Metagenomic next-generation sequencing diagnosis of peripheral pulmonary infectious lesions through virtual navigation, radial EBUS, ultrathin bronchoscopy, and ROSE

Combination of metagenomic next-generation sequencing and conventional tests unraveled pathogen profiles in infected patients undergoing allogeneic hematopoietic stem cell transplantation in Jilin Province of China

Background

Infection is the main cause of death for patients after allogeneic hematopoietic stem cell transplantation (HSCT). However, pathogen profiles still have not been reported in detail due to their heterogeneity caused by geographic region.

Objective

To evaluate the performance of metagenomic next-generation sequencing (mNGS) and summarize regional pathogen profiles of infected patients after HSCT.

Methods

From February 2021 to August 2022, 64 patients, admitted to the Department of Hematology of The First Hospital of Jilin University for HSCT and diagnosed as suspected infections, were retrospectively enrolled.

Results

A total of 38 patients were diagnosed as having infections, including bloodstream (n =17), pulmonary (n =16), central nervous system (CNS) (n =4), and chest (n =1) infections. Human betaherpesvirus 5 (CMV) was the most common pathogen in both bloodstream (n =10) and pulmonary (n =8) infections, while CNS (n =2) and chest (n =1) infections were mainly caused by Human gammaherpesvirus 4 (EBV). For bloodstream infection, Mycobacterium tuberculosis complex (n =3), Staphylococcus epidermidis (n =1), and Candida tropicalis (n =1) were also diagnosed as causative pathogens. Furthermore, mNGS combined with conventional tests can identify more causative pathogens with high sensitivity of 82.9% (95% CI 70.4-95.3%), and the total coincidence rate can reach up to 76.7% (95% CI 64.1-89.4%).

Conclusions

Our findings emphasized the importance of mNGS in diagnosing, managing, and ruling out infections, and an era of more rapid, independent, and impartial diagnosis of infections after HSCT can be expected.

Clinical application of metagenomic next-generation sequencing in patients with different organ system infection: A retrospective observational study

Microbiological identification is essential for appropriate treatment, but conventional methods are time-consuming and have a low sensitivity. In contrast, metagenomic next-generation sequencing (mNGS) is a culture-free and hypothesis-free technique that can detect a wide array of potential pathogens. This study aimed to reveal the overall diagnostic value of mNGS for infectious diseases of different organ systems and compare the sensitivity and specificity of mNGS with conventional methods. In a retrospective cohort study, 94 patients with mNGS results were enrolled, and clinical data were recorded and analyzed to compare the positive rate of mNGS with traditional methods including as smears, serological tests, and traditional PCR, etc. In this study, mNGS and culture were both positive in 12.77% cases and were both negative in 23.4% cases. There were positive results in 56 cases (54.26%) only by mNGS and 4 cases (4.26%) were positive only by culture. There were significant differences in sensitivity of pathogen detection between of ID and NID group for mNGS (χ2 = 10.461, P = .001)and conventional methods(χ2 = 7.963, P = .005). The positive predictive values and negative predictive values of diagnosing infectious disease by mNGS were 94.12% and 30.77%, respectively. mNGS increased the sensitivity rate by approximately 53.66% compared with that of culture (78.05% vs24.39%; χ2 = 47.248, P < .001) and decreased the specificity rate by 12.5% compared with that of culture (66.67% vs 100.0%; χ2 = 4.8, P = .028). mNGS can identify emerging or rare pathogen and further guide treatment regimens. mNGS has advantages in identifying overall pathogens and bacteria, however, there was no obvious advantage in identifying fungi, virus and tuberculosis. mNGS has higher specificity than conventional methods in identifying pathogens and advantages in detecting emerging or rare pathogens.

Joint application of metagenomic next-generation sequencing and histopathological examination for the diagnosis of pulmonary infectious disease

IMPORTANCE

The diagnosis of some pulmonary infectious diseases and their pathogens is very difficult. A more precise diagnosis of pulmonary infectious diseases can help clinicians use proper antibiotics as well as reduce the development of drug-resistant bacteria. In this study, we performed both mNGS and pathology on lung puncture biopsy tissue from patients and found that combined mNGS and histopathology testing was significantly more effective than histopathology testing alone in detecting infectious diseases and identifying infectious diseases. In addition, the combined approach improves the detection rate of pathogenic microorganisms in infectious diseases and can be used to guide precision clinical treatment.

Combination of transbronchial cryobiopsy based clinic-radiologic-pathologic strategy and metagenomic next-generation sequencing for differential diagnosis of rapidly progressive diffuse parenchymal lung diseases

Background

The complicated spectrum of rapidly progressive diffused parenchymal lung diseases (RP-DPLD) creates obstacles to the precise diagnosis and treatment. We evaluated the differential diagnostic value of transbronchial cryobiopsy (TBCB) based clinic-radiologic-pathologic (CRP) strategy combined with bronchoalveolar lavage fluid (BALF) metagenomic next-generation sequencing (mNGS) in RP-DPLD patients.

Methods

RP-DPLD patients who underwent the diagnostic strategy of TBCB-based CRP combined with BALF mNGS at Shanghai East Hospital from May 2020 to Oct 2022 were retrospectively analyzed. Clinical characteristics were summarized, including demographic data, high-resolution computed tomography (HRCT) findings, histopathology of TBCB and microbiological results. Diagnostic value of the combined strategy, as well as the sensitivity, specificity, and positive detection rates of mNGS were evaluated.

Results

A total of 115 RP-DPLD patients were enrolled, with a mean age of 64.4 years old and a male proportion of 54.8%. The pulmonary imaging findings in most patients were complex and diverse, with all patients showing bilateral lung diffuse lesions in HRCT, and progressively aggravated imaging changes within one month. After combining TBCB-based CRP strategy with mNGS, all participants received a corresponding diagnosis with 100% diagnostic yield. In these patients, 58.3% (67/115) were diagnosed with noninfectious RP-DPLD and 41.7% (48/115) with infection-related RP-DPLD. There were 86.1% of cases with known etiology according to the DPLD classification. BALF mNGS and traditional pathogen detection methods were performed in all patients, the positive detection rates were 50.4% (58/115) and 32.2% (37/115), respectively. Meanwhile, the mNGS showed significantly higher sensitivity and negative predictive value than the traditional pathogen detection methods for the diagnosis of infection-related RP-DPLD (100% vs 60.4% (p<0.001), 100% vs 75.6% (p<0.001), respectively). Among noninfectious RP-DPLD patients, the true negative rate of mNGS was 85.1% (57/67). All patients had their treatment regimen modified and the 30-day mortality was 7.0%.

Conclusion

The novel strategy of TBCB-based CRP combined with mNGS provided dependable and sufficient evidence for the diagnosis, meanwhile further improved the accuracy of RP-DPLD treatment, as well as the prognosis of patients. Our results highlight the significant value of combined strategy in determining whether the RP-DPLD patients were infection associated or not.

Metagenomic next-generation sequencing of bronchoalveolar lavage fluid from children with severe pneumonia in pediatric intensive care unit

Background

Severe pneumonia due to lower respiratory tract infections (LRTIs) is a significant cause of morbidity and mortality in children. Noninfectious respiratory syndromes resembling LRTIs can complicate the diagnosis and may also make targeted therapy difficult because of the difficulty of identifying LRTI pathogens. In the present study, a highly sensitive metagenomic next-generation sequencing (mNGS) approach was used to characterize the microbiome of bronchoalveolar lavage fluid (BALF) in children with severe lower pneumonia and identify pathogenic microorganisms that may cause severe pneumonia. The purpose of this study was to use mNGS to explore the potential microbiomes of children with severe pneumonia in a PICU.

Methods

We enrolled patients meeting diagnostic criteria for severe pneumonia admitted at PICU of the Children’s Hospital of Fudan University, China, from February 2018 to February 2020. In total, 126 BALF samples were collected, and mNGS was performed at the DNA and/or RNA level. The pathogenic microorganisms in BALF were identified and correlated with serological inflammatory indicators, lymphocyte subtypes, and clinical symptoms.

Results

mNGS of BALF identified potentially pathogenic bacteria in children with severe pneumonia in the PICU. An increased BALF bacterial diversity index was positively correlated with serum inflammatory indicators and lymphocyte subtypes. Children with severe pneumonia in the PICU had the potential for coinfection with viruses including Epstein–Barr virus, Cytomegalovirus, and Human betaherpesvirus 6B, the abundance of which was positively correlated with immunodeficiency and pneumonia severity, suggesting that the virus may be reactivated in children in the PICU. There was also the potential for coinfection with fungal pathogens including Pneumocystis jirovecii and Aspergillus fumigatus in children with severe pneumonia in the PICU, and an increase in potentially pathogenic eukaryotic diversity in BALF was positively associated with the occurrence of death and sepsis.

Conclusions

mNGS can be used for clinical microbiological testing of BALF samples from children in the PICU. Bacterial combined with viral or fungal infections may be present in the BALF of patients with severe pneumonia in the PICU. Viral or fungal infections are associated with greater disease severity and death.

Metagenomic Next-Generation Sequencing Assists in the Diagnosis of Mediastinal Aspergillus fumigatus Abscess in an Immunocompetent Patient: A Case Report and Literature Review

Background

Aspergillus fumigatus is an opportunistic fungal pathogen, which is commonly found in lungs and rarely causes infections in mediastinum. Mediastinal Aspergillus abscess is a serious infectious condition, and is characterized by difficult diagnosis due to its clinical manifestations being nonspecific.

Case Presentation

Here, we report a case of a mediastinal Aspergillus fumigatus abscess in an immunocompetent patient. The patient was a 45-year-old woman who presented with a 20-day history of sore throat without any underlying diseases. Chest computed tomography (CT) showed a mass in the anterior superior mediastinum. Metagenomic next-generation sequencing (mNGS) identified Aspergillus fumigatus sequences in endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) tissue, indicating the mediastinal Aspergillus fumigatus infection of this patient. The following mediastinal biopsy histological analysis and tissue fungi culture also suggested Aspergillus fumigatus infection, confirming the mNGS detection. The patient was diagnosed with mediastinal aspergillosis caused by Aspergillus fumigatus. After timely voriconazole treatment, the patient was discharged with good condition.

Conclusion

Our study presented a rare case with mediastinal Aspergillus fumigatus abscess in an immunocompetent patient. As a new clinical diagnostic method, mNGS could assist timely diagnosis and precise treatment of Aspergillus infection.

Diagnostic value and safety of ultrathin bronchoscope and endobronchial ultrasonography with a guide sheath combined with rapid on-site evaluation system for peripheral pulmonary infectious diseases

BACKGROUND

The aim of this study was to investigate the diagnostic value and safety of ultrathin bronchoscope and endobronchial ultrasonography with a guide sheath (EBUS-GS) combined with rapid on-site evaluation (ROSE) system for peripheral pulmonary infectious diseases.

METHODS

The clinical data of 196 patients visiting our hospital, who had peripheral pulmonary lesions (PPLs) indicated by spiral computed tomography (CT) of the chest and were finally diagnosed as infectious PPLs, were retrospectively collected. Then the patients were divided into ultrathin bronchoscope + ROSE group, EBUS-GS + ROSE group and ultrathin bronchoscope + EBUS-GS + ROSE group based on different diagnostic techniques. Moreover, the general conditions, diagnostic results and specific operation parameters of the patients were recorded, and the diagnostic rate, sensitivity and complications were compared.

RESULTS

In ultrathin bronchoscope + EBUS-GS + ROSE group, the time of localizing lesions and operation time were the shortest, and the grade of bronchi reached by the bronchoscope was the highest. The differences were significant between any two groups (P<0.05). Patients with bacterial pneumonia, and patients with pulmonary tuberculosis and nontuberculous mycobacterial disease, ultrathin bronchoscope + EBUS-GS + ROSE group exhibited the highest definite diagnosis rate of bronchoscope and diagnostic sensitivity of ROSE system, with significant differences from those of the other two groups (P<0.05). The incidence rates of complications were low in all groups, and there were no significant differences between any two groups (P>0.05).

CONCLUSIONS

Ultrathin bronchoscope and EBUS-GS combined with ROSE system can prominently decrease the time of localizing lesions and operation time, remarkably improve the diagnostic accuracy and sensitivity and result in fewer complications.

Application of metagenomic next-generation sequencing in the diagnosis of urinary tract infection in patients undergoing cutaneous ureterostomy

Objective

Urinary tract infection (UTI) is an inflammatory response of the urothelium to bacterial invasion and is a common complication in patients with cutaneous ureterostomy (CU). For such patients, accurate and efficient identification of pathogens remains a challenge. The aim of this study included exploring utility of metagenomic next-generation sequencing (mNGS) in assisting microbiological diagnosis of UTI among patients undergoing CU, identifying promising cytokine or microorganism biomarkers, revealing microbiome diversity change and compare virulence factors (VFs) and antibiotic resistance genes (ARGs) after infection.

Methods

We performed a case-control study of 50 consecutive CU patients from December 2020 to January 2021. According to the clinical diagnostic criteria, samples were divided into infected group and uninfected group and difference of urine culture, cytokines, microorganism, ARGs and VFs were compared between the two groups.

Results

Inflammatory responses were more serious in infected group, as evidenced by a significant increase in IFN-α (p=0.031), IL-1β (0.023) and IL-6 (p=0.018). Clinical culture shows that there is higher positive rate in infected group for most clinical pathogens like Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Candida auris etc. and the top three pathogens with positive frequencies were E. coli, K. pneumoniae, and Enterococcus faecalis. Benchmarking clinical culture, the total sensitivity is 91.4% and specificity is 76.3% for mNGS. As for mNGS, there was no significant difference in microbiome α- diversity between infected and uninfected group. Three species biomarkers including Citrobacter freundii, Klebsiella oxytoca, and Enterobacter cloacae are enriched in infected group based on Lefse. E. cloacae were significantly correlated with IL-6 and IL-10. K. oxytoca were significantly correlated with IL-1β. Besides, the unweighted gene number and weighted gene abundance of VFs or ARGs are significantly higher in infected group. Notablely, ARGs belonging to fluoroquinolones, betalatmas, fosfomycin, phenicol, phenolic compound abundance is significantly higher in infected group which may have bad effect on clinical treatment for patients.

Conclusion

mNGS, along with urine culture, will provide comprehensive and efficient reference for the diagnosis of UTI in patients with CU and allow us to monitor microbial changes in urine of these patients. Moreover, cytokines (IL-6, IL-1β, and IFN-a) or microorganisms like C. freundii, K. oxytoca or E. cloacae are promising biomarkers for building effective UTI diagnostic model of patients with CU and seriously the VFs and ARGs abundance increase in infected group may play bad effect on clinical treatment.

Diagnostic Value of Metagenomic Next-Generation Sequencing for Pneumonia in Immunocompromised Patients

Introduction

The diagnosis of pulmonary infection and the identification of pathogens are still clinical challenges in immunocompromised patients. Metagenomic next-generation sequencing (mNGS) has emerged as a promising infection diagnostic technique. However, its diagnostic value in immunocompromised patients needs further exploration.

Purposes

This study was to evaluate the diagnostic value of mNGS compared with comprehensive conventional pathogen tests (CTs) in the etiology of pneumonia in immunocompromised patients and immunocompetent patients.

Methods

We retrospectively reviewed 53 patients who were diagnosed with pneumonia from May 2019 to June 2021. There were 32 immunocompromised patients and 21 immunocompetent patients with pneumonia who received both mNGS and CTs. The diagnostic performance was compared between mNGS and CTs in immunocompromised patients, using the composite diagnosis as the reference standard. And, the diagnostic value of mNGS for mixed infections was further analyzed.

Results

Compared to immunocompetent patients, the most commonly pathogens, followed by Cytomegalovirus, Pneumocystis jirovecii and Klebsiella pneumoniae in immunocompromised patients. Furthermore, more mixed infections were diagnosed, and bacterial-fungal-virus coinfection was the most frequent combination (43.8%). mNGS can detect more types of pathogenic microorganisms than CTs in both groups (78.1% vs. 62.5%, P = 0.016and 57.1% vs. 42.9%, P = 0.048). The overall diagnostic positive rate of mNGS for pathogens was higher in immunocompromised patients (P = 0.002). In immunocompromised patients, a comparable diagnostic accuracy of mNGS and CTs was found for bacterial, fungal, and viral infections and coinfection. mNGS had a much higher sensitivity for bacterial infections (92.9% vs. 50%, P < 0.001) and coinfections (68.8% vs. 48.3%, P < 0.05), and it had no significant advantage in the detection of fungal infections, mainly due to the high sensitivity for Pneumocystis jirovecii in both groups.

Conclusion

mNGS is more valuable in immunocompromised patients and exhibits apparent advantages in detecting bacterial and mixed infections. It may be an alternative or complementary diagnostic method for the diagnosis of complicated infections in immunocompromised patients.

Analysis of Negative Results of Metagenomics Next-Generation Sequencing in Clinical Practice

Background

Metagenomics next-generation sequencing (mNGS) has been increasingly used in the clinic, which provides a powerful tool for the etiological diagnosis of infectious diseases. Precise treatment can be carried out according to the positive mNGS results. However, the role of negative results of mNGS remains poorly defined in clinical practice.

Methods

The results of 1,021 samples from patients who received the mNGS test at Zhongshan Hospital, Fudan University, between January 2019 and December 2019 were analyzed.

Results

There were 308 samples (30.17%) of negative results included in the current study. The top 2 types of negative samples were blood (130/308) and tissue (63/308), which also accounted for the highest negative proportion in diseases. Sputum and bronchoalveolar lavage fluid (BALF) were more likely to have positive results. In false-negative results (defined as negative in mNGS test but reported positive in other sample types or assays), 118 samples were found when compared to regular microbiological assays. The negative predictive value (NPV) of mNGS was 95.79% [95%CI, 93.8%–97.8%] as compared to culture and smear. Mycobacterium, Aspergillus, and Mycoplasma ranked as the top 3 microorganisms on the undetected pathogen list.

Conclusions

The present data indicate that when the mNGS test is negative, the negative prediction accuracy rate of the original specimen is significant. However, other laboratory assays results and clinical presentations should always be carefully considered prior to drawing a diagnosis.

Screening Biomarkers and Constructing a Predictive Model for Symptomatic Urinary Tract Infection and Asymptomatic Bacteriuria in Patients Undergoing Cutaneous Ureterostomy: A Metagenomic Next-Generation Sequencing Study

Objectives. To investigate the clinical diagnostic value of differential flora as biomarkers in patients with symptomatic urinary tract infection (UTI) and asymptomatic bacteriuria (ASB) undergoing cutaneous ureterostomy based on metagenomic next-generation sequencing and construct predictive models to provide a scientific reference for clinical diagnosis and treatment. Material and Methods. According to standard procedures, samples were taken from each patient for routine tests (urine, ureteral stent, and skin swab around the stoma). Cytokine levels in the blood were also detected. Urinary microflora were measured by mNGS, and potential biomarkers for distinguishing UTI and ASB were identified by differential flora. Finally, we generated the predictive models for ASB and UTI using the Lasso method and cytokine levels. Results. Urine culture was performed for 50 patients with cutaneous ureterostomy; 44 of these patients developed bacteriuria. The incidence of symptomatic bacteriuria was 54.55%. Biomarker analysis showed that Propionimicrobium lymphophilum, Staphylococcus haemolyticus, Stenotrophomonas maltophilia, Ralstonia insidiosa, and Aspergillus sydowii all had good predictive performance and were combined in a single model. The predictive model exhibited good prediction performance (area under the curve $\left(\text{AUC}\right)=0.8729$ , $\text{sensitivity}=80\%$ , $\text{specificity}=83.3\%$ , and $\text{cutoff}=1.855$ ). We also identified a significant negative correlation between the weight sum of the abundance for these five characteristic pathogens (Sum_weighted_Reads) and levels of the cytokine IL-6 and IL-1β ( $P<0.05$ ). Conclusion. mNGS had a higher positive detection rate for pathogens in urine samples. The selected differential bacteria can be used as biomarkers of ASB and UTI, and the prediction model has good predictive performance. Analysis also showed that the occurrence of symptoms was related to individual immunity. Combined with the Sum_weighted_Reads cutoff and cytokine levels (IL-6 and IL-1β) of differential flora, it was possible to judge the severity of symptoms in cutaneous ureterostomy patients with bacteriuria and provide new insights for the treatment and intervention of ASB and UTI.

Metagenomic Next-Generation Sequencing vs. Traditional Pathogen Detection in the Diagnosis of Infection After Allogeneic Hematopoietic Stem Cell Transplantation in Children

Infection is a severe complication of allo-HSCT in children, however, the accurate detection of the infection is hard. In this study, we traced the records of 101 pediatric recipients with allo-HSCT to investigate the pathogens of infection, and collected 54 bronchoalveolar lavage fluid, 32 blood, and 15 cerebrospinal fluid samples. In these samples, 87 was with post-transplant infection and 14 without infection. Using the metagenomic next-generation sequencing (mNGS) and traditional pathogen detection, we compared their sensitivity and specificity to detect pathogens of infection. Our results showed that mNGS was more sensitive (89.7%) than conventional pathogen detection (21.8%), with a difference of 67.9% (P < 0.001), However, mNGS was less specific (78.5%) than traditional methods (92.9%), with a difference of 14.4% (P = 0.596). The sensitivity of mNGS for diagnosing pulmonary infections, bloodstream infections or viremia, and CNS infections post-transplant were 91.7, 85.7, and 90.9%, respectively. In contrast, the sensitivity of conventional testing for diagnosing pulmonary infections, bloodstream infections or viremia, and CNS infections post-transplant were 22.9, 21.4, and 18.2%, respectively. There were significant differences in the sensitivity of mNGS and conventional testing in BALF, blood, and CSF samples, with P values of 0.000, 0.000, and 0.002 respectively. Among the patients with pulmonary infection, 11 pathogens were both identified by mNGS and conventional testing, and 33 by mNGS only. The percentage with the mNGS-positive result was 44/48 (91.7%), including viruses (n = 12), bacteria (n = 17), fungi (n = 9) and mixed infections (n = 6). Among the patients diagnosed with fungal pneumonia (n = 9), the most prevalent pathogenic fungi were Pneumocystis jiroveci (n = 6), which were also detected in 4 patients with mixed infectious pneumonia. In the 28 blood specimens of patients with bloodstream infections or viremia, five patients were positive by both mNGS and conventional testing, 19 were positive by mNGS, and 1 was positive by traditional testing only. The percentage with the mNGS-positive results was 24/28 (85.7%), including viruses (n = 12), bacteria (n = 4), fungi (n = 3), and mixed infections (n = 5). Of the 15 CSF specimens enrolled, 11 patients were eventually diagnosed with CNS infections. Ten pathogens were identified by mNGS in the 11 patients, including viruses (n = 8), bacteria (n = 1), and fungi (n = 1). These results suggest that mNGS is more sensitive than conventional pathogen detection for diagnosing infections post HSCT in children which may help the clinic diagnosis. Pneumocystis jiroveci was the most frequent pathogen of pulmonary infections post-transplant, while viruses were the most common pathogens of CNS infections in allo-HSCT recipients.

The Diagnostic Value of Metagenomic Next-Generation Sequencing in Lower Respiratory Tract Infection

Lower respiratory tract infections are associated with high morbidity and mortality and significant clinical harm. Due to the limited ability of traditional pathogen detection methods, anti-infective therapy is mostly empirical. Therefore, it is difficult to adopt targeted drug therapy. In recent years, metagenomic next-generation sequencing (mNGS) technology has provided a promising means for pathogen-specific diagnosis and updated the diagnostic strategy for lower respiratory tract infections. This article reviews the diagnostic value of mNGS for lower respiratory tract infections, the impact of different sampling methods on the detection efficiency of mNGS, and current technical difficulties in the clinical application of mNGS.

Functional lower airways genomic profiling of the microbiome to capture active microbial metabolism

BACKGROUND

Microbiome studies of the lower airways based on bacterial 16S rRNA gene sequencing assess microbial community structure but can only infer functional characteristics. Microbial products, such as short-chain fatty acids (SCFAs), in the lower airways have significant impact on the host's immune tone. Thus, functional approaches to the analyses of the microbiome are necessary.

METHODS

Here we used upper and lower airway samples from a research bronchoscopy smoker cohort. In addition, we validated our results in an experimental mouse model. We extended our microbiota characterisation beyond 16S rRNA gene sequencing with the use of whole-genome shotgun (WGS) and RNA metatranscriptome sequencing. SCFAs were also measured in lower airway samples and correlated with each of the sequencing datasets. In the mouse model, 16S rRNA gene and RNA metatranscriptome sequencing were performed.

RESULTS

Functional evaluations of the lower airway microbiota using inferred metagenome, WGS and metatranscriptome data were dissimilar. Comparison with measured levels of SCFAs shows that the inferred metagenome from the 16S rRNA gene sequencing data was poorly correlated, while better correlations were noted when SCFA levels were compared with WGS and metatranscriptome data. Modelling lower airway aspiration with oral commensals in a mouse model showed that the metatranscriptome most efficiently captures transient active microbial metabolism, which was overestimated by 16S rRNA gene sequencing.

CONCLUSIONS

Functional characterisation of the lower airway microbiota through metatranscriptome data identifies metabolically active organisms capable of producing metabolites with immunomodulatory capacity, such as SCFAs.

Metagenomic Next-Generation Sequencing for Pathogenic Diagnosis and Antibiotic Management of Severe Community-Acquired Pneumonia in Immunocompromised Adults

Background

Metagenomic next-generation sequencing (mNGS) is a promising technique for pathogens diagnosis. However, application of mNGS in immunocompromised adults with severe community-acquired pneumonia (SCAP) is relatively limited.

Methods

We retrospectively reviewed 23 immunocompromised and 21 immunocompetent SCAP patients with mNGS detection from April 2019 to December 2019. The performances of pathogenic diagnosis and subsequently antibiotic adjustment in immunocompromised SCAP patients were compared to immunocompetent SCAP patients. The defined by days of therapy (DOT) method was used for estimate daily antibiotic use.

Results

There was a significant difference in the diagnostic positivity rate between mNGS and conventional test in both groups (P<0.001). Compared to immunocompetent patients, more mixed pathogens in immunocompromised patients were found (P=0.023). Before the availability of mNGS, the DOTs in immunocompromise patients were higher than immunocompetent patients (3.0 [3.0, 4.0] vs. 3.0 [2.0, 3.0], P=0.013). Compared to immunocompetent patients, immunocompromised patients had fewer full pathogen covered empirical antibiotic therapy (14.7% vs. 57.1%, P=0.022), more adjustments of antibiotic treatment (87.0%) vs. 57.1%, P=0.027). More than a half (13 of 23) SCAP patients in immunosuppressed group had reduced or downgraded antibiotic adjustments based on the results.

Conclusions

mNGS may be a useful technique for detecting mixed pathogens and personalized antibiotic treatment in immunocompromised SCAP patients.

Application of metagenomic next-generation sequencing (mNGS) combined with rapid on-site cytological evaluation (ROSCE) for the diagnosis of Chlamydia psittaci pneumonia

We evaluated the application of metagenomic next-generation sequencing (mNGS) combined with rapid on-site cytological evaluation (ROSCE) in the diagnosis of Chlamydia psittaci pneumonia, to provide a basis for an accurate diagnosis. Clinical data from three patients with C. psittaci pneumonia diagnosed by the combination of mNGS and ROSCE from June 2019 to June 2020 in the Department of Respiratory and Critical Care Medicine of Tianjin Medical University General Hospital were reviewed. Three patients with community-acquired pneumonia failed to respond to the initial treatment, and were finally diagnosed by bronchoscopic lung biopsy and alveolar lavage fluid (BALF) mNGS. According to the ROSCE cytologic characteristics, the scope of the lesions was narrowed to inflammatory lesions excluding tumor and other non-infectious lesions. Subsequently, mNGS results confirmed that the three patients were infected by C. psittaci, sequence numbers 2066, 126, and 1077, respectively. Two patients developed severe pneumonia and required organ function support. The other patient had recurrent high fever and severe headache, which significantly complicated clinical diagnosis and treatment. Eventually, the treatment plan was adjusted according to the mNGS results, resulting in gradual improvement of symptoms and satisfactory prognosis. mNGS combined with ROSCE is effective for the accurate diagnosis and treatment of C. psittaci pneumonia, having significant advantages in comparison with other detection methods, particularly in the cases of rare pathogens, mixed pathogen infections, and immunodeficient patients.

High-Throughput Metagenomics for Identification of Pathogens in the Clinical Settings

The application of sequencing technology is shifting from research to clinical laboratories owing to rapid technological developments and substantially reduced costs. However, although thousands of microorganisms are known to infect humans, identification of the etiological agents for many diseases remains challenging as only a small proportion of pathogens are identifiable by the current diagnostic methods. These challenges are compounded by the emergence of new pathogens. Hence, metagenomic next-generation sequencing (mNGS), an agnostic, unbiased, and comprehensive method for detection, and taxonomic characterization of microorganisms, has become an attractive strategy. Although many studies, and cases reports, have confirmed the success of mNGS in improving the diagnosis, treatment, and tracking of infectious diseases, several hurdles must still be overcome. It is, therefore, imperative that practitioners and clinicians understand both the benefits and limitations of mNGS when applying it to clinical practice. Interestingly, the emerging third-generation sequencing technologies may partially offset the disadvantages of mNGS. In this review, mainly: a) the history of sequencing technology; b) various NGS technologies, common platforms, and workflows for clinical applications; c) the application of NGS in pathogen identification; d) the global expert consensus on NGS-related methods in clinical applications; and e) challenges associated with diagnostic metagenomics are described.

Diagnosis of complication in lung transplantation by TBLB + ROSE + mNGS

Lung transplantation is a potentially life-saving therapy for patients with terminal respiratory illnesses. Long-term survival is limited by the development of a variety of opportunistic infections and rejection. Optimal means of differential diagnosis of infection and rejection have not been established. With these challenges in mind, we tried to use transbronchial lung biopsy (TBLB) rapid on-site cytological evaluation (ROSE), metagenomic next-generation sequencing (mNGS), and routine histologic examination to timely distinguish infection and rejection, and accurately detect etiologic pathogens. We reviewed the medical records of all patients diagnosed with infection or rejection by these means from December 2017 to September 2018 in our center. We identified seven recipients whose clinical course was complicated by infection or rejection. Three patients were diagnosed with acute rejection, organizing pneumonia, and acute fibrinoid organizing pneumonia, respectively. Four of the seven patients were diagnosed with infections, including Pneumocystis carinii pneumonia, cytomegalovirus, Aspergillus, and bacterial pneumonia. These patients recovered after proper treatment. TBLB + ROSE + mNGS might be a good method to accurately detect etiologic pathogens, which may help us to facilitate the use of targeted and precision medicine therapy in postoperative complications and avoid unnecessary potential adverse effects of drugs.

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.