Community-acquired infections are infections that occur within 48 hours of a patient’s admission to the hospital or infections that occurred before the patient was admitted to the hospital. Infections can be categorized into hospital-acquired infections and community-acquired infections based on where and when they occur. Hospital-acquired infections are infections acquired by patients during hospitalization, including infections that occur during hospitalization and infections acquired during hospitalization that occur after discharge. Hospital-acquired infections also include infections acquired by medical staff in the hospital, infections that are in the incubation period when hospitalized and have occurred before hospitalization are not hospital-acquired infections, and infections other than hospital-acquired infections are community-acquired infections. Community infections mainly include respiratory tract infections, bloodstream infections, urinary tract infections, central nervous system infections, skin and soft tissue infections. Elderly people with COPD, hypertension, diabetes and other underlying diseases, as well as immunocompromised people, are the main groups of community infections.