LAUSR

AIMS To perform a prospective diagnostic study exploring the clinical utility of metagenomic next-generation sequencing (mNGS) in diagnosing community-acquired pneumonia (CAP), and revealing resistome differences in bronchoalveolar lavage fluid (BALF) from CAP patients with varying severity of admission base on Pneumonia Patient Outcomes Research Team (PORT) risk classes. METHODS AND RESULTS We compared the diagnostic performances of mNGS and conventional testing for the detection of pathogens in BALF from 59 CAP patients, and performed resistome differences analysis of metagenomic data from 59 BALF samples, namely 25 from CAP patients with PORT score I (I group),14 from CAP patients with PORT score II (II group),12 from CAP patients with PORT score III (III group), and 8 from CAP patients with PORT score IV (IV group). The diagnostic sensitivities of mNGS and conventional testing for the detection of pathogens in BALF in patients with CAP were 96.6% (57/59) and 30.5% (18/59), respectively. There was a significant difference in the overall relative abundance of resistance genes between the four groups (P = 0.014). The results of Principal coordinate analysis based on Bray-Curtis dissimilarities showed that there were significant differences in the composition of resistance genes among the I, II, III, and IV groups (P = 0.007). A large number of ARGs, such as those affiliated with multidrug, tetracycline, aminoglycoside, and fosfomycin resistance, were enriched in the IV group. CONCLUSIONS In conclusion, mNGS has a high diagnostic value in CAP. There were significant differences present in microbiota resistance to antibiotics in BALF from CAP patients in different PORT risk classes, which should attract enough attention.