OBJECTIVE To investigate the application of metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF) in the detection of pathogens of pulmonary infection.

METHODS The clinical data of 98 patients with pulmonary infections admitted to NO. 2 People′s Hospital of Fuyang City from Jan. 2023 to Jan. 2024 were retrospectively analyzed, mNGS and traditional pathogenicity test were performed in BALF, and comprehensive clinical judgment (using a combination of alveolar lavage fluid, sputum, blood, etc. to assess) was used as the gold standard to evaluate the differences between mNGS and traditional pathogenicity tests in the pathogenic diagnosis of pulmonary infections, compare the pathogen detection rates in pulmonary infections complicated with underlying diseases, severe and non-severe illness and different infection types, and to analyze the impact on clinical adjustment of anti-infection regimens.

RESULTS The positive detection rate of mNGS for pulmonary infection pathogens was 88.78%, higher than that of traditional pathogenology (P < 0.001). The time required for mNGS was (16.57±2.64) h, shorter than that of traditional pathogenology (P < 0.05). The positive detection rates of mNGS in patients with and without underlying diseases were 93.02% and 85.45%, respectively, higher than those of traditional pathogenology (P < 0.05). The positive detection rates of mNGS in severe and non-severe patients were 91.43% and 87.30%, respectively, higher than those of traditional pathogenology (P < 0.05). A total of 122 strains of pathogens were detected in 87 patients with positive mNGS tests, and EB virus was not detected. A total of 75 strains of pathogens were detected in 54 patients with positive traditional pathogenetic tests, and Neisseria, Rhizopus, parvovirus, and Chlamydia psittaci were not detected. The detection rate of bacteria by mNGS was 58.20%, higher than that by traditional pathogenetic tests (P=0.034). The detection rates of mNGS test for monotypic infection and mixed infection were 85.51% and 93.10%, respectively, higher than those by traditional pathogenetic test (P < 0.05). In pulmonary infections, mNGS guided adjustment of anti-infective treatment in 53.06% of patients, 60.47% of those in the group with underlying pulmonary disease, and 47.27% of those without underlying disease (P=0.194). Among severe cases, 68.57% had their anti-infective treatment plan adjusted, compared to 44.44% of non-severe patients (P=0.022).

CONCLUSION The mNGS of BALF idenfies some rare pathogens, improves the detection rate of pathogens in pulmonary infections, and may guide the clinical adjustment of anti-infective strategies.