Infections can easily occur after surgery, commonly due to the following reasons: first, contaminated surgery, especially in trauma patients with severe local soft tissue contusions, and secondary infections can easily occur. Secondly, for gastrointestinal surgery, digestive tract surgery, and respiratory surgery, which are also open surgeries, it is easy to have postoperative infections, abdominopelvic abscesses and pleural effusions, and the patient will also show fever. Thirdly, for long and major surgeries, secondary infections are also likely to occur during the operation, so for major surgeries lasting more than three hours, additional antimicrobial treatment can also be given during the operation, and anti-infection should also be actively carried out after the operation. For patients with obvious pus and pus cavity infections, pus should also be retained for pathogenic examination, and clinical use of drugs should be directed. In patients with a low immune system, multiple underlying diseases may also predispose to infection.