The clinical significance of in-house metagenomic next-generation sequencing for bronchoalveolar lavage fluid diagnostics in patients with lower respiratory tract infections

Evaluation of Different Sampling Methods Combined with Metagenomic Next-Generation Sequencing of Respiratory Specimens in Etiological Diagnosis of Patients with Severe Pneumonia

Objective

To evaluate the value of respiratory specimens collected via different sampling methods combined with metagenomic next-generation sequencing (mNGS) in the etiological diagnosis of severe pneumonia.

Methods

A total of 117 patients with severe pneumonia between 2019 and 2024 were included in this study, with 60 patients undergoing endotracheal aspiration (ETA) and 57 undergoing bronchoalveolar lavage (BAL), respectively. Patient records were retrospectively reviewed. Both ETA and BAL samples were tested using mNGS and conventional microbiological tests (CMT) to compare the detection rates, microbial profiles and their effects on clinical outcomes.

Results

The positive rates of mNGS for ETA and BAL samples were 96.7% and 80.7%, respectively, which were higher than CMT. A total of 39 pathogenic microorganisms were detected, of which Klebsiella pneumoniae, Candida albicans and herpes simplex virus-4 (HSV-4), and cytomegalovirus (CMV) were the most commonly detected as bacteria, fungi and viruses, respectively. The percentages of Pseudomonas aeruginosa (30.0% vs 12.3%, p = 0.019) and Stenotrophomonas maltophilia (25.0% vs 8.8%, p = 0.020) were significantly higher in the ETA group compared to the BALF group. The detection rate of three or more microorganisms was notably higher in the ETA group. No significant differences existed in antibiotics adjustment between the groups. The ETA group experienced a higher frequency of continuous renal replacement therapy (CRRT), mechanical ventilation and complications. There was no significant difference in the hospital length of stay, duration of mechanical ventilation and mortality between both groups.

Conclusion

Respiratory specimens collected by different sampling methods yield different microbial findings. ETA and BAL combined with mNGS play a role in guiding the pathogenetic diagnosis of patients with severe pneumonia. However, it is recommended that their sampling methods be determined by clinical symptoms and patient conditions.

The diagnostic value of bronchoalveolar lavage fluid metagenomic next-generation sequencing in critically ill patients with respiratory tract infections

Metagenomic next-generation sequencing (mNGS) is an unbiased and rapid method for detecting pathogens. This study enrolled 145 suspected severe pneumonia patients who were admitted to the Affiliated Hospital of Jining Medical University. This study primarily aimed to determine the diagnostic performance of mNGS and conventional microbiological tests (CMTs) using bronchoalveolar lavage fluid samples for detecting pathogens. Our findings indicated that mNGS performed significantly higher sensitivity (97.54% vs 28.68%, P < 0.001), coincidence (90.34% vs 35.17%, P < 0.001), and negative predictive value (80.00% vs 13.21%, P < 0.001) but performed lower specificity than CMTs (52.17% vs 87.5%, P < 0.001). Streptococcus pneumoniae as the most common bacterial pathogen had the largest proportion (22.90%, 30/131) in this study. In addition to bacteria, fungi, and virus, mNGS can detect a variety of atypical pathogens such as Mycobacterium tuberculosis and non-tuberculous. Mixed infections were common in patients with severe pneumonia, and bacterial-fungal-viral-atypical pathogens were the most complicated infection. After adjustments of antibiotics based on mNGS and CMTs, the clinical manifestation improved in 139 (95.86%, 139/145) patients. Our data demonstrated that mNGS had significant advantage in diagnosing respiratory tract infections, especially atypical pathogens and fungal infections. Pathogens were detected timely and comprehensively, contributing to the adjustments of antibiotic treatments timely and accurately, improving patient prognosis and decreasing mortality potentially.IMPORTANCEMetagenomic next-generation sequencing using bronchoalveolar lavage fluid can provide more comprehensive and accurate pathogens for respiratory tract infections, especially when considering the previous usage of empirical antibiotics before admission or complicated clinical presentation. This technology is expected to play an important role in the precise application of antimicrobial drugs in the future.

Association between Clinical Characteristics and Microbiota in Bronchiectasis Patients Based on Metagenomic Next-Generation Sequencing Technology

This study aimed to investigate the disparities between metagenomic next-generation sequencing (mNGS) and conventional culture results in patients with bronchiectasis. Additionally, we sought to investigate the correlation between the clinical characteristics of patients and their microbiome profiles. The overarching goal was to enhance the effective management and treatment of bronchiectasis patients, providing a theoretical foundation for healthcare professionals. A retrospective survey was conducted on 67 bronchiectasis patients admitted to The First Hospital of Jiaxing from October 2019 to March 2023. Clinical baseline information, inflammatory indicators, and pathogen detection reports, including mNGS, conventional blood culture, bronchoalveolar lavage fluid (BALF) culture, and sputum culture results, were collected. By comparing the results of mNGS and conventional culture, the differences in pathogen detection rate and pathogen types were explored, and the diagnostic performance of mNGS compared to conventional culture was evaluated. Based on the various pathogens detected by mNGS, the association between clinical characteristics of bronchiectasis patients and mNGS microbiota results was analyzed. The number and types of pathogens detected by mNGS were significantly larger than those detected by conventional culture. The diagnostic efficacy of mNGS was significantly superior to conventional culture for all types of pathogens, particularly in viral detection (p < 0.01). Regarding pathogen detection rate, the bacteria with the highest detection rate were Pseudomonas aeruginosa (17/58) and Haemophilus influenzae (11/58); the fungus with the highest detection rate was Aspergillus fumigatus (10/21), and the virus with the highest detection rate was human herpes virus 4 (4/11). Differences were observed between the positive and negative groups for P. aeruginosa in terms of common scoring systems for bronchiectasis and whether the main symptom of bronchiectasis manifested as thick sputum (p < 0.05). Significant distinctions were also noted between the positive and negative groups for A. fumigatus regarding Reiff score, neutrophil percentage, bronchiectasis etiology, and alterations in treatment plans following mNGS results reporting (p < 0.05). Notably, 70% of patients with positive A. fumigatus infection opted to change their treatment plans. The correlation study between clinical characteristics of bronchiectasis patients and mNGS microbiological results revealed that bacteria, such as P. aeruginosa, and fungi, such as A. fumigatus, were associated with specific clinical features of patients. This underscored the significance of mNGS in guiding personalized treatment approaches. mNGS could identify multiple pathogens in different types of bronchiectasis samples and was a rapid and effective diagnostic tool for pathogen identification. Its use was recommended for diagnosing the causes of infections in bronchiectasis patients.

Clinical Value of Sampling Time of Metagenomic Next-Generation Sequencing in Patients with Severe Pneumonia

Objective

Severe pneumonia is a common infectious disease with high morbidity and mortality. Early etiological diagnosis is crucial for improving the prognosis. The aim of this study is to evaluate the clinical value of sampling time of mNGS in patients with severe pneumonia.

Methods

This retrospective study enrolled 105 patients with severe pneumonia. mNGS was performed on bronchoalveolar lavage fluid (BALF). Patients were divided into the sampling time ≤ 72h vs sampling time >72h groups and survivors vs non-survivors groups according to their sampling time and prognosis. Clinical characteristics, the adjustment of antibiotics and clinical prognostic value were evaluated.

Results

Our study showed that, early sampling of mNGS can significantly shorten the mechanical ventilation time (p = 0.007) and hospitalization time (p = 0.004). In the non-survivors group, CURB-65, SOFA, and APACHE II scores were higher. Age (OR: 1.051, 95% CI: 1.004-1.100, p = 0.034), chronic respiratory diseases (OR: 4.639, 95% CI: 1.260-17.082, p = 0.021), immunosuppression (OR: 5.008, 95% CI: 1.617-15.510, p = 0.005) and SOFA score on the day of mNGS sampling (OR: 1.492, 95% CI: 1.212-1.837, p < 0.001) were independent risk factors of in-hospital mortality. The most common pathogens were Klebsiella pneumoniae and Human gammaherpesvirus 4. The proportion of appropriate and targeted antibiotics adjusted was significantly higher than that in the sampling time > 72h group, and the proportion of antifungal and antiviral agents adjusted was lower. In the early sampling group, it was significantly decreased in the CRP, PCT level and NEU% at discharge.

Conclusion

This study demonstrated that early sampling of mNGS could shorten the time of mechanical ventilation and hospitalization of patients with severe pneumonia. Patients with higher SOFA score on the day of sampling had a poorer prognosis. It emphasizes that early sampling of mNGS has a positive value.