Hospital infections are divided into endogenous and exogenous infections depending on the source of infection. Endogenous infection means that the body carries various pathogens before the occurrence of hospital infection, and when the body’s immunity decreases, certain pathogens cause spontaneous infection in the body, resulting in morbidity. Exogenous infection refers to infection caused by pathogens that do not exist in the patient’s body in the hospital, usually caused by foreign environment or flora brought by others, including direct infection between patients, between patients and medical staff, visitors or companions, and also includes indirect infection caused by water, air, medical equipment, other items, etc.