Application of mNGS in the Etiological Analysis of Lower Respiratory Tract Infections and the Prediction of Drug Resistance

Enhancing the detection sensitivity of mNGS in Bronchoalveolar Lavage Fluid through cell counting: An empirical study

OBJECTIVES

Lower respiratory tract infections pose significant clinical challenges due to their high morbidity and mortality rates. While metagenomic next-generation sequencing (mNGS) has emerged as a promising diagnostic tool, its sensitivity is often compromised by host DNA contamination that overwhelms microbial signals. Selective host DNA depletion through cell lysis effectively reduces host DNA; however, it has an impact on microorganisms with relatively thin cell walls, and samples with low host content may introduce more environment or reagent-derived microbial contamination, interfering the detection results. Methods for determining host DNA depletion based on sample type, sample characteristics or using spike-in controls to monitor sensitivity do not fully consider the potential limitations of host depletion technology on microbial detection, nor do they evaluate the possible significant impact on detection efficiency. This study aimed to develop a pre-analytical method for accurate host DNA content assessment.

METHODS

We established a cell-counting-based method for precise cellular content measurement in clinical bronchoalveolar lavage fluid (BALF) samples. The protocol involved: (1) evaluating the linearity and robustness of cell-counting dyes in BALF samples with varying characteristics, (2) assessing the correlation between cell counts and extracted nucleic acid mass, (3) investigating cellular counting thresholds for host depletion in clinical BALF analysis, and (4) implementing the optimized cell-counting method in clinical mNGS testing to guide selective-lysis treatment.

RESULTS

Acridine orange/propidium iodide (AO/PI) staining demonstrated superior performance compared to trypan blue and 4',6-diamidino-2-phenylindole (DAPI), particularly in turbid and bloody BALF samples. Implementing a host depletion threshold at 1 × 106 cell counts significantly improves pathogen detection rates in high host background samples, while effectively preserving the detection sensitivity for pathogens in moderate and low host background samples.

CONCLUSIONS

Our findings demonstrate that cell counting serves as a reliable pre-analytical tool for determining optimal selective-lysis treatment in BALF mNGS testing, enhancing diagnostic accuracy while preserving pathogen integrity.

Microbiota profiling from biopsied tissues in complex infections: a diagnostic and prognostic analysis through metagenomic next-generation sequencing

Background

Infectious diseases that require tissue biopsy are usually more difficult to diagnose through conventional microbiological tests (CMT), and knowledge of the infection microbiota pattern from biopsied tissues remains incomplete. Our study aimed to investigate the diagnostic and prognostic value of metagenomic next-generation sequencing (mNGS), characterize the microbiota profile from biopsied tissues, and examine its relationship with clinical outcomes.

Methods

This retrospective cohort study included 110 patients who underwent tissue biopsy and sent both mNGS and CMT due to suspected complex infection. Microbiota patterns were illustrated via unsupervised hierarchical clustering analysis. Multivariate regression analysis was used to investigate the effect measures.

Results

The sensitivity of mNGS was significantly higher than that of CMT regarding bacteria (87.23% vs 40.43%, P=0.01), viruses (100% vs 5.56%, P<0.001), and fungi (87.5% vs 28.6%, P=0.04). Polymicrobial infection accounted for 45.2% (33/73) of the infection samples. In skeletal articular biopsied tissues, Staphylococcus presented the highest mean abundance among different species of bacteria (21.2% of all bacterial reads, standard deviation (SD) 38.9). Anaerobic bacteria (24.0%, SD 25.9) represented the most common bacteria in biopsied tissue from the lung or mediastinum. The presence of gram-negative bacteria (adjusted OR 5.21, 95% CI 1.39-19.43, P=0.01), Enterobacteriaceae (adjusted OR 5.71, 95% CI 1.17-28.03, P=0.03) and Staphylococcus (adjusted OR 8.64, 95% CI 1.95-38.34, P=0.005) was associated with an increased risk of treatment failure. Early mNGS sampling within 7 days after admission was associated with a significantly decreased risk of all-cause mortality (HR 0.18, 95% CI 0.04-0.94; P=0.04), treatment failure (OR 0.17, 95% CI 0.05-0.66; P=0.01), and increased probability of clinical resolution (OR 3.03, 95% CI 1.24-7.40; P=0.01).

Conclusion

mNGS demonstrates significant diagnostic and prognostic efficacy in patients undergoing tissue biopsy for suspected complex infections. The presence of Gram-negative bacteria, Enterobacteriaceae, and Staphylococcus is associated with a higher probability of treatment failure, which underscores the advantage of using mNGS to guide more aggressive antibiotic strategies.

Metagenomic next-generation sequencing of bronchoalveolar lavage fluid samples offers diagnostic utility in bacteriologically negative pulmonary tuberculosis

Rapid diagnosing Mycobacterium tuberculosis (M. tb) in patients with pulmonary tuberculosis (PTB) cases is critical, particularly in cases without bacteriologically confirmed disease, as it enables timely treatment initiation and can thus interrupt further disease transmission. In this study, the utility of metagenomic next-generation sequencing (mNGS) as a diagnostic tool was evaluated using samples of bronchoalveolar lavage fluid (BALF) samples from 300 bacteriologically negative PTB (BN-PTB) patients hospitalized from January 2020 through December 2023. The diagnostic performance of mNGS was compared to that of acid-fast staining (AFS), conventional Roche culture, and the Xpert method among these BN-PTB patients, using clinical diagnosis as the gold standard. The final analyses enrolled 112 PTB patients and 188 non-PTB cases. These analyses revealed that mNGS-based M. tb detection yields a sensitivity of 94.64 % (106/112), a specificity of 98.94 % (186/188), a positive predictive value (PPV) of 98.15 % (106/108), and a negative predictive value (NPV) of 96.88 % (186/192). This mNGS approach outperformed the AFS, Roche culture, and Xpert methods in terms of sensitivity, specificity, PPV, and NPV (p < 0.05). The superior diagnostic performance of this approach was further supported by its area under the curve and corresponding confidence intervals. Together, these data demonstrate that mNGS can improve the detection of M. tb in BALF samples from BN-PTB patients with high levels of speed, sensitivity, and specificity. This mNGS approach may thus be a valuable diagnostic tool for the rapid detection of M. tb in BN-PTB, providing a foundation for the precision diagnosis and treatment of PTB in the future.

Metagenomic analysis of pathogenic microorganisms in bloodstream infections following venomous snakebites

PURPOSE

This study aimed to investigate the biometric characterization of pathogenic microorganisms associated with bloodstream infections in patients bitten by venomous snakes, and to determine whether the composition of these microorganisms influences the effects of snake venom.

METHODS

The composition and relative abundance of microorganisms were statistically analyzed using metagenomic next-generation sequencing (mNGS) on blood samples from patients with varying degrees of snakebite injuries. These patients were admitted to the our study.

RESULTS

In the light injury group (group L), the dominant phylum and genus were Pseudomonadota (73.31%) and Pseudomonas (35.32%). In the moderate injury group (group M), the predominant phylum was Bacillota (56.74%) and Aerococcus (45.45%). There was no statistically significant difference in the microbial composition between group L and group M based on α- and β-diversity analyses. LEfSe differential analysis revealed that the absolute abundances of Actinomycetota and Actinomycetes were higher in group L, while Pseudomonas aeruginosa emerged as a significantly differential species in Group M.

CONCLUSION

The study found that differences in bacterial bloodstream infections due to venomous snakebite may enhance the effects of snake venom, leading to more severe injuries. The mNGS technique can rapidly detect pathogens related to venomous snakebites and has the potential for broader clinical use.

Rapid and accurate diagnosis of urinary tract infections using targeted next-generation sequencing: A multicenter comparative study with metagenomic sequencing and traditional culture methods

BACKGROUND

Urinary tract infections (UTIs) rank among the most prevalent bacterial infections globally. Traditional urine culture methods have significant limitations in detection time and sensitivity, prompting the need to evaluate targeted next-generation sequencing (tNGS) as a potential diagnostic tool.

METHODS

The study included a discovery cohort of 400 suspected UTI patients (202 analyzed) and a validation cohort of 200 patients (110 analyzed). The study assessed detection time, concordance rates, ability to identify polymicrobial infections, and antibiotic resistance genes (ARGs). Both clear and turbid urine samples were evaluated across different clinical settings.

RESULTS

In the discovery cohort, tNGS demonstrated 96.5% concordance with culture-positive samples, while showing superior specificity in culture-negative specimens (53.1% vs 28.1% for mNGS). Detection time for tNGS (12.89 h) was notably shorter than mNGS (17.38 h) and traditional culture (61.48 h). tNGS exhibited remarkable capability in identifying polymicrobial infections (55.4% of samples), significantly outperforming both mNGS (27.7%) and traditional culture methods, which failed to detect any co-infections. The method showed particular strength in detecting fastidious organisms like Ureaplasma parvum and fungal species such as Candida tropicalis. For antibiotic resistance prediction, tNGS detected more ARGs (52.67% vs 41.22% for mNGS) and achieved 100% sensitivity for vancomycin and methicillin resistance in Gram-positive pathogens. The validation cohort confirmed tNGS's robust performance, maintaining high concordance rates for both culture-positive (90.00%) and culture-negative samples (55.00%), demonstrating consistent reliability across different clinical settings CONCLUSIONS: tNGS demonstrates advantages in rapid and accurate UTI diagnosis, particularly in detecting polymicrobial infections and analyzing antibiotic resistance genes. It shows promise as an effective complementary tool for UTI diagnostics.

Integrating DNA and RNA sequencing for enhanced pathogen detection in respiratory infections

BACKGROUND

The clinical value of shotgun metagenomic next-generation sequencing (mNGS) in improving the detection rates of respiratory pathogens is well-established. However, mNGS is complex and expensive. This study designed and evaluated the performance of targeted NGS (tNGS) in diagnosing respiratory infections.

METHODS

We retrospectively included samples from 281 patients with lower respiratory tract infections to establish thresholds of pathogens. Subsequently, target pathogens were selected and a probe hybridization system was established. The performance and clinical manifestations of tNGS for 306 pathogens were evaluated using clinical and simulated samples.

RESULTS

The tNGS method took 16 h with sequencing data sizes of 5 M reads. The limit-of-detection of tNGS was 100-200 CFU/mL, respectively. Bioinformatics simulation confirmed the method's high specificity and robustness. In 281 patients of clinical validation cohort, tNGS exhibited a sensitivity of 97.73% and specificity of 75.41% compared to the composite reference standard, which notably surpasses those of culture-based and conventional microbiological methods (CMT). In detecting bacterial and viral infection, tNGS demonstrated superior sensitivity relative to CMT. Notably, 61.40% of target viruses were subtype-resolved with the initial establishment of reliable typing cutoffs, with the subtyping results being completely consistent with the PCR results. tNGS allowed for concurrent identification of antimicrobial resistance (AMR) markers and viral subtyping. 80.56% of AMR markers identified by tNGS were consistent with antimicrobial susceptibility testing.

CONCLUSION

This research established the robust performance of our tailored tNGS assay in the simultaneous detection of DNA and RNA pathogens, underscoring its prospective suitability for widespread use in clinical diagnostics.

Prospective study on diagnostic efficacy of targeted NGS vs. traditional testing for respiratory infections in myelosuppressed hematology patients

Background

Respiratory tract infections are a significant complication in myelosuppressed hematological patients, especially those with myelosuppression. Traditional microbiological testing methods often show limitations in sensitivity, turnaround time, and cost, making them less effective in this vulnerable population. This study aimed to evaluate the diagnostic efficacy of targeted next-generation sequencing (tNGS) compared to traditional microbiological testing methods (TMT) in detecting respiratory infections among myelosuppressed hematological patients.

Methods

This prospective study included 20 patients aged ≥15 years with myelosuppressed hematological disease and respiratory infection, admitted to the hematology department of Fuyang People's Hospital between January and May 2024. Eligible patients underwent both 198-pathogen respiratory tract infection targeted NGS panel (198-pathogen RTI tNGS panel) and TMT. Exclusion criteria included refusal of tNGS or incomplete sputum collection. The diagnostic performance of 198-pathogen RTI tNGS panel was assessed against TMT, with diagnoses confirmed by three independent hematology experts. The study adhered to ethical guidelines and obtained informed consent from all participants.

Results

tNGS demonstrated a 100% pathogen detection rate compared to 40% with traditional testing (p < 0.001). It identified a broader spectrum of pathogens, including bacteria, viruses, and fungi, many of which were missed by TMT. The most common pathogens isolated in the clinical specimens detected by TMT was Epstein-Barr virus. The most common pathogens isolated in the clinical specimens detected by 198-pathogen RTI tNGS was novel coronavirus, human respiratory syncytial virus type B, and influenza A virus. The sensitivity of tNGS was 94.74%, with a positive predictive value of 100%. The turnaround time for tNGS was significantly shorter, averaging 24 h, enabling quicker adjustments to antimicrobial therapy. In 75% of cases, the tNGS results directly influenced changes in treatment regimens, improving clinical outcomes.

Conclusion

tNGS offers superior sensitivity, a broader pathogen detection range, and a faster turnaround time compared to traditional microbiological testing methods. It provides a practical and efficient diagnostic option for respiratory infections in hematological patients, particularly those unable to undergo invasive procedures such as bronchoalveolar lavage. The use of tNGS may enhance clinical management and improve patient outcomes in this population.

Host DNA depletion assisted metagenomic sequencing of bronchoalveolar lavage fluids for diagnosis of pulmonary tuberculosis

Metagenomic next-generation sequencing (mNGS) has greatly improved our understanding of pathogens in infectious diseases such as pulmonary tuberculosis (PTB). However, high human DNA background (> 95%) impedes the detection sensitivity of mNGS in identifying intracellular Mycobacterium tuberculosis (MTB), posing a pressing challenge for MTB diagnosis. Therefore, there is an urgent need to improve MTB diagnosis performance in PTB patients. In this study, we optimized mNGS method for diagnosis of PTB. This led to the development of the host DNA depletion assisted mNGS (HDA-mNGS) technique, which we compared with conventional mNGS and the host DNA depletion-assisted Nanopore sequencing (HDA-Nanopore) in diagnostic performance. We collected 105 bronchoalveolar lavage fluid (BALF) samples from suspected PTB patients across three medical centers to assess the clinical performance of these methods. The results of our study showed that HDA-mNGS had the highest sensitivity (72.0%) and accuracy (74.5%) in PTB detection. This was significantly higher compared to mNGS (51.2%, 58.2%) and HDA-Nanopore (58.5%, 62.2%). Furthermore, HDA-mNGS provided an increased coverage of the MTB genome by up to 16-fold. Antibiotic resistance gene analysis indicated that HDA-mNGS could provide increased depth to the detection of Antimicrobial resistance (AMR) locus more effectively. These findings indicate that HDA-mNGS can significantly improve the clinical performance of PTB diagnosis for BALF samples, offering great potential in managing antibiotic resistance in PTB patients.

Application of metagenomic next-generation sequencing (mNGS) to describe the microbial characteristics of diabetic foot ulcers at a tertiary medical center in South China

BACKGROUND

Diabetic foot ulcers (DFUs) are characterized by dynamic wound microbiome, the timely and accurate identification of pathogens in the clinic is required to initiate precise and individualized treatment. Metagenomic next-generation sequencing (mNGS) has been a useful supplement to routine culture method for the etiological diagnosis of DFUs. In this study, we utilized a routine culture method and mNGS to analyze the same DFU wound samples and the results were compared.

METHODS

Forty samples from patients with DFUs at a tertiary medical center in South China were collected, the microorganisms were identified with mNGS and routine culture method simultaneously.

RESULTS

The results showed that the positive detection rate of microorganisms in DFUs with mNGS was much higher (95% vs. 60%). Thirteen strains of microorganisms were detected with routine culture method, and seventy-seven strains were detected with mNGS. Staphylococcus aureus was the most common microorganism detected with culture method, while Enterococcus faecalis was the most common microorganism detected with mNGS. The false negative rate of the culture method was 35%, that was, 14 samples with negative results with culture method were found to be positive with mNGS.

CONCLUSION

The mNGS method had a higher positive detection rate and identified a broader spectrum of microorganisms in DFUs, thus, mNGS provided a more comprehensive understanding of the microbiome of DFUs to facilitate the development of timely and optimal treatment.

TRIAL REGISTRATION

The study was conducted in accordance with the Declaration of Helsinki and approved by the Ethical Review Committee of the Fujian Medical University Union Hospital (approval number 2021KY054).

The role of metagenomic next-generation sequencing in diagnosing and managing post-kidney transplantation infections

Kidney transplantation (KT) is a life-saving treatment for patients with end-stage renal disease, but post-transplant infections remain one of the most significant challenges. These infections, caused by a variety of pathogens, can lead to prolonged hospitalization, graft dysfunction, and even mortality, particularly in immunocompromised patients. Traditional diagnostic methods often fail to identify the causative organisms in a timely manner, leading to delays in treatment and poorer patient outcomes. This review explores the application of metagenomic next-generation sequencing (mNGS) in the diagnosis of post-KT infections. mNGS allows for the rapid, comprehensive detection of a wide range of pathogens, including bacteria, viruses, fungi, and parasites, without the need for culture-based techniques. We discuss the advantages of mNGS in early and accurate pathogen identification, its role in improving patient management, and the potential challenges in its clinical implementation. Additionally, we consider the future prospects of mNGS in overcoming current diagnostic limitations and its potential for guiding targeted therapies, particularly in detecting antimicrobial resistance and emerging pathogens. This review emphasizes the promise of mNGS as an essential tool in improving the diagnosis and treatment of infections in KT recipients.

Comparison of the Impact of tNGS with mNGS on Antimicrobial Management in Patients with LRTIs: A Multicenter Retrospective Cohort Study

Background

tNGS and mNGS are valuable tools for diagnosing pathogens in lower respiratory tract infections (LRTIs), which subsequently influence treatment strategies. However, the impact of tNGS and mNGS on antimicrobial stewardship in patients with LRTIs remains unclear.

Methods

Patients diagnosed with LRTIs who underwent tNGS or mNGS between June 2021 and January 2024 were included. Patients who underwent both tNGS and conventional microbiologic tests (CMTs) were grouped into the tNGS group, the others were divided into the mNGS group. Then, the diagnostic efficacy of tNGS and mNGS was compared, along with their impact on antimicrobial management and clinical outcomes.

Results

548 patients with an initial diagnosis of LRTIs who underwent tNGS or mNGS were evaluated. Finally, 321 patients were analyzed, with 117 patients in tNGS group and 204 patients in mNGS group. The overall pathogen detection rates for tNGS and mNGS were 89.74% and 89.71% (P=0.991). The distribution of detected pathogens was similar between tNGS and mNGS, with bacteria being the predominant microorganisms. The proportions of patients who underwent antimicrobial agent changes and received targeted therapy were not significantly different between tNGS and mNGS groups (P=0.270; P=0.893). Additionally, no significant differences were noted in the rates of antibiotic de-escalation, escalation, or changes in the opposite direction (all P>0.05). The same results was observed in the proportions of patients with addition or reductions in antiviral, antifungal, and antibacterial agents (all P>0.05). Hospital stays, improvement rate and mortality rate were also similar (all P>0.05).

Conclusion

tNGS and mNGS demonstrate comparable overall pathogen yield rates in patients with LRTIs. Furthermore, tNGS is also comparable to mNGS in terms of adjusting antimicrobial treatments and clinical outcomes, tNGS meets the clinical needs of most patients with LRTIs and can be firstly used for these patients.

Application of bronchoalveolar lavage fluid cytomorphology in diagnosing Nocardia otitidiscaviarum: a case report

BACKGROUND

Nocardiosis is a rare infectious disease, which is frequently underdiagnosed because of the distinct bacterial shape of the causative agent and its developmental history. The morphological analysis of bronchoalveolar lavage fluid can facilitate the detection of pathogenic bacteria by observing cellular-bacterial interactions.

CASE PRESENTATION

An immunocompetent 67-year-old male patient of Asian ethnicity developed a cough without apparent cause 20 days earlier. We initially discovered mycobacteria that appeared to be Nocardia in the cytomorphological examination of bronchoalveolar lavage fluid, which was later determined to be Nocardia otitidiscaviarum through metagenomic next-generation sequencing and microbiological cultures. The patient was eventually diagnosed with Nocardia pneumonitis after other testing and clinical signs were considered. After anti-infective treatment, the patient improved and was discharged.

CONCLUSION

Several diagnostic approaches were used in this case, and the importance of cell morphology as an early screening method was emphasized for suspected Nocardia infection.

Characteristics, symptoms, and outcomes of patients with Vibrio vulnificus infection in Hainan, China: A retrospective study

With global temperatures on the rise and an expanding seafood trade, infections by Vibrio vulnificus, particularly in warm coastal areas like Hainan, China, are increasingly prevalent. These bacteria are notorious for causing grave infections with a high fatality rate. This study aims to dissect the clinical features, laboratory findings, treatment modalities, and patient outcomes associated with V vulnificus infections in Hainan Province. The medical records and clinical data of intensive care unit patients from Hainan General Hospital were retrospectively analyzed. Conventional sequencing and metagenomic sequencing were used to identify V vulnificus. The study involved 10 patients (9 males and 1 female) with a median age of 60.5 years, predominantly fishermen, with infections mainly occurring between May and October. Of note, 2 cases were linked to plant-related injuries. The typical manifestations included fever, pain, swelling, hemorrhagic vesicles, septic shock, and multi-organ dysfunction. It was found that delayed hospital admissions were associated with elevated Sequential Organ Failure Assessment and Acute Physiology and Chronic Health Evaluation II scores and increased mortality. Laboratory results indicated a robust inflammatory response, and interventions comprised antibiotic therapy and surgical procedures. A mortality rate of 50% was recorded. Vigilance for V vulnificus infections is crucial in coastal locales. The study endorses immediate and assertive treatment strategies, including the use of targeted antibiotics and surgical interventions, to enhance patient survival rates. A call for heightened awareness, intensified surveillance, and expanded research is essential to combat this life-threatening condition.

Multiple skin abscesses due to Nocardia neocaledoniensis: a case report and literature review

N. neocaledoniensis is a very rare infectious pathogen that causes human disease, particularly in immunocompromised individuals. In this case report, we describe the successful diagnosis of N. neocaledoniensis in a patient confirmed by mNGS and the treatment of multiple skin abscesses due to N. neocaledoniensis infection. mNGS is an important diagnostic method complementary to routine bacterial culture and identification methods, especially for rare, novel, co-infected pathogens, and pathogens that are difficult to culture. This report may provide a reference for the clinical treatment and diagnosis of N. neocaledoniensis infection in humans.

Development of prediction models for carbapenem-resistant Klebsiella pneumoniae acquisition and prognosis in adult patients

Objectives

To explore the risk factors and clinical outcomes of carbapenem-resistant Klebsiella pneumoniae (CRKP) infection and establish nomograms to predict the probability of CRKP infection and mortality in adult patients.

Methods

Patients infected with KP from August 2019 to April 2021 in a tertiary hospital in Shanghai were enrolled. Risk factors associated with CRKP and 30-day mortality were identified using multivariate logistic regression analysis and Cox regression analysis.

Results

Overall, 467 patients with KP infection were enrolled, wherein 210 (45.0%) patients were infected with CRKP and 257 (55.0%) patients with carbapenem-susceptible K. pneumoniae (CSKP). Five factors, namely Charlson's Comorbidity Index (CCI) ≥ 3, the use of central venous catheterization, prior hospitalization during the 3 months before infection, and previous exposure to carbapenems and broad-spectrum β-lactams, were found to be independently associated with CRKP infection. Based on these parameters, the nomogram showed a better performance as indicated by C-index of 0.94 (95% confidence interval [CI]: 0.92-0.96) and well-fitted calibration curves. CRKP was independently associated with 30-day mortality. Multivariate Cox regression analysis revealed that age ≥65 years, higher CCI scores, higher Sequential Organ Failure Assessment scores, the presence of respiratory failure, albumin levels ≤30 g/L, and non-appropriate treatments in 3 days, were associated with 30-day mortality.

Conclusion

The predictive nomogram established in this study can facilitate the clinicians to make better clinical decisions when treating patients with KP infection.

An Investigation into Diagnostic Strategies for Central Nervous System Infections Through the Integration of Metagenomic Next-Generation Sequencing and Conventional Diagnostic Methods

Purpose

The optimal strategy for detecting central nervous system infections (CNSI) in cerebrospinal fluid (CSF) samples remains unclear.

Methods

In a one-year, multicenter retrospective study, we examined the efficacy of metagenomic next-generation sequencing (mNGS) in comparison to conventional pathogen diagnostic techniques for CSF in diagnosing CNSI. We calculated the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and Youden index for each diagnostic approach. Additionally, receiver operating characteristic (ROC) curves were constructed, and the area under the curve (AUC) was determined to assess the diagnostic performance of each method.

Results

The study included 68 patients, comprising both adults and children, who were suspected of having CNSI. Through the application of comprehensive clinical interpretation (CCI), the sensitivity and specificity of mNGS were found to be 67.6% (95% confidence interval [CI]: 50.85-80.87%) and 45.8% (95% CI: 27.89-64.92%), respectively. In comparison, traditional pathogenic diagnostic methods indicated that the culture method demonstrated a sensitivity of 10.6% (95% CI: 4.63-22.6%) and a specificity of 100% (95% CI: 84.54-100%). Furthermore, the sensitivity and specificity of the peripheral blood nucleated cell count were determined to be 34.0% (95% confidence interval: 22.17-48.33%) and 57.1% (95% confidence interval: 36.54-75.53%), respectively. CSF nucleated cell count demonstrated a sensitivity of 66.0% (95% confidence interval [CI]: 51.67-77.83%) and a specificity of 61.9% (95% CI: 40.87-79.25%). In comparison, the CSF protein content exhibited a sensitivity of 63.8% (95% CI: 49.54-76.03%) and a specificity of 57.1% (95% CI: 36.54-75.53%). When combining mNGS with traditional methodologies, the overall sensitivity increased to 91.3% (95% CI: 79.67-96.56%), although the specificity was reduced to 18.2% (95% CI: 7.31-38.51%). The area under the ROC curve for culture, peripheral blood nucleated cell count, mNGS, CSF nucleated cell count, and CSF protein content were 0.8088, 0.6038, 0.6103, 0.5588, and 0.5588, respectively. The variation in CSF nucleated cell count did not significantly affect the diagnostic efficacy of mNGS.

Conclusion

Currently, both mNGS and traditional diagnostic methods encounter substantial challenges in diagnosing CNSI.

Epidemiological characteristics of severe community-acquired pneumonia in children admitted to two tertiary hospitals in Shihezi, Xinjiang Region, China in 2023: a cross-sectional analysis

Background

Severe community-acquired pneumonia (SCAP) in children is associated with high morbidity and mortality, and the data of epidemiological characteristics of SCAP in Shihezi area were inadequate. The main pathogens responsible for SCAP may vary dramatically according to the geographical area. We identified two tertiary hospitals with better medical level and the largest number of hospitalized children in Shihezi as sentinel hospitals. The primary purpose of the study is to cross-sectionally summarize the epidemiological characteristics of SCAP in children admitted to hospitals in Shihezi, Xinjiang, China in 2023.

Methods

SCAP was defined as involving the respiratory and other systems, accompanied by significant systemic toxic symptoms. We prospectively included all patients <15 years old who diagnosed with SCAP according to the SCAP diagnostic criteria. We enrolled all patients <15 years who were diagnosed with SCAP during the study period (January to December 2023), a total of 309 cases were included from two sentinel hospitals in Shihezi, Xinjiang, from January to December 2023. Basic information and clinical data were collected on a standardized questionnaire, and respiratory samples were obtained for the detection of 27 respiratory pathogens using a panel, targeted next-generation sequencing (t-NGS), and metagenomic next-generation sequencing (mNGS).

Results

We enrolled 309 patients aged 1-14 years: 157 males (50.8%) and 152 females (49.2%). There were 45 infants (1 month to 1 year, 14.6%), 33 toddlers (>1-3 years, 10.7%), 121 preschool children (>3-7 years, 39.2%), and 110 school-age children (>7-14 years, 35.6%). Overall, the number of SCAP cases in spring was 39 (12.6%), in summer was 44 (14.2%), in autumn was 137 (44.3%), and in winter was 89 (28.8%). A total of 572 pathogens were detected in this study, primarily Mycoplasma pneumoniae (MP) (n=120, 21.0%), respiratory syncytial virus (RSV) (n=82 strains, 14.3%), and Streptococcus pneumoniae (SP) (n=67, 11.7%). MP was prevalent mainly during the cold season of autumn, with its detection starting from July and reaching a peak detection rate in November. By studying the interaction among 22 common respiratory pathogens, we found a strong negative correlation between MP and SP, yet the highest number of co-infected cases involved MP and SP. Seventy-six (63.3% of all MP) SCAP were identified as macrolide-resistant (all with mutations at the A2063G site). MP SCAP was associated with prolonged illness duration and fever spikes. We observed incidence of pediatric SCAP showed an inverse trend with PM2.5 level changes.

Conclusions

The most common pathogens responsible for SCAP in the Shihezi region in 2023 were MP, RSV, and SP. MP was the primary cause of SCAP in children, and increased risk of co-infections, and high prevalence of macrolides resistance-all related to mutations at the A2063G site. Early identification of SCAP pathogen epidemiological characteristics can reduce severe case occurrence.

Advantages of metagenomic next-generation sequencing in the management of ANCA-associated vasculitis patients with suspected pulmonary infection as a rule-out tool

OBJECTIVE

Pulmonary infection is one of the leading causes of death in patients with ANCA-associated vasculitis (AAV). It is sometimes difficult to differentiate pulmonary infection from pulmonary involvement of vasculitis in AAV patients. Fiberoptic bronchoscopy and bronchoalveolar lavage fluid (BALF) assays are useful diagnostic methods. In addition to conventional microbiological tests (CMTs), metagenomic next-generation sequencing (mNGS) facilitates rapid and sensitive detection of various pathogens. The current study aimed to evaluate the advantages of additional BALF mNGS in the management of pulmonary infection in AAV patients.

METHODS

27 patients with active AAV and suspected pulmonary infection whose BALF samples were tested by mNGS and CMTs and 17 active AAV patients whose BALF were tested by CMTs alone were retrospectively recruited. The results of microbiological tests, and adjustments of treatment following BALF mNGS, were described. The durations of antimicrobial treatment and in-hospital mortality in patients were compared.

RESULTS

Among the 27 patients whose BALF samples were tested by mNGS, 25.9% of patients did not have evidence of pathogenic microorganism in their BALF samples, 55.6% had polymicrobial infections, including bacteria, fungi and viruses. Of these 27 patients, 40.7% did not have evidence of pathogenic microorganism in their BALF or serum samples according to CMTs. Patients in the BALF mNGS/CMT group received a significantly shorter duration of antibacterial and total antimicrobial treatment than patients in the CMT alone group (17.3 ± 14.7 vs. 27.9 ± 19.0 days, P = 0.044; 18.9 ± 15.0 vs. 29.5 ± 17.7 days, P = 0.040, respectively). Fewer patients in the BALF mNGS/CMT group died than in the CMT alone group (4/27 vs. 7/17, P = 0.049).

CONCLUSION

Compared with CMT alone, additional mNGS tests may shorten the duration of antimicrobial treatment and possibly decrease death from severe infection by providing precise and quick diagnosis of infection.

Comparative analysis of metagenomic and targeted next-generation sequencing for pathogens diagnosis in bronchoalveolar lavage fluid specimens

Background

Although the emerging NGS-based assays, metagenomic next-generation sequencing (mNGS) and targeted next-generation sequencing (tNGS), have been extensively utilized for the identification of pathogens in pulmonary infections, there have been limited studies systematically evaluating differences in the efficacy of mNGS and multiplex PCR-based tNGS in bronchoalveolar lavage fluid (BALF) specimens.

Methods

In this study, 85 suspected infectious BALF specimens were collected. Parallel mNGS and tNGS workflows to each sample were performed; then, we comparatively compared their consistency in detecting pathogens. The differential results for clinically key pathogens were confirmed using PCR.

Results

The microbial detection rates of BALF specimens by the mNGS and tNGS workflows were 95.18% (79/83) and 92.77% (77/83), respectively, with no significant difference. mNGS identified 55 different microorganisms, whereas tNGS detected 49 pathogens. The comparative analysis of mNGS and tNGS revealed that 86.75% (72/83) of the specimens were complete or partial concordance. Particularly, mNGS and tNGS differed significantly in detection rates for some of the human herpesviruses only, including Human gammaherpesvirus 4 (P<0.001), Human betaherpesvirus 7 (P<0.001), Human betaherpesvirus 5 (P<0.05) and Human betaherpesvirus 6 (P<0.01), in which tNGS always had higher detection rates. Orthogonal testing of clinically critical pathogens showed a total coincidence rate of 50% for mNGS and PCR, as well as for tNGS and PCR.

Conclusions

Overall, the performance of mNGS and multiplex PCR-based tNGS assays was similar for bacteria and fungi, and tNGS may be superior to mNGS for the detection of DNA viruses. No significant differences were seen between the two NGS assays compared to PCR.

Efficacy of targeted next generation sequencing for pathogen detection in lower respiratory tract infections

OBJECTIVE

To investigate the diagnostic utility of targeted next-generation sequencing (tNGS) in the diagnosis of lower respiratory tract infections.

METHODS

Patients with lower respiratory tract infection in East Area of Yantai Yantaishan Hospital from December 2021 to September 2023 were retrospectively analyzed. Sputum samples were tested using both tNGS technology and conventional microbiological examination. Data were collected on general clinical features and test outcomes. The study evaluated the efficacy of tNGS by comparing its positive detection rate against traditional methods and analyzing detection differences among patients with varying clinical characteristics. Receiver operating characteristic (ROC) analysis was used to determine the diagnostic accuracy of both testing methods.

RESULTS

A total of 281 patients were included, with corresponding sputum specimens. The tNGS method showed a higher positivity rate of 90.0%, significantly outperforming the conventional method's rate of 70.82% (P<0.05). Among 199 patients with concordant positive results, 38.22% fully agreed, while 53.40% completely disagreed between the two methods. Mycobacterium tuberculosis, Candida albicans, and Pseudomonas aeruginosa were the most frequently detected pathogens, respectively. tNGS significantly reduced the time required for pathogen detection (P<0.001) and identified a higher rate of mixed infections compared to conventional methods (49.11% vs 2.85%, P<0.001). Positive tNGS detection rates significantly differed between patients with abnormal vs normal C-reactive protein or procalcitonin levels. The AUC for tNGS was 0.867, indicating superior diagnostic accuracy over the conventional method (P<0.05).

CONCLUSIONS

tNGS technology demonstrates a high positivity rate and rapid pathogen detection in lower respiratory tract infections, with notable advantages in identifying mixed infections. This method shows potential for enhancing diagnostic accuracy and treatment decisions in clinical settings.

Severe community-acquired pneumonia caused by Chlamydia abortus in China: a case report

Background

Chlamydia abortus causes abortions in ruminants; it can also cause miscarriages and stillbirths in pregnant women. However, it rarely causes pneumonia in humans. Here, we report a case of severe community-acquired pneumonia caused by C. abortus.

Case presentation

On admission to our hospital, a 74-year-old woman reported that she had had a fever, cough, phlegm in her throat, and shortness of breath for 10 days. In the local hospital, she was initially diagnosed with community-acquired pneumonia and treated with piperacillin-tazobactam for 4 days. However, her condition worsened, and she was therefore transferred to our hospital. On arrival at our emergency department, she was diagnosed with severe community-acquired pneumonia and treated with a high-flow nasal cannula and meropenem; she was then transferred to the Department of Respiratory Medicine. There, her condition continued to worsen despite continued treatment with the high-flow nasal cannula and omadacycline. After 24 h and emergency tracheal intubation, the patient was sent to the intensive care unit (ICU) for further treatment. The doctors in the ICU again adjusted the treatment, this time to meropenem along with mechanical ventilation; they also instituted methylprednisolone, ulinastatin, nadroparin calcium, and human immunoglobulin. In addition, bronchoalveolar lavage fluid was sent for metagenomic next-generation sequencing (mNGS). Subsequent mNGS suggested the presence of C. abortus, sequence number 5072; we therefore discontinued the meropenem and implemented a combination of doxycycline and moxifloxacin. After 8 days of treatment in the ICU, the patient's condition improved; she was then extubated and, 3 days later, transferred back to the respiratory medicine department. The respiratory physician continued to administer doxycycline and moxifloxacin for 4 days, after which the patient was discharged with medication. A month later, a repeat computed tomography (CT) scan of the chest suggested that the lesions in both lungs had been largely absorbed.

Conclusion

C. abortus can occasionally cause pneumonia in humans and, rarely, severe, life-threatening pneumonia. mNGS is uniquely suited for the early detection of this unusual infection. The combination of doxycycline and quinolones has been shown to be effective in severe pneumonia caused by C. abortus.

Integrative analyses identify opportunistic pathogens of patients with lower respiratory tract infections based on metagenomic next-generation sequencing

Lower respiratory tract infections (LRTIs) represent some of the most globally prevalent and detrimental diseases. Metagenomic next-generation sequencing (mNGS) technology has effectively addressed the requirement for the diagnosis of clinical infectious diseases. This study aimed at identifying and classifying opportunistic pathogens from the respiratory tract-colonizing microflora in LRTI patients using data acquired from mNGS analyses. A retrospective study was performed employing the mNGS data pertaining to the respiratory samples derived from 394 LRTIs patients. Linear discriminant analysis effect size (LEfSe) analysis was conducted to discern the discriminant bacteria. Receiver operating characteristic curves (ROC) were established to demonstrate discriminant bacterial behavior to distinguish colonization from infection. A total of 443 discriminant bacteria were identified and segregated into three cohorts contingent upon their correlation profiles, detection frequency, and relative abundance in order to distinguish pathogens from colonizing microflora. Among them, 119 emerging opportunistic pathogens (cohort 2) occupied an average area under the curve (AUC) of 0.976 for exhibiting the most prominent predictability in distinguishing colonization from infection, 39 were colonizing bacteria (cohort 1, 0.961), and 285 were rare opportunistic pathogens (cohort 3, 0.887). The LTRIs patients appeared modular in the form of cohorts depicting complex microbial co-occurrence networks, reduced diversity, and a high degree of antagonistic interactions in the respiratory tract microbiome. The study findings indicate that therapeutic interventions should target interaction networks rather than individual microbes, providing an innovative perspective for comprehending and combating respiratory infections. Conclusively, this study reports a profile of LRTIs-associated bacterial colonization and opportunistic pathogens in a relatively large-scale cohort, which might serve as a reference panel for the interpretation of mNGS results in clinical practice.

Diagnostic Role of Metagenomic Next-Generation Sequencing in Tubercular Orthopedic Implant-Associated Infection

Objective

The diagnosis of tubercular orthopedic implant-associated infection (TB-IAI) is challenging. This study evaluated the value of metagenomic next-generation sequencing (mNGS) for the diagnosis of TB-IAI and developed a standardized diagnostic procedure for TB-IAI.

Methods

The records of all patients with TB-IAI diagnosed and treated at our institution between December 2018 and September 2022 were retrospectively reviewed. Patient demographic characteristics, medical history, laboratory test, microbial culture, histopathology, and mNGS results, and time to diagnosis were recorded. The diagnostic efficiency of mNGS for TB-IAI was assessed by comparing the results and diagnostic time with that of other diagnostic modalities.

Results

Ten patients were included in the analysis, including eight with prosthetic joint infections and two with fracture-related infections. The mNGS positivity rate was 100% (10/10), which was higher than that of TB-antibody (11%, 1/9), real-time quantitative polymerase chain reaction (22%, 2/9), T-SPOT.TB (25%, 2/8), purified protein derivative (50%, 4/8), microbial culture (50%, 5/10), and histopathology (20%, 2/10). mNGS shortened the time to diagnosis of TB-IAI. A standardized diagnostic procedure for TB-IAI was developed based on the findings.

Conclusion

mNGS is useful for the diagnosis of TB-IAI. mNGS is recommended in cases where it is difficult to identify a pathogen using routine diagnostic tests. The standardized diagnostic procedure might improve TB-IAI diagnosis.

Importance

TB-IAI is a rare infection, which occurs after orthopedic surgery and hard to diagnose microbiologically. mNGS is a new detection technique not yet discussed in current literature as a means for TB-IAI diagnostics. Here we describe a cohort of patients with TB-IAI diagnosed by mNGS show high efficiency of mNGS for detection of this pathology and present a clinical algorithm supplementing conventional methods for TB-IAI assessment.

Diagnostic value of DNA or RNA-based metagenomic next-generation sequencing in lower respiratory tract infections

Objectives

We aimed to evaluate and compare the diagnostic performance of RNA-mNGS and DNA-mNGS workflow in bacterial pneumonia, fungal pneumonia and tuberculosis.

Methods

A total of 134 cases suspected pneumonia undergoing both DNA and RNA based mNGS of bronchoalveolar lavage fluid (BALF) and also traditional etiological examination were evaluated retrospectively.Sensitivity, specificity, PPV, NPV and accuracy rate of DNA and RNA based mNGS were estimated.

Results

In the diagnosis performance of bacterial pathogens in LRTIs,the specificity of RNA-mNGS was higher than that of DNA-mNGS(82.3 % vs. 61.9 %, P < 0.01). There was no significant difference of sensitivity between the two process(71.4 % vs. 85.7 %, P = 0.375).In the diagnosis performance of fungal pathogens in LRTIs,the specificity of RNA-mNGS was higher than that of DNA-mNGS (72.3 % vs. 27.3 %,p < 0.001). There was no significant difference of sensitivity between the two process(96.5 % vs. 98.8 %,p = 0.125).In the diagnosis performance of tuberculosis in LRTIs,the sensitivity of DNA-mNGS was higher than that of RNA-mNGS (91.7 % vs. 33.3 %,p = 0.016),the specificity was similar in the two process (100 %).

Conclusions

RNA-mNGS may reduced the misdiagnosis rate of bacterial and fungal pathogens in LRTIs.Compared to RNA-mNGS, DNA-mNGS may could improve the diagnostic rate of tuberculosis.

Antimicrobial resistance prediction by clinical metagenomics in pediatric severe pneumonia patients

BACKGROUND

Antimicrobial resistance (AMR) is a major threat to children's health, particularly in respiratory infections. Accurate identification of pathogens and AMR is crucial for targeted antibiotic treatment. Metagenomic next-generation sequencing (mNGS) shows promise in directly detecting microorganisms and resistance genes in clinical samples. However, the accuracy of AMR prediction through mNGS testing needs further investigation for practical clinical decision-making.

METHODS

We aimed to evaluate the performance of mNGS in predicting AMR for severe pneumonia in pediatric patients. We conducted a retrospective analysis at a tertiary hospital from May 2022 to May 2023. Simultaneous mNGS and culture were performed on bronchoalveolar lavage fluid samples obtained from pediatric patients with severe pneumonia. By comparing the results of mNGS detection of microorganisms and antibiotic resistance genes with those of culture, sensitivity, specificity, positive predictive value, and negative predictive value were calculated.

RESULTS

mNGS detected bacterial in 71.7% cases (86/120), significantly higher than culture (58/120, 48.3%). Compared to culture, mNGS demonstrated a sensitivity of 96.6% and a specificity of 51.6% in detecting pathogenic microorganisms. Phenotypic susceptibility testing (PST) of 19 antibiotics revealed significant variations in antibiotics resistance rates among different bacteria. Sensitivity prediction of mNGS for carbapenem resistance was higher than penicillins and cephalosporin (67.74% vs. 28.57%, 46.15%), while specificity showed no significant difference (85.71%, 75.00%, 75.00%). mNGS also showed a high sensitivity of 94.74% in predicting carbapenem resistance in Acinetobacter baumannii.

CONCLUSIONS

mNGS exhibits variable predictive performance among different pathogens and antibiotics, indicating its potential as a supplementary tool to conventional PST. However, mNGS currently cannot replace conventional PST.

Epidemiologic analysis of antimicrobial resistance in hospital departments in China from 2022 to 2023

Bacterial drug resistance monitoring in hospitals is a crucial aspect of healthcare management and a growing concern worldwide. In this study, we analysed the bacterial drug resistance surveillance in our hospital from 2022 Q1 to 2023 Q2. The main sampling sources were respiratory, blood, and urine-based, and the main clinical infections were respiratory and genitourinary in nature. Specimens were inoculated and cultured; bacterial strains were isolated using a VITEK® 2 Compact 60-card automatic microorganism identifier (bioMerieux, Paris, France) and their matching identification cards were identified, and manual tests were supplemented for strain identification. The most common Gram-positive bacteria detected were Staphylococcus aureus, followed by Enterococcus faecalis (E. faecalis), Staphylococcus epidermidis (S. epidermidis), and Staphylococcus haemolyticus (S. haemolyticus). The most common Gram-negative bacteria detected were Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The most prevalent multidrug-resistant bacteria were those producing extended-spectrum beta-lactamases, followed by methicillin-resistant Staphylococcus aureus, followed by carbapenem-resistant Enterobacterales. This study suggests that the prevention and control of infections in the respiratory and genitourinary systems should be the focus of anti-infective work and that the use of antimicrobials should be reduced and regulated to prevent the emergence and spread of resistant bacteria.

Simultaneous identification of DNA and RNA pathogens using metagenomic sequencing in cases of severe acute respiratory infection

Metagenomic next-generation sequencing (mNGS) is a valuable technique for identifying pathogens. However, conventional mNGS requires the separate processing of DNA and RNA genomes, which can be resource- and time-intensive. To mitigate these impediments, we propose a novel method called DNA/RNA cosequencing that aims to enhance the efficiency of pathogen detection. DNA/RNA cosequencing uses reverse transcription of total nucleic acids extracted from samples by using random primers, without removing DNA, and then employs mNGS. We applied this method to 85 cases of severe acute respiratory infections (SARI). Influenza virus was identified in 13 cases (H1N1: seven cases, H3N2: three cases, unclassified influenza type: three cases) and was not detected in the remaining 72 samples. Bacteria were present in all samples. Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii were detected in four influenza-positive samples, suggesting coinfections. The sensitivity and specificity for detecting influenza A virus were 73.33% and 95.92%, respectively. A κ value of 0.726 indicated a high level of concordance between the results of DNA/RNA cosequencing and SARI influenza virus monitoring. DNA/RNA cosequencing enhanced the efficiency of pathogen detection, providing a novel capability to strengthen surveillance and thereby prevent and control infectious disease outbreaks.

Determination of Ideal Factors for Early Adoption and Standardization of Metagenomic Next-generation Sequencing for Respiratory System Infections

BACKGROUND

Metagenomic next-generation sequencing (mNGS) demonstrates great promise as a diagnostic tool for determining the cause of pathogenic infections. The standard diagnostic procedures (SDP) include smears and cultures and are typically viewed as less sensitive and more time-consuming when compared to mNGS. There are concerns about the logistics and ease of transition from SDP to mNGS. mNGS lacks standardization of collection processes, databases, and sequencing. Additionally, there is the burden of training clinicians on interpreting mNGS results.

OBJECTIVE

Until now, few studies have explored factors that could be used as early adoption candidates to ease the transition between SDP and mNGS. This study evaluated 123 patients who had received both SDP and mNGS and compared several variables across a diagnostic test evaluation.

METHODS

The diagnostic test evaluation observed metrics such as sensitivity, specificity, positive and negative likelihood ratios (PLR, NLR), positive and negative predictive values (PPV, NPV), and accuracy. Factors included various sample sources such as bronchoalveolar lavage fluid (BALF), lung tissue, and cerebral spinal fluid (CSF). An additional factor observed was the patient's immune status.

RESULTS

Pathogen detection was found to be significantly greater for mNGS for total patients, BALF sample source, CSF sample source, and non-immunocompromised patients (p<0.05). Pathogen detection was found to be insignificant for lung tissue sample sources and immunocompromised patients. Sensitivity, PLR, NLR, PPV, NPV, and accuracy appeared to be higher with mNGS for the total patients, BALF sample source, and non-immunocompromised patients when compared with SDP (p<0.05).

CONCLUSION

With higher metrics in sensitivity, specificity, PLR, NLR, PPV, NPV, and accuracy for overall patients, mNGS may prove a better diagnostic tool than SDP. When addressing sample sources, mNGS for BALF-collected samples appeared to have higher scores than SDP for the same metrics. When patients were in a non-immunocompromised state, mNGS also demonstrated greater diagnostic benefits to BALF and overall patients compared to SDP. This study demonstrates that using BALF as a sample source and selecting non-immunocompromised patients may prove beneficial as early adoption factors for mNGS standard protocol. Such a study may pave the road for mNGS as a routine clinical method for determining the exact pathogenic etiology of lung infections.

Economic impact of metagenomic next-generation sequencing versus traditional bacterial culture for postoperative central nervous system infections using a decision analysis mode: study protocol for a randomized controlled trial

IMPORTANCE

Diagnosing and treating postoperative central nervous system infections (PCNSIs) remains challenging due to the low detection rate and time-consuming nature of traditional methods for identifying microorganisms in cerebrospinal fluid. Metagenomic next-generation sequencing (mNGS) technology provides a rapid and comprehensive understanding of microbial composition in PCNSIs by swiftly sequencing and analyzing the microbial genome. The current study aimed to assess the economic impact of using mNGS versus traditional bacterial culture-directed PCNSIs diagnosis and therapy in post-neurosurgical patients from Beijing Tiantan Hospital. mNGS is a relatively expensive test item, and whether it has the corresponding health-economic significance in the clinical application of diagnosing intracranial infection has not been studied clearly. Therefore, the investigators hope to explore the clinical application value of mNGS detection in PCNSIs after neurosurgery.

Application of Multiplex Fluorescence Polymerase Chain Reaction for Detecting Pathogenic Bacteria in Sputum Samples from Patients with Lower Respiratory Tract Infection

Objective

In this study, we conducted a multi-center research on six common lower respiratory tract pathogens using novel multiplex fluorescence quantitative polymerase chain reaction (PCR), and investigated the additional diagnostic value of this method, to provide a molecular diagnostic basis for clinical practice.

Methods

From March 2019 to October 2021, a total of 2047 respiratory sputum samples were collected from Hunan Provincial People's Hospital (the First Affiliated Hospital of Hunan Normal University), Hunan Provincial Children's Hospital, Jiangxi Provincial Children's Hospital, and Wuhan Infectious Disease Hospital. The samples were analyzed using a novel multiplex fluorescence quantitative PCR method for Klebsiella pneumoniae, Streptococcus pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, Legionella pneumophila, and Staphylococcus aureus. The results were compared to the results of bacterial culture and sequencing, as well as the results of third-party kits.

Results

Compared to the bacterial culture method, 2047 samples were detected with a sensitivity of 100%, a specificity of 72.22%, and an overall compliance rate of 81.91%. Compared to the sequencing method, the positive agreement percentage was 99.88%, the negative agreement percentage was 97.72%, and the overall agreement rate was 98.84%. Compared to similar control reagents, the positive agreement percentage was 100%, negative agreement percentage was 79.79%, and overall compliance rate was 96.19%.

Conclusion

The multiplex fluorescence PCR method has the advantages of simultaneously detecting multiple pathogenic bacteria and reducing the duration of pathogen culture identification. Combined detection can increase the detection rate, which has favorable performance and application prospects.

Secondary Infection Surveillance with Metagenomic Next-Generation Sequencing in COVID-19 Patients: A Cross-Sectional Study

Background

Metagenomic next-generation sequencing (mNGS) is a promising tool for improving antimicrobial therapy and infection control decision-making in complex infections. Secondary infection surveillance using mNGS in COVID-19 patients has rarely been reported.

Methods

Respiratory pathogen and antibiotic resistance prediction were evaluated by BALF mNGS for 192 hospitalized COVID-19 patients between December 2022 and February 2023.

Results

Secondary infection was confirmed in 83.3% (160/192) of the COVID-19 patients, with bacterial infections (45%, 72/160) predominating, followed by mixed bacterial and fungal infections (20%, 32/160), and fungal infections (17.5%, 28/160). The incidence of bacterial or viral secondary infection was significantly higher in patients who were admitted to the ICU, received mechanical ventilation, or developed severe pneumonia (all p<0.05). Klebsiella pneumoniae (n=30, 8.4%) was the most prevalent pathogen associated with secondary infection followed by Acinetobacter baumannii (n=29, 8.1%), Candida albicans (n=29, 8.1%), Aspergillus fumigatus (n=27, 7.6%), human herpes simplex virus type 1 (n=23, 6.4%), Staphylococcus aureus (n=20, 5.6%) and Pneumocystis jiroveci (n=14, 3.9%). The overall concordance between the resistance genes detected by mNGS and the reported phenotypic resistance in 69 samples containing five clinically important pathogens (ie, K. pneumoniae, A. baumannii, S. aureus, P. aeruginosa and E. coli) that caused secondary infection was 85.5% (59/69).

Conclusion

mNGS can detect pathogens causing secondary infection and predict antimicrobial resistance for COVID19 patients. This is crucial for initiating targeted treatment and rapidly detect unsuspected spread of multidrug-resistant pathogens.

Diagnosis and treatment of Whipple disease after kidney transplantation: A case report

BACKGROUND

Kidney transplantation is the standard treatment for end-stage renal disease. Particularly, rare and specific pathogenic infections which are asymptomatic are often difficult to diagnose, causing delayed and ineffective treatment and thus seriously affecting prognosis. Tropheryma whipplei (T. whipplei) is a Gram-positive actinomycete widely found in soil, sewage, and other external environments and is present in the population as an asymptomatic pathogen. There is relatively little documented research on T. whipplei in renal transplant patients, and there are no uniform criteria for treating this group of post-transplant patients. This article describes the treatment of a 42-year-old individual with post-transplant T. whipplei infection following kidney transplantation.

CASE SUMMARY

To analyze clinical features of Whipple's disease and summarize its diagnosis and treatment effects after renal transplantation. Clinical data of a Whipple's disease patient treated in the affiliated hospital of Guizhou Medical University were collected and assessed retrospectively. The treatment outcomes and clinical experience were then summarized via literature review. The patient was admitted to the hospital due to recurrent diarrhea for 1 mo, shortness of breath, and 1 wk of fever, after 3 years of renal transplantation. The symptoms of the digestive and respiratory systems were not significantly improved after adjusting immunosuppressive regimen and anti-diarrheal, empirical antibiotic treatments. Bronchoscopic alveolar fluid was collected for meta-genomic next-generation sequencing (mNGS). The deoxyribonucleic acid sequence of Tropheryma whipplei was detected, and Whipple's disease was diagnosed. Meropenem, ceftriaxone, and other symptomatic treatments were given, and water-electrolyte balance was maintained. Symptoms resolved quickly, and the patient was discharged after 20 d of hospitalization. The compound sulfamethoxazole tablet was continued for 3 mo after discharge. No diarrhea, fever, and other symptoms occurred during the 6-month follow-up.

CONCLUSION

Whipple's disease is rare, with no specific symptoms, which makes diagnosis difficult. Polymerase chain reaction or mNGS should be immediately performed when the disease is suspected to confirm the diagnosis.

Microbial Community Characterization and Molecular Resistance Monitoring in Geriatric Intensive Care Units in China Using mNGS

Background

Surface pathogens in the ICU pose a global public health threat, especially to elderly patients who are immunocompromised. To detect these pathogens, unbiased methods such as metagenomic next-generation sequencing (mNGS) are increasingly utilized for environmental microbiological surveillance.

Methods

In a six-month study from January to July 2022, we investigated microbial communities in Chinese geriatric ICUs by regularly monitoring multiple surfaces at three-month intervals. Using mNGS sequencing, we analyzed microorganisms present at eight specific locations within the ICU. Additionally, we compared pathogen profiles and drug resistance genes between patient cultures and environmental samples collected during the same period.

Results

The microbial composition remained relatively stable over time, but significant differences in alpha diversities were observed among various surfaces such as floors, hands, pumps, trolleys, and ventilator inlets/outlets. Surfaces with high contact frequency for healthcare workers, including workstations, ventilator panels, trolleys, pumps, and beds, harbored pathogenic microorganisms such as Acinetobacter baumannii, Cutibacterium acnes, Staphylococcus haemolyticus, Pseudomonas aeruginosa, and Enterococcus faecium. Acinetobacter baumannii, particularly the carbapenem-resistant strain (CRAB), was the most frequently identified pathogen in geriatric ICU patients regardless of testing method used. The mNGS approach enabled detection of viruses, fungi, and parasites that are challenging to culture. Additionally, an abundance of drug resistance genes was found in almost all environmental samples.

Conclusion

The microbial composition and abundance in the ICU remained relatively constant over time. The floor exhibited the highest microbial diversity and abundance in the ICU environment. Drug-resistant genes in the ICU environment may migrate between patients. Overall, mNGS is an emerging and powerful tool for microbiological monitoring of the hospital environment.

Clinical features and treatment outcomes of Vibrio vulnificus infection in the coastal city of Ningbo, China

Background

Vibrio vulnificus is a gram-negative, opportunistic pathogen common to warm waters worldwide. Human V. vulnificus infection is rare and typically affects those residing in coastal areas during the summer months, but it causes rapid deterioration and is fatal.

Methods

The medical records of six patients with sepsis caused by V. vulnificus infection who were treated at the First Affiliated Hospital of Ningbo University from 2020 to 2022 were retrospectively reviewed. The patient demographics, clinical symptoms, laboratory test results, treatments, and outcomes are summarized.

Results

Vibrio vulnificus infection was confirmed by blood or pus culture, 16S ribosomal DNA sequencing, and metagenomic next-generation sequencing. All six patients were male with pre-existing liver diseases and two reported consuming seafood before the onset of symptoms. Of the six patients, four succumbed to the disease, two recovered, and one underwent leg amputation.

Conclusion

Vibrio vulnificus infection progresses rapidly and is highly fatal, thus prompt and aggressive treatment is necessary. Vibrio vulnificus infection should be considered in older (>40 years) patients with a history of liver disease and recent consumption of seafood or exposure to seawater, especially those residing in coastal areas during the summer months.

Building a nomogram plot based on the nanopore targeted sequencing for predicting urinary tract pathogens and differentiating from colonizing bacteria

Background

The identification of uropathogens (UPBs) and urinary tract colonizing bacteria (UCB) conduces to guide the antimicrobial therapy to reduce resistant bacterial strains and study urinary microbiota. This study established a nomogram based on the nanopore-targeted sequencing (NTS) and other infectious risk factors to distinguish UPB from UCB.

Methods

Basic information, medical history, and multiple urine test results were continuously collected and analyzed by least absolute shrinkage and selection operator (LASSO) regression, and multivariate logistic regression was used to determine the independent predictors and construct nomogram. Receiver operating characteristics, area under the curve, decision curve analysis, and calibration curves were used to evaluate the performance of the nomogram.

Results

In this study, the UPB detected by NTS accounted for 74.1% (401/541) of all urinary tract microorganisms. The distribution of ln(reads) between UPB and UCB groups showed significant difference (OR = 1.39; 95% CI, 1.246-1.551, p < 0.001); the reads number in NTS reports could be used for the preliminary determination of UPB (AUC=0.668) with corresponding cutoff values being 7.042. Regression analysis was performed to determine independent predictors and construct a nomogram, with variables ranked by importance as ln(reads) and the number of microbial species in the urinary tract of NTS, urine culture, age, urological neoplasms, nitrite, and glycosuria. The calibration curve showed an agreement between the predicted and observed probabilities of the nomogram. The decision curve analysis represented that the nomogram would benefit clinical interventions. The performance of nomogram with ln(reads) (AUC = 0.767; 95% CI, 0.726-0.807) was significantly better (Z = 2.304, p-value = 0.021) than that without ln(reads) (AUC = 0.727; 95% CI, 0.681-0.772). The rate of UPB identification of nomogram was significantly higher than that of ln(reads) only (χ^2 = 7.36, p-value = 0.009).

Conclusions

NTS is conducive to distinguish uropathogens from colonizing bacteria, and the nomogram based on NTS and multiple independent predictors has better prediction performance of uropathogens.

Application of metagenomic next-generation sequencing in the diagnosis of pulmonary invasive fungal disease

Background

Metagenomic next-generation sequencing (mNGS) is increasingly being used to detect pathogens directly from clinical specimens. However, the optimal application of mNGS and subsequent result interpretation can be challenging. In addition, studies reporting the use of mNGS for the diagnosis of invasive fungal infections (IFIs) are rare.

Objective

We critically evaluated the performance of mNGS in the diagnosis of pulmonary IFIs, by conducting a multicenter retrospective analysis. The methodological strengths of mNGS were recognized, and diagnostic cutoffs were determined.

Methods

A total of 310 patients with suspected pulmonary IFIs were included in this study. Conventional microbiological tests (CMTs) and mNGS were performed in parallel on the same set of samples. Receiver operating characteristic (ROC) curves were used to evaluate the performance of the logarithm of reads per kilobase per million mapped reads [lg(RPKM)], and read counts were used to predict true-positive pathogens.

Result

The majority of the selected patients (86.5%) were immunocompromised. Twenty species of fungi were detected by mNGS, which was more than was achieved with standard culture methods. Peripheral blood lymphocyte and monocyte counts, as well as serum albumin levels, were significantly negatively correlated with fungal infection. In contrast, C-reactive protein and procalcitonin levels showed a significant positive correlation with fungal infection. ROC curves showed that mNGS [and especially lg(RPKM)] was superior to CMTs in its diagnostic performance. The area under the ROC curve value obtained for lg(RPKM) in the bronchoalveolar lavage fluid of patients with suspected pulmonary IFIs, used to predict true-positive pathogens, was 0.967, and the cutoff value calculated from the Youden index was −5.44.

Conclusions

In this study, we have evaluated the performance of mNGS-specific indicators that can identify pathogens in patients with IFIs more accurately and rapidly than CMTs, which will have important clinical implications.

Application value of blood metagenomic next-generation sequencing in patients with connective tissue diseases

Objective

This study aimed to analyze the application value of blood metagenomic next-generation sequencing (mNGS) in patients with connective tissue diseases (CTDs) to provide a reference for infection diagnosis and guidance for treatment.

Methods

A total of 126 CTD patients with suspected infections who were hospitalized in the Department of Rheumatology, the Second Hospital of Shanxi Medical University from January 2020 to December 2021 were enrolled in this study. We retrospectively reviewed the results of mNGS and conventional diagnostic tests (CDTs).

Results

Systemic lupus erythematosus (SLE) and polymyositis/dermatomyositis (DM/PM) had the highest incidence of infections. The positive pathogen detection rates of mNGS were higher than those of CDT. The virus infections are the most common type in CTD patients with single or mixed infection, especially Human gammaherpesvirus 4 (EBV), Human betaherpesvirus 5 (CMV), and Human alphaherpesvirus 1. The incidence of prokaryote and eukaryote infections is secondary to viruses. Bloodstream infections of rare pathogens such as Pneumocystis jirovecii should be of concern. Meanwhile, the most common mixed infection was bacterial–virus coinfection.

Conclusion

mNGS has incremental application value in patients with CTD suspected of co-infection. It has a high sensitivity, and a wide detection range for microorganisms in CTD patients. Furthermore, the high incidence of opportunistic virus infections in CTD patients should be of sufficient concern.

Risk Factors and Outcome of Sepsis in Traumatic Patients and Pathogen Detection Using Metagenomic Next-Generation Sequencing

Objective

Sepsis, a life-threatening clinical syndrome, is a leading cause of mortality after experiencing multiple traumas. Once diagnosed with sepsis, patients should be given an appropriate empiric antimicrobial treatment followed by the specific antibiotic therapy based on blood culture due to its rapid progression to tissue damage and organ failure. In this study, we aimed to analyze the risk factors and outcome of sepsis in traumatic patients and to investigate the performance of metagenomic next-generation sequencing (mNGS) compared with standard microbiological diagnostics in post-traumatic sepsis.

Methods

The study included 528 patients with multiple traumas among which there were 142 cases with post-traumatic sepsis. Patients' demographic and clinical data were recorded. The outcome measures included mortality during the emergency intensive care unit (EICU), EICU length of stay (LOS), all-cause 28-day mortality, and total ventilator days in 28 days after admission. A total of 89 blood samples from 89 septic patients underwent standard microbiological blood cultures and 89 samples of peripheral blood (n = 21), wound secretion (n = 41), bronchoalveolar lavage fluid (BALF) (19), ascites (n = 5), and sputum (n = 3) underwent mNGS. Pathogen detection was compared between standard microbiological blood cultures and mNGS.

Results

The sepsis group and non-sepsis group exhibited significant differences regarding shock on admission, blood transfusion, mechanical ventilation, body temperature, heart rate, WBC count, neutrophil count, hematocrit, urea nitrogen, creatinine, CRP, D-D dimer, PCT, scores of APACHE II, sequential organ failure assessment (SOFA), and Injury Severity Score (ISS) on admission to the EICU, and Multiple Organ Dysfunction Syndromes (MODS) (P < 0.05). Multivariate logistic regression analysis showed that scores of APACHE II, SOFA, and ISS on admission, and MODS were independent risk factors for the occurrence of sepsis in patients with multiple traumas. The 28-day mortality was higher in the sepsis group than in the non-sepsis group (45.07% vs. 19.17%, P < 0.001). The mortality during the EICU was higher in the sepsis group than in the non-sepsis group (P=0.002). The LOS in the EICU in the sepsis group was increased compared with the non-sepsis group (P=0.004). The total ventilator days in 28 days after admission in the sepsis group was increased compared with the non-sepsis group (P < 0.001). Multivariate logistic regression analysis showed that septic shock, APACHE II score on admission, SOFA score, and MODS were independent risk factors of death for patients with post-traumatic sepsis. The positive detection rate of mNGS was 91.01% (81/89), which was significantly higher than that of standard microbiological blood cultures (39.33% (35/89)). Standard microbiological blood cultures and mNGS methods demonstrated double positive results in 33 (37.08%) specimens and double-negative results in 8 (8.99%) specimens, while 46 (51.69%) samples and 2 (2.25%) samples had positive results only with mNGS or culture alone, respectively.

Conclusion

Our study identifies risk factors for the incidence and death of sepsis in traumatic patients and shows that mNGS may serve as a better diagnostic tool for the identification of pathogens in post-traumatic sepsis than standard microbiological blood cultures.