mNGS
The application value of metagenomic next-generation sequencing (mNGS) in detecting pathogenic bacteria was evaluated to promote the rational and accurate use of antibiotics. A total of 180 patients with severe infections were included in this study. Based on their different symptoms, bronchoalveolar lavage fluid (BALF) or blood samples were collected for conventional microbiological testing (CMT) and mNGS. The results indicated that the etiological diagnosis rate of mNGS (78.89%) was significantly higher than that of CMT (20%) (p<0.001). Notably, mNGS exhibited greater sensitivity towards rare pathogens such as Chlamydia pneumoniae, Mycobacterium tuberculosis complex, and Legionella pneumophila, which were undetectable by CMT. Additionally, 64 cases underwent blood culture, BALF culture, and mNGS testing. Analysis revealed that the positive rate of blood culture (3.1%) was lower than that of BALF (25%), and the positive rate of CMT from both types was significantly lower than that of mNGS (89.1%) (p<0.001). In this study, 168 mNGS results were accepted, and 116 patients had their antibiotic therapy adjustment based on mNGS. Paired analysis indicated that white blood cell count (WBC), procalcitonin (PCT), C-reactive protein (CRP), and neutrophil (NEU) percentage provided valuable therapeutic guidance. The survival rate of patients was 55.36%, influenced by patient physical condition and age. Our data indicated that mNGS had  significant auxiliary value in the clinical diagnosis and treatment for critically ill patients, especially for those with negative CMT results and clinically undefined infections. mNGS could broaden the detection scope, especially for special pathogens, and improve the detection rate, providing powerful assistance for early clinical diagnosis and treatment.