Antibiotics are widely used in liver surgery and play a crucial role in preventing and controlling inflammatory liver infections as well as improving perioperative safety in liver surgery. However, clinical misuse of antibiotics not only increases the economic burden of patients, but also often can cause difficult to manage complications and liver damage such as bacterial resistance and secondary infections, and can create a false sense of security for surgeons to neglect proper surgical operations. Therefore, how to correctly and reasonably choose antibiotics in liver surgery deserves attention. A, the characteristics of liver surgery infection liver surgery infection often involves the biliary system at the same time, so most of the aerobic bacteria and anaerobic bacteria mixed infection. Aerobic bacteria such as Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa are mainly Gram-negative bacilli, Gram-positive bacteria such as Enterococcus spp. and Staphylococcus spp. are common; anaerobic bacteria such as Bacteroides fragilis, Clostridium perfringens and anaerobic cocci are mainly. Aerobic bacteria and anaerobic bacteria are symbiotic, and then aggravate the liver inflammatory infection and clinical symptoms. Second, the selection of antibacterial drugs The application of antibiotics in liver surgery is broadly divided into two situations: prophylactic application and therapeutic application. The selection of antibiotics should be based on the results of pathogenic testing and drug sensitivity testing, but in clinical practice, pathogenic testing often has poor timeliness and low detection rate and other defects. Therefore, in the application of antibiotics, often first based on previous treatment experience to choose, after the return of the corresponding pathogenic test results, and then combined with the clinical situation to re-examine the treatment plan, if necessary, to be adjusted in a timely manner. 1, prophylactic application As with other abdominal surgery, routine prophylactic application of antibiotics in the perioperative period of liver surgery, mainly to prevent surgical site infection. The principles of using prophylactic antibiotics are: ① broad antibacterial spectrum, covering common infectious strains of liver surgery; ② safe application, less toxic side effects, especially hepatotoxicity; ③ no resistance to bacteria commonly infected in the hospital; ④ suitable price. In addition, the pharmacokinetic characteristics of antibiotics should be taken into account, and the drugs used should not only form a higher concentration of action in the blood, but also in the liver and biliary tissues as well as in the bile. Therefore, priority should be given to antibiotics that can be excreted from the liver into the bile. Studies have shown that the common antibiotics with bile concentrations higher than serum concentrations include piperacillin, ceftriaxone, cefoperazone, moxifloxacin, rifamycin, clindamycin, ampicillin, etc. The bile concentrations of the first five of these antibiotics can reach more than ten times the serum concentration. There is no consensus on what antibiotics are best for prophylactic use, mainly based on the drugs available at the time and the doctor’s habits, but at home and abroad most advocate the first choice of cephalosporin. 2, therapeutic application 1) antibiotic treatment for complications of infection after liver surgery The oozing of liver trauma, bile leakage or excessive residual necrotic liver tissue on the liver cut surface after liver surgery are important causes of postoperative infection, especially intrahepatic bile duct stones and chronic liver abscess when liver resection trauma is more likely to be contaminated, and there are more opportunities for postoperative infection. If the postoperative treatment is improper or poor drainage, or drainage is removed too early, it is bound to cause subdiaphragmatic infection, peritonitis or secondary bleeding, and death may occur due to severe toxic shock or excessive blood loss. Among 171 patients who underwent hepatectomy for hepatocellular carcinoma, the incidence of SSI was 21% (36), including 27 patients in the organ or cavity, and the postoperative mortality rate in these patients (11%) was significantly higher than that in patients without infection (0, 7%), and statistical analysis showed that bile leak and bleeding were independent risk factors for triggering SSI in the organ or cavity. This finding again suggests that precise aseptic surgical practice at the time of surgery, including strict asepsis, thorough hemostasis, and proper and adequate drainage, among others, are the key actions to prevent complicating infections after liver surgery. Although the key to the treatment of abdominal infection is the removal of necrotic tissue and unobstructed drainage, antibiotic therapy is still essential to prevent and treat the local spread of infection, control systemic infection, and reduce complications of infection. In addition, antibiotic therapy not only significantly improves the efficacy of surgical procedures, but also cures certain co-infections and avoids reoperation. Abdominal infections are usually a mixture of multiple bacteria, most commonly Escherichia coli, Streptococcus, Klebsiella, and anaerobic bacteria, so a broad-spectrum antibiotic is required, and empirical use of glycosides or cephalosporin antibiotics in combination with ornidazole or moxifloxacin monotherapy may be preferred. In severe cases, two to three antibiotics may be used in combination. This is followed by timely adjustment based on pathogenic and drug-sensitive testing of the puncture drainage fluid. Infection of hepatic surgical incision also belongs to the category of SSI, and there is no specificity in the selection and treatment of antibiotics for other SSIs except that the infected incision requires local debridement. 2) Bacterial liver abscess Bacterial liver abscess is the most common infectious disease in liver surgery, mostly secondary lesions. It can be divided into abdominal-derived liver abscess, traumatic or post-surgical liver abscess and hematogenous liver abscess. Based on experience, when biliary or other abdominal-derived liver abscesses are suspected, broad-spectrum penicillin piperacillin, cefoperazone and ceftriaxone of three generations of cephalosporins can be used first against Escherichia coli, Klebsiella, and anaerobic-like bacilli. These antibiotics are excreted by the liver and also have strong bactericidal activity against Pseudomonas aeruginosa. In addition, the anti-anaerobic drug tinidazole or ornidazole should be added at the same time, and moxifloxacin monotherapy can also be used. Second-generation cephalosporins and aminoglycoside antibiotics (gentamicin, amikacin) have lower concentrations in liver tissue and bile than their serum concentrations and are generally not used as the preferred regimen, but can be used in combination with beta-lactam antibiotics. In severe cases of infection, moxifloxacin, a fluoroquinolone, or imipenem or meropenem, a carbapenem, can be used directly. It is important to note that methicillin-resistant Staphylococcus, Enterococcus faecalis, and Narcolemmophilus maltophilia are resistant to both imipenem and meropenem. In suspected hematogenous liver abscesses, benzocillin, cloxacillin or a cephalosporin generation should be used mainly against Staphylococcus aureus and streptococci. Vancomycin may also be used directly in severe cases of infection. To take into account the possible presence of gram-negative rods, it is best to combine with an aminoglycoside antibiotic or a fluoroquinolone. In the early stages of empirical dosing, coverage of enterococci is generally not necessary. Bacterial liver abscesses mostly require puncture and drainage or incision and drainage, and nowadays ultrasound-guided percutaneous puncture and drainage is mostly used. For liver abscesses without liquefied necrosis or only before tissue necrosis, puncture and drainage is not appropriate. Percutaneous transhepatic route is generally chosen for percutaneous drainage to reduce pus leakage, which can also be combined with irrigation. When the pus is reduced or absent, the flushing fluid is clear and the liver tissue grows well, the drainage tube can be removed.