Abstract：Objective: To analyze the application value of BAL combined with mNGS in detecting pathogens of secondary pulmonary infection in immunosuppressed patients. Methods: The clinical data of 60 patients with immunosuppressed secondary lung infections admitted to our hospital from January 2022 to June 2024 were retrospectively analysed. All patients underwent traditional pathogenicity testing and BAL combined with mNGS testing, and the positivity rate of pathogen detection, the distribution of pathogenicity, the consistency of confirmatory results, and the diagnostic efficacy of the two testing methods were compared. Results: The positive rate of pathogens detected by BAL combined with mNGS (88.33%) was higher than traditional pathogen detection (40.00%) (P<0.05). Secondary pulmonary infections in immunosuppressed patients mainly included bacterial infection, fungal infection and viral infection, and nearly half were mixed infections. Bacterial infections were mainly caused by Streptococcus pneumoniae, Staphylococcus aureus, and Klebsiella pneumoniae. Fungal infections were mainly caused by Aspergillus and Pneumocystis. The viruses are predominantly cytomegalovirus, influenza virus, and neocoronavirus. The detection rates of bacteria, fungi and viruses by BAL combined with mNGS (41.67%, 30.00% and 48.33%) were higher than traditional pathogen detection (20.00%, 13.33% and 25.00%) (P<0.05). Compared with confirmed diagnosis results, Kappa value of BAL combined with mNGS detection was 0.838, indicating high consistency (P<0.05). Kappa value of traditional pathogen detection was 0.046, indicating low consistency (P>0.05). The sensitivity, diagnostic coincidence rate and negative predictive value of pathogen detection by BAL combined with mNGS were 98.11%, 96.67%, and 85.71%, respectively, which were all higher than those of traditional etiology, which were 41.51%, 45.00% and 13.89% respectively (P<0.05). Conclusion: BAL combined with mNGS has relatively high value in detecting pathogens of secondary pulmonary infection in immunosuppressed patients.
2025, Vol. 31 
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