Diagnosis of bacterial sepsis: why are tests for bacteremia not sufficient?

Rapid Diagnostic Tests and Antimicrobial Stewardship Programs for the Management of Bloodstream Infection: What Is Their Relative Contribution to Improving Clinical Outcomes? A Systematic Review and Network Meta-analysis

BACKGROUND

Evidence about the clinical impact of rapid diagnostic tests (RDTs) for the diagnosis of bloodstream infections is limited, and whether RDT are superior to conventional blood cultures (BCs) embedded within antimicrobial stewardship programs (ASPs) is unknown.

METHODS

We performed network meta-analyses using results from studies of patients with bloodstream infection with the aim of comparing the clinical impact of RDT (applied on positive BC broth or whole blood) to conventional BC, both assessed with and without ASP with respect to mortality, length of stay (LOS), and time to optimal therapy.

RESULTS

Eighty-eight papers were selected, including 25 682 patient encounters. There was an appreciable amount of statistical heterogeneity within each meta-analysis. The network meta-analyses showed a significant reduction in mortality associated with the use of RDT + ASP versus BC alone (odds ratio [OR], 0.72; 95% confidence interval [CI], .59-.87) and with the use of RDT + ASP versus BC + ASP (OR, 0.78; 95% CI, .63-.96). No benefit in survival was found associated with the use of RDT alone nor with BC + ASP compared to BC alone. A reduction in LOS was associated with RDT + ASP versus BC alone (OR, 0.91; 95% CI, .84-.98) whereas no difference in LOS was shown between any other groups. A reduced time to optimal therapy was shown when RDT + ASP was compared to BC alone (-29 hours; 95% CI, -35 to -23), BC + ASP (-18 hours; 95% CI, -27 to -10), and to RDT alone (-12 hours; 95% CI, -20 to -3).

CONCLUSIONS

The use of RDT + ASP may lead to a survival benefit even when introduced in settings already adopting effective ASP in association with conventional BC.

Beyond the Horizon: A Comprehensive Review of Contemporary Strategies in Sepsis Management Encompassing Predictors, Diagnostic Tools, and Therapeutic Advances

This comprehensive review offers a detailed exposition of contemporary strategies in sepsis management, encompassing predictors, diagnostic tools, and therapeutic advances. The analysis elucidates the dynamic nature of sepsis, emphasizing the crucial role of early detection and intervention. The multifaceted strategies advocate for a holistic and personalized approach to sepsis care from traditional clinical methodologies to cutting-edge technologies. The implications for clinical practice underscore clinicians' need to adapt to evolving definitions, integrate advanced diagnostic tools, and embrace precision medicine. Integrating artificial intelligence and telemedicine necessitates a commitment to training and optimization. Judicious antibiotic use and recognition of global health disparities emphasize the importance of a collaborative, global effort in sepsis care. Looking ahead, recommendations for future research underscore priorities such as longitudinal studies on biomarkers, precision medicine trials, implementation science in technology, global health interventions, and innovative antibiotic stewardship strategies. These research priorities aim to contribute to transformative advancements in sepsis management, ultimately enhancing patient outcomes and reducing the global impact of this critical syndrome.

Ten Clinical Pearls in Microbiology: How Effective Collaboration Optimizes Patient Care

Medical microbiology laboratories play an essential role in patient care-appertaining to infectious diseases diagnostics and treatment, infection prevention, and antimicrobial stewardship. Collaboration between clinicians and the microbiology laboratory can promote and enhance the safety, quality, and efficiency of patient care. We review practical, evidence-informed core concepts to explicate how effective partnership between clinicians and the microbiology laboratory improves patient outcomes.

Using the Traditional Ex Vivo Whole Blood Model to Discriminate Bacteria by Their Inducible Host Responses

Whole blood models are rapid and versatile for determining immune responses to inflammatory and infectious stimuli, but they have not been used for bacterial discrimination. Staphylococcus aureus, S. epidermidis and Escherichia coli are the most common causes of invasive disease, and rapid testing strategies utilising host responses remain elusive. Currently, immune responses can only discriminate between bacterial 'domains' (fungi, bacteria and viruses), and very few studies can use immune responses to discriminate bacteria at the species and strain level. Here, whole blood was used to investigate the relationship between host responses and bacterial strains. Results confirmed unique temporal profiles for the 10 parameters studied: IL-6, MIP-1α, MIP-3α, IL-10, resistin, phagocytosis, S100A8, S100A8/A9, C5a and TF3. Pairwise analysis confirmed that IL-6, resistin, phagocytosis, C5a and S100A8/A9 could be used in a discrimination scheme to identify to the strain level. Linear discriminant analysis (LDA) confirmed that (i) IL-6, MIP-3α and TF3 could predict genera with 95% accuracy; (ii) IL-6, phagocytosis, resistin and TF3 could predict species at 90% accuracy and (iii) phagocytosis, S100A8 and IL-10 predicted strain at 40% accuracy. These data are important because they confirm the proof of concept that host biomarker panels could be used to identify bacterial pathogens.

Evaluation of Blood Culture Results in Patients with Malignancy in Erzurum Province, Turkey

Background

Bloodstream infections are a serious public health problem that requires follow-up with blood culture; this negatively affects the course of the disease and patient healthcare costs in patients with malignancy. This study aimed to determine the growth frequency of pathogens and their antibiotic resistance profiles in the blood cultures of patients with hematological and oncogenic malignancies.

Materials and methods

The results of 7451 blood cultures, obtained from 2926 patients between January 2017 and January 2022, were evaluated retrospectively. Of these cultures, 3969 were obtained from patients with malignancy (diagnostic codes C00-D48 in ICD-10) and 3482 from patients without malignancy. The hospital information management system modules were used to acquire patient data and blood culture results.

Results

Various microorganisms grew in 10.1% of blood cultures. Of these organisms, 64.1% were isolated from cases of malignancy. Of the pathogens, 49.2% were gram-negative bacteria, 47.7% were gram-positive bacteria, and 3.1% were fungi. The most frequently isolated bacteria were methicillin-resistant coagulase-negative staphylococci (3.2%), Escherichia coli (2.3%), Klebsiella pneumoniae (1.0%), methicillin-sensitive coagulase-negative staphylococci (0.7%), and Staphylococcus aureus (0.6%). Pathogen positivity was highest in the patient cultures with urinary system cancer (23.9%), thyroid and other endocrine gland cancers (20.6%), female and male genital organ cancers (18.2%/16.9%), and digestive organ cancer (14.2%). Gram-negative bacteria to ampicillin, piperacillin, and sulfamethoxazole-trimethoprim and Gram-positive bacteria to penicillin, erythromycin, and sulfamethoxazole-trimethoprim were highly resistant. Combined resistance to imipenem and meropenem was observed in 25 Gram-negative bacteria. Twelve (48%) of the carbapenem-resistant bacteria were isolated from patients with lymphoid, hematopoietic, and related tissue malignant neoplasia.

Conclusion

This study reported microorganisms and their antimicrobial resistance in the blood cultures of malignant patients, a special patient group. It pointed out that the antibiotic resistance of Staphylococcus, Klebsiella pneumoniae, and E. coli is high enough to cause problems in the treatment of patients with malignancy.

Cell-free DNA as diagnostic and prognostic biomarkers for adult sepsis: a systematic review and meta-analysis

Although cell-free DNA (cfDNA) is an emerging sepsis biomarker, the use of cfDNA, especially as diagnostic and prognostic indicators, has surprisingly not been systemically analyzed. Data of adult patients with sepsis that conducted cfDNA measurement within 24 h of the admission was collected from PubMed, ScienceDirect, Scopus, and Cochrane Library until October 2022. The Quality in Prognosis Studies (QUIPS) and Quality Assessment in Diagnostic Studies-2 (QUADAS-2) tools were used to reduce the risk of biased assessment. The mean difference (MD) of cfDNA concentration and the standardized mean difference (SMD) between populations was calculated using Review Manager (RevMan) version 5.4.1 package software. Pooled analysis from 18 included studies demonstrated increased serum cfDNA levels in sepsis when compared with healthy control (SMD = 1.02; 95% confidence interval (CI) 0.46-1.57) or non-sepsis patients in the intensive care unit (ICU) (SMD = 1.03; 95% CI 0.65-1.40), respectively. Meanwhile, a slight decrease in the statistical value was observed when compared with non-sepsis ICU patients with SIRS (SMD = 0.74; 95% 0.41-1.06). The lower cfDNA levels were also observed in sepsis survivors compared to the non-survivors (SMD at 1.43; 95%CI 0.69-2.17) with the pooled area under the receiver operating characteristic curve (AUC) of 0.76 (95% CI 0.64-0.87) for the mortality prediction. Levels of cfDNA showed a pooled sensitivity of 0.81 (95% CI 0.75-0.86) and specificity of 0.72 (95% CI 0.65-0.78) with pooled diagnostic odd ratio (DOR) at 25.03 (95% CI 5.48-114.43) for the identification of sepsis in critically ill conditions. The cfDNA levels were significantly higher in patients with sepsis and being a helpful indicator for the critically ill conditions of sepsis. Nevertheless, results of the test must be interpreted carefully with the context of all clinical situations.

Clinical burden of invasive Escherichia coli disease among older adult patients treated in hospitals in the United States

BACKGROUND

Invasive extraintestinal pathogenic Escherichia coli disease (IED) can lead to severe outcomes, particularly among older adults. However, the clinical burden of IED in the U.S. has not been well characterized.

METHODS

IED encounters among patients ≥ 60 years old were identified using the PINC AI™ Healthcare Database (10/01/2015-03/31/2020) by either a positive E. coli culture in blood or another normally sterile body site and ≥ 1 sign of systemic inflammatory response syndrome or signs of sepsis, or a positive E. coli culture in urine with urinary tract infection and signs of sepsis. Medical resource utilization, clinical outcomes, and E. coli isolate characteristics were descriptively reported during the first IED encounter and during the following year (observation period).

RESULTS

Overall, 19,773 patients with IED were included (mean age: 76.8 years; 67.4% female; 78.5% with signs of sepsis). Most encounters involved community-onset IED (94.3%) and required hospitalization (96.5%; mean duration: 6.9 days), with 32.4% of patients being admitted to the intensive care unit (mean duration: 3.7 days). Most E. coli isolates were resistant to ≥ 1 antibiotic category (61.7%) and 34.4% were resistant to ≥ 3 antibiotic categories. Following their first IED encounter, 34.8% of patients were transferred to a skilled nursing/intermediate care facility, whereas 6.8% had died. During the observation period, 36.8% of patients were rehospitalized, 2.4% had IED recurrence, and in-hospital death increased to 10.9%.

CONCLUSIONS

IED is associated with substantial clinical burden at first encounter with considerable long-term consequences. Findings demonstrate the need for increased IED awareness and highlight potential benefits of prevention.

Direct-from-Blood Detection of Pathogens: a Review of Technology and Challenges

Blood cultures have been the staple of clinical microbiology laboratories for well over half a century, but gaps remain in our ability to identify the causative agent in patients presenting with signs and symptoms of sepsis. Molecular technologies have revolutionized the clinical microbiology laboratory in many areas but have yet to present a viable alternative to blood cultures. There has been a recent surge of interest in utilizing novel approaches to address this challenge. In this minireview, I discuss whether molecular tools will finally give us the answers we need and the practical challenges of incorporating them into the diagnostic algorithm.

Point-of-care diagnostics for sepsis using clinical biomarkers and microfluidic technology

Sepsis is a life-threatening immune response which is caused by a wide variety of sources and is a leading cause of mortality globally. Rapid diagnosis and appropriate antibiotic treatment are critical for successful patient outcomes; however, current molecular diagnostic techniques are time-consuming, costly and require trained personnel. Additionally, there is a lack of rapid point-of-care (POC) devices available for sepsis detection despite the urgent requirements in emergency departments and low-resource areas. Recent advances have been made toward developing a POC test for early sepsis detection that will be more rapid and accurate compared to conventional techniques. Within this context, this review discusses the use of current and novel biomarkers for early sepsis diagnosis using microfluidics devices for POC testing.

Diagnostic Value of Neutrophil CD64 in Sepsis Patients in the Intensive Care Unit: A Cross-Sectional Study

Little is known about the role of neutrophil CD64 (nCD64) in detecting sepsis early in Asian populations. We examined the cut-off and predictive values of nCD64 for diagnosing sepsis in Vietnamese intensive care units (ICU) patients. A cross-sectional study was conducted at the ICU of Cho Ray Hospital between January 2019 and April 2020. All 104 newly admitted patients were included. Sensitivity (Sens), specificity (Spec), positive and negative predictive values (PPV and NPV), and receiver operating characteristic (ROC) curves were calculated to compare the diagnostic values of nCD64 with those of procalcitonin (PCT) and white blood cell (WBC) for sepsis. The median nCD64 value in sepsis patients was statistically higher than that of non-sepsis patients (3106 [1970-5200] vs. 745 [458-906] molecules/cell, p < 0.001). ROC analysis found that the AUC value of nCD64 was 0.92, which was higher than that of PCT (0.872), WBC (0.637), and nCD64 combined, with WBC (0.906) and nCD64 combined with WBC and PCT (0.919), but lower than that of nCD64 combined with PCT (0.924). With an AUC value of 0.92, the nCD64 index of 1311 molecules/cell-detected sepsis with 89.9% Sens, 85.7% Spec, 92.5% PPV, and 81.1% NPV. nCD64 can be a useful marker for early sepsis diagnosis in ICU patients. nCD64 combined with PCT may improve the diagnostic accuracy.

Association between timing and adequacy of antibiotics and adverse outcomes in patients with sepsis and septic shock: A multicentre retrospective cohort study

OBJECTIVES

To investigate the association between the timing and adequacy of antibiotics administered to patients presenting with culture-positive sepsis and septic shock to the ED and in-hospital mortality and/or intensive care unit (ICU) admission.

METHODS

Multicentre retrospective cohort study of ED presentations at four metropolitan hospitals in Sydney, Australia between January 2017 and November 2019. Encounters for patients aged ≥16 years meeting specified criteria for sepsis or septic shock with antibiotic administration within the first 6 h of presentation were included.

RESULTS

Of 7611 encounters included in the study, 2328 (31%) were culture positive, and 2228 (29%) met the criteria for septic shock. In culture-positive sepsis encounters, partial or inadequate antibiotic coverage was associated with higher risk of death or ICU admission (adjusted odds ratio [AOR] 1.50, 95% confidence interval [CI] 1.04-2.06 and 1.95, 95% CI 1.28-2.99, respectively). This effect was not significant in septic shock encounters (AOR 1.10, 95% CI 0.64-1.88) with partial coverage and (AOR 1.63, 95% CI 0.81-3.3) inadequate coverage. Time to antibiotics was not significantly associated with the risk of mortality/ICU admission. This inference remained the same when analysis was restricted to cases with adequate antibiotic coverage.

CONCLUSIONS

In a large multicentre sample of patients with culture-positive sepsis, inadequacy of antibiotics was associated with higher risk of in-hospital mortality or ICU admission.

Multisite validation of a host response signature for predicting likelihood of bacterial and viral infections in patients with suspected influenza

BACKGROUND

Indiscriminate use of antimicrobials and antimicrobial resistance is a public health threat. IMX-BVN-1, a 29-host mRNA classifier, provides two separate scores that predict likelihoods of bacterial and viral infections in patients with suspected acute infections. We validated the performance of IMX-BVN-1 in adults attending acute health care settings with suspected influenza.

METHOD

We amplified 29-host response genes in RNA extracted from blood by NanoString nCounter. IMX-BVN-1 calculated two scores to predict probabilities of bacterial and viral infections. Results were compared against the infection status (no infection; highly probable/possible infection; confirmed infection) determined by clinical adjudication.

RESULTS

Amongst 602 adult patients (74.9% ED, 16.9% ICU, 8.1% outpatients), 7.6% showed in-hospital mortality and 15.5% immunosuppression. Median IMX-BVN-1 bacterial and viral scores were higher in patients with confirmed bacterial (0.27) and viral (0.62) infections than in those without bacterial (0.08) or viral (0.21) infection, respectively. The AUROC distinguishing bacterial from nonbacterial illness was 0.81 and 0.87 when distinguishing viral from nonviral illness. The bacterial top quartile's positive likelihood ratio (LR) was 4.38 with a rule-in specificity of 88%; the bacterial bottom quartile's negative LR was 0.13 with a rule-out sensitivity of 96%. Similarly, the viral top quartile showed an infinite LR with rule-in specificity of 100%; the viral bottom quartile had a LR of 0.22 and a rule-out sensitivity of 85%.

CONCLUSION

IMX-BVN-1 showed high accuracy for differentiating bacterial and viral infections from noninfectious illness in patients with suspected influenza. Clinical utility of IMX-BVN will be validated following integration into a point of care system.

Label-Free Optical Detection of Pathogenic Bacteria and Fungi at Extremely Low Cell Densities for Rapid Antibiotic Susceptibility Testing

Antibiotic resistance is a rapidly expanding public health problem across the globe leading to prolonged hospital admissions, increased morbidity and mortality, and associated high healthcare costs. Effective treatment of bacterial infections requires timely and correct antibiotic administration to the patients which relies on rapid phenotyping of disease-causing bacteria. Currently, antibiotic susceptibility tests can take several days and as a result, indiscriminate antibiotic use has exacerbated the evolution and spread of antibiotic resistance in clinical and community settings. In order to address this problem, we have developed a novel optical apparatus that we called RUSD (Rapid Ultra-Sensitive Detection). RUSD is built around a hollow silica fiber and utilizes bacterial cells as spatial light modulators. This generates a highly sensitive modulation transfer function due to the narrow reflectivity angle in the fiber-media interface. We leveraged the RUSD technology to allow for robust bacterial and fungal detection. RUSD can now detect pathogenic cell densities in a large dynamic window (OD600 from ∼10−7 to 10−1). Finally, we can generate dose response curves for various pathogens and antimicrobial compounds within one to three hours by using RUSD. Our antibiotic- susceptibility testing (AST) assay that we call iFAST (in-Fiber-Antibiotic-Susceptibility-Testing) is fast, highly sensitive, and does not change the existing workflow in clinical settings as it is compatible with FDA-approved AST. Thus, RUSD platform is a viable tool that will expedite decision-making process in the treatment of infectious diseases and positively impact the antibiotic resistance problem in the long term by minimizing the use of ineffective antibiotics.

Aeromonas and Human Health Disorders: Clinical Approaches

The genus Aeromonas comprises more than 30 Gram-negative bacterial species and naturally inhabitants from aquatic environments. These microorganisms, commonly regarded as pathogens of fish and several other animals, have been gaining prominence on medical trial due to its ability to colonize and infect human beings. Besides water, Aeromonas are widely spreaded on most varied sources like soil, vegetables, and food; Although its opportunistic nature, they are able to cause infections on immunocompromised or immunocompetent patients. Aeromonas species regarded as potential human pathogens are usually A. hydrophila, A. caviae, and A. veronii biovar sobria. The main clinical manifestations are gastrointestinal tract disorders, wound, and soft tissue infections, as well as septicemia. Regarding to antibiotic responses, the bacteria present a diversified susceptibility profile and show inherence resistance to ampicillin. Aeromonas, as an ascending genus in microbiology, has been carefully studied aiming comprehension and development of methods for detection and medical intervention of infectious processes, not fully elucidated in medicine. This review focuses on current clinical knowledge related to human health disorders caused by Aeromonas to contribute on development of efficient approaches able to recognize and impair the pathological processes.

Molecular diagnosis of bacteremia in a pediatric intensive care unit: a step forward

Aim: T2Bacteria^® Panel detects six ESKAPE pathogens in around 3.5 h directly in whole blood. Our aim was to compare T2Bacteria with simultaneous blood culture in critically ill children with suspected bloodstream infection. Materials & methods: Retrospective study of critically ill children admitted to our tertiary-care center (2018-2020). Results: A total of 60 patients were recruited, including 63 episodes and 75 T2Bacteria/blood cultures were performed. Overall agreement between T2Bacteria and blood culture was 78.7% with a discordance of 21.3% (16/75 samples). Conclusion: T2Bacteria Panel may be useful in critically ill children providing an accurate and fast diagnosis of bacteremia directly from blood sample and detecting pathogens not recovered in blood cultures.

Blood Cultures and Molecular Diagnostics in Intensive Care Units to Diagnose Sepsis: A Bayesian Latent Class Model Analysis

Background

Confirmation of sepsis by standard blood cultures (STD) is often inconclusive due to slow growth and low positivity. Molecular diagnostics (MOL) are faster and may have higher positivity, but test performance can be inaccurately estimated if STD methods are used as comparators. Bayesian latent class models (LCMs) can evaluate diagnostic methods when there is no "gold standard." Intensive care unit studies that have used LCMs to combine and compare STD and MOL method performance and estimate the prevalence of sepsis have not been described.

Patients and methods

Results from an ICU sepsis study that used both tests simultaneously were analyzed. Bayesian LCMs combined prior prevalence of sepsis, prior diagnostic characteristics of the two methods, and the study results to estimate the posterior prevalence and diagnostic characteristics. Sensitivity analyses were performed using objective (published studies) and subjective (expert opinion) prior parameters. Positive predictive values (PPVs) of the prevalence of sepsis were estimated for all combinations of test results.

Results

The range of posterior estimates was: sepsis prevalence (0.38-0.88), sensitivities (STD: 0.2-0.35, MOL: 0.56-0.86), and specificities (STD: 0.87-0.99, MOL: 0.72-0.95). The PPV (sepsis) of both tests being positive was (0.72-0.99).

Conclusion

LCMs combined two imperfect methods to estimate prevalence, PPV, and diagnostic characteristics. The posterior estimates (STD sensitivity < MOL and STD specificity > MOL) seem to reflect the clinical experience appropriately. The high PPV when both methods show positive results can be useful for ruling in disease.

How to cite this article

Sampath S, Baby J, Krishna B, Dendukuri N, Thomas T. Blood Cultures and Molecular Diagnostics in Intensive Care Units to Diagnose Sepsis: A Bayesian Latent Class Model Analysis. Indian J Crit Care Med 2021;25(12):1402-1407.

Using machine learning to predict blood culture outcomes in the emergency department: a single-centre, retrospective, observational study

OBJECTIVES

To develop predictive models for blood culture (BC) outcomes in an emergency department (ED) setting.

DESIGN

Retrospective observational study.

SETTING

ED of a large teaching hospital in the Netherlands between 1 September 2018 and 24 June 2020.

PARTICIPANTS

Adult patients from whom BCs were collected in the ED. Data of demographic information, vital signs, administered medications in the ED and laboratory and radiology results were extracted from the electronic health record, if available at the end of the ED visits.

MAIN OUTCOME MEASURES

The primary outcome was the performance of two models (logistic regression and gradient boosted trees) to predict bacteraemia in ED patients, defined as at least one true positive BC collected at the ED.

RESULTS

In 4885 out of 51 399 ED visits (9.5%), BCs were collected. In 598/4885 (12.2%) visits, at least one of the BCs was true positive. Both a gradient boosted tree model and a logistic regression model showed good performance in predicting BC results with area under curve of the receiver operating characteristics of 0.77 (95% CI 0.73 to 0.82) and 0.78 (95% CI 0.73 to 0.82) in the test sets, respectively. In the gradient boosted tree model, the optimal threshold would predict 69% of BCs in the test set to be negative, with a negative predictive value of over 94%.

CONCLUSIONS

Both models can accurately identify patients with low risk of bacteraemia at the ED in this single-centre setting and may be useful to reduce unnecessary BCs and associated healthcare costs. Further studies are necessary for validation and to investigate the potential clinical benefits and possible risks after implementation.

Effect of Anti-Inflammatory and Antimicrobial Cosupplementations on Sepsis Prevention in Critically Ill Trauma Patients at High Risk for Sepsis

Background: Sepsis development in patients with trauma is associated with bad prognosis. This study investigated the effect of immunomodulatory interventions in major trauma patients at high risk for sepsis. Methods: In a randomized, double-blinded, controlled design, severe trauma patients were stratified by leukocyte anti-sedimentation rate (LAR) test into high risk (HR) and low risk (LR) for sepsis. The HR patients were randomly allocated into intravenous vitamin C plus vitamin B1 (HR-CB), intramuscular vitamin D plus oral Lactobacillus probiotics (HR-DP), or control (HR-C) groups. The clinical trial was registered at clinicaltrials.gov (https://clinicaltrials.gov/show/NCT04216459). Outcomes: The primary outcome was Acute Physiologic Assessment and Chronic Health Evaluation score II (APACHE II) score. Secondary outcomes included sepsis incidence, changes in Sequential Organ Failure Assessment (SOFA) score, and serum monocyte chemoattractant protein-1 (MCP-1) on day 6 from baseline, 28-day mortality, intensive care unit (ICU), and hospital discharge. Results: The HR-DP, HR-CB, and LR groups showed a significantly lower incidence of sepsis development (20%, 20%, and 16%, respectively, versus 60% in the HR-C group, p-value = 0.004). The three groups also showed a significant improvement in APACHE II and SOFA scores. Besides, MCP-1 levels were significantly decreased in HR-DP and HR-CB groups compared to the HR-C group (p-value ≤ 0.05). Significantly decreased mortality (10% and 16% versus 60% in the HR-C group) and increased ICU discharge (95% and 84% versus 45% in the HR-C group) were observed in HR-CB and LR groups (p-value = 0.001). Conclusion: Both combinations of interventions improved APACHE II scores and reduced sepsis incidence in trauma patients. The LAR combined with injury severity score were good sepsis predictors.

Revising Host Phenotypes of Sepsis Using Microbiology

Background: There is wide heterogeneity in sepsis in causative pathogens, host response, organ dysfunction, and outcomes. Clinical and biologic phenotypes of sepsis are proposed, but the role of pathogen data on sepsis classification is unknown. Methods: We conducted a secondary analysis of the Recombinant Human Activated Protein C (rhAPC) Worldwide Evaluation in Severe Sepsis (PROWESS) Study. We used latent class analysis (LCA) to identify sepsis phenotypes using, (i) only clinical variables ("host model") and, (ii) combining clinical with microbiology variables (e.g., site of infection, culture-derived pathogen type, and anti-microbial resistance characteristics, "host-pathogen model"). We describe clinical characteristics, serum biomarkers, and outcomes of host and host-pathogen models. We tested the treatment effects of rhAPC by phenotype using Kaplan-Meier curves. Results: Among 1,690 subjects with severe sepsis, latent class modeling derived a 4-class host model and a 4-class host-pathogen model. In the host model, alpha type (N = 327, 19%) was younger and had less shock; beta type (N=518, 31%) was older with more comorbidities; gamma type (N = 532, 32%) had more pulmonary dysfunction; delta type (N = 313, 19%) had more liver, renal and hematologic dysfunction and shock. After the addition of microbiologic variables, 772 (46%) patients changed phenotype membership, and the median probability of phenotype membership increased from 0.95 to 0.97 (P < 0.01). When microbiology data were added, the contribution of individual variables to phenotypes showed greater change for beta and gamma types. In beta type, the proportion of abdominal infections (from 20 to 40%) increased, while gamma type patients had an increased rate of lung infections (from 50 to 78%) with worsening pulmonary function. Markers of coagulation such as d-dimer and plasminogen activator inhibitor (PAI)-1 were greater in the beta type and lower in the gamma type. The 28 day mortality was significantly different for individual phenotypes in host and host-pathogen models (both P < 0.01). The treatment effect of rhAPC obviously changed in gamma type when microbiology data were added (P-values of log rank test changed from 0.047 to 0.780). Conclusions: Sepsis host phenotype assignment was significantly modified when microbiology data were added to clinical variables, increasing cluster cohesiveness and homogeneity.

A Novel 29-Messenger RNA Host-Response Assay From Whole Blood Accurately Identifies Bacterial and Viral Infections in Patients Presenting to the Emergency Department With Suspected Infections: A Prospective Observational Study

OBJECTIVES

The rapid diagnosis of acute infections and sepsis remains a serious challenge. As a result of limitations in current diagnostics, guidelines recommend early antimicrobials for suspected sepsis patients to improve outcomes at a cost to antimicrobial stewardship. We aimed to develop and prospectively validate a new, 29-messenger RNA blood-based host-response classifier Inflammatix Bacterial Viral Non-Infected version 2 (IMX-BVN-2) to determine the likelihood of bacterial and viral infections.

DESIGN

Prospective observational study.

SETTING

Emergency Department, Campus Benjamin Franklin, Charité-Universitätsmedizin Berlin, Germany.

PATIENTS

Three hundred twelve adult patients presenting to the emergency department with suspected acute infections or sepsis with at least one vital sign change.

INTERVENTIONS

None (observational study only).

MEASUREMENTS AND MAIN RESULTS

Gene expression levels from extracted whole blood RNA was quantified on a NanoString nCounter SPRINT (NanoString Technologies, Seattle, WA). Two predicted probability scores for the presence of bacterial and viral infection were calculated using the IMX-BVN-2 neural network classifier, which was trained on an independent development set. The IMX-BVN-2 bacterial score showed an area under the receiver operating curve for adjudicated bacterial versus ruled out bacterial infection of 0.90 (95% CI, 0.85-0.95) compared with 0.89 (95% CI, 0.84-0.94) for procalcitonin with procalcitonin being used in the adjudication. The IMX-BVN-2 viral score area under the receiver operating curve for adjudicated versus ruled out viral infection was 0.83 (95% CI, 0.77-0.89).

CONCLUSIONS

IMX-BVN-2 demonstrated accuracy for detecting both viral infections and bacterial infections. This shows the potential of host-response tests as a novel and practical approach for determining the causes of infections, which could improve patient outcomes while upholding antimicrobial stewardship.

Surface Design for Antibacterial Materials: From Fundamentals to Advanced Strategies

Healthcare-acquired infections as well as increasing antimicrobial resistance have become an urgent global challenge, thus smart alternative solutions are needed to tackle bacterial infections. Antibacterial materials in biomedical applications and hospital hygiene have attracted great interest, in particular, the emergence of surface design strategies offer an effective alternative to antibiotics, thereby preventing the possible development of bacterial resistance. In this review, recent progress on advanced surface modifications to prevent bacterial infections are addressed comprehensively, starting with the key factors against bacterial adhesion, followed by varying strategies that can inhibit biofilm formation effectively. Furthermore, "super antibacterial systems" through pre-treatment defense and targeted bactericidal system, are proposed with increasing evidence of clinical potential. Finally, the advantages and future challenges of surface strategies to resist healthcare-associated infections are discussed, with promising prospects of developing novel antimicrobial materials.

A 29-mRNA host response test from blood accurately distinguishes bacterial and viral infections among emergency department patients

BACKGROUND

Whether or not to administer antibiotics is a common and challenging clinical decision in patients with suspected infections presenting to the emergency department (ED). We prospectively validate InSep, a 29-mRNA blood-based host response test for the prediction of bacterial and viral infections.

METHODS

The PROMPT trial is a prospective, non-interventional, multi-center clinical study that enrolled 397 adult patients presenting to the ED with signs of acute infection and at least one vital sign change. The infection status was adjudicated using chart review (including a syndromic molecular respiratory panel, procalcitonin and C-reactive protein) by three infectious disease physicians blinded to InSep results. InSep (version BVN-2) was performed using PAXgene Blood RNA processed and quantified on NanoString nCounter SPRINT. InSep results (likelihood of bacterial and viral infection) were compared to the adjudicated infection status.

RESULTS

Subject mean age was 64 years, comorbidities were significant for diabetes (17.1%), chronic obstructive pulmonary disease (13.6%), and severe neurological disease (6.8%); 16.9% of subjects were immunocompromised. Infections were adjudicated as bacterial (14.1%), viral (11.3%) and noninfected (0.25%): 74.1% of subjects were adjudicated as indeterminate. InSep distinguished bacterial vs. viral/noninfected patients and viral vs. bacterial/noninfected patients using consensus adjudication with AUROCs of 0.94 (95% CI 0.90-0.99) and 0.90 (95% CI 0.83-0.96), respectively. AUROCs for bacterial vs. viral/noninfected patients were 0.88 (95% CI 0.79-0.96) for PCT, 0.80 (95% CI 0.72-89) for CRP and 0.78 (95% CI 0.69-0.87) for white blood cell counts (of note, the latter biomarkers were provided as part of clinical adjudication). To enable clinical actionability, InSep incorporates score cutoffs to allocate patients into interpretation bands. The Very Likely (rule in) InSep bacterial band showed a specificity of 98% compared to 94% for the corresponding PCT band (> 0.5 µg/L); the Very Unlikely (rule-out) band showed a sensitivity of 95% for InSep compared to 86% for PCT. For the detection of viral infections, InSep demonstrated a specificity of 93% for the Very Likely band (rule in) and a sensitivity of 96% for the Very Unlikely band (rule out).

CONCLUSIONS

InSep demonstrated high accuracy for predicting the presence of both bacterial and viral infections in ED patients with suspected acute infections or suspected sepsis. When translated into a rapid, point-of-care test, InSep will provide ED physicians with actionable results supporting early informed treatment decisions to improve patient outcomes while upholding antimicrobial stewardship. Registration number at Clinicaltrials.gov NCT03295825.

Oxycytosis and the role of triboelectricity and oxidation in bacteria clearing from the bloodstream

Until recently, little was known about the mechanism for killing and clearing bacteria from the bloodstream. Leukocyte phagocytosis could not be a mechanism for catching, killing and removing bacteria from the bloodstream because of many reasons. Recently accumulated data have led to the conclusion that in bacteremia, bacteria are quickly removed from the blood and erythrocytes are the main cells that capture, kill and remove bacteria. Data were also obtained that erythrocytes catch bacteria by triboelectric charge attraction and kill them by oxygen released from oxyhemoglobin. This phenomenon has been named oxycytosis by analogy with the term phagocytosis. Oxycytosis has been discussed in a number of published articles, but the specific mechanism of triboelectric charging and the mechanism of killing bacteria by oxidation, have not yet been detailed. The purpose of this review is to provide a more detailed explanation of the process of triboelectric charging and capture of bacteria by erythrocytes and destruction of bacteria by oxidation. For the first time, the review presents various variants of oxycytosis (two-stage, three-stage, multi-stage), depending on the resistance of the pathogen to oxidation. The review also discusses the biological significance of oxycytosis and its impact on the understanding of bacteremia and sepsis.

Bacterial profile and multi-drug resistance pattern of bacterial isolates among septicemia suspected cases: a meta-analysis report in Ethiopia

Background

Bloodstream infections (BSIs) are one of the most common infections seen in all age groups and in all locations. The current knowledge on the patterns of bacterial profile, and its antibiotic resistance are essential to design and implement appropriate interventions. This study was conducted to assess the prevalence and multi-drug resistance pattern of bacterial isolates among septicemia and/or bacteremia suspected cases in Ethiopia.

Methods

Searching was conducted in databases of PubMed, Research Gate, Scopus and Google Scholar. In addition, manual searching is also conducted in bibliographies of included studies and in other meta-analysis studies. Required data were extracted from articles published up to 2020 on the bacterial profile of septicemia in Ethiopia, and analyzed using comprehensive meta-analysis version 3.3.0 software.

Results

A total of 5,823 septicemia suspected cases were extracted from 18 included studies and the overall blood culture positive rate of 31.9% (95% CI: 0.261–0.382). Of these, the overall Gram positive and Gram negative isolates was 57.8% (95% CI: 0.534–0.584) and 42.2% (95% CI: 0.416–0.466), respectively. Among Gram positives, predominantly reported isolates was Staphylococcus  aureus (47.9%: 480 of 1,003), followed by Coagulase-Negative Staphylococcus (42.7%: 428 of 1,003), whereas among Gram negatives, the most frequently reported isolates was Klebsiella species (29.8%: 218 of 731), followed by Escherichia  coli (23.1%: 169 of 731). Significant levels of resistance was reported against ampicillin, amoxicillin, ceftriaxone, co-trimoxazole and tetracycline with a pooled resistance range of 40.6–55.3% in Gram positive and 52.8–85.7% in Gram negative isolates. The pooled estimates of multi-drugs resistance (MDR) was (66.8%) among Gram positives and (80.5%) among Gram negatives, with the overall MDR rate of (74.2%).

Conclusions

The reported blood culture positive rates among septicemia cases were relatively high. Second, the level of drug and multi-drug resistant isolates against commonly prescribed antibiotics was significant. However, the scarcity of data on culture confirmed septicemia cases as well as patterns of antimicrobial resistance may overshadow the problem.

A simple magnetic-assisted microfluidic method for rapid detection and phenotypic characterization of ultralow concentrations of bacteria

Isolation and enumeration of bacteria at ultralow concentrations and antibiotic resistance profiling are of great importance for early diagnosis and treatment of bacteremia. In this work, we describe a simple, rapid, and versatile magnetic-assisted microfluidic method for rapid bacterial detection. The developed method enables magnetophoretic loading of bead-captured bacteria into the microfluidic chamber under external static and dynamic magnetic fields in 4 min. A shallow microfluidic chamber design that enables the monolayer orientation and transportation of the beads and a glass substrate with a thickness of 0.17 mm was utilized to allow high-resolution fluorescence imaging for quantitative detection. Escherichia coli (E. coli) with green fluorescent protein (GFP)-expressing gene and streptavidin-modified superparamagnetic microbeads were used as model bacteria and capturing beads, respectively. The specificity of the method was validated using Lactobacillus gasseri as a negative control group. The limit of detection and limit of quantification values were determined as 2 CFU/ml and 10 CFU/ml of E. coli, respectively. The magnetic-assisted microfluidic method is a versatile tool for the detection of ultralow concentrations of viable bacteria with the linear range of 5-5000 CFU/ml E. coli in 1 h, and providing growth curves and phenotypic characterization bead-captured E. coli in the following 5 h of incubation. Our results are promising for future rapid and sensitive antibiotic susceptibility testing of ultralow numbers of viable cells.

Serum N-Glycomics Stratifies Bacteremic Patients Infected with Different Pathogens

Bacteremia—i.e., the presence of pathogens in the blood stream—is associated with long-term morbidity and is a potential precursor condition to life-threatening sepsis. Timely detection of bacteremia is therefore critical to reduce patient mortality, but existing methods lack precision, speed, and sensitivity to effectively stratify bacteremic patients. Herein, we tested the potential of quantitative serum N-glycomics performed using porous graphitized carbon liquid chromatography tandem mass spectrometry to stratify bacteremic patients infected with Escherichia coli (n = 11), Staphylococcus aureus (n = 11), Pseudomonas aeruginosa (n = 5), and Streptococcus viridans (n = 5) from healthy donors (n = 39). In total, 62 N-glycan isomers spanning 41 glycan compositions primarily comprising complex-type core fucosylated, bisecting N-acetylglucosamine (GlcNAc), and α2,3-/α2,6-sialylated structures were profiled across all samples using label-free quantitation. Excitingly, unsupervised hierarchical clustering and principal component analysis of the serum N-glycome data accurately separated the patient groups. P. aeruginosa-infected patients displayed prominent N-glycome aberrations involving elevated levels of fucosylation and bisecting GlcNAcylation and reduced sialylation relative to other bacteremic patients. Notably, receiver operating characteristic analyses demonstrated that a single N-glycan isomer could effectively stratify each of the four bacteremic patient groups from the healthy donors (area under the curve 0.93–1.00). Thus, the serum N-glycome represents a new hitherto unexplored class of potential diagnostic markers for bloodstream infections.

A Multi-mRNA Host-Response Molecular Blood Test for the Diagnosis and Prognosis of Acute Infections and Sepsis: Proceedings from a Clinical Advisory Panel

Current diagnostics are insufficient for diagnosis and prognosis of acute infections and sepsis. Clinical decisions including prescription and timing of antibiotics, ordering of additional diagnostics and level-of-care decisions rely on understanding etiology and implications of a clinical presentation. Host mRNA signatures can differentiate infectious from noninfectious etiologies, bacterial from viral infections, and predict 30-day mortality. The 29-host-mRNA blood-based InSep^TM test (Inflammatix, Burlingame, CA, formerly known as HostDx^TM Sepsis) combines machine learning algorithms with a rapid point-of-care platform with less than 30 min turnaround time to enable rapid diagnosis of acute infections and sepsis, as well as prediction of disease severity. A scientific advisory panel including emergency medicine, infectious disease, intensive care and clinical pathology physicians discussed technical and clinical requirements in preparation of successful introduction of InSep into the market. Topics included intended use; patient populations of greatest need; patient journey and sample flow in the emergency department (ED) and beyond; clinical and biomarker-based decision algorithms; performance characteristics for clinical utility; assay and instrument requirements; and result readouts. The panel identified clear demand for a solution like InSep, requirements regarding test performance and interpretability, and a need for focused medical education due to the innovative but complex nature of the result readout. Innovative diagnostic solutions such as the InSep test could improve management of patients with suspected acute infections and sepsis in the ED, thereby lessening the overall burden of these conditions on patients and the healthcare system.