrhagic shock has its initial deranged macro-hemodynamic variables in the blood volume and venous return. In cardiogenic shock there is a primary pump failure that has cardiac output/mean arterial pressure as initial deranged variables. In Inflammatory Shock it is the microcirculation that is mainly affected, while the initial deranged macrocirculation variable is the total peripheral resistance hit by systemic inflammatory response.