Acinetobacter baumannii is an important pathogen of nosocomial infection. In recent years, the infection is increasing day by day, and its drug resistance is becoming more and more serious, which has aroused serious concern of clinical and microbiologists. Ab mainly causes respiratory tract infection, but also septicemia, urinary tract infection and secondary meningitis. Ab is widely distributed in hospital environment and can survive for a long time, which poses a great threat to critically ill patients and patients in CCU and ICU. Also known as ICU acquired infection. Carbapenem-resistant Acinetobacter baumannii has developed rapidly in China, and recently "all-resistant" Acinetobacter baumannii has appeared.