Metagenomics to Assist in the Diagnosis of Bloodstream Infection

Metagenomic next-generation sequencing of plasma cell-free DNA improves the early diagnosis of suspected infections

BACKGROUND

Metagenomic next-generation sequencing (mNGS) could improve the diagnosed efficiency of pathogens in bloodstream infections or sepsis. Little is known about the clinical impact of mNGS test when used for the early diagnosis of suspected infections. Herein, our main objective was to assess the clinical efficacy of utilizing blood samples to perform mNGS for early diagnosis of suspected infections, as well as to evaluate its potential in guiding antimicrobial therapy decisions.

METHODS

In this study, 212 adult hospitalized patients who underwent blood mNGS test in the early stage of suspected infections were enrolled. Diagnostic efficacy of mNGS test and blood culture was compared, and the clinical impact of mNGS on clinical care was analyzed.

RESULTS

In our study, the total detection rate of blood mNGS was significantly higher than that of culture method (74.4% vs. 12.1%, P < 0.001) in the paired mNGS test and blood culture. Blood stream infection (107, 67.3%) comprised the largest component of all the diseases in our patients, and the detection rate of single blood sample subgroup was similar with that of multiple type of samples subgroup. Among the 187 patients complained with fever, there was no difference in the diagnostic efficacy of mNGS when blood specimens or additional other specimens were used in cases presenting only with fever. While, when patients had other symptoms except fever, the performance of mNGS was superior in cases with specimens of suspected infected sites and blood collected at the same time. Guided by mNGS results, therapeutic regimens for 70.3% cases (149/212) were changed, and the average hospitalized days were significantly shortened in cases with the earlier sampling time of admission.

CONCLUSION

In this study, we emphasized the importance of blood mNGS in early infectious patients with mild and non-specific symptoms. Blood mNGS can be used as a supplement to conventional laboratory examination, and should be performed as soon as possible to guide clinicians to perform appropriate anti-infection treatment timely and effectively. Additionally, combining the contemporaneous samples from suspected infection sites could improve disease diagnosis and prognoses. Further research needs to be better validated in large-scale clinical trials to optimize diagnostic protocol, and the cost-utility analysis should be performed.

Metagenomic next-generation sequencing in detecting pathogens in pediatric oncology patients with suspected bloodstream infections

BACKGROUND

Studies on mNGS application in pediatric oncology patients, who are at high risk of infection, are quite limited.

METHODS

From March 2020 to June 2022, a total of 224 blood samples from 195 pediatric oncology patients who were suspected as bloodstream infections were enrolled in this study. Their clinical and laboratory data were retrospectively reviewed, and the diagnostic performance of mNGS was assessed.

RESULTS

Compared to the reference tests, mNGS showed significantly higher sensitivity (89.8% vs 32.5%, P < 0.001) and clinical agreement (76.3% vs 51.3%, P < 0.001) in detecting potential pathogens and distinguishing BSI from non-BSI. Especially, mNGS had an outstanding performance for virus detection, contributing to 100% clinical diagnosed virus. Samples from patients with neutropenia showed higher incidence of bacterial infections (P = 0.035). The most identified bacteria were Escherichia coli, and the overall infections by gram-negative bacteria were significantly more prevalent than those by gram-positive ones (90% vs 10%, P < 0.001). Overall, mNGS had an impact on the antimicrobial regimens' usage in 54.3% of the samples in this study.

CONCLUSIONS

mNGS has the advantage of rapid and effective pathogen diagnosis in pediatric oncology patients with suspected BSI, especially for virus.

IMPACT

Compared with reference tests, mNGS showed significantly higher sensitivity and clinical agreement in detecting potential pathogens and distinguishing bloodstream infections (BSI) from non-BSI. mNGS is particularly prominent in clinical diagnosed virus detection. The incidence of bacterial infection was higher in patients with neutropenia, and the overall infection rate of Gram-negative bacteria was significantly higher than that of Gram-positive bacteria. mNGS affects the antimicrobial regimens' usage in more than half of patients.

Clinical metagenomic sequencing of plasma microbial cell-free DNA for febrile neutropenia in patients with acute leukaemia

OBJECTIVES

To evaluate the diagnostic performance and clinical impact of metagenomic next-generation sequencing (mNGS) of plasma microbial cell-free DNA (mcfDNA) in febrile neutropenia (FN).

METHODS

In a 1-year, multicentre, prospective study, we enrolled 442 adult patients with acute leukaemia with FN and investigated the usefulness of mNGS of plasma mcfDNA for identification of infectious pathogens. The results of mNGS were available to clinicians in real time. The performance of mNGS testing was evaluated in comparison with blood culture (BC) and a composite standard that incorporated standard microbiological testing and clinical adjudication.

RESULTS

In comparison with BC, the positive and negative agreements of mNGS were 81.91% (77 of 94) and 60.92% (212 of 348), respectively. By clinical adjudication, mNGS results were categorized by infectious diseases specialists as definite (n = 76), probable (n = 116), possible (n = 26), unlikely (n = 7), and false negative (n = 5). In 225 mNGS-positive cases, 81 patients (36%) underwent antimicrobials adjustment, resulting in positive impact on 79 patients and negative impact on two patients (antibiotics overuse). Further analysis indicated that mNGS was less affected by prior antibiotics exposure than BC.

DISCUSSION

Our results indicate that mNGS of plasma mcfDNA increased the detection of clinically significant pathogens and enabled early optimization of antimicrobial therapy in patients with acute leukaemia with FN.

Direct identification of pathogens via microbial cellular DNA in whole blood by MeltArray

Rapid identification of pathogens is critical for early and appropriate treatment of bloodstream infections. The various culture-independent assays that have been developed often have long turnaround times, low sensitivity and narrow pathogen coverage. Here, we propose a new multiplex PCR assay, MeltArray, which uses intact microbial cells as the source of genomic DNA (gDNA). The successive steps of the MeltArray assay, including selective lysis of human cells, microbial cell sedimentation, microbial cellular DNA extraction, target-specific pre-amplification and multiplex PCR detection, allowed the detection of 35 major bloodstream infectious pathogens in whole blood within 5.5 h. The limits of detection varied depending on the pathogen and ranged from 1 to 5 CFU/mL. Of 443 blood culture samples, including 373 positive blood culture samples and 70 negative blood culture samples, the MeltArray assay showed a sensitivity of 93.8% (350/373, 95% confidence interval [CI] = 90.7%-96.0%), specificity of 98.6% (69/70, 95% CI = 91.2%-99.9%), positive predictive value of 99.7% (95% CI = 98.1%-99.9%), and negative predictive value of 75.0% (95% CI = 64.7%-83.2%). The MeltArray detection results of 16 samples differed from MALDI-TOF and were confirmed by Sanger sequencing. Further testing of 110 whole blood samples from patients with suspected bloodstream infections using blood culture results revealed that the MeltArray assay had a clinical sensitivity of 100% (9/9, 95% CI = 62.8%-100.0%), clinical specificity of 74.5% (70/94, 95% CI = 64.2%-82.7%), positive predictive value of 27.3% (95% CI = 13.9%-45.8%), and negative predictive value of 100.0% (95% CI = 93.5%-100.0%). Compared with metagenomic next-generation sequencing, the MeltArray assay displayed a positive agreement of 85.7% (6/7, 95% CI = 42.0%-99.2%) and negative agreement of 100.0% (4/4, 95% CI = 39.6%-100.0%). We conclude that the MeltArray assay can be used as a rapid and reliable tool for direct identification of pathogens in bloodstream infections.

Exploring the Utility of Multiplex Infectious Disease Panel Testing for Diagnosis of Infection in Different Body Sites: A Joint Report of the Association for Molecular Pathology, American Society for Microbiology, Infectious Diseases Society of America, and Pan American Society for Clinical Virology

The use of clinical molecular diagnostic methods for detecting microbial pathogens continues to expand and, in some cases, supplant conventional identification methods in various scenarios. Analytical and clinical benefits of multiplex molecular panels for the detection of respiratory pathogens have been demonstrated in various studies. The use of these panels in managing different patient populations has been incorporated into clinical guidance documents. The Association for Molecular Pathology's Infectious Diseases Multiplex Working Group conducted a review of the current benefits and challenges to using multiplex PCR for the detection of pathogens from gastrointestinal tract, central nervous system, lower respiratory tract, and joint specimens. The Working Group also discusses future directions and novel approaches to detection of pathogens in alternate specimen types, and outlines challenges associated with implementation of these multiplex PCR panels.

Genome-wide identification and functional analysis of dysregulated alternative splicing profiles in sepsis

BACKGROUND

An increasing body of evidence now shows that the long-term mortality of patients with sepsis are associated with various sepsis-related immune cell defects. Alternative splicing (AS), as a sepsis-related immune cell defect, is considered as a potential immunomodulatory therapy target to improve patient outcomes. However, our understanding of the role AS plays in sepsis is currently insufficient.

AIM

This study investigated possible associations between AS and the gene regulatory networks affecting immune cells. We also investigated apoptosis and AS functionality in sepsis pathophysiology.

METHODS

In this study, we assessed publicly available mRNA-seq data that was obtained from the NCBI GEO dataset (GSE154918), which included a healthy group (HLTY), a mild infection group (INF1), asepsis group (Seps), and a septic shock group (Shock). A total of 79 samples (excluding significant outliers) were identified by a poly-A capture method to generate RNA-seq data. The variable splicing events and highly correlated RNA binding protein (RBP) genes in each group were then systematically analyzed.

RESULTS

For the first time, we used systematic RNA-seq analysis of sepsis-related AS and identified 1505 variable AS events that differed significantly (p <= 0.01) across the four groups. In the sepsis group, the genes related to significant AS events, such as, SHISA5 and IFI27, were mostly enriched in the cell apoptosis pathway. Furthermore, we identified differential splicing patterns within each of the four groups. Significant differences in the expression of RNA Binding Protein(RBP) genes were observed between the control group and the sepsis group. RBP gene expression was highly correlated with variant splicing events in sepsis, as determined by co-expression analysis; The expression of DDX24, CBFA2T2, NOP, ILF3, DNMT1, FTO, PPRC1, NOLC1 RBPs were significant reduced in sepsis compared to the healthy group. Finally, we constructed an RBP-AS functional network.

CONCLUSION

Analysis indicated that the RBP-AS functional network serves as a critical post-transcriptional mechanism that regulates the development of sepsis. AS dysregulation is associated with alterations in the regulatory gene expression network that is involved in sepsis. Therefore, the RBP-AS expression network could be useful in refining biomarker predictions in the development of new therapeutic targets for the pathogenesis of sepsis.

Identification of bacterial and fungal pathogens directly from clinical blood cultures using whole genome sequencing

Bloodstream infections are a major cause of morbidity and mortality worldwide. Early administration of appropriate antimicrobial therapy can improve patient survival and prevent antimicrobial resistance (AMR). Whole genome sequencing (WGS) can provide information for pathogen identification, AMR prediction and sequence typing earlier than current phenotypic diagnostic methods. WGS was performed on 97 clinical blood specimens and matched culture isolate pairs. Specimen/isolate pairs were MLST sequence-typed and further characterization was performed on Streptococcus species. WGS correctly identified 91.7% of clinical specimens and 93.2% of matched isolates representing 35 different microbial species. MLST types were assigned for 89.9% of matched cultures and 21.7% of blood specimens, with higher success for blood culture specimens extracted within 3 days (52% characterized) than 7 days (9.3%). This study demonstrates the potential use of WGS for identification and characterization of pathogens directly from blood culture specimens to facilitate timely initiation of appropriate antimicrobial therapies.

Metagenomics by next-generation sequencing (mNGS) in the etiological characterization of neonatal and pediatric sepsis: A systematic review

Introduction

Pediatric and neonatal sepsis is one of the main causes of mortality and morbidity in these age groups. Accurate and early etiological identification is essential for guiding antibiotic treatment, improving survival, and reducing complications and sequelae. Currently, the identification is based on culture-dependent methods, which has many limitations for its use in clinical practice, and obtaining its results is delayed. Next-generation sequencing enables rapid, accurate, and unbiased identification of multiple microorganisms in biological samples at the same time. The objective of this study was to characterize the etiology of neonatal and pediatric sepsis by metagenomic techniques.

Methods

A systematic review of the literature was carried out using the PRISMA-2020 guide. Observational, descriptive, and case report studies on pediatric patients were included, with a diagnostic evaluation by clinical criteria of sepsis based on the systemic inflammatory response, in sterile and non-sterile biofluid samples. The risk of bias assessment of the observational studies was carried out with the STROBE-metagenomics instrument and the CARE checklist for case reports.

Results and Discussion

Five studies with a total of 462 patients were included. Due to the data obtained from the studies, it was not possible to perform a quantitative synthesis (meta-analysis). Based on the data from the included studies, the result identified that mNGS improves the etiological identification in neonatal and pediatric sepsis, especially in the context of negative cultures and in the identification of unusual microorganisms (bacteria that are difficult to grow in culture, viruses, fungi, and parasites). The number of investigations is currently limited, and the studies are at high risk of bias. Further research using this technology would have the potential to improve the rational use of antibiotics.

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.

A case of disseminated Legionnaires’ disease: The value of metagenome next-generation sequencing in the diagnosis of Legionnaires

Background

Legionella rarely causes hospital-acquired pneumonia (HAP), although it is one of the most common pathogens of community-acquired pneumonia. Hospital-acquired Legionnaires’ disease, mainly occurring in immunocompromised patients, is often delayed in diagnosis with high mortality. The use of the metagenome Next-Generation Sequencing (mNGS) method, which is fast and unbiased, allows for the early detection and identification of microorganisms using a culture-independent strategy.

Case report

A 52-year-old male, with a past medical history of Goods syndrome, was admitted due to nephrotic syndrome. The patient developed severe pneumonia, rhabdomyolysis, and soft tissue infection after receiving immunosuppressive therapy. He did not respond well to empiric antibiotics and was eventually transferred to the medical intensive care unit because of an acute respiratory failure and septic shock. The patient then underwent a comprehensive conventional microbiological screening in bronchoalveolar lavage fluid (BALF) and blood, and the results were all negative. As a last resort, mNGS of blood was performed. Extracellular cell-free and intracellular DNA fragments of Legionella were detected in plasma and blood cell layer by mNGS, respectively. Subsequent positive results of polymerase chain reaction for Legionella in BALF and soft tissue specimens confirmed the diagnosis of disseminated Legionnaires’ disease involving the lungs, soft tissue, and blood stream. The patient’s condition improved promptly after a combination therapy of azithromycin and moxifloxacin. He was soon extubated and discharged from ICU with good recovery.

Conclusion

Early recognition and diagnosis of disseminated Legionnaires’ disease is challenging. The emergence and innovation of mNGS of blood has the potential to address this difficult clinical issue.

Metagenomic next-generation sequencing may assist diagnosis of cat-scratch disease

Bartonella henselae, the pathogen that causes cat-scratch disease (CSD), is relatively rare in the clinic. CSD usually causes mild clinical manifestations, which self-heal in a matter of weeks. However, in immunocompromised patients, CSD may cause systemic disorders that can lead to critical illness. Due to the diversity of symptom signs and the lack of a golden standard for diagnosis, identifying atypical CSD in a timely manner presents a challenge. Metagenomic next-generation sequencing (mNGS), is a promising technology that has been widely used in the detection of pathogens in clinical infectious diseases in recent years. mNGS can detect multiple pathogens quickly and accurately from any given source. Here, we present a case of atypical CSD, which was diagnosed using mNGS. The patient manifested a fever of unknown infectious origin, and routine antibiotic treatment was ineffective. mNGS was employed to test the patient’s peripheral blood, which led to the detection of B. henselae. This was rarely seen in previous CSD reports. We surmised that the patient presented with atypical CSD and thus a targeted therapy was recommended. Crucially, the patient recovered rapidly. Based on this case study findings, we recommend that CSD should be included in the differential diagnosis for fever of unknown origin and that mNGS may be helpful in the diagnosis of CSD.

The diagnostic value of next-generation sequencing technology in sepsis

Objective

This study aims to assess the clinical utility of next-generation sequencing (NGS) in sepsis diagnosis.

Methods

A prospective study was conducted on patients with a high suspicion of sepsis by unknown pathogens from January 2017 to December 2021. Blood samples were taken from patients to perform NGS, blood culture (BC), leucocyte (WBC), procalcitonin (PCT), creatinine (CREA), Albumin (ALB) and C-reactive protein (CRP) tests.

Results

The feedback time for BC was 3~5 days for bacteria and 5~7 days for fungi, while the turnover time for NGS was only 24 h. The clinical diagnosis was considered the “gold standard”. 83 patients passed our inclusion criteria and were separated into two groups by clinical diagnosis. 62 met the clinical diagnosis criteria for sepsis and 21 were non-sepsis. The data from the two groups were retrospectively compared and analyzed. Of 62 sepsis in 83 patients, 8(9.64%) were diagnosed by both BC and NGS, 51 (61.45%) by NGS only, 1(1.20%) by BC and 2 (2.41%) by conventional testing only; PCT, CREA, CRP levels and the detection rate of NGS and BC were higher in the sepsis group than in the non-sepsis group, while ALB levels were lower (p&lt;0.05). The logistic regression results in our study revealed that NGS and ALB were independent prediction factors for sepsis (p&lt;0.05), the area under the receiver operating characteristic curve (AUC), sensitivity and specificity of NGS for diagnosing sepsis was 0.857, 95.16% and 76.19%, while ALB was 0.728, 58.06%, 80.95%, respectively. The combination’s sensitivity, specificity and AUC of NGS and ALB were 93.55%, 85.71% and 0.935, greater than that of Albumin or NGS only (both p&lt;0.05).

Conclusion

NGS can effectively and quickly identify pathogens, thereby emerges as a promising technology for sepsis diagnosis. Combination of NGS and ALB can be used for early screening and is more powerful than NGS or ALB only.

[Clinical application value of peripheral blood metagenomic next-generation sequencing test for patients with hematological diseases accompanied by fever]

Objective: To investigate the clinical application value of peripheral blood metagenomic next-generation sequencing (mNGS) test for patients with hematological diseases accompanied by fever. Methods: The blood mNGS results and clinical data of inpatients with hematological diseases accompanied by fever treated in the Hematology Department of Tianjin Medical University General Hospital in March 2020 to June 2021were retrospectively analyzed. A total of 90 patients with 98 cases of specimens were included. The pathogen distribution characteristics and mNGS test performance were analyzed. Results: The positive rate of peripheral blood mNGS was significantly higher than that of traditional examination (68.37% vs 37.76%, P<0.001) and blood culture (68.37% vs 9.18%, P<0.001) . Viral, bacterial, and fungal infections accounted for 38.81%, 14.93%, and 2.99% in patients with single-pathogen infections, respectively. Polymicrobial infections accounted for 43.28%, in which viral and bacterial coinfections were the most common type (25.37%) . There were 55 virus-positive cases (82.09%) , 30 bacteria-positive cases (44.78%) , and 14 fungus-positive cases (20.90%) . The clinical approval rate of peripheral blood mNGS was 64.63% (63/98) . The sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of peripheral blood mNGS were 75.68%, 36.07%, 41.79%, and 70.97%, respectively, and the overall consistency rate with traditional examination was 51.02%. Of the 22 pulmonary infection cases with no detectable pathogens by conventional tests, the pathogens were identified by peripheral blood mNGS in 14 cases, 10 of which were clinically approved. Conclusion: The positive rate of peripheral blood mNGS was significantly higher than that of blood culture and traditional laboratory examination. Peripheral blood mNGS had a high clinical recognition rate, sensitivity, and NPV in the detection of pathogens in patients with hematological diseases accompanied by fever.

Clinical Application and Influencing Factor Analysis of Metagenomic Next-Generation Sequencing (mNGS) in ICU Patients With Sepsis

Objective

To analyze the clinical application and related influencing factors of metagenomic next-generation sequencing (mNGS) in patients with sepsis in intensive care unit (ICU).

Methods

The study included 124 patients with severe sepsis admitted to the ICU in the First Affiliated Hospital of Zhengzhou University from June 2020 to September 2021. Two experienced clinicians took blood mNGS and routine blood cultures of patients meeting the sepsis diagnostic criteria within 24 hours after sepsis was considered, and collection the general clinical data.

Results

mNGS positive rate was higher than traditional blood culture (67.74% vs. 19.35%). APACHE II score [odds ratio (OR)=1.096], immune-related diseases (OR=6.544), and hypertension (OR=2.819) were considered as positive independent factors for mNGS or culture-positive. The sequence number of microorganisms and pathogen detection (mNGS) type had no effect on prognosis. Age (OR=1.016), female (OR=5.963), myoglobin (OR=1.005), and positive virus result (OR=8.531) were independent risk factors of sepsis mortality. Adjusting antibiotics according to mNGS results, there was no statistical difference in the prognosis of patients with sepsis.

Conclusion

mNGS has the advantages of rapid and high positive rate in the detection of pathogens in patients with severe sepsis. Patients with high APACHE II score, immune-related diseases, and hypertension are more likely to obtain positive mNGS results. The effect of adjusting antibiotics according to mNGS results on the prognosis of sepsis needs to be further evaluated.

Clinical Metagenomic Next-Generation Sequencing for Diagnosis of Secondary Glaucoma in Patients With Cytomegalovirus-Induced Corneal Endotheliitis

Glaucoma is the second leading cause of blindness globally. Growing scientific evidence indicated that inflammation of the trabecular meshwork induced by corneal endotheliitis could lead to secondary glaucoma. Cytomegalovirus (CMV) has been identified as the most common herpes virus in corneal endotheliitis patients. Early detection is critical in preventing endothelial cell loss, and patient management should vary based on different pathological factors. However, routine culture and real-time polymerase chain reaction (qPCR) have difficult in distinguishing whether CMV, Varicella Zoster Virus (VZV) or Herpes Simplex Virus (HSV) causes endothiliitis. This may result in inappropriate treatment, which may prolong or aggravate the status of disease. We compared the sensitivity and specificity of qPCR and Metagenomic Next-Generation Sequencing (mNGS) in the aqueous humor of patients with suspected CMV endotheliitis in this study. Our results showed that four out of 11 (36.4%) of our patients were positive for CMV by qPCR, whereas mNGS had a 100% detection rate of CMV. Our findings implied that mNGS could be a useful diagnostic tool for CMV-induced endotheliitis.

Diagnostic performance of the metagenomic next-generation sequencing in lung biopsy tissues in patients suspected of having a local pulmonary infection

Purpose

This study aims to evaluate the diagnostic application and performance of the metagenomic next-generation sequencing (mNGS) in patients suspected of local pulmonary infection by comparing it to the traditional pathogen detection methods in lung tissue specimens obtained by a computerized tomography-guided biopsy (CT-guided biopsy).

Methods

We retrospectively reviewed patients, admitted to the First Affiliated Hospital of Wenzhou Medical University, China from May 2018 to December 2020, who were suspected of local pulmonary infection. All cases received a CT-guided lung biopsy, tissue samples were sent both for conventional examinations (CE) and mNGS tests. The sensitivity and specificity of the two diagnostic approaches were compared.

Results

106 patients enrolled, 76 patients were diagnosed with a pulmonary infection. Among 49 patients with identified pathogens, CE confirmed pathogenic infections in 32 cases. Mycobacterium spp. and fungi accounted for 37.5% (12/32) and 28.1% (9/32), respectively, with bacteria 34.4% (11/32). The mNGS examination detected extra pathogenic microorganisms in 22 patients that were consistent with the patients' clinical and radiographic pictures. The sensitivity of mNGS was 53.9% vs. 42.1% for the CE, while the specificity was 56.7% versus 96.7%. For detection rate, mNGS was significantly superior to CE in bacterial (96.3% vs. 40.7%, p < 0.05), and mixed infections (100% vs. 50%, p < 0.05), but inferior to CE in fungal (60% vs. 90%, p > 0.05) and Mycobacterium spp. infections (66.7% vs. 100%, p > 0.05) with no significant difference. Among 31 cases diagnosed with lung abscess, the diagnostic performance of the detection rate was 67.7% (21/31) in favour of mNGS compared to 29.0% (9/31) for CE (p < 0.05). Most polymicrobial infections were induced by anaerobic species that coexisted with Streptococcus constellatus. And Klebsiella pneumoniae was the most common isolated monomicrobial infection.

Conclusions

The most commonly detected causative pathogens for local pulmonary infections were bacteria, Mycobacterium spp. and fungi. Compared with the CE, the advantages of mNGS in the pathogens detection lie in the discovery of bacterial and mixed infections, as well as in the detection of lung abscess. Conversely, mNGS is not good enough to be recommendable for the detection of Mycobacterium spp. and fungi.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01912-4.

Value of CRP, PCT, and NLR in Prediction of Severity and Prognosis of Patients With Bloodstream Infections and Sepsis

Objective

To investigate the value of C-reactive protein (CRP), procalcitonin (PCT), and neutrophil to lymphocyte ratio (NLR) in assessing the severity of disease in patients with bloodstream infection and sepsis, and to analyze the relationship between the levels of three inflammatory factors and the prognosis of patients.

Methods

The clinical data of 146 patients with bloodstream infection and sepsis admitted to our intensive care unit (ICU) from October 2016 to May 2020 were retrospectively analyzed. The differences in the levels of inflammatory indicators such as CRP, PCT, and NLR within 24 h in patients with bloodstream infection sepsis with different conditions (critical group, non-critical group) and the correlation between these factors and the condition (acute physiology and chronic health evaluation II, APACHE II score) were analyzed. In addition, the prognosis of all patients within 28 days was counted, and the patients were divided into death and survival groups according to their mortality, and the risk factors affecting their death were analyzed by logistic regression, and the receiver operating characteristic (ROC) curve was used to analyze the value of the relevant indicators in assessing the prognosis of patients.

Results

The levels of NLR, CRP, PCT, total bilirubin (TBIL), glutamic oxaloacetic transaminase (AST), and serum creatinine (Scr) were significantly higher in the critically ill group than in the non-critically ill group, where correlation analysis revealed a positive correlation between CRP, PCT, and NLR and APACHE II scores (P < 0.05). Univariate logistic regression analysis revealed that CRP, PCT, NLR, and APACHE II scores were associated with patient prognosis (P < 0.05). Multi-factor logistic regression analysis found that PCT, NLR, and APACHE II scores were independent risk factors for patient mortality within 28 days (P < 0.05). ROC curve analysis found that PCT and NLR both had an AUC area > 0.7 in predicting patient death within 28 days (P < 0.05).

Conclusion

Inflammatory factors such as NLR, CRP, and PCT have important clinical applications in the assessment of the extent of disease and prognosis of patients with bloodstream infection and sepsis.

Metagenomic Next-Generation Sequencing for Diagnosing Infections in Lung Transplant Recipients: A Retrospective Study

Background: Accurate identification of pathogens is essential for the diagnosis and control of infections. We aimed to compare the diagnostic performance of metagenomic next-generation sequencing (mNGS) and conventional detection methods (CDM) in lung transplant recipients (LTRs).

Methods: We retrospectively analyzed 107 LTRs with suspected infection of pulmonary, blood, central nervous system or chest wall between March 2018 and November 2020. Bronchoalveolar lavage fluid and other body fluids were subject to pathogen detection by both mNGS and CDM.

Results: Of the 163 specimens, 84 (51.5%) tested positive for both mNGS and culture, 19 (11.7%) of which were completely consistent, 44 (27.0%) were partially congruent, and 21 (12.9%) were discordant (kappa = .215; p = .001). Compared with CDM, mNGS detected a higher diversity of pathogens. Moreover, the turn-around time was significantly shorter for mNGS compared with culture (2.7 ± .4 vs. 5.5 ± 1.6 days, p &lt; .001). As an auxiliary method, treatment strategies were adjusted according to mNGS findings in 31 cases (29.0%), including eight patients with non-infectious diseases, who were finally cured.

Conclusion: mNGS can identify pathogens with a shorter turn-around time and therefore provide a more accurate and timely diagnostic information to ascertaining pulmonary infections. mNGS might have a role in differentiating infectious from non-infectious lung diseases in LTRs.

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.

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.

Literature on Applied Machine Learning in Metagenomic Classification: A Scoping Review

Applied machine learning in bioinformatics is growing as computer science slowly invades all research spheres. With the arrival of modern next-generation DNA sequencing algorithms, metagenomics is becoming an increasingly interesting research field as it finds countless practical applications exploiting the vast amounts of generated data. This study aims to scope the scientific literature in the field of metagenomic classification in the time interval 2008-2019 and provide an evolutionary timeline of data processing and machine learning in this field. This study follows the scoping review methodology and PRISMA guidelines to identify and process the available literature. Natural Language Processing (NLP) is deployed to ensure efficient and exhaustive search of the literary corpus of three large digital libraries: IEEE, PubMed, and Springer. The search is based on keywords and properties looked up using the digital libraries' search engines. The scoping review results reveal an increasing number of research papers related to metagenomic classification over the past decade. The research is mainly focused on metagenomic classifiers, identifying scope specific metrics for model evaluation, data set sanitization, and dimensionality reduction. Out of all of these subproblems, data preprocessing is the least researched with considerable potential for improvement.

Whole blood genome-wide transcriptome profiling and metagenomics next-generation sequencing in young infants with suspected sepsis in a low-and middle-income country: A study protocol

Conducting collaborative and comprehensive epidemiological research on neonatal sepsis in low- and middle-income countries (LMICs) is challenging due to a lack of diagnostic tests. This prospective study protocol aims to obtain epidemiological data on bacterial sepsis in newborns and young infants at Kamuzu Central Hospital in Lilongwe, Malawi. The main goal is to determine if the use of whole blood transcriptome host immune response signatures can help in the identification of infants who have sepsis of bacterial causes. The protocol includes a detailed clinical assessment with vital sign measurements, strict aseptic blood culture protocol with state-of-the-art microbial analyses and RNA-sequencing and metagenomics evaluations of host responses and pathogens, respectively. We also discuss the directions of a brief analysis plan for RNA sequencing data. This study will provide robust epidemiological data for sepsis in neonates and young infants in a setting where sepsis confers an inordinate burden of disease.

Liquid biopsy for invasive mold infections in hematopoietic cell transplant recipients with pneumonia through next-generation sequencing of microbial cell-free DNA in plasma

BACKGROUND

Non-invasive diagnostic options are limited for invasive mold infections (IMI). We evaluated the performance of a plasma microbial cell-free DNA sequencing (mcfDNA-Seq) test for diagnosing pulmonary IMI after hematopoietic cell transplant (HCT).

METHODS

We retrospectively assessed the diagnostic performance of plasma mcfDNA-Seq NGS in 114 HCT recipients with pneumonia after HCT who had stored plasma obtained within 14 days of diagnosis of Proven/Probable Aspergillus IMI (n=51), Proven/Probable non-Aspergillus IMI (n=24), Possible IMI (n=20), and non-IMI controls (n=19). Sequences were aligned to a database including >400 fungi. Organisms above a fixed significance threshold were reported.

RESULTS

Among 75 patients with Proven/Probable pulmonary IMI, mcfDNA-Seq detected ≥1 pathogenic mold in 38 patients (sensitivity, 51%; 95% CI, 39%-62%). When restricted to samples obtained within 3 days of diagnosis, sensitivity increased to 61%. McfDNA-Seq had higher sensitivity for Proven/Probable non-Aspergillus IMI (sensitivity, 79%; 95% CI, 56%-93%) compared to Aspergillus IMI (sensitivity, 31%; 95% CI, 19%-46%). McfDNA-Seq also identified non-Aspergillus molds in an additional 7 patients in the Aspergillus subgroup and Aspergillus in 1 patient with Possible IMI. Among 19 non-IMI pneumonia controls, mcfDNA-Seq was negative in all samples suggesting a high specificity (95% CI, 82%-100%) and up to 100% positive predictive value (PPV) with estimated negative predictive values (NPV) of 81%-99%. The mcfDNA-seq assay was complementary to serum GMI testing; in combination, they were positive in 84% of individuals with Proven/Probable pulmonary IMI.

CONCLUSIONS

Non-invasive mcfDNA-Seq had moderate sensitivity and high specificity, NPV, and PPV for pulmonary IMI after HCT, particularly for non-Aspergillus.

Plasma Metagenomic Next-Generation Sequencing Assay for Identifying Pathogens: a Retrospective Review of Test Utilization in a Large Children's Hospital

Plasma metagenomic next-generation sequencing (mNGS) is a new diagnostic method used to potentially identify multiple pathogens with a single DNA-based diagnostic test. The test is expensive, and little is understood about where it fits into the diagnostic schema. We describe our experience at Texas Children's Hospital with the mNGS assay by Karius from Redwood City, CA, to determine whether mNGS offers additional diagnostic value when performed within 1 week before or after conventional testing (CT) (i.e., concurrently). We performed a retrospective review of all patients who had mNGS testing from April to June of 2019. Results for mNGS testing, collection time, time of result entry into the electronic medical record, and turnaround time were compared to those for CT performed concurrently. Discordant results were further reviewed for changes in antimicrobials due to the additional organism(s) identified by mNGS. Sixty patients had mNGS testing; the majority were immunosuppressed (62%). There was 61% positive agreement and 58% negative agreement between mNGS and CT. The mean time of result entry into the electronic medical record for CT was 3.5 days earlier than the mean result time for mNGS. When an additional organism(s) was identified by mNGS, antimicrobials were changed 26% of the time. On average, CT provided the same result as mNGS, but sooner than mNGS. When additional organisms were identified by mNGS, there was no change in management in the majority of cases. Overall, mNGS added little diagnostic value when ordered concurrently with CT.

Whole blood genome-wide transcriptome profiling and metagenomics next-generation sequencing in young infants with suspected sepsis in low-and middle-income countries: A study protocol

Conducting collaborative and comprehensive epidemiological research on neonatal sepsis in low- and middle-income countries (LMICs) is challenging due to a lack of diagnostic tests. This prospective study protocol aims to obtain epidemiological data on bacterial sepsis in newborns and young infants at Kamuzu Central Hospital in Lilongwe, Malawi. The main goal is to determine if the use of whole blood transcriptome host immune response signatures can help in the identification of infants who have sepsis of bacterial causes. The protocol includes a detailed clinical assessment with vital sign measurements, strict aseptic blood culture protocol with state-of-the-art microbial analyses and RNA-sequencing and metagenomics evaluations of host responses and pathogens, respectively. We also discuss the directions of a brief analysis plan for RNA sequencing data. This study will provide robust epidemiological data for sepsis in neonates and young infants in a setting where sepsis confers an inordinate burden of disease.

Shotgun-Metagenomics on Positive Blood Culture Bottles Inoculated With Prosthetic Joint Tissue: A Proof of Concept Study

Clinical metagenomics is actively moving from research to clinical laboratories. It has the potential to change the microbial diagnosis of infectious diseases, especially when detection and identification of pathogens can be challenging, such as in prosthetic joint infection (PJI). The application of metagenomic sequencing to periprosthetic joint tissue (PJT) specimens is often challenged by low bacterial load in addition to high level of inhibitor and contaminant host DNA, limiting pathogen recovery. Shotgun-metagenomics (SMg) performed directly on positive blood culture bottles (BCBs) inoculated with PJT may be a convenient approach to overcome these obstacles. The aim was to test if it is possible to perform SMg on PJT inoculated into BCBs for pathogen identification in PJI diagnosis. Our study was conducted as a laboratory method development. For this purpose, spiked samples (positive controls), negative control and clinical tissue samples (positive BCBs) were included to get a comprehensive overview. We developed a method for preparation of bacterial DNA directly from PJT inoculated in BCBs. Samples were processed using MolYsis5 kit for removal of human DNA and DNA extracted with BiOstic kit. High DNA quantity/quality was obtained, and no inhibition was observed during the library preparation, allowing further sequencing process. DNA sequencing reads obtained from the BCBs, presented a low proportion of human reads (<1%) improving the sensitivity of bacterial detection. We detected a 19-fold increase in the number of reads mapping to human in a sample untreated with MolYsis5. Taxonomic classification of clinical samples identified a median of 96.08% (IQR, 93.85-97.07%; range 85.7-98.6%) bacterial reads. Shotgun-metagenomics results were consistent with the results from a conventional BCB culture method, validating our approach. Overall, we demonstrated a proof of concept that it is possible to perform SMg directly on BCBs inoculated with PJT, with potential of pathogen identification in PJI diagnosis. We consider this a first step in research efforts needed to face the challenges presented in PJI diagnoses.

A Collaborative Tale of Diagnosing and Treating Chronic Pulmonary Aspergillosis, from the Perspectives of Clinical Microbiologists, Surgical Pathologists, and Infectious Disease Clinicians

Chronic pulmonary aspergillosis (CPA) refers to a spectrum of Aspergillus-mediated disease that is associated with high morbidity and mortality, with its true prevalence vastly underestimated. The diagnosis of CPA includes characteristic radiographical findings in conjunction with persistent and systemic symptoms present for at least three months, and evidence of Aspergillus infection. Traditionally, Aspergillus infection has been confirmed through histopathology and microbiological studies, including fungal culture and serology, but these methodologies have limitations that are discussed in this review. The treatment of CPA requires an individualized approach and consideration of both medical and surgical options. Most Aspergillus species are considered susceptible to mold-active triazoles, echinocandins, and amphotericin B; however, antifungal resistance is emerging and well documented, demonstrating the need for novel therapies and antifungal susceptibility testing that correlates with clinical response. Here, we describe the clinical presentation, diagnosis, and treatment of CPA, with an emphasis on the strengths and pitfalls of diagnostic and treatment approaches, as well as future directions, including whole genome sequencing and metagenomic sequencing. The advancement of molecular technology enables rapid and precise species level identification, and the determination of molecular mechanisms of resistance, bridging the clinical infectious disease, anatomical pathology, microbiology, and molecular biology disciplines.

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.

Case Report: Comparison of Plasma Metagenomics to Bacterial PCR in a Case of Prosthetic Valve Endocarditis

Molecular assays for infectious diseases have emerged as important clinical decision-making tools. Unbiased, metagenomic next-generation sequencing is a novel approach holding promise to detect pathogens missed by conventional modalities and to deconvolute admixed nucleic acid sequences from polymicrobial infections in order to identify constituent pathogens. Recent studies have raised concerns about the clinical impact of metagenomics assays and whether their expense is justified. Here, we report a case of polyclonal Streptococcus cristatus endocarditis in a 14-year-old woman with a history of Tetralogy of Fallot. Three sets of admission blood cultures and a commercial plasma metagenomics assay were negative for pathogens, despite persistent vegetations observed on the valve during a later procedure. Multiple strains of Streptococcus cristatus were identified from the explanted valve by amplicon-based 16S rRNA sequencing, confirming the patient had received appropriate antibiotic therapy. This case highlights limitations in the use and interpretation of clinical metagenomics for infectious disease diagnosis and indicates that the clinical yield of these tools may depend upon infection type and anatomic location.