Next-generation sequencing diagnostics of bacteremia in sepsis (Next GeneSiS-Trial): Study protocol of a prospective, observational, noninterventional, multicenter, clinical trial

Microbial cell-free DNA-sequencing as an addition to conventional diagnostics in neonatal sepsis

BACKGROUND

Bloodstream infections remain a challenge for neonatologists, as traditional culture-based methods are time-consuming and rely on adequate blood volume. Next-generation sequencing (NGS) offers an alternative, as it can identify microbial cell-free DNA (mcfDNA) in a small blood sample, providing rapid pathogen detection. This study aimed to assess the diagnostic performance of DISQVER®-NGS compared to blood cultures in neonatal patients with suspected sepsis.

METHODS

In neonates with suspected sepsis, blood cultures and samples for NGS were prospectively collected. Patients were divided into four categories: 1) sepsis, blood culture positive, 2) clinical sepsis, culture negative, 3) suspected sepsis, 4) validation cohort.

RESULTS

NGS detected bacterial, viral or fungal mcfDNA in 24 of 82 samples. Blood cultures were collected in 46 of 84 patients (15/46 positive). DISQVER® correctly identified pathogens in 9/15 patients with a positive blood culture, two with intrinsic resistance to their antibiotic regimen. In seven samples NGS reported the mcfDNA of bacteria that could have theoretically grown in culture but did not.

CONCLUSIONS

NGS may enhance sensitivity in sepsis diagnostics by detecting mcfDNA in neonates with suspected sepsis. Interpreting NGS results requires correlation with clinical data, laboratory values, and routine microbiological tests for a comprehensive understanding of the patient's condition.

IMPACT

Conventional blood culture methods have limitations in accuracy and turnaround time. The study aimed to investigate the diagnostic performance of the Next-Generation Sequencing method DISQVER® compared to traditional blood cultures in neonatal patients with suspected sepsis. Our findings suggest that NGS has the potential to augment the precision of conventional diagnostic techniques, can lead to improved detection of pathogens and targeted treatment approaches in neonatal sepsis. It is emphasized that further validation and integration with clinical and microbiological data are required to ensure optimal clinical utility.

Suppression PCR-Based Selective Enrichment Sequencing for Pathogen and Antimicrobial Resistance Detection on Cell-Free DNA in Sepsis-A Targeted, Blood Culture-Independent Approach for Rapid Pathogen and Resistance Diagnostics in Septic Patients

Sepsis is a life-threatening syndrome triggered by infection and accompanied by high mortality, with antimicrobial resistances (AMRs) further escalating clinical challenges. The rapid and reliable detection of causative pathogens and AMRs are key factors for fast and appropriate treatment, in order to improve outcomes in septic patients. However, current sepsis diagnostics based on blood culture is limited by low sensitivity and specificity while current molecular approaches fail to enter clinical routine. Therefore, we developed a suppression PCR-based selective enrichment sequencing approach (SUPSETS), providing a molecular method combining multiplex suppression PCR with Nanopore sequencing to identify most common sepsis-causative pathogens and AMRs using plasma cell-free DNA. Applying only 1 mL of plasma, we targeted eight pathogens across three kingdoms and ten AMRs in a proof-of-concept study. SUPSETS was successfully tested in an experimental research study on the first ten clinical samples and revealed comparable results to clinical metagenomics while clearly outperforming blood culture. Several clinically relevant AMRs could be additionally detected. Furthermore, SUPSETS provided first pathogen and AMR-specific sequencing reads within minutes of starting sequencing, thereby potentially decreasing time-to-results to 11-13 h and suggesting diagnostic potential in sepsis.

From Shadows to Spotlight: Enhancing Bacterial DNA Detection in Blood Samples through Cutting-Edge Molecular Pre-Amplification

One of the greatest challenges to the use of molecular methods for diagnostic purposes is the detection of target DNA that is present only in low concentrations. One major factor that negatively impacts accuracy, diagnostic sensitivity, and specificity is the sample matrix, which hinders the attainment of the required detection limit due to the presence of residual background DNA. To address this issue, various methods have been developed to enhance sensitivity through targeted pre-amplification of marker sequences. Diagnostic sensitivity to the single molecular level is critical, particularly when identifying bloodstream infections. In cases of clinically manifest sepsis, the concentration of bacteria in the blood may reach as low as one bacterial cell/CFU per mL of blood. Therefore, it is crucial to achieve the highest level of sensitivity for accurate detection. In the present study, we have established a method that fills the analytical gap between low concentrations of molecular markers and the minimum requirements for molecular testing. For this purpose, a sample preparation of whole blood samples with a directly downstream pre-amplification was developed, which amplifies specific species and resistance markers in a multiplex procedure. When applying pre-amplification techniques, the sensitivity of the pathogen detection in whole blood samples was up to 100 times higher than in non-pre-amplified samples. The method was tested with blood samples that were spiked with several Gram-positive and Gram-negative bacterial pathogens. By applying this method to artificial spiked blood samples, it was possible to demonstrate a sensitivity of 1 colony-forming unit (CFU) per millilitre of blood for S. aureus and E. faecium. A detection limit of 28 and 383 CFU per ml of blood was achieved for E. coli and K. pneumoniae, respectively. If the sensitivity is also confirmed for real clinical blood samples from septic patients, the novel technique can be used for pathogen detection without cultivation, which might help to accelerate diagnostics and, thus, to decrease sepsis mortality rates.

The Value of Next-Generation Sequencing in Diagnosis and Therapy of Critically Ill Patients with Suspected Bloodstream Infections: A Retrospective Cohort Study

Bloodstream infection (BSI), a frequent cause of severe sepsis, is a life-threatening complication in critically ill patients and still associated with a high mortality rate. Rapid pathogen identification from blood is crucial for an early diagnosis and the treatment of patients with suspected BSI. For this purpose, novel diagnostic tools on the base of genetic analysis have emerged for clinical application. The aim of this study was to assess the diagnostic value of additional next-generation sequencing (NGS) pathogen test for patients with suspected BSI in a surgical ICU and its potential impact on antimicrobial therapy. In this retrospective single-centre study, clinical data and results from blood culture (BC) and NGS pathogen diagnostics were analysed for ICU patients with suspected BSI. Consecutive changes in antimicrobial therapy and diagnostic procedures were evaluated. Results: 41 cases with simultaneous NGS and BC sampling were assessed. NGS showed a statistically non-significant higher positivity rate than BC (NGS: 58.5% (24/41 samples) vs. BC: 21.9% (9/41); p = 0.056). NGS detected eight different potentially relevant bacterial species, one fungus and six different viruses, whereas BC detected four different bacterial species and one fungus. NGS results affected antimicrobial treatment in 7.3% of cases. Conclusions: NGS-based diagnostics have the potential to offer a higher positivity rate than conventional culture-based methods in patients with suspected BSI. Regarding the high cost, their impact on anti-infective therapy is currently limited. Larger randomized prospective clinical multicentre studies are required to assess the clinical benefit of this novel diagnostic technology.

The Role of Gut Microbiota in the Clinical Outcome of Septic Patients: State of the Art and Future Perspectives

Sepsis is a life-threatening multiple-organ dysfunction caused by a dysregulated host response to infection, with high mortality worldwide; 11 million deaths per year are attributable to sepsis in high-income countries. Several research groups have reported that septic patients display a dysbiotic gut microbiota, often related to high mortality. Based on current knowledge, in this narrative review, we revised original articles, clinical trials, and pilot studies to evaluate the beneficial effect of gut microbiota manipulation in clinical practice, starting from an early diagnosis of sepsis and an in-depth analysis of gut microbiota.

RAPIDprep: A Simple, Fast Protocol for RNA Metagenomic Sequencing of Clinical Samples

Emerging infectious disease threats require rapid response tools to inform diagnostics, treatment, and outbreak control. RNA-based metagenomics offers this; however, most approaches are time-consuming and laborious. Here, we present a simple and fast protocol, the RAPIDprep assay, with the aim of providing a cause-agnostic laboratory diagnosis of infection within 24 h of sample collection by sequencing ribosomal RNA-depleted total RNA. The method is based on the synthesis and amplification of double-stranded cDNA followed by short-read sequencing, with minimal handling and clean-up steps to improve processing time. The approach was optimized and applied to a range of clinical respiratory samples to demonstrate diagnostic and quantitative performance. Our results showed robust depletion of both human and microbial rRNA, and library amplification across different sample types, qualities, and extraction kits using a single workflow without input nucleic-acid quantification or quality assessment. Furthermore, we demonstrated the genomic yield of both known and undiagnosed pathogens with complete genomes recovered in most cases to inform molecular epidemiological investigations and vaccine design. The RAPIDprep assay is a simple and effective tool, and representative of an important shift toward the integration of modern genomic techniques with infectious disease investigations.

No evidence for a common blood microbiome based on a population study of 9,770 healthy humans

Human blood is conventionally considered sterile but recent studies suggest the presence of a blood microbiome in healthy individuals. Here we characterized the DNA signatures of microbes in the blood of 9,770 healthy individuals using sequencing data from multiple cohorts. After filtering for contaminants, we identified 117 microbial species in blood, some of which had DNA signatures of microbial replication. They were primarily commensals associated with the gut (n = 40), mouth (n = 32) and genitourinary tract (n = 18), and were distinct from pathogens detected in hospital blood cultures. No species were detected in 84% of individuals, while the remainder only had a median of one species. Less than 5% of individuals shared the same species, no co-occurrence patterns between different species were observed and no associations between host phenotypes and microbes were found. Overall, these results do not support the hypothesis of a consistent core microbiome endogenous to human blood. Rather, our findings support the transient and sporadic translocation of commensal microbes from other body sites into the bloodstream.

Metagenomics next-generation sequencing provides insights into the causative pathogens from critically ill patients with pneumonia and improves treatment strategies

Background

The metagenomics next-generation sequencing (mNGS) is a promising technique for pathogens diagnosis. However, whether the application of mNGS in critically ill patients with pneumonia could cause anti-infection treatment adjustment and thereby affect the prognosis of these patients has not been explored.

Methods

We retrospectively collected the clinical data of patients diagnosed with pulmonary infection in the ICU of the Affiliated Hospital of Qingdao University from January 2018 to January 2021. These patients with pneumonia were divided into mNGS group and no-mNGS group by whether being performed NGS or not. The clinical data, including demographics, illness history, APACHE II score, length of mechanical ventilation, length of stay in the hospital, length of stay in ICU and outcome, were collected. In addition, the data of pathogens and anti-infection treatment before and after NGS were also collected. Propensity score matching was performed to evaluate the mortality and deterioration rate between NGS group and non-NGS group.

Results

A total of 641 patients diagnosed with pneumonia were screened, and 94 patients were excluded based on exclusion criteria. Finally, 547 patients were enrolled, including 160 patients being performed NGS. Among these 160 patients, 142 cases had NGS-positive results. In addition, new pathogens were detected in 132 specimens by NGS, which included 82 cases with virus, 18 cases with fungus, 17 cases with bacteria, 14 cases with mycoplasma, and 1 case with mycobacterium tuberculosis. Anti-infection treatments were adjusted in some patients who performed NGS, including 48 anti-bacterial treatments, 20 antifungal treatments and 20 antiviral treatments. There were no significant differences in the mortality and deterioration rate between NGS and non-NGS group, but it exhibited a trend that the mortality and deterioration rate of NGS group was lower than non-NGS group after the propensity score matching analysis (15.8% vs 24.3%, P=0.173; 25.6% vs 37.8%, P=0.093).

Conclusion

NGS could affect the anti-infection treatments and had a trend of reducing the mortality and deterioration rate of critically ill patients with pneumonia.

Fast Track Diagnostic Tools for Clinical Management of Sepsis: Paradigm Shift from Conventional to Advanced Methods

Sepsis is one of the deadliest disorders in the new century due to specific limitations in early and differential diagnosis. Moreover, antimicrobial resistance (AMR) is becoming the dominant threat to human health globally. The only way to encounter the spread and emergence of AMR is through the active detection and identification of the pathogen along with the quantification of resistance. For better management of such disease, there is an essential requirement to approach many suitable diagnostic techniques for the proper administration of antibiotics and elimination of these infectious diseases. The current method employed for the diagnosis of sepsis relies on the conventional culture of blood suspected infection. However, this method is more time consuming and generates results that are false negative in the case of antibiotic pretreated samples as well as slow-growing microbes. In comparison to the conventional method, modern methods are capable of analyzing blood samples, obtaining accurate results from the suspicious patient of sepsis, and giving all the necessary information to identify the pathogens as well as AMR in a short period. The present review is intended to highlight the culture shift from conventional to modern and advanced technologies including their limitations for the proper and prompt diagnosing of bloodstream infections and AMR detection.

Diagnostic value of metagenomic next-generation sequencing in sepsis and bloodstream infection

Objective

To evaluate the diagnostic value of metagenomic next-generation sequencing (mNGS) in sepsis and bloodstream infection (BSI).

Methods

A retrospective analysis of patients diagnosed with sepsis and BSI at the First Affiliated Hospital of Zhengzhou University from January 2020 to February 2022 was conducted. All the patients underwent blood culture and were divided into mNGS group and non-mNGS group according to whether mNGS was performed or not. The mNGS group was further divided into early group (< 1 day), intermediate group (1-3 days), and late group (> 3 days) according to the time of mNGS inspection.

Results

In 194 patients with sepsis and BSI, the positive rate of mNGS for identifying pathogens was significantly higher than that of blood culture (77.7% vs. 47.9%), and the detection period was shorter (1.41 ± 1.01 days vs. 4.82 ± 0.73 days); the difference was statistically significant (p < 0.05). The 28-day mortality rate of the mNGS group (n = 112) was significantly lower than that of the non-mNGS group (n = 82) (47.32% vs. 62.20%, p = 0.043). The total hospitalization time for the mNGS group was longer than that for the non-mNGS group (18 (9, 33) days vs. 13 (6, 23) days, p = 0.005). There was no significant difference in the ICU hospitalization time, mechanical ventilation time, vasoactive drug use time, and 90-day mortality between the two groups (p > 0.05). Sub-group analysis of patients in the mNGS group showed that the total hospitalization time and the ICU hospitalization time in the late group were longer than those in the early group (30 (18, 43) days vs. 10 (6, 26) days, 17 (6, 31) days vs. 6 (2, 10) days), and the ICU hospitalization time in the intermediate group was longer than that in the early group (6 (3, 15) days vs. 6 (2, 10) days); the differences were statistically significant (p < 0.05). The 28-day mortality rate of the early group was higher than that of the late group (70.21% vs. 30.00%), and the difference was statistically significant (p = 0.001).

Conclusions

mNGS has the advantages of a short detection period and a high positive rate in the diagnosis of pathogens causing BSI and, eventually, sepsis. Routine blood culture combined with mNGS can significantly reduce the mortality of septic patients with BSI. Early detection using mNGS can shorten the total hospitalization time and the ICU hospitalization time of patients with sepsis and BSI.

Next-Generation Sequencing Applications for the Study of Fungal Pathogens

Next-generation sequencing (NGS) has become a widely used technology in biological research. NGS applications for clinical pathogen detection have become vital technologies. It is increasingly common to perform fast, accurate, and specific detection of clinical specimens using NGS. Pathogenic fungi with high virulence and drug resistance cause life-threatening clinical infections. NGS has had a significant biotechnological impact on detecting bacteria and viruses but is not equally applicable to fungi. There is a particularly urgent clinical need to use NGS to help identify fungi causing infections and prevent negative impacts. This review summarizes current research on NGS applications for fungi and offers a visual method of fungal detection. With the development of NGS and solutions for overcoming sequencing limitations, we suggest clinicians test specimens as soon as possible when encountering infections of unknown cause, suspected infections in vital organs, or rapidly progressive disease.

[Which biomarkers for diagnosis and guidance of anti-infection treatment in sepsis?]

To date no biomarker has been identified bringing together perfect sensitivity and specificity to discriminate between inflammation and infections. Since the 1930s new markers of tissue damage and endothelial damage have been identified but which are incapable of identifying infections in every clinical setting to enable initiation of early antibiotic treatment. In this review the most important classical biomarkers and upcoming new PCR-based approaches are addressed. These markers are highlighted with respect to special clinical settings and to control the success of antibiotic treatment. The issue of discrimination between inflammation and infection is not yet solved. Based on one single biomarker it is impossible to decide whether infection is the reason for the patient's worsening condition but the combination of biomarkers or the integration of new biomarkers may be a meaningful supplement. The measurement of different biomarkers of infection or inflammation is part of the routine in critical care and will be essential in the future.

Fast and precise pathogen detection and identification of overlapping infection in patients with CUTI based on metagenomic next-generation sequencing: A case report

RATIONALE

The gold standard for pathogen detection and identification of complicated urinary tract infection (CUTI) remains quantitative urine culture, however, the diagnostic value of urine culture remains limited due to the time-consuming procedure and low detection rate. Here we report a case of successfully using Metagenomic next-generation sequencing (mNGS) provided fast and precise detection and identification of overlapping infection in patients with CUTI with no similar reports or studies published before to the best of our knowledge.

PATIENT CONCERNS

A 70-year-old male was admitted to hospital due to elevated serum creatinine for 2 weeks.

DIAGNOSES

Acute exacerbation of chronic renal failure and CUTI were the most critical diagnosis on admission.

INTERVENTIONS

Blood purification, bladder irrigation and aggressive anti-infective therapy were administered. But the empirical anti-infection therapy and the adjustment of treatment according to the evidence of urine culture drug sensitivity had no obvious effect. We further carried out urinary PMseq-DNA detection and the results showed overlapping infection with Enterococcus faecium, Enterococcus hirae, Pseudomonas aeruginosa, Pseudomonas denitrificans and Candida albicans. According to the genetic test results, linezolid, meropenem and fluconazole triple anti-infection treatment was given.

OUTCOMES

After adjusting the treatment, the infection was basically controlled in 10 days, and even the renal function was significantly improved, dialysis independence was achieved after 3 months.

LESSONS

Our case illustrated the potential application of mNGS in detecting pathogenic microorganisms in patients with CUTI especially when overlapping infections are present.

The effects of early restrictive fluid resuscitation on the clinical outcomes in sepsis patients

OBJECTIVE

To investigate the effects of early restrictive fluid resuscitation (RFR) on the clinical outcomes in sepsis patients.

METHODS

A total of 122 sepsis patients admitted to our hospital were recruited for this study and divided into a study group (the SG, n=56) and a control group (the CG, n=66) according to the treatment method each patient was administered. The SG was administered early RFR, and the CG was administered adequate fluid resuscitation. The clinical data were analyzed retrospectively in both groups. The total infusion volumes, the hemorrhage amounts, the urine outputs, and the Acute Physiology and Chronic Health Evaluation (APACHE II) scores were compared between the two groups. In addition, the heart rates, the mean arterial pressure levels, the central venous pressure levels, and the cardiac function indices were compared between the two groups at 1-7 days after the procedures. The survival and the complication incidence rates were followed up.

RESULTS

The SG showed significantly lower heart rates and mean arterial pressure levels and higher central venous pressure levels than the CG at 1-7 days after the procedures (P<0.05). The cardiac troponin, N-terminal brain pro-natriuretic peptide, and C-reactive protein levels at 3-7 days after the procedures in the SG were significantly lower than the levels in the CG (P<0.05). The cardiac output, stroke volume, and left ventricular ejection fraction scores in the SG were significantly higher than they were in the CG (P<0.05). The survival rate in the SG was significantly higher than it was in the CG at 16, 32, and 64 days after the procedures (P<0.05). The incidence of complications in the SG was lower than it was in the CG (P<0.05).

CONCLUSION

Early RFR can remarkably improve the clinical outcomes, the myocardial injury and survival rates, and the multiple complications incidence rate in sepsis patients.

Detection of Pathogenic Bacteria From Septic Patients Using 16S Ribosomal RNA Gene-Targeted Metagenomic Sequencing

BACKGROUND

Conventional blood cultures were compared to plasma cell-free DNA-based 16S ribosomal RNA (rRNA) gene polymerase chain reaction (PCR)/next-generation sequencing (NGS) for detection and identification of potential pathogens in patients with sepsis.

METHODS

Plasma was prospectively collected from 60 adult patients with sepsis presenting to the Mayo Clinic (Minnesota) Emergency Department from March through August 2019. Results of routine clinical blood cultures were compared to those of 16S rRNA gene NGS.

RESULTS

Nineteen (32%) subjects had positive blood cultures, of which 13 yielded gram-negative bacilli, 5 gram-positive cocci, and 1 both gram-negative bacilli and gram-positive cocci. 16S rRNA gene NGS findings were concordant in 11. For the remaining 8, 16S rRNA gene NGS results yielded discordant detections (n = 5) or were negative (n = 3). Interestingly, Clostridium species were additionally detected by 16S rRNA gene NGS in 3 of the 6 subjects with gastrointestinal sources of gram-negative bacteremia and none of the 3 subjects with urinary sources of gram-negative bacteremia. In the 41 remaining subjects, 16S rRNA gene NGS detected at least 1 potentially pathogenic organism in 17. In 15, the detected microorganism clinically correlated with the patient's syndrome. In 17 subjects with a clinically defined infectious syndrome, neither test was positive; in the remaining 7 subjects, a noninfectious cause of clinical presentation was identified.

CONCLUSIONS

16S rRNA gene NGS may be useful for detecting bacteria in plasma of septic patients. In some cases of gram-negative sepsis, it may be possible to pinpoint a gastrointestinal or urinary source of sepsis based on the profile of bacteria detected in plasma.

Metagenomic evidence for a polymicrobial signature of sepsis

Our understanding of the host component of sepsis has made significant progress. However, detailed study of the microorganisms causing sepsis, either as single pathogens or microbial assemblages, has received far less attention. Metagenomic data offer opportunities to characterize the microbial communities found in septic and healthy individuals. In this study we apply gradient-boosted tree classifiers and a novel computational decontamination technique built upon SHapley Additive exPlanations (SHAP) to identify microbial hallmarks which discriminate blood metagenomic samples of septic patients from that of healthy individuals. Classifiers had high performance when using the read assignments to microbial genera [area under the receiver operating characteristic (AUROC=0.995)], including after removal of species ‘culture-confirmed’ as the cause of sepsis through clinical testing (AUROC=0.915). Models trained on single genera were inferior to those employing a polymicrobial model and we identified multiple co-occurring bacterial genera absent from healthy controls. While prevailing diagnostic paradigms seek to identify single pathogens, our results point to the involvement of a polymicrobial community in sepsis. We demonstrate the importance of the microbial component in characterising sepsis, which may offer new biological insights into the aetiology of sepsis, and ultimately support the development of clinical diagnostic or even prognostic tools.

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.

Optimising Treatment Outcomes for Children and Adults Through Rapid Genome Sequencing of Sepsis Pathogens. A Study Protocol for a Prospective, Multi-Centre Trial (DIRECT)

Background

Sepsis contributes significantly to morbidity and mortality globally. In Australia, 20,000 develop sepsis every year, resulting in 5,000 deaths, and more than AUD$846 million in expenditure. Prompt, appropriate antibiotic therapy is effective in improving outcomes in sepsis. Conventional culture-based methods to identify appropriate therapy have limited yield and take days to complete. Recently, nanopore technology has enabled rapid sequencing with real-time analysis of pathogen DNA. We set out to demonstrate the feasibility and diagnostic accuracy of pathogen sequencing direct from clinical samples, and estimate the impact of this approach on time to effective therapy when integrated with personalised software-guided antimicrobial dosing in children and adults on ICU with sepsis.

Methods

The DIRECT study is a pilot prospective, non-randomized multicentre trial of an integrated diagnostic and therapeutic algorithm combining rapid direct pathogen sequencing and software-guided, personalised antibiotic dosing in children and adults with sepsis on ICU.

Participants and interventions

DIRECT will collect microbiological and pharmacokinetic samples from approximately 200 children and adults with sepsis admitted to one of four ICUs in Brisbane. In Phase 1, we will evaluate Oxford Nanopore Technologies MinION sequencing direct from blood in 50 blood culture-proven sepsis patients recruited from consecutive patients with suspected sepsis. In Phase 2, a further 50 consecutive patients with suspected sepsis will be recruited in whom MinION sequencing will be combined with Bayesian software-guided (ID-ODS) personalised antimicrobial dosing.

Outcome measures

The primary outcome is time to effective antimicrobial therapy, defined as trough drug concentrations above the MIC of the pathogen. Secondary outcomes are diagnostic accuracy of MinION sequencing from whole blood, time to pathogen identification and susceptibility testing using sequencing direct from whole blood and from positive blood culture broth.

Discussion

Rapid pathogen sequencing coupled with antimicrobial dosing software has great potential to overcome the limitations of conventional diagnostics which often result in prolonged inappropriate antimicrobial therapy. Reduced time to optimal antimicrobial therapy may reduce sepsis mortality and ICU length of stay. This pilot study will yield key feasibility data to inform further, urgently needed sepsis studies. Phase 2 of the trial protocol is registered with the ANZCTR (ACTRN12620001122943).

Trial registration

Registered with the Australia New Zealand Clinical Trials Registry Number ACTRN12620001122943

Efficacy and prognosis of continuous renal replacement therapy at different times in the treatment of patients with sepsis-induced acute kidney injury

OBJECTIVE

To investigate the efficacy and prognosis of CRRT at different times in the treatment of sepsis-induced acute kidney injury (SAKI).

METHODS

A total of 156 patients with SAKI were grouped into two groups in accordance with a random number table, with 78 patients in each group. Patients in the observation group (OG) were treated with early CRRT, and in the control group (CG), patients were treated with delayed CRRT. According to whether the patients died, there were 51 cases in the death group and 105 in the survival group. Renal function and inflammatory factors were compared before and after treatment; univariate and multilateral comparison were conducted to analyze the survival status of the patients.

RESULTS

After treatment, the blood urea nitrogen (BUN) and serum creatinine (Scr) in both groups fell below those prior to treatment, while the estimated glomerular filtration rate (eGFR) was elevated (P<0.01); the decrease of BUN and Scr in the OG was greater than that of the other group, while increase eGFR was more than that the other group (P<0.01). After treatment, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in both groups decreased compared to that prior to treatment (P<0.001); the decrease of the three factors in the OG was greater than that in the CG (P<0.05). The 60-day survival rate of patients in the OG was 76.92%, which was higher that of 57.69% in the CG (P<0.05). The age, acute physiology and chronic health enquiry (APACHE-II) score and proportion of chronic obstructive pulmonary disease (COPD) in the death group was elevated compared to those in the survival group, while the number of patients with early CRRT and eGFR level before treatment were lower than those in the survival group (P<0.05). Age was an independent risk factor for the prognosis of SAKI, and early CRRT was a protective factor for the prognosis (P<0.05).

CONCLUSION

Early CRRT for SAKI can improve the renal function and inflammatory state effectively, and reduce the mortality of patients. Age is an independent risk factor affecting the prognosis of patients with SAKI, and early CRRT is a protective factor for the prognosis.

A Comparison of Blood Pathogen Detection Among Droplet Digital PCR, Metagenomic Next-Generation Sequencing, and Blood Culture in Critically Ill Patients With Suspected Bloodstream Infections

Metagenomic next-generation sequencing (mNGS) and droplet digital PCR (ddPCR) have recently demonstrated a great potential for pathogen detection. However, few studies have been undertaken to compare these two nucleic acid detection methods for identifying pathogens in patients with bloodstream infections (BSIs). This prospective study was thus conducted to compare these two methods for diagnostic applications in a clinical setting for critically ill patients with suspected BSIs. Upon suspicion of BSIs, whole blood samples were simultaneously drawn for ddPCR covering 20 common isolated pathogens and four antimicrobial resistance (AMR) genes, mNGS, and blood culture. Then, a head-to-head comparison was performed between ddPCR and mNGS. A total of 60 episodes of suspected BSIs were investigated in 45 critically ill patients, and ddPCR was positive in 50 (83.3%), mNGS in 41 (68.3%, not including viruses), and blood culture in 10 (16.7%) episodes. Of the 10 positive blood cultures, nine were concordantly identified by both mNGS and ddPCR methods. The head-to-head comparison showed that ddPCR was more rapid (~4 h vs. ~2 days) and sensitive (88 vs. 53 detectable pathogens) than mNGS within the detection range of ddPCR, while mNGS detected a broader range of pathogens (126 vs. 88 detectable pathogens, including viruses) than ddPCR. In addition, a total of 17 AMR genes, including 14 bla_KPC and 3 mecA genes, were exclusively identified by ddPCR. Based on their respective limitations and strengths, the ddPCR method is more useful for rapid detection of common isolated pathogens as well as AMR genes in critically ill patients with suspected BSI, whereas mNGS testing is more appropriate for the diagnosis of BSI where classic microbiological or molecular diagnostic approaches fail to identify causative pathogens.

Evaluation of superinfection, antimicrobial usage, and airway microbiome with metagenomic sequencing in COVID-19 patients: A cohort study in Shanghai

Background

In COVID-19 patients, information regarding superinfection, antimicrobial assessment, and the value of metagenomic sequencing (MS) could help develop antimicrobial stewardship.

Method

This retrospective study analyzed 323 laboratory-confirmed COVID-19 patients for co-infection rate and antimicrobial usage in the Shanghai Public Health Clinical Center (SPHCC) from January 23rd to March 14th 2020. The microbiota composition was also investigated in patients with critically severe COVID-19.

Results

The total population co-infection rate was 17/323 (5.3%) and 0/229 (0), 4/78 (5.1%), and 13/16 (81.3%) for the mild, severe, and critically severe subgroups, respectively. Proven fungal infection was significantly associated with a higher mortality rate (p = 0.029). In critically severe patients, the rate of antimicrobials and carbapenem usage were 16/16 (100%) and 13/16 (81.3%), respectively, in which the preemptive and empiric antimicrobial days accounted for 51.6% and 30.1%, respectively. Targeted therapy only accounted for 18.3%. MS was implemented to detect non-COVID-19 virus co-existence and the semi-quantitative surveillance of bacteremia, with clear clinical benefit seen in cases with MS-based precision antimicrobial management. Airway microbiome analysis suggested that the microbiota compositions in critically severe COVID-19 patients were likely due to intubation and mechanical ventilation.

Conclusions

In the SPHCC cohort, we observed a non-negligible rate of super-infection, especially for the critically ill COVID-19 patients. Fungal co-infection requires intensive attention due to the high risk of mortality, and the clinical benefit of MS in guiding antimicrobial management warrants further investigation.

Role of Rapid Diagnostics in Diagnosis and Management of Patients With Sepsis

Delayed administration of active anti-infective therapy is associated with increased rates of adverse events, mortality, and costs among sepsis patients. Inherent limitations of conventional culture identification methods and the lengthy turnaround time of antimicrobial susceptibility testing are significant barriers to the timely delivery of life-saving therapy, particularly among antibiotic-resistant infections. Culture-independent diagnostic techniques that detect pathogens and antimicrobial resistance genes within clinical samples present a tremendous benefit to timely diagnosis and management of patients. Improved outcomes for rapid intervention with rapid diagnostics have been documented and include decreased mortality rates, decreased health care delivery costs, and faster delivery of appropriate therapeutics.

Indwelling Device-Associated Biofilms in Critically Ill Cancer Patients-Study Protocol

Health care-associated infections are a leading cause of inpatient complications. Rapid pathogen detection/identification is a major challenge in sepsis management that highly influences the successful outcome. The current standard of microorganism identification relies on bacterial growth in culture, which has several limitations. Gene sequencing research has developed culture-independent techniques for microorganism identification, with the aim to improve etiological diagnosis and, therefore, to change sepsis outcome. A prospective, observational, non-interventional, single-center study was designed that assesses biofilm-associated pathogens in a specific subpopulation of septic critically ill cancer patients. Indwelling device samples will be collected in septic patients at the moment of the removal of the arterial catheter, central venous catheter, endotracheal tube and urinary catheter. Concomitantly, clinical data regarding 4 sites (nasal, pharyngeal, rectal and skin) of pathogen colonization at the time of hospital/intensive care admission will be collected. The present study aims to offer new insights into biofilm-associated infections and to evaluate the infection caused by catheter-specific and patient-specific biofilm-associated pathogens in association with the extent of colonization. The analysis relies on the two following detection/identification techniques: standard microbiological method and next generation sequencing (NGS). Retrospectively, the study will estimate the clinical value of the NGS-based detection and its virtual potential in changing patient management and outcome, notably in the subjects with missing sepsis source or lack of response to anti-infective treatment.

Multiple myeloma with Echinococcus granulosus infection diagnosed by detection of oligoclonal bands: A case report

RATIONALE

Isoelectric focusing electrophoresis (IFE) is currently recognized as the gold standard for detecting oligoclonal bands (OCBs) in cerebrospinal fluid (CSF). To the best of our knowledge, however, no study has reported on type III OCBs using IFE. In this paper, we report on a rare case of multiple myeloma (MM) with Echinococcus granulosus infection diagnosed by IFE.

PATIENT CONCERNS

A 71-year-old man complained of weakness of the right lower extremity accompanied with fever (temperature range 37.8°C-38.2°C) for more than 6 months.

DIAGNOSES

MM with E granulosus infection.

INTERVENTIONS

The IFE results identified a unique monoclonal band, indicating that the patient may have MM in conjunction with a distinct pathogen infection. He received anthelmintic treatment and bortezomib-thalidomide-dexamethasone therapy.

OUTCOMES

The patient was followed up for 15 months. During that time, his temperature returned to normal, his Medical Research Council Grading of Muscle Power scale became 5, and his vital signs stabilized.

LESSONS

Detection of OCB type III indicated that the patient was diagnosed with MM accompanied by E granulosus infection. Thus, IFE of CSF may be an auxiliary diagnostic method for MM in the future.

Sensitive universal detection of blood parasites by selective pathogen-DNA enrichment and deep amplicon sequencing

BACKGROUND

Targeted amplicon deep sequencing (TADS) has enabled characterization of diverse bacterial communities, yet the application of TADS to communities of parasites has been relatively slow to advance. The greatest obstacle to this has been the genetic diversity of parasitic agents, which include helminths, protozoa, arthropods, and some acanthocephalans. Meanwhile, universal amplification of conserved loci from all parasites without amplifying host DNA has proven challenging. Pan-eukaryotic PCRs preferentially amplify the more abundant host DNA, obscuring parasite-derived reads following TADS. Flaherty et al. (2018) described a pan-parasitic TADS method involving amplification of eukaryotic 18S rDNA regions possessing restriction sites only in vertebrates. Using this method, host DNA in total DNA extracts could be selectively digested prior to PCR using restriction enzymes, thereby increasing the number of parasite-derived reads obtained following NGS. This approach showed promise though was only as sensitive as conventional PCR.

RESULTS

Here, we expand on this work by designing a second set of pan-eukaryotic primers flanking the priming sites already described, enabling nested PCR amplification of the established 18S rDNA target. This nested approach facilitated introduction of a second restriction digestion between the first and second PCR, reducing the proportional mass of amplifiable host-derived DNA while increasing the number of PCR amplification cycles. We applied this method to blood specimens containing Babesia, Plasmodium, various kinetoplastids, and filarial nematodes and confirmed its limit of detection (LOD) to be approximately 10-fold lower than previously described, falling within the range of most qPCR methods.

CONCLUSIONS

The assay detects and differentiates the major malaria parasites of humans, along with several other clinically important blood parasites. This represents an important step towards a TADS-based universal parasite diagnostic (UPDx) test with a sufficient LOD for routine applications. Video Abstract.

Effects of viral infection and microbial diversity on patients with sepsis: A retrospective study based on metagenomic next-generation sequencing

BACKGROUND

The study aims to investigate the performance of a metagenomic next-generation sequencing (NGS)-based diagnostic technique for the identification of potential bacterial and viral infections and effects of concomitant viral infection on the survival rate of intensive care unit (ICU) sepsis patients.

METHODS

A total of 74 ICU patients with sepsis who were admitted to our institution from February 1, 2018 to June 30, 2019 were enrolled. Separate blood samples were collected from patients for blood cultures and metagenomic NGS when the patients' body temperature was higher than 38 °C. Patients' demographic data, including gender, age, ICU duration, ICU scores, and laboratory results, were recorded. The correlations between pathogen types and sepsis severity and survival rate were evaluated.

RESULTS

NGS produced higher positive results (105 of 118; 88.98%) than blood cultures (18 of 118; 15.25%) over the whole study period. Concomitant viral infection correlated closely with sepsis severity and had the negative effect on the survival of patients with sepsis. However, correlation analysis indicated that the bacterial variety did not correlate with the severity of sepsis.

CONCLUSIONS

Concurrent viral load correlates closely with the severity of sepsis and the survival rate of the ICU sepsis patients. This suggests that prophylactic administration of antiviral drugs combined with antibiotics may be beneficial to ICU sepsis patients.

Evaluation of High-Throughput Next-Generation Sequencing Applied in the Pathogenic Diagnosis of Bloodstream Infections

Background: Bloodstream infection (BSI) has been one of the biggest headaches for clinicians, as it not only aggravates symptoms but also increases the length of stay, the cost of hospitalization, and the side effects caused by antibiotics. It is an urgent need for clinicians to develop timely and accurate methods to find microorganisms. Currently, the gold standard for diagnosing BSI is blood culture, but it takes three to eight days to produce results, and its positive rate is extremely low. Next-generation sequencing (NGS) has emerged as a better technology desperately needed by doctors and patients to diagnose BSI. Objectives: This study compared NGS and blood culture methods in clinical patients with BSI. Methods: In this study, blood culture and NGS were used to analyze the blood of patients with BSI in different departments of the First Affiliated Hospital of Kunming Medical University. Results: Next-generation sequencing detected 60 pathogens in 63 blood samples, while blood culture detected 15 pathogens in 336 blood samples from 63 patients who were clinically considered to be infected. Pathogens detected by NGS included bacteria, fungi, and viruses, while blood culture only found bacteria and fungi. The positive rates of blood culture diagnosis and NGS diagnosis in BSI patients were 23.8% (15/63) (CI: 13.3% - 34.3%) and 95% (60/63) (CI: 90% - 100%), respectively. Conclusions: Our results showed that NGS creates a new diagnostic platform for patients with BSI. Its wide detection range, high positive rate, and characteristics of rapid detection will benefit patients with BSI.

Impact of donor lung colonized bacteria detected by next-generation sequencing on early post-transplant outcomes in lung transplant recipients

Background

The effect of donor lung colonized bacteria on the prognosis of lung transplantation is not clear. We used the technique of next-generation sequencing (NGS) to detect the colonized bacteria from the lower respiratory tract and analyzed whether the colonized bacteria of donor lung could affect the outcomes of lung transplantation.

Methods

Seventeen patients who underwent lung transplantation from March 2018 to June 2018 at Wuxi People’s Hospital affiliated to Nanjing Medical University were included in this study. Twelve cases of donor lung were obtained, and 17 lung transplants were performed, including 12 single lung transplantation and 5 bilateral lung transplantation. The colonized bacteria in the lower lobe tissue of donor lung were detected by NGS, and the bacteria culture method was used to detect the bacteria in the airway secretion before and after the operation. The information of length of extracorporeal membrane oxygenation (ECMO) support, mechanical ventilation time, length of intensive care unit (ICU) stay, duration of fever and length of hospital stay were collected for prognostic analysis.

Results

Compared with bacterial culture methods, the positive rate by using NGS in the lungs were higher (52.9% vs 41.2%). Among the patients who were transplanted with donor lungs with detected bacteria by NGS before surgery, only one patient (1/9) developed the same bacteria after lung transplantation. Based on results of NGS and bacterial culture, there was no association between the colonized bacteria in donor lungs and the patients’ outcomes of immediate posttransplant period.

Conclusion

NGS showed more sensitive than bacterial culture for detection of bacteria. The colonized bacteria in different parts of the lung are inconsistent. There is no association between the colonized bacteria in donor lungs and short-term outcome of lung transplantation patients.

A rapid high-throughput sequencing-based approach for the identification of unknown bacterial pathogens in whole blood

High-throughput DNA sequencing (HTS) of pathogens in whole blood samples is hampered by the high host/pathogen nucleic acids ratio. We describe a novel and rapid bacterial enrichment procedure whose implementation is exemplified in simulated bacteremic human blood samples. The procedure involves depletion of the host DNA, rapid HTS and bioinformatic analyses. Following this procedure, Y. pestis, F. tularensis and B. anthracis spiked-in samples displayed an improved host/pathogen DNA ratio of 2.5-5.9 orders of magnitude, in samples with bacteria spiked-in at 103-105 CFU/ml. The procedure described in this study enables rapid and detailed metagenomic profiling of pathogens within 8-9 h, circumventing the challenges imposed by the high background present in the bacteremic blood and by the unknown nature of the sample.

Liquid biopsy for infectious diseases: a focus on microbial cell-free DNA sequencing

Metagenomic next-generation sequencing (mNGS) of microbial cell-free DNA (mcfDNA sequencing) is becoming an attractive diagnostic modality for infectious diseases, allowing broad-range pathogen detection, noninvasive sampling, and rapid diagnosis. At this key juncture in the translation of metagenomics into clinical practice, an integrative perspective is needed to understand the significance of emerging mcfDNA sequencing technology. In this review, we summarized the actual performance of the mcfDNA sequencing tests recently used in health care settings for the diagnosis of a variety of infectious diseases and further focused on the practice considerations (challenges and solutions) for improving the accuracy and clinical relevance of the results produced by this evolving technique. Such knowledge will be helpful for physicians, microbiologists and researchers to understand what is going on in this quickly progressing field of non-invasive pathogen diagnosis by mcfDNA sequencing and promote the routine implementation of this technique in the diagnosis of infectious disease.

Metagenomic Next-Generation Sequencing versus Traditional Pathogen Detection in the Diagnosis of Peripheral Pulmonary Infectious Lesions

Purpose

The aim of this study was to evaluate the value of metagenomic next-generation sequencing (mNGS) in peripheral pulmonary infection management by comparing the diagnostic yield of mNGS and traditional pathogen detection methods on interventional specimens obtained by bronchoscopy.

Patients and Methods

This study enrolled patients suspected with pulmonary infection who were admitted to Tianjin Medical University General Hospital from June 2018 to August 2019. Specimens were obtained from bronchoscopy for mNGS analysis and traditional pathogen detection (including bronchoalveolar lavage fluid microbial culture, smear microscopy, and lung biopsy histopathology), and the diagnostic yields were compared between mNGS and traditional methods to evaluate the diagnostic value of mNGS in peripheral pulmonary infection diagnosis.

Results

In this study, by comparing mNGS with traditional pathogen detection, the results indicated that, first, mNGS identified at least one microbial species in almost 89% of the patients with pulmonary infection; second, mNGS detected microbes related to human diseases in 94.49% of samples from pulmonary infection patients who had received negative results from traditional pathogen detection; third, the accuracy and sensitivity of mNGS are higher than those of traditional pathogen detection; and, finally, mNGS could simultaneously detect and identify a large variety of pathogens.

Conclusion

Metagenomic NGS analysis provided fast and precise pathogen detection and identification, contributing to prompt and accurate treatment of peripheral pulmonary infection.

Diagnosing Bacteremia in Real Time Using Next-Generation Sequencing-Based Technology

This commentary highlights the article by Grumaz et al that describes the use of molecular sequencing for fast detection of pathogens directly from blood samples from septic patients.

Fast I(n)dentification of Pathogens in Neonates (FINDPATH-N): protocol for a prospective pilot cohort study of next-generation sequencing for pathogen identification in neonates with suspected sepsis

INTRODUCTION

Sepsis is a major source of morbidity and mortality in neonates; however, identification of the causative pathogens is challenging. Many neonates have negative blood cultures despite clinical evidence of sepsis. Next-generation sequencing (NGS) is a high-throughput, parallel sequencing technique for DNA. Pathogen-targeted enrichment followed by NGS has the potential to be more sensitive and faster than current gold-standard blood culture. In this pilot study, we will test the feasibility and pathogen detection patterns of pathogen-targeted NGS in neonates with suspected sepsis. Additionally, the distribution and diagnostic accuracy of biomarkers cell-free DNA and protein C levels at two time points will be explored.

METHODS AND ANALYSIS

We will conduct a prospective, pilot observational study. Neonates over 1 kg with suspected sepsis from a single tertiary care children's hospital will be recruited for the study. Recruitment will be censored at 200 events or 6 months' duration. Two blood study samples will be taken: the first simultaneous to the blood culture (time=0 hour, for NGS and biomarkers) via an exception to consent (deferred consent) and another 24 hours later after prospective consent (biomarkers only). Neonates will be adjudicated into those with clinical sepsis, culture-proven sepsis and without sepsis based on clinical criteria. Feasibility parameters (eg, recruitment) and NGS process time will be reported.For analysis, NGS results will be described in aggregate, compared with the simultaneous blood culture (sensitivity and specificity) and reviewed via expert panel for plausibility. Pilot data for biomarker distribution and diagnostic accuracy (sensitivity and specificity) for distinguishing between septic and non-septic neonates will be reported.

ETHICS AND DISSEMINATION

Ethics approval has been granted by the Hamilton Integrated Research Ethics Board. We will seek publication of study results in peer-reviewed journals.

Direct-from-blood RNA sequencing identifies the cause of post-bronchoscopy fever

Background

Antibiotic resistance is rising at disturbing rates and contributes to the deaths of millions of people yearly. Antibiotic resistant infections disproportionately affect those with immunocompromising conditions, chronic colonization, and frequent antibiotic use such as transplant patients or those with cystic fibrosis. However, clinicians lack the diagnostic tools to confidently diagnose and treat infections, leading to widespread use of empiric broad spectrum antimicrobials, often for prolonged duration.

Case presentation

A 22 year-old Caucasian female with cystic fibrosis received a bilateral orthotopic lung transplantation 5 months prior to the index hospitalization. She underwent routine surveillance bronchoscopy and was admitted for post-procedure fever. A clear cause of infection was not identified by routine methods. Imaging and bronchoscopic lung biopsy did not identify an infectious agent or rejection. She was treated with a prolonged course of antimicrobials targeting known colonizing organisms from prior bronchoalveolar lavage cultures (Pseudomonas, Staphylococcus aureus, and Aspergillus). However, we identified Stenotrophomonas maltophilia in two independent whole blood samples using direct-pathogen sequencing, which was not identified by other methods.

Conclusions

This case represents a common clinical conundrum: identification of infection in a high-risk, complex patient. Here, direct-pathogen sequencing identified a pathogen that would not otherwise have been identified by common techniques. Had results been clinically available, treatment could have been customized, avoiding a prolonged course of broad spectrum antimicrobials that would only exacerbate resistance. Direct-pathogen sequencing is poised to fill a diagnostic gap for pathogen identification, allowing early identification and customization of treatment in a culture-independent, pathogen-agnostic manner.

Direct Detection of Pathogens in Bloodstream During Sepsis: Are We There Yet?

Background

Advances in medicine have improved our understanding of sepsis, but it remains a major cause of morbidity and mortality. The detection of pathogens that cause sepsis remains a challenge for clinical microbiology laboratories.

Content

Routine blood cultures are time-consuming and are negative in a large proportion of cases, leading to excessive use of broad-spectrum antimicrobials. Molecular testing direct from patient blood without the need for incubation has the potential to fill the gaps in our diagnostic armament and complement blood cultures to provide results in a timely manner. Currently available platforms show promise but have yet to definitively address gaps in sensitivity and specificity.

Summary

Significant strides have been made in the detection of pathogens directly from blood. A number of hurdles, however, remain before this technology can be adapted for routine use.

Incremental value of metagenomic next generation sequencing for the diagnosis of suspected focal infection in adults

OBJECTIVES

Microbiological diagnosis is essential during clinical management of focal infections. Metagenomic next generation sequencing (mNGS) has been reported as a promising diagnostic tool in infectious diseases. However, little is known about the clinical utility of mNGS in focal infections.

METHODS

We conducted a single-center retrospective study to investigate impact of mNGS on focal infection diagnosis and compared it with conventional methods, including culture, pathological examination, Xpert MTB/RIF, etc. 98 suspected focal infections cases were enrolled, and medical records were reviewed to determine their rates of detection, time-to-identification, and clinical outcomes.

RESULTS

mNGS showed a satisfying diagnostic positive percent agreement of 86.30% (95% CI: 75.79-92.88%) in a variety of tissues, compared to 45.21% (95% CI: 33.68-57.24%) for culture and 57.53% (95% CI: 45.43-68.84%)f for conventional methods (p < 0.0125), and detected an extra 34 pathogenic microorganisms. Time requirement for pathogen identification using mNGS ranges from 31 h to 55 h, which showed an advantage over culture. (82.36 h; 95%CI: 65.83, 98.89; P < 0.05) CONCLUSIONS: mNGS showed promising potential in pathogenic diagnosis during focal infections and might enable clinicians to make more timely and targeted therapeutic decisions.

When not to start antibiotics: avoiding antibiotic overuse in the intensive care unit

BACKGROUND

Most intensive care unit (ICU) patients receive broad-spectrum antibiotics. While lifesaving in some, in others these treatments may be unnecessary and place patients at risk of antibiotic-associated harms.

OBJECTIVES

To review the literature exploring how we diagnose infection in patients in the ICU and address the safety and utility of a 'watchful waiting' approach to antibiotic initiation with selected patients in the ICU.

SOURCES

A semi-structured search of PubMed and Cochrane Library databases for articles published in English during the past 15 years was conducted.

CONTENT

Distinguishing infection from non-infectious mimics in ICU patients is uniquely challenging. At present, we do not have access to a rapid point-of-care test that reliably differentiates between individuals who need antibiotics and those who do not. A small number of studies have attempted to compare early aggressive versus conservative antimicrobial strategies in the ICU. However, this body of literature is small and not robust enough to guide practice.

IMPLICATIONS

This issue will not likely be resolved until there are diagnostic tests that rapidly and reliably identify the presence or absence of infection in the ICU population. In the meantime, prospective trials that identify clinical situations wherein it is safe to delay or withhold antibiotic initiation in the ICU until the presence of an infection is proven are warranted.

Messages from the third International Conference on Clinical Metagenomics (ICCMg3)

Clinical metagenomics (CMg), referring to as the application of metagenomic sequencing of clinical samples in order to recover clinically-relevant information, has been rapidly evolving these last years. Following this trend, we held the third International Conference on Clinical Metagenomics (ICCMg3) in Geneva in October 2018. During the two days of the conference, several aspects of CMg were addressed, which we propose to summarize in the present manuscript. During this ICCMg3, we kept on following the progresses achieved worldwide on clinical metagenomics, but also this year in clinical genomics. Besides, the use of metagenomics in cancer diagnostic and management was addressed. Some new challenges have also been raised such as the way to report clinical (meta)genomics output to clinicians and the pivotal place of ethics in this expanding field.

Gut Microbiome in Critical Illness (Review)

Radical changes in the composition, diversity and metabolic activity of gut microbiome in critically ill patients most probably affect adversely the outcome of treatment. Microbiota dysfunction may be a predictor and presumably the main cause of infectious complications and sepsis. Clinicists use objective scales for evaluation of patient condition severity including specific parameters of disorders of organs and systems; however, microbiota function is not considered specific and, hence, not evaluated. Technical capabilities of the recent decade have allowed characterizing the intestinal microbiota and that helped understanding the ongoing processes. The authors have analyzed data about the role of intestinal microbiota as a metabolic 'reactor' during critical states, possible complications related to misbalance of 'harmful' and 'beneficial' bacteria, and examined potential of a targeted therapy aimed directly at correction of intestinal microbiota. Search for papers was carried out using Scopus and Web of Science databases 2001 to 2018 years: (Gut Microbiota) AND (Critically ill OR Intensive care unit), key words taken for the search were: intestinal microbiota, metabolism, sepsis, antibiotics, critically ill patients, multiple organ failure. A number of questions in understanding of the interaction between gut microbiome and host remain open. It is necessary to take into account interference of microbial metabolism while assessing metabolome of patients with sepsis. Among low-molecular compounds found in blood of sepsis patients, special attention should be paid to molecules that can be classified as ‘common metabolites’ of humans and bacteria, for example, degradation products of aromatic compounds, which many-fold rise in blood of septic patients. It is necessary to take into consideration and experimentally model changes in the human internal environment, which occur during radical transformation of microbiome in critically ill patients. Such approach brings in new prospects for objective monitoring of diseases by evaluating metabolic profile at a particular moment of time based on integral indices reflecting the status of microbiome/metabolome system, which will supply new targets for therapeutic intervention in future.