Metagenomic next-generation sequencing reveals microbial community characteristics during acute exacerbations of interstitial pneumonia and their associations with clinical phenotypes.

Objective: Accurate pathogen detection is crucial for clinical management of interstitial lung diseases (ILDs), but conventional culture methods (CMT) have limited sensitivity. This study evaluated the diagnostic performance of metagenomic next-generation sequencing (mNGS) versus CMT in ILD patients and characterized differences in lower respiratory microbiome between stable (Stable) and acute exacerbation (AE) stage, as well as their associations with clinical indicators. Methods: We retrospectively analyzed ILD patients admitted between September 2021 and November 2023. Multidisciplinary discussion (MDT)-based comprehensive diagnosis served as the reference standard. We compared the sensitivity, specificity, and accuracy of mNGS and CMT. Microbiome analyses were performed to assess community composition and diversity in the Stable and AE groups, and to explore correlations with clinical features (e.g., frequency of exacerbations, oxygenation index, inflammatory markers). Results: The sensitivity of mNGS (95.60%) was significantly higher than that of CMT (32.20%). In 61.80% of patients, only mNGS yielded positive results, highlighting its diagnostic advantage. A total of 77 microorganisms were detected; bacteria accounted for 66.67% (e.g., Streptococcus pneumoniae, Haemophilus parainfluenzae). Among fungi, Candida albicans and Pneumocystis jirovecii predominated. Microbial diversity was significantly lower in the AE group than in the Stable group ( Conclusion: Patients in the AE group exhibited altered microbial community structures, and increased fungal colonization may be associated with disease progression, suggesting new targets for clinical intervention.