Optimal testing parameters for blood cultures

Hospital mortality and length of stay associated with Enterobacterales positive blood cultures: a multicenter analysis

Delayed time to antimicrobial susceptibility results can impact patients' outcomes. Our study evaluated the impact of susceptibility turnaround time (TAT) and inadequate empiric antibacterial therapy (IET) in patients with bloodstream infections (BSI) caused by Enterobacterales (ENT) species on in-hospital mortality and length of stay (LOS). This retrospective, multicenter investigation which included 29,570 blood ENT-positive admissions across 161 US healthcare facilities evaluated the association between antimicrobial susceptibility testing (AST) TAT, carbapenem susceptibility, and empiric therapy on post-BSI in-hospital mortality and LOS following an ENT BSI event in adult patients. After adjusting for outcomes covariates, post-BSI in-hospital mortality was significantly higher for patients in the IET vs adequate empiric therapy (AET) group [odds ratio (OR): 1.61 (95% CI: 1.32, 1.98); P < 0.0001], and when AST TAT was >63 h [OR:1.48 (95% CI: 1.16, 1.90); P = 0.0017]. Patients with carbapenem non-susceptible (carb-NS) ENT BSI had significantly higher LOS (16.6 days, 95% CI: 15.6, 17.8) compared to carbapenem susceptible (carb-S, 12.2 days, 95% CI: 11.8, 12.6), (P < 0.0001). Extended AST TAT was significantly associated with longer LOS for TAT of 57-65 h and >65 h (P = 0.005 and P< 0.0001, respectively) compared to TAT ≤42 h (reference). Inadequate empiric therapy (IET), carb-NS, and delayed AST TAT are significantly associated with adverse hospital outcomes in ENT BSI. Workflows that accelerate AST TAT for ENT BSIs and facilitate timely and adequate therapy may reduce post-BSI in-hospital mortality rate and LOS.IMPORTANCEFor patients diagnosed with bloodstream infections (BSI) caused by Enterobacterales (ENT), delayed time to antimicrobial susceptibility (AST) results can significantly impact in-hospital mortality and hospital length of stay. However, this relationship between time elapsed from blood culture collection to AST results has only been assessed, to date, in a limited number of publications. Our study focuses on this important gap using retrospective data from 29,570 blood ENT-positive admissions across 161 healthcare facilities in the US as we believe that a thorough understanding of the dynamic between AST turnaround time, adequacy of empiric therapy, post-BSI event mortality, and hospital length of stay will help guide effective clinical management and optimize outcomes of patients with ENT infections.

Infective endocarditis

First described more than 350 years ago, infective endocarditis represents a global health concern characterised by infections affecting the native or prosthetic heart valves, the mural endocardium, a septal defect, or an indwelling cardiac device. Over recent decades, shifts in causation and epidemiology have been observed. Echocardiography remains pivotal in the diagnosis of infective endocarditis, with alternative imaging modalities gaining significance. Multidisciplinary management requiring expertise of cardiologists, cardiovascular surgeons, infectious disease specialists, microbiologists, radiologists and neurologists, is imperative. Current recommendations for clinical management often rely on observational studies, given the limited number of well conducted randomised controlled trials studying infective endocarditis due to the rarity of the disease. In this Seminar, we provide a comprehensive overview of optimal clinical practices in infective endocarditis, highlighting key aspects of pathophysiology, pathogens, diagnosis, management, prevention, and multidisciplinary approaches, providing updates on recent research findings and addressing remaining controversies in diagnostic accuracy, prevention strategies, and optimal treatment.

Bone and Joint Infections in Children With Sickle Cell Disease in French Guiana: A 13-year Retrospective Multicenter Review

INTRODUCTION

Sickle cell disease (SCD) is a genetic disorder with a high infectious morbidity and mortality and a heterogeneous distribution in France. One of the challenges is to differentiate a bone and joint infection (BJI) from a vaso-occlusive crisis. This challenge is particularly prevalent in French Guiana, an overseas territory with the highest incidence of SCD in France. The aim of this study was to describe the epidemiology of BJI in children with SCD in French Guiana.

METHOD

This was a retrospective multicentric descriptive study of SCD patients living in French Guiana aged under 18 and diagnosed with a BJI between 2010 and 2022. These BJI were divided into 2 groups: those with microbiological documentation (d-BJI) and those without microbiological identification (ud-BJI).

RESULTS

A total of 53 episodes of BJI in 42 patients (mean age 7.2 years) were reported. Clinical symptoms on arrival were comparable between the d-BJI and ud-BJI groups. Patients in the d-BJI group had longer average hospital stays (40.4 days vs. 16.8 days, P = 0.01) and Salmonella spp. were the most identified bacteria (n = 8/13). White blood cell count was greater in the d-BJI group (30.3 G/L vs. 18.G/L, P = 0.01) and a collection was more frequently identified on imaging (11/13 vs. 16/40, P = 0.01) in this group. Initial in-hospital antibiotic therapy was longer in the d-BJI group (17.2 days vs. 12.8, P = 0.02), as were infection-related complications (9/13 vs. 12/40 P = 0.01).

CONCLUSION

BJI in children with SCD is not sufficiently microbiologically documented. Progress must be made to improve the documentation of BJI.

Infection of Transcatheter Valvular Devices

PURPOSE OF REVIEW

This review explores the epidemiology, clinical traits, and diagnosis of Transcatheter Aortic Valve Replacement-Associated Infective Endocarditis (TAVR-IE) and mitral transcatheter edge-to-edge repair infective endocarditis (TEER-IE), focusing on a multimodal imaging approach. It addresses the rising prevalence of TAVR and TEER, emphasizing the need to understand long-term complications and clinical consequences, which poses significant challenges despite advancements in valve technology.

RECENT FINDINGS

Studies report a variable incidence of TAVR-IE and TEER-IE influenced by diverse patient risk profiles and procedural factors. Younger age, male gender, and certain comorbidities emerge as patient-related risk factors. Procedure-related factors include intervention location, valve type, and technical aspects. Microbiologically, Staphylococcus aureus, Viridans Group Streptococcus, and Enterococcus are frequently encountered pathogens. TAVR-IE and TEER-IE diagnosis involves a multimodal imaging approach due to limitations in echocardiography. Blood cultures and imaging aid identification, with Fluorescence in situ hybridization is showing promise. Treatment encompasses medical management with antibiotics and, when necessary, surgical intervention. The management approach requires a multidisciplinary "Endocarditis Team." This review underscores the need for continued research to refine risk prediction, enhance diagnostic accuracy, and optimize management strategies for TAVR-IE, considering the evolving landscape of transcatheter interventions.

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

Melting temperature mapping method in children: Rapid identification of pathogenic microbes

INTRODUCTION

The melting temperature (Tm) mapping method (TM) identifies bacterial species by intrinsic patterns of Tm values in the 16S ribosomal RNA gene (16S rDNA) extracted directly from whole blood. We examined potential clinical application of TM in children with bloodstream infection (BSI).

METHODS

This was a prospective observational study at a children's hospital in Japan from 2018 to 2021. In patients with diagnosed or suspected BSI, we investigated the match rates of pathogenic bacteria identified by TM and blood culture (BC), the inspection time to identification of TM, and the amount of bacterial DNA in blood samples.

RESULTS

The median age of 81 patients (93 samples) was 3.6 years. Of 23 samples identified by TM, 11 samples matched the bacterial species with BC (positive-match rate, 48 %). Of 64 TM-negative samples, 62 samples were negative for BC (negative-match rate, 97 %). Six samples, including one containing two pathogenic bacterial species, were not suitable for TM identification. In total, the matched samples were 73 of 93 samples (match rate, 78 %). There were seven samples identified by TM in BC-negative samples from blood collected after antibiotic therapy. Interestingly, the bacteria were matched with BC before antibiotic administration. These TM samples contained as many 16S rDNA copies as the BC-positive samples. The median inspection time to identification using TM was 4.7 h.

CONCLUSIONS

In children with BSI, TM had high negative-match rates with BC, the potential to identify the pathogenic bacteria even in patients on antibiotic therapy, and more rapid identification compared to BC.

REGISTERING CLINICAL TRIALS

UMIN000041359https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000047220.

An emergency department intervention to improve earlier detection of community-onset bloodstream infection among hospitalized patients

BACKGROUND

Blood cultures (BCs) are essential microbiologic tests, but blood culturing diagnostic stewardship is frequently poor. We aimed to study the process-related failures and to evaluate the effect of an emergency department (ED) intervention on BCs collection practices and yield.

METHODS

We implemented an ED-quality improvement intervention including educational sessions, phlebotomists addition, promoting single-site strategy for BC-collection and preanalytical data feedback. BC-bottles collected, positive BCs, blood volumes and documentation of collection times were measured, before (December 2021-August 2022) and after (September 2022-July 2023) intervention. Results were corrected to hospitalizations admissions or days. We used interrupted-time series analyses for comparisons.

RESULTS

A total of 64,295 BC bottles were evaluated, 26,261 before and 38,034 postintervention. The median ED-BCs collected per week increased from 88 to 105 BCs (P < .0001), resulting from increased early sampling (P = .0001). Solitary BCs decreased (95%-28%), documented times increased (2.8%-25%), and average blood volume increased (3 mL to 4.5 mL) postintervention. Community-onset Bloodstream infections (BSIs) increased (39.6-52 bottles/1,000 admissions, P = .0001), while Health care-associated BSIs decreased (39-27 bottles/10,000 days, P = .0042). Contamination rates did not change.

CONCLUSIONS

An ED-focused intervention based on the education sessions and single-site strategy improved culturing stewardship and facilitated the early identification of BSI without an increase in contamination.

Retrospective cohort study comparing two versus three blood culture sets in people who inject drugs

BACKGROUND

The current standard of drawing two vs three blood culture sets lacks adequate guidance. Because people who inject drugs are at higher risk for bacteraemia and life-threatening infection, consideration of a third blood culture becomes more important.

AIM

To investigate the risks and benefits of obtaining two versus three blood culture sets.

METHODS

Retrospective cohort study of adults who inject drugs at a multicentre catch-net hospital system from 2017-2022.

FINDINGS

998 people who inject drugs and 2278 blood culture sets were analysed. There were 1618 episodes with two blood culture sets and 660 episodes with three. A potential benefit of adding a third blood culture was seen in 30 (4.5%) episodes. However, only 13 (2.0%) episodes showed pathogen-identifying benefit, as 17 (2.6%) involved known inadequately treated infections or the same pathogen in another culture. The number of blood culture sets needed to achieve diagnostic benefit was 51. There were more contaminants for three blood culture sets (65, 9.8%) than for two (114, 7.0%) (p < 0.00001). By adding a third blood culture, the risk of a contaminant increased by 39.7%; the number of blood culture sets needed to find a contaminant was 36. Of 122 episodes with only contaminants and available for analysis, 111 (91.0%) experienced at least one complication. 33 (27.0%) patients experienced either prolonged admission, readmission, or unnecessary antibiotic administration.

CONCLUSIONS

The benefits of possibly isolating a pathogen from a third blood culture set do not universally outweigh the risks for contaminant growth for people who inject drugs. A third blood culture should be considered in specific clinical scenarios (i.e. inadequately treated endocarditis and osteomyelitis).

Research progress of metal-organic framework nanozymes in bacterial sensing, detection, and treatment

The high efficiency and specificity of enzymes make them play an important role in life activities, but the high cost, low stability and high sensitivity of natural enzymes severely restrict their application. In recent years, nanozymes have become convincing alternatives to natural enzymes, finding utility across diverse domains, including biosensing, antibacterial interventions, cancer treatment, and environmental preservation. Nanozymes are characterized by their remarkable attributes, encompassing high stability, cost-effectiveness and robust catalytic activity. Within the contemporary scientific landscape, metal-organic frameworks (MOFs) have garnered considerable attention, primarily due to their versatile applications, spanning catalysis. Notably, MOFs serve as scaffolds for the development of nanozymes, particularly in the context of bacterial detection and treatment. This paper presents a comprehensive review of recent literature pertaining to MOFs and their pivotal role in bacterial detection and treatment. We explored the limitations and prospects for the development of MOF-based nanozymes as a platform for bacterial detection and therapy, and anticipate their great potential and broader clinical applications in addressing medical challenges.

Advances in sepsis biomarkers

Sepsis, a dysregulated host immune response to an infectious agent, significantly increases morbidity and mortality for hospitalized patients worldwide. This chapter reviews (1) the basic principles of infectious diseases, pathophysiology and current definition of sepsis, (2) established sepsis biomarkers such lactate, procalcitonin and C-reactive protein, (3) novel, newly regulatory-cleared/approved biomarkers, such as assays that evaluate white blood cell properties and immune response molecules, and (4) emerging biomarkers and biomarker panels to highlight future directions and opportunities in the diagnosis and management of sepsis.

[Guideline-conform treatment of sepsis]

The time to administration of broad-spectrum antibiotics and (secondarily) to the initiation of hemodynamic stabilization are the most important factors influencing survival of patients with sepsis and septic shock; however, the basic prerequisite for the initiation of an adequate treatment is that a suspected diagnosis of sepsis is made first. Therefore, the treatment of sepsis, even before it has begun, is an interdisciplinary and interprofessional task. This article provides an overview of the current state of the art in sepsis treatment and points towards new evidence that has the potential to change guideline recommendations in the coming years. In summary, the following points are critical: (1) sepsis must be diagnosed as soon as possible and the implementation of a source control intervention (in case of a controllable source) has to be implemented as soon as (logistically) possible. (2) In general, intravenous broad-spectrum antibiotics should be given within the first hour after diagnosis if sepsis or septic shock is suspected. In organ dysfunction without shock, where sepsis is a possible but unlikely cause, the results of focused advanced diagnostics should be awaited before a decision to give broad-spectrum antibiotics is made. If it is not clear within 3 h whether sepsis is the cause, broad-spectrum antibiotics should be given when in doubt. Administer beta-lactam antibiotics as a prolonged (or if therapeutic drug monitoring is available, continuous) infusion after an initial loading dose. (3) Combination treatment with two agents for one pathogen group should remain the exception (e.g. multidrug-resistant gram-negative pathogens). (4) In the case of doubt, the duration of anti-infective treatment should rather be shorter than longer. Procalcitonin can support the clinical decision to stop (not to start!) antibiotic treatment! (5) For fluid treatment, if hypoperfusion is present, the first (approximately) 2L (30 ml/kg BW) of crystalloid solution is usually safe and indicated. After that, the rule is: less is more! Any further fluid administration should be carefully weighed up with the help of dynamic parameters, the patient's clinical condition and echo(cardio)graphy.

Derivation and External Validation of the Ottawa Bloodstream Infection Model for Acutely Ill Adults

BACKGROUND

Knowing the probability that patients have a bloodstream infection (BSI) could influence the ordering of blood cultures and interpretation of their preliminary results. Many previous BSI probability models have limited applicability and accuracy. This study used currently recommended modeling techniques and a large sample to derive and validate the Ottawa BSI Model.

METHODS

At a tertiary care teaching hospital, we retrieved a random sample of 4180 adults having blood cultures in our emergency department or during the initial 48 h of the encounter. Variable selection was based on clinical experience and a systematic review of previous model performance. Model performance was measured in a temporal external validation group of 4680 patients.

RESULTS

A total of 327 derivation patients had a BSI (8.0%). BSI risk increased with increased number of culture sets (2 sets: adjusted odds ratio [aOR] 1.52 [1.10-2.11]; 3 sets: 1.99 [0.86-4.58]); with indwelling catheter (aOR 2.07 [1.34-3.20); with increasing temperature, heart rate, and neutrophil-lymphocyte ratio; and with decreasing systolic blood pressure, platelet count, urea-creatinine ratio, and estimated glomerular filtration rate. In the temporal external validation group, model discrimination was good (c-statistic 0.71 [0.69-0.74]) and calibration was very good (integrated calibration index .016 [.010-.024]). Exclusion of validation patients with acute SARS-CoV-2 infection improved discrimination slightly (c-statistic 0.73 [0.69-0.76]).

CONCLUSIONS

The Ottawa BSI Model uses commonly available data to return an expected BSI probability for acutely ill patients. However, it cannot exclude BSI and its complexity requires computational assistance to use.

A clinical decision rule to rule out bloodstream infection in the emergency department: retrospective multicentric observational cohort study

BACKGROUND

We aimed to identify patients at low risk of bloodstream infection (BSI) in the ED.

METHODS

We derived and validated a prediction model to rule out BSI in the ED without the need for laboratory testing by determining variables associated with a positive blood culture (BC) and assigned points according to regression coefficients. This retrospective study included adult patients suspected of having BSI (defined by at least one BC collection) from two European ED between 1 January 2017 and 31 December 2019. The primary end point was the BSI rate in the validation cohort for patients with a negative Bacteremia Rule Out Criteria (BAROC) score. The effect of adding laboratory variables to the model was evaluated as a second step in a two-step diagnostic strategy.

RESULTS

We analysed 2580 patients with a mean age of 64 years±21, of whom 46.1% were women. The derived BAROC score comprises 12 categorical clinical variables. In the validation cohort, it safely ruled out BSI without BCs in 9% (58/648) of patients with a sensitivity of 100% (95% CI 95% to 100%), a specificity of 10% (95% CI 8% to 13%) and a negative predictive value of 100% (95% CI 94% to 100%). Adding laboratory variables (creatinine ≥177 µmol/L (2.0 mg/dL), platelet count ≤150 000/mm3 and neutrophil count ≥12 000/mm3) to the model, ruled out BSI in 10.2% (58/570) of remaining patients who had been positive on the BAROC score. The BAROC score with laboratory results had a sensitivity of 100% (95% CI 94% to 100%), specificity of 11% (95% CI 9% to 14%) and negative predictive value of 100% (95% CI 94 to 100%). In the validation cohort, there was no evidence of a difference in discrimination between the area under the receiver operating characteristic for BAROC score with versus without laboratory testing (p=0.6).

CONCLUSION

The BAROC score safely identified patients at low risk of BSI and may reduce BC collection in the ED without the need for laboratory testing.

Etiology of Fever and Associated Outcomes Among Adults Receiving Chemotherapy for the Treatment of Solid Tumors in Uganda

Background

Little is known about the microbiology and outcomes of chemotherapy-associated febrile illness among patients in sub-Saharan Africa. Understanding the microbiology of febrile illness could improve antibiotic selection and infection-related outcomes.

Methods

From September 2019 through June 2022, we prospectively enrolled adult inpatients at the Uganda Cancer Institute who had solid tumors and developed fever within 30 days of receiving chemotherapy. Evaluation included blood cultures, malaria rapid diagnostic tests, and urinary lipoarabinomannan testing for tuberculosis. Serum cryptococcal antigen was evaluated in participants with human immunodeficiency virus (HIV). The primary outcome was the mortality rate 40 days after fever onset, which we estimated using Cox proportional hazards models.

Results

A total of 104 febrile episodes occurred among 99 participants. Thirty febrile episodes (29%) had ≥1 positive microbiologic result. The most frequently identified causes of infection were tuberculosis (19%) and bacteremia (12%). The prevalence of tuberculosis did not differ by HIV status. The 40-day case fatality ratio was 25%. There was no difference in all-cause mortality based on HIV serostatus, presence of neutropenia, or positive microbiologic results. A universal vital assessment score of >4 was associated with all-cause mortality (hazard ratio, 14.5 [95% confidence interval, 5-42.7]).

Conclusions

The 40-day mortality rate among Ugandan patients with solid tumors who developed chemotherapy-associated febrile illness was high, and few had an identified source of infection. Tuberculosis and bacterial bloodstream infections were the leading diagnoses associated with fever. Tuberculosis should be included in the differential diagnosis for patients who develop fever after receiving chemotherapy in tuberculosis-endemic settings, regardless of HIV serostatus.

Development of an Optically Induced Dielectrophoresis (ODEP) Microfluidic System for High-Performance Isolation and Purification of Bacteria

For the rapid detection of bacteria in a blood sample, nucleic acid amplification-based assays are believed to be promising. Nevertheless, the nucleic acids released from the dead blood cells or bacteria could affect the assay performance. This highlights the importance of the isolation of live bacteria from blood samples. To address this issue, this study proposes a two-step process. First, a blood sample was treated with the immuno-magnetic microbeads-based separation to remove the majority of blood cells. Second, an optically induced dielectrophoresis (ODEP) microfluidic system with an integrated dynamic circular light image array was utilized to further isolate and purify the live bacteria from the remaining blood cells based on their size difference. In this work, the ODEP microfluidic system was developed. Its performance for the isolation and purification of bacteria was evaluated. The results revealed that the method was able to harvest the live bacteria in a high purity (90.5~99.2%) manner. Overall, the proposed method was proven to be capable of isolating and purifying high-purity live bacteria without causing damage to the co-existing cells. This technical feature was found to be valuable for the subsequent nucleic-acid-based bacteria detection, in which the interferences caused by the nontarget nucleic acids could be eliminated.

Blood culture quality assurance: findings from a RCPAQAP Key Incident Monitoring and Management Systems (KIMMS) audit of blood culture performance

Blood cultures (BC) are the gold standard investigation for bloodstream infection. Standards exist for BC quality assurance, but key quality indicators are seldom measured. The Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) Key Incident Monitoring and Management Systems (KIMMS) invited laboratories for the first time to participate in an audit to determine adult BC positivity rates, contamination rates, sample fill volumes and the proportion received as a single set. The overall aim of the KIMMS audit was to provide laboratories with a mechanism for peer review and benchmarking. Results from 45 laboratories were analysed. The majority of laboratories (n=28, 62%) reported a positivity rate outside the recommended range of 8-15%. Contamination rates ranged from zero (n=5) to 12.5%, with seven laboratories (15%) reporting a contamination rate greater than the recommended 3%. Fifteen laboratories (33%) reported an average fill volume of less than the recommended 8-10 mL per bottle, with 11 laboratories (24%) reporting fill volumes of 5 mL or less whilst 13 (28%) laboratories were not able to provide any fill volume data. Thirteen laboratories (29%) reported that 50% or more of BC were received as single set, and eight (17%) were not able to report this data. This audit highlights there are deficiencies in BC quality measures across laboratories. To support BC quality improvement efforts, RCPAQAP KIMMS will offer a yearly BC quality assurance audit to encourage laboratories to monitor their BC quality performance.

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.

Guidelines for Diagnosis and Management of Infective Endocarditis in Adults: A WikiGuidelines Group Consensus Statement

Importance

Practice guidelines often provide recommendations in which the strength of the recommendation is dissociated from the quality of the evidence.

Objective

To create a clinical guideline for the diagnosis and management of adult bacterial infective endocarditis (IE) that addresses the gap between the evidence and recommendation strength.

Evidence Review

This consensus statement and systematic review applied an approach previously established by the WikiGuidelines Group to construct collaborative clinical guidelines. In April 2022 a call to new and existing members was released electronically (social media and email) for the next WikiGuidelines topic, and subsequently, topics and questions related to the diagnosis and management of adult bacterial IE were crowdsourced and prioritized by vote. For each topic, PubMed literature searches were conducted including all years and languages. Evidence was reported according to the WikiGuidelines charter: clear recommendations were established only when reproducible, prospective, controlled studies provided hypothesis-confirming evidence. In the absence of such data, clinical reviews were crafted discussing the risks and benefits of different approaches.

Findings

A total of 51 members from 10 countries reviewed 587 articles and submitted information relevant to 4 sections: establishing the diagnosis of IE (9 questions); multidisciplinary IE teams (1 question); prophylaxis (2 questions); and treatment (5 questions). Of 17 unique questions, a clear recommendation could only be provided for 1 question: 3 randomized clinical trials have established that oral transitional therapy is at least as effective as intravenous (IV)-only therapy for the treatment of IE. Clinical reviews were generated for the remaining questions.

Conclusions and Relevance

In this consensus statement that applied the WikiGuideline method for clinical guideline development, oral transitional therapy was at least as effective as IV-only therapy for the treatment of IE. Several randomized clinical trials are underway to inform other areas of practice, and further research is needed.

Comparison of pathogen detection consistency between metagenomic next-generation sequencing and blood culture in patients with suspected bloodstream infection

The application of metagenomic next-generation sequencing (mNGS) has gradually been carried out by clinical practitioner. However, few studies have compared it with blood cultures in patients suffering from suspected bloodstream infections. The purpose of this study was to compare the detection of pathogenic microorganisms by these two assays in patients with suspected bloodstream infection. We retrospectively studied patients with fever, chills, antibiotic use for more than 3 days, suspected bloodstream infection, and admission to the emergency department of Ruijin Hospital from January 2020 to June 2022. All patients had blood drawn on the same day for blood mNGS and blood cultures. Clinical and laboratory parameters were collected on the day blood was drawn. The detection of pathogenic microorganisms by the two methods was compared. Risk factors and in-hospital mortality in patients with bloodstream infections were analysed separately for these two assays. In all 99 patients, the pathogenic microorganisms detection rate in blood mNGS was significantly higher than that in blood culture. Blood mNGS was consistent with blood culture in only 12.00% of all positive bacterial and fungal test results. The level of CRP is related to bacteraemia, fungaemia and viraemia detected by blood mNGS. No clear risk factors could be found in patients with a positive blood culture. In critically ill patients, both tests failed to improve patient outcomes. In patients with suspected bloodstream infection, mNGS is not yet a complete replacement for blood cultures.

Improving Blood Culture Quality with a Medical Staff Educational Program: A Prospective Cohort Study

Purpose

Blood cultures (BCs) are essential laboratory tests for diagnosing blood stream infections. BC diagnostic improvement depends on several factors during the preanalytical phase outside of innovative technologies. In order to evaluate the impact of an educational program on BC quality improvement, a total of 11 hospitals across China were included from June 1st 2020 to January 31st 2021.

Methods

Each hospital recruited 3 to 4 wards to participate. The project was divided into three different periods, pre-implementation (baseline), implementation (educational activities administered to the medical staff) and post-implementation (experimental group). The educational program was led by hospital microbiologists and included professional presentations, morning meetings, academic salons, seminars, posters and procedural feedback.

Results

The total number of valid BC case report forms was 6299, including 2739 sets during the pre-implementation period and 3560 sets during the post-implementation period. Compared with the pre-implementation period, some indicators, such as the proportion of patients who had 2 sets or more, volume of blood cultured, and BC sets per 1000 patient days, were improved in the post-implementation period (61.2% vs 49.8%, 18.56 vs 16.09 sets, and 8.0 vs 9.0mL). While BC positivity and contamination rates did not change following the educational intervention (10.44% vs 11.97%, 1.86% vs 1.94%, respectively), the proportion of coagulase negative staphylococci-positive samples decreased in BSI patients (6.87% vs 4.28%).

Conclusion

Therefore, medical staff education can improve BC quality, especially increasing volume of blood cultured as the most important variable to determine BC positivity, which may lead to improved BSI diagnosis.

Time-series prediction and detection of potential pathogens in bloodstream infection using mcfDNA sequencing

Introduction

Next-generation sequencing of microbial cell free DNA (mcfDNA-seq) has emerged as a promising diagnostic method for blood stream infection (BSI) and offers the potential to detect pathogens before blood culture. However, its application is limited by a lack of clinical validation.

Methods

We conducted sequential mcfDNA-seq on blood samples from ICU participants at high risk of BSI due to pneumonia, or intravascular catheterization; and explored whether mcfDNA-seq could diagnose and detect pathogens in advance of blood culture positivity. Blood culture results were used as evaluation criteria.

Results

A total of 111 blood samples were collected during the seven days preceding and on the day of onset of 16 BSI episodes from 13 participants. The diagnostic and total predictive sensitivity of mcfDNA-seq were 90% and 87.5%, respectively. The proportion of pathogenic bacteria was relatively high in terms of both diagnosis and prediction. The reads per million of etiologic agents trended upwards in the days approaching the onset of BSI.

Discussion

Our work found that mcfDNA-seq has high diagnostic sensitivity and could be used to identify pathogens before the onset of BSI, which could help expand the clinical application of mcfDNA-seq.

Are multiple blood cultures advantageous for canine patients?

Successful treatment of bacteremic patients depends largely on timely detection of blood-borne pathogens. Failure to detect an infection and/or contamination of blood samples can substantially delay the proper treatment. To increase the detection rate of blood-borne pathogens, well-established guidelines on blood collection and processing have been practiced in human medicine. Investigations involving human blood cultures have shown that the multiple blood sample approach significantly improves the detection rate of bacterial pathogens in the blood. Unfortunately, veterinary-specific blood culture guidelines have not been defined. Therefore, we compared detection rates of blood-borne pathogens between single and multiple blood culture approaches in a retrospective study of the clinical data from canine blood culture cases. We analyzed the data that had been collected over ~6 y and 8 mo from 177 dogs admitted to a veterinary medical teaching hospital. The triple blood culture approach increased the detection rate of blood-borne pathogens by 19.5% compared to single sampling. The optimal timing between multiple sample collections remains to be determined.

Impact of a strategy based on unique blood culture sampling on contamination rate and detection of bloodstream infections in critically ill patients

BACKGROUND

Unique blood culture (UBC) has been proposed to limit the number of venipuncture and to decrease the risk of BC contaminations (BCC) without affecting their yield. We hypothesized that a multi-faceted program based on UBC in the ICU may reduce the rate of contaminants with a similar performance for bloodstream infections (BSI) identification.

METHODS

In a before and after design, we compared the proportion of BSI and BCC. A first 3-year period with multi-sampling (MS) strategy followed by a 4-month washout period, where staff received education and training for using UBC, and a 32-month period, where UBC was routinely used, while education and feedback were maintained. During the UBC period, a large volume of blood (40 mL) was sampled through a unique venipuncture with additional BC collections discouraged for 48 h.

RESULTS

Of the 4,491 patients included (35% female patients, mean age 62 years) 17,466 BC were collected. The mean volume of blood per bottle collected increased from 2.8 ± 1.8 mL to 8.2 ± 3.9 mL between the MS and UBC periods, P < 0.01. A 59.6% reduction (95% CI 56.7-62.3; P < 0.001) of BC bottles collected per week was observed between the MS and UBC periods. The rate of BCC per patient decreased between the two periods from 11.2% to 3.8% (73.4% reduction; P < 0.001) for the MS and UBC periods, P < 0.001. Meanwhile, the rate of BSI per patient remained stable at 13.2% and 13.2% for the MS and UBC periods, P = 0.98.

CONCLUSIONS

In ICU patients, a strategy based on UBC reduces the contamination rate of cultures without affecting their yield.

Current Views on Infective Endocarditis: Changing Epidemiology, Improving Diagnostic Tools and Centering the Patient for Up-to-Date Management

Infective endocarditis (IE) is a rare but potentially life-threatening disease, sometimes with longstanding sequels among surviving patients. The population at high risk of IE is represented by patients with underlying structural heart disease and/or intravascular prosthetic material. Taking into account the increasing number of intravascular and intracardiac procedures associated with device implantation, the number of patients at risk is growing too. If bacteremia develops, infected vegetation on the native/prosthetic valve or any intracardiac/intravascular device may occur as the final result of invading microorganisms/host immune system interaction. In the case of IE suspicion, all efforts must be focused on the diagnosis as IE can spread to almost any organ in the body. Unfortunately, the diagnosis of IE might be difficult and require a combination of clinical examination, microbiological assessment and echocardiographic evaluation. There is a need of novel microbiological and imaging techniques, especially in cases of blood culture-negative. In the last few years, the management of IE has changed. A multidisciplinary care team, including experts in infectious diseases, cardiology and cardiac surgery, namely, the Endocarditis Team, is highly recommended by the current guidelines.

Iron-Modified Blood Culture Media Allow for the Rapid Diagnosis and Isolation of the Slow-Growing Pathogen Francisella tularensis

The life-threatening disease tularemia is caused by Francisella tularensis, an intracellular Gram-negative bacterial pathogen. Due to the high mortality rates of the disease, as well as the low respiratory infectious dose, F. tularensis is categorized as a Tier 1 bioterror agent. The identification and isolation from clinical blood cultures of F. tularensis are complicated by its slow growth. Iron was shown to be one of the limiting nutrients required for F. tularensis metabolism and growth. Bacterial growth was shown to be restricted or enhanced in the absence or addition of iron. In this study, we tested the beneficial effect of enhanced iron concentrations on expediting F. tularensis blood culture diagnostics. Accordingly, bacterial growth rates in blood cultures with or without Fe²⁺ supplementation were evaluated. Growth quantification by direct CFU counts demonstrated significant improvement of growth rates of up to 6 orders of magnitude in Fe²⁺-supplemented media compared to the corresponding nonmodified cultures. Fe²⁺ supplementation significantly shortened incubation periods for successful diagnosis and isolation of F. tularensis by up to 92 h. This was achieved in a variety of blood culture types in spite of a low initial bacterial inoculum representative of low levels of bacteremia. These improvements were demonstrated with culture of either Francisella tularensis subsp. tularensis or subsp. holarctica in all examined commercial blood culture types routinely used in a clinical setup. Finally, essential downstream identification assays, such as matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS), immunofluorescence, or antibiotic susceptibility tests, were not affected in the presence of Fe²⁺. To conclude, supplementing blood cultures with Fe²⁺ enables a significant shortening of incubation times for F. tularensis diagnosis, without affecting subsequent identification or isolation assays. IMPORTANCE In this study, we evaluated bacterial growth rates of Francisella tularensis strains in iron (Fe)-enriched blood cultures as a means of improving and accelerating bacterial growth. The shortening of the culturing time should facilitate rapid pathogen detection and isolation, positively impacting clinical diagnosis and enabling prompt onset of efficient therapy.

Equine blood cultures: Can we do better?

Blood culture is considered the gold standard test for documenting bacteraemia in patients with suspected bacterial sepsis in veterinary and human medicine. However, blood culture often fails to yield bacterial growth even though the clinical picture is strongly suggestive of bacterial sepsis, or contaminating organisms can overgrow the true pathogen, making accurate diagnosis and appropriate management of this life-threatening condition very challenging. Methodology for collecting blood cultures in equine medicine, and even in human hospitals, is not standardised, and many variables can affect the yield and type of microorganisms cultured. Microbiological culture techniques used in the laboratory and specific sample collection techniques, including volume of blood collected, aseptic technique utilised, and the site, timing and frequency of sample collection, all have substantial impact on the accuracy of blood culture results. In addition, patient-specific factors such as husbandry factors, the anatomical site of the primary infection, and changing microflora in different geographic locations, also can impact blood cultures. Thus, blood cultures obtained in practice may not always accurately define the presence or absence of, or specific organisms causing, bacteraemia in horses and foals with suspected sepsis. Erroneous blood culture results can lead to inappropriate antimicrobial use, which can result in poor outcomes for individual patients and contribute to the development of antimicrobial resistance in the patient's microflora and the environmental microcosm. This review summarises current indications and methodology, and specific factors that may be optimised, for equine blood culture, with particular focus on available literature from neonatal foals with suspected bacterial sepsis. To standardise and optimise blood culture techniques in horses and foals, future research in this area should be aimed at determining the optimal volume of blood that should be collected for culture, and the ideal site, timing, and frequency of sample collection.

Follow-up blood cultures in Staphylococcus aureus bacteremia: a probability-based optimization

Staphylococcus aureus bacteremia (SAB) is a relevant finding which prompts a thorough diagnostic work-up. Follow-up blood cultures (BC) are essential in this work-up. We investigate the probability of detecting an ongoing bacteremia after initiation of active therapy according to the number of BC taken at key time points. A retrospective analysis of all patients with SAB in a 6-year period was performed. Total number of BCs taken and the positivity was registered for each day after start of therapy. A positivity-rate was corrected using a logistic mixed effects model. Observed detection frequencies were applied to calculate detection probabilities using binomial distributions. Three hundred and seventeen cases were withheld for analysis. A BC bottle positivity rate of 66.7% was found 1 day after initiation of active therapy, which decreased to 48.5% on day 4. When using 1 set of FU-BC, 73.4% of persisting SABs are detected. To maintain a probability of detection of ≥ 90%, 2 BC sets should be taken on day 2 and day 4 after start of therapy. In 10 of 109 patients with positive FU-BC, skip phenomena were registered, with a significant higher proportion in patients with < 4 BC bottles taken (14%) than when ≥ 4 BC bottles were taken (4.1%). We recommend taking 2 BC sets on days 2 and 4 after start of therapy in order to detect ≥ 90% of persisting SABs, limiting skip phenomena and blood volume required. We strongly advice against taking a single BC set as follow-up for SAB.

Revisiting factors associated with blood culture positivity: Critical factors after the introduction of automated continuous monitoring blood culture systems

Blood culture is the main tool used to identify causative pathogens. Adequate volume and number of culture sets are considered key to blood culture positivity rate. It is not known whether these factors remain critical to the positivity rate after the introduction of automated continuous blood culture system monitoring. We measured blood volume per bottle and described the distribution of blood volume and number of culture sets. Multivariate logistic regression was performed to determine the independent association of blood volume, number of culture sets, diagnosis of sepsis in a patient, and other covariates with blood culture results. Only 6.9% of the blood culture bottle volumes complied with the guidance (8-10 mL), with the highest culture positivity rate (18%). Of the culture events, only one set of blood was cultured in 60.9% of events. In the multivariate analysis, blood culture volume per event (odds ratio [OR], 1.09 [95% confidence interval [CI], 1.06-1.11]), patients with a diagnosis of sepsis (OR, 2.86 [95% CI, 2.06-3.98]), and samples from the emergency department (OR, 2.29 [95% CI, 1.72-3.04]), but not the number of culture sets (OR, 0.74 [95% CI, 0.50-1.12]), were observed to be statistically significant with respect to blood culture positivity rate. Our results revealed that the total blood culture volume and the diagnosis of sepsis were critical factors affecting blood culture positivity rate. However, the proportion of blood culture bottles with the optimal blood volume was very low, and optimizing blood volume would be key to increasing blood culture positivity rate.

Implementation of Antibiotic Stewardship Improves the Quality of Blood Culture Diagnostics at an Intensive Care Unit of a University Hospital

Background: Bloodstream infections increase morbidity and mortality in hospitalized patients and pose a significant burden for health care systems worldwide. Optimal blood culture diagnostics are essential for early detection and specific treatment. After assessing the quality parameters at a surgical intensive care unit for six months, we implemented a diagnostic stewardship bundle (DSB) to optimize blood culture diagnostics and then reevaluated its effects after six months. Material and Methods: All patients ≥18 years old and on the ward were included: pre-DSB 137 and post-DSB 158. The standard quality parameters were defined as the number of blood culture sets per diagnostic episode (≥2), the rate of contamination (2–3%), the rate of positivity (5–15%), the collection site (≥1 venipuncture per episode) and the filling volume of the bottles (8–10 mL, only post-DSB). The DSB included an informational video, a standard operating procedure, and ready-to-use paper crates with three culture sets. Results: From pre- to post-interventional, the number of ≥2 culture sets per episode increased from 63.9% (257/402) to 81.3% (230/283), and venipunctures increased from 42.5% (171/402) to 77.4% (219/283). The positivity rate decreased from 15.1% (108/714) to 12.8% (83/650), as did the contamination rate (3.8% to 3.6%). The majority of the aerobic bottles were filled within the target range (255/471, 54.1%), but in 96.6%, the anaerobic bottles were overfilled (451/467). Conclusions: The implementation of DSB improved the quality parameters at the unit, thus optimizing the blood culture diagnostics. Further measures seem necessary to decrease the contamination rate and optimize bottle filling significantly.

Considerations in evaluating equipment-free blood culture bottles: A short protocol for use in low-resource settings

Use of equipment-free, “manual” blood cultures is still widespread in low-resource settings, as requirements for implementation of automated systems are often not met. Quality of manual blood culture bottles currently on the market, however, is usually unknown. An acceptable quality in terms of yield and speed of growth can be ensured by evaluating the bottles using simulated blood cultures. In these experiments, bottles from different systems are inoculated in parallel with blood and a known quantity of bacteria. Based on literature review and personal experiences, we propose a short and practical protocol for an efficient evaluation of manual blood culture bottles, aimed at research or reference laboratories in low-resource settings. Recommendations include: (1) practical equivalence of horse blood and human blood; (2) a diverse selection of 10 to 20 micro-organisms to be tested (both slow- and fast-growing reference organisms); (3) evaluation of both adult and pediatric bottle formulations and blood volumes; (4) a minimum sample size of 120 bottles per bottle type; (5) a formal assessment of usability. Different testing scenarios for increasing levels of reliability are provided, along with practical tools such as worksheets and surveys that can be used by laboratories wishing to evaluate manual blood culture bottles.

Blood culture practices in patients with a central line at an academic medical center-Iowa, 2020

We analyzed blood-culture practices to characterize the utilization of the Infectious Diseases Society of America (IDSA) recommendations related to catheter-related bloodstream infection (CRBSI) blood cultures. Most patients with a central line had only peripheral blood cultures. Increasing the utilization of CRBSI guidelines may improve clinical care, but may also affect other quality metrics.

Blood Culture Utilization in the Hospital Setting: a Call for Diagnostic Stewardship

There has been significant progress in detection of bloodstream pathogens in recent decades with the development of more sensitive automated blood culture detection systems and the availability of rapid molecular tests for faster organism identification and detection of resistance genes. However, most blood cultures in clinical practice do not grow organisms, suggesting that suboptimal blood culture collection practices (e.g., suboptimal blood volume) or suboptimal selection of patients to culture (i.e., blood cultures ordered for patients with low likelihood of bacteremia) may be occurring. A national blood culture utilization benchmark does not exist, nor do specific guidelines on when blood cultures are appropriate or when blood cultures are of low value and waste resources. Studies evaluating the potential harm associated with excessive blood cultures have focused on blood culture contamination, which has been associated with significant increases in health care costs and negative consequences for patients related to exposure to unnecessary antibiotics and additional testing. Optimizing blood culture performance is important to ensure bloodstream infections (BSIs) are diagnosed while minimizing adverse events from overuse. In this review, we discuss key factors that influence blood culture performance, with a focus on the preanalytical phase, including technical aspects of the blood culture collection process and blood culture indications. We highlight areas for improvement and make recommendations to improve current blood culture practices among hospitalized patients.

Blood Culture Contamination: A Single General Hospital Experience of 2-Year Retrospective Study

In the event of blood culture contamination (BCC), blood culture (BC) needs to be repeated. This may delay appropriate treatment, prolong hospitalization and, consequently, increase its costs. The aim of the study was to assess the frequency of BCC and associated factors in a general hospital in Poland based on reports of BC in samples submitted for laboratory testing in 2019−2020. BCC is recognized when bacteria (especially those belonging to natural human microbiota) are isolated from a single sample and no clinical signs indicated infection. True positive BC is confirmed by the growth of bacteria in more than one set of blood samples with the corresponding clinical signs present. The structure of BC sets, microorganisms, and laboratory costs of BCC were analyzed. Out of 2274 total BC cases, 11.5% were true positive BC and 9.5% were BCC. Of all the BCC identified in the entire hospital, 72% was from Internal Medicine (IM) and Intensive Care Unit (ICU) combined. When single sets for BC were used in IM in 2020, the use increased to 85% compared with 2019 (p < 0.05). The predominant isolates were coagulase-negative staphylococci (84%). The estimated extra laboratory costs of BCC exceeded EUR 268,000. The BCC was a more serious problem than expected, including non-recommended using of single BC sets. Compliance with the BC collection procedure should be increased in order to reduce BCC and thus extra hospital costs.

An Improvement in Diagnostic Blood Culture Conditions Allows for the Rapid Detection and Isolation of the Slow Growing Pathogen Yersinia pestis

Plague, caused by the human pathogen Yersinia pestis, is a severe and rapidly progressing lethal disease that has caused millions of deaths globally throughout human history and still presents a significant public health concern, mainly in developing countries. Owing to the possibility of its malicious use as a bio-threat agent, Y. pestis is classified as a tier-1 select agent. The prompt administration of an effective antimicrobial therapy, essential for a favorable patient prognosis, requires early pathogen detection, identification and isolation. Although the disease rapidly progresses and the pathogen replicates at high rates within the host, Y. pestis exhibits a slow growth in vitro under routinely employed clinical culturing conditions, complicating the diagnosis and isolation. In the current study, the in vitro bacterial growth in blood cultures was accelerated by the addition of nutritional supplements. We report the ability of calcium (Ca+2)- and iron (Fe+2)-enriched aerobic blood culture media to expedite the growth of various virulent Y. pestis strains. Using a supplemented blood culture, a shortening of the doubling time from ~110 min to ~45 min could be achieved, resulting in increase of 5 order of magnitude in the bacterial loads within 24 h of incubation, consequently allowing the rapid detection and isolation of the slow growing Y. pestis bacteria. In addition, the aerobic and anaerobic blood culture bottles used in clinical set-up were compared for a Y. pestis culture in the presence of Ca+2 and Fe+2. The comparison established the superiority of the supplemented aerobic cultures for an early detection and achieved a significant increase in the yields of the pathogen. In line with the accelerated bacterial growth rates, the specific diagnostic markers F1 and LcrV (V) antigens could be directly detected significantly earlier. Downstream identification employing MALDI-TOF and immunofluorescence assays were performed directly from the inoculated supplemented blood culture, resulting in an increased sensitivity and without any detectable compromise of the accuracy of the antibiotic susceptibility testing (E-test), critical for subsequent successful therapeutic interventions.

Analysis of Blood Culture Data Influences Future Epidemiology of Bloodstream Infections: A 5-year Retrospective Study at a Tertiary Care Hospital in India

Background

Blood cultures are the most significant samples received in a microbiology laboratory. Good quality control of pre-analytic, analytic, and post-analytic stages can have a significant impact on patient outcomes. Here, we present the improvements brought about by reviewing blood culture data with clinicians at a tertiary care institute in India.

Methods

Four-year blood culture data (phase I—February 2014–February 2018) were shared with clinicians in the clinical grand round. Several take-home messages were discussed in a quiz format, and a number of holistic quality control measures were implemented at different levels. Based on observable changes in blood culture reports, another dataset was analyzed and compared in phase II (April 2018–April 2019).

Results

In phase II, the blood culture contamination rate improved from 6 to 2% along with four times reduction in ICU isolates and three times increased isolation of salmonellae and pneumococci. The development of resistance in Klebsiella pneumoniae to carbapenems and piperacillin–tazobactam was reduced. Colistin resistance in ICU isolates hovered around 15%. Vaccine-preventable pneumococcal serotypes were predominant in the under-five age-group. Typhoidal salmonellae were more commonly isolated from adults with 50% showing sensitivity to pefloxacin and 97% to ampicillin, chloramphenicol, and cotrimoxazole. Candida parapsilosis was the leading non-albicans Candida (NAC). Fluconazole resistance was observed in 50% of NAC.

Conclusion

Reviewing blood culture data with clinicians mutually helped us to improve the overall quality of blood culture reports. It had a major impact on epidemiological trends and thus, found to be superior to just sharing an antibiogram with the clinicians.

How to cite this article

Sharma A, Samaddar A, Maurya A, Hada V, Narula H, Shrimali T, et al. Analysis of Blood Culture Data Influences Future Epidemiology of Bloodstream Infections: A 5-year Retrospective Study at a Tertiary Care Hospital in India. Indian J Crit Care Med 2021;25(11):1258–1262.

Single-site sampling versus multi-site sampling for blood cultures; A retrospective clinical study

Objectives The performance of blood cultures (BC) relies on optimal sampling. Sepsis guidelines do not specify which sampling protocol to use, but recommend two sets of BC bottles, each set containing one aerobic and one anaerobic bottle. For the single-site sampling (SSS) protocol, only one venipuncture is performed for all four bottles. The predominating multi-site sampling (MSS) protocol implies that BC bottles are collected from two separate venipuncture sites. The aim of this study was to compare SSS and MSS. Primary outcomes were number of BC sets collected, sample volume and diagnostic performance. Methods This was a retrospective clinical study comparing BC results in an emergency department before and after changing the sampling protocol to SSS from MSS. All BC samples were incubated in the BacT/ALERT BC system. Results The analysis included 5,248 patients before and 5,364 patients after the implementation of SSS. There was a significantly higher proportion of positive BCs sampled with SSS compared to MSS, 1,049/5,364 (19.56%) and 932/5,248 (17.76%) respectively (P=0.018). This difference was due to a higher proportion of solitary BC sets (two BC bottles) in MSS. Analyzing only patients with the recommended four BC bottles, there was no difference in positivity. SSS had a higher proportion of BC bottles with the recommended sample volumes of 8-12 ml than MSS (P<0.001). Conclusions Changing the sampling protocol to SSS from MSS resulted in higher positivity rates, higher sample volume and fewer solitary BC sets. These advantages of SSS should be considered in future sepsis guidelines.

Neonatal blood culture inoculant volume: feasibility and challenges

BACKGROUND

Clinicians often express concerns about poor sensitivity of blood cultures in neonates resulting from inadequate inoculant volumes. Our objective was to determine the inoculant volume sent for neonatal sepsis evaluations and identify areas of improvement.

METHODS

Single-center prospective observational study of infants undergoing sepsis evaluation. Blood volume was determined by clinician documentation over 21 months, and additionally by weighing culture bottles during 12 months. Adequate volume was defined as ≥1 mL total inoculant per evaluation. For first-time evaluations, local guidelines recommend sending an aerobic-anaerobic pair with 1 mL inoculant in each.

RESULTS

There were 987 evaluations in 788 infants. Clinicians reported ≥1 mL total inoculant in 96.9% evaluations. Among 544 evaluations where bottles were weighed, 93.4% had ≥1 mL total inoculant. Very low birth weight infants undergoing evaluations >7 days after birth had the highest proportion of inadequate inoculants (14.4%). Only 3/544 evaluations and 26/1011 bottles had total inoculant <0.5 mL. Ninety evaluations had <1 mL in both aerobic and anaerobic bottles despite a total inoculant volume that allowed inoculation of ≥1 mL in one of the bottles.

CONCLUSIONS

Obtaining recommended inoculant volumes is feasible in majority of neonates. Measuring inoculant volumes can focus improvement efforts and improve test reliability.

IMPACT

Clinicians express concern about the unreliability of neonatal blood cultures because of inadequate inoculant volume. We investigated over 900 evaluations and found >90% of evaluations have ≥1 mL inoculant. Monitoring adequacy of blood culture technique can identify areas of improvement and may allay concerns about blood culture reliability. Current recommendations for adequate inoculant volume for blood cultures are met in a majority of neonates. Areas of improvement include preterm late-onset sepsis evaluations and distribution techniques during inoculation.

Surface enhanced Raman scattering for the multiplexed detection of pathogenic microorganisms: towards point-of-use applications

Surface enhanced Raman scattering (SERS) is a technique that demonstrates a number of advantages for the rapid, specific and sensitive detection of pathogenic microorganisms. In this review, an overview of label-free and label-based SERS approaches, including microfluidics, nucleic acid detection and immunoassays, for the multiplexed detection of pathogenic bacteria and viruses from the last decade will be discussed, as well as their transition into promising point-of-use detection technologies in industrial and medical settings.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members.As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Next-generation sequencing diagnostics of bacteremia in pediatric sepsis

INTRODUCTION

Sepsis and septic shock are the most severe forms of infection affecting predominantly elderly people, preterm and term neonates, and young infants. Even in high-income countries sepsis causes about 8% of admissions to pediatric intensive care units (PICUs). Early diagnosis, rapid anti-infective treatment, and prompt hemodynamic stabilization are crucial for patient survival. In this context, it is essential to identify the causative pathogen as soon as possible to optimize antimicrobial treatment. To date, culture-based diagnostic procedures (e.g., blood cultures) represent the standard of care. However, they have 2 major problems: on the one hand, in the case of very small sample volumes (and thus usually in children), they are not sufficiently sensitive. On the other hand, with a time-to-result of 2 to 5 days, blood cultures need a relatively long time for the anti-infective therapy to be calculated. To overcome these problems, culture-independent molecular diagnostic procedures such as unbiased sequence analysis of circulating cell-free DNA (cfDNA) from plasma samples of septic patients by next-generation sequencing (NGS) have been tested successfully in adult septic patients. However, these results still need to be transferred to the pediatric setting.

METHODS

The Next GeneSiPS-Trial is a prospective, observational, non-interventional, multicenter study used to assess the diagnostic performance of an NGS-based approach for the identification of causative pathogens in (preterm and term) neonates (d1-d28, n = 50), infants (d29 to <1 yr, n = 50), and toddlers (1 yr to <5 yr, n = 50) with suspected or proven severe sepsis or septic shock (according to the pediatric sepsis definition) by the use of the quantitative sepsis indicating quantifier (SIQ) score in comparison to standard of care (culture-based) microbiological diagnostics. Potential changes in anti-infective treatment regimens based on these NGS results will be estimated retrospectively by a panel of 3 independent clinical specialists.

DISCUSSION

Neonates, infants, and young children are significantly affected by sepsis. Fast and more sensitive diagnostic approaches are urgently needed. This prospective, observational, non-interventional, multicenter study seeks to evaluate an NGS-based approach in critically ill children suffering from sepsis.

TRIAL REGISTRATION

DRKS-ID: DRKS00015705 (registered October 24, 2018). https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00015705.

Clinical Evaluation of an Improved Metagenomic Next-Generation Sequencing Test for the Diagnosis of Bloodstream Infections

BACKGROUND

Metagenomic next-generation sequencing (mNGS) of plasma cell-free DNA has emerged as a promising diagnostic technology for bloodstream infections. However, a major limitation of current mNGS assays is the high rate of false-positive results due to contamination.

METHODS

We made novel use of 3 control groups-external negative controls under long-term surveillance, blood samples with a negative result in conventional tests, and a group of healthy people-that were combined and dedicated to distinguishing contaminants arising from specimen collection, sample processing, and human normal flora. We also proposed novel markers to filter out false-positive interspecies calls. This workflow was applied retrospectively to 209 clinical plasma samples from patients with suspected bloodstream infections. Every pathogen identified by the mNGS test was reviewed to assess the diagnostic performance of the workflow.

RESULTS

Our mNGS workflow showed clinical sensitivity of 87.1%, clinical specificity of 80.2%, positive predictive value of 77.9%, and negative predictive value of 88.6% compared with the composite reference standard. Notably, mNGS showed great improvement in clinical specificity compared with the current test while keeping clinical sensitivity at a high level.

CONCLUSION

The mNGS workflow with multiple control groups dedicated to distinguishing nonpathogen microbes from real causal pathogens has reducing false-positive results. This contribution, with its optimization of workflow and careful use of controls, can help mNGS become a powerful tool for identifying the pathogens responsible for bloodstream infections.

Enteric Fever Diagnosis: Current Challenges and Future Directions

Enteric fever is a life-threatening systemic febrile disease caused by Salmonella enterica serovars Typhi and Paratyphi (S. Typhi and S. Paratyphi). Unfortunately, the burden of the disease remains high primarily due to the global spread of various drug-resistant Salmonella strains despite continuous advancement in the field. An accurate diagnosis is critical for effective control of the disease. However, enteric fever diagnosis based on clinical presentations is challenging due to overlapping symptoms with other febrile illnesses that are also prevalent in endemic areas. Current laboratory tests display suboptimal sensitivity and specificity, and no diagnostic methods are available for identifying asymptomatic carriers. Several research programs have employed systemic approaches to identify more specific biomarkers for early detection and asymptomatic carrier detection. This review discusses the pros and cons of currently available diagnostic tests for enteric fever, the advancement of research toward improved diagnostic tests, and the challenges of discovering new ideal biomarkers and tests.

Active Monitoring and Feedback to Improve Blood Culture Fill Volumes and Positivity Across a Large Integrated Health System

BACKGROUND

The sensitivity of blood cultures increases with the volume of blood collected. However, hospitals face challenges in collecting adequate volume, and underfilled blood bottles are ubiquitous.

METHODS

Blood bottle fill volumes were measured using an automated monitoring system across multiples sites (10 hospitals, 3 laboratories) within a large suburban/urban health system. Baseline fill volumes were measured for 4 months. A quality improvement program was then implemented over 36 months. Strategies to improve fill volumes included education, standardized data collection, novel and unblinded information cascades, targeted communication, and bottle markings for blood collectors.

RESULTS

A total of 516 201 blood cultures were evaluated over 40 months. In the preimplementation period (January-April 2015), no hospitals collected the recommended 8-10 mL/bottle, and the average system fill volume was 2.3 mL. In the final postimplementation period (January-April 2018), 7 of 10 hospitals achieved ≥8 mL per bottle and the system average increased to 8.6 mL (P < .0001). The positivity rate increased 20%, from 7.39% to 8.85% (P < .001), whereas the contamination rate did not change and remained low. Compared to the preimplementation period, the odds of positive cultures containing potential pathogens increased to 1.18 (95% confidence interval, 1.05-1.32; P = .003).

CONCLUSIONS

Here we show that underfilled blood cultures are extremely common but that operational and educational strategies can result in sustained improvements across a complex network of hospitals and laboratories. This leads to increased detection of pathogens, which can have tremendous impact on the management of bloodstream infections and sepsis.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Infectious Complications in Paediatric Haematopoetic Cell Transplantation for Acute Lymphoblastic Leukemia: Current Status

Haematopoietic stem cell transplantation (HSCT) in paediatric patients with acute lymphoblastic leukaemia (ALL) is associated with a variety of infectious complications which result in significant morbidity and mortality. These patients are profoundly immunocompromised, and immune reconstitution after HSCT generally occurs in astrictly defined order. During the early phase after HSCT until engraftment, patients are at risk of infections due to presence of neutropenia and mucosal damage, with Gramme-positive and Gramme-negative bacteria and fungi being the predominant pathogens. After neutrophil recovery, the profound impairment of cell-mediated immunity and use of glucocorticosteroids for control of graft-vs.-host disease (GvHD) increases the risk of invasive mould infection and infection or reactivation of various viruses, such as cytomegalovirus, varicella zoster virus, Epstein-Barr virus and human adenovirus. In the late phase, characterised by impaired cellular and humoral immunity, particularly in conjunction with chronic GvHD, invasive infections with encapsulated bacterial infections are observed in addition to fungal and viral infections. HSCT also causes a loss of pretransplant naturally acquired and vaccine-acquired immunity; therefore, complete reimmunization is necessary to maintain long-term health in these patients. During the last two decades, major advances have been made in our understanding of and in the control of infectious complications associated with HSCT. In this article, we review current recommendations for the diagnosis, prophylaxis and treatment of infectious complications following HSCT for ALL in childhood.

Blood culture quality assurance: what Australasian laboratories are measuring and opportunities for improvement

Blood cultures are among the most important specimen types received and processed by the microbiology laboratory. Several publications list which variables should be measured to ensure quality. We undertook a qualitative structured questionnaire of Australian and New Zealand clinical microbiology laboratories to document current blood culture practices and to determine whether expected quality standards are being met. Questions included a wide range of pre-analytical, analytical, and post-analytical aspects of blood cultures from adults. The responses from 71 laboratories were analysed. Compliance was high for use of a biological safety cabinet (90%), incubating for 5 days (86%), and commenting on likely contaminants (85%). While Gram stains were reported within 2 hours during normal hours (93%), reporting was slower after hours (59%), p<0.001. The volume of blood collected for a clinical episode was poorly monitored with only 11% (n=8) of laboratories regularly auditing the number of blood culture sets and 3% (n=2) monitoring adequacy of fill. Most laboratories received blood cultures from off-site with just 34% (n=21) meeting guidance for loading bottles onto the analyser within 4 hours. More laboratories met standards for loading bottles onto the analyser during working hours than after hours: 87% vs 56%, p<0.001. Most laboratories did not monitor the contamination rate, 56% (n=40), and only 27% (n=19) knew their rate was below the guidance threshold of less than -3%. Considerable opportunities exist to improve quality assurance of blood culture practice in Australia and New Zealand, especially for the most critical aspect affecting culture sensitivity, the volume of blood collected.