1) prospectively collected the patients with the proposed infection, confirmed the infection or excluded the infection through mNGS detection combined with traditional pathogen detection methods and clinical characteristics, compared the detection performance of mNGS and traditional methods, and explored the significance of mNGS microbial map characteristics for the diagnosis/exclusion of infection; 2) real-time dynamic monitoring of the pathogen and microecology of infected patients during the targeted drug use, and evaluation of the efficacy in combination with other indicators; 3) to explore the significance of the number of pathogen sequences before the clinical withdrawal of drugs to the clinical practice.

Inclusion Criteria:

• 18 to 75 years old
• expected length of stay in ICU was > 24 h
• suspected infected patients (PSI or CPIS, qSOFA or SIRS)

Exclusion Criteria:

• Pregnant and lactating women
• Who has not signed the informed consent
• the researchers considered that others were not suitable for the study