Pathogenic bacteria such as pneumococcus invade the human blood circulation and grow and multiply within it or produce toxins, causing severe symptoms of lung infection or toxicity. The septic bacteria are the most common. The common features of pyogenic inflammation are redness, swelling, heat, pain and dysfunction. It means that the pathogenic bacteria invade the body’s blood circulation, grow and multiply, produce toxins, and cause severe symptoms of pulmonary infection or toxicity. Inhalation injury, tracheotomy or intubation, aspiration, pulmonary edema, pulmonary atelectasis, shock, surgical anesthesia, invasive infection of traumatic surface, septic thrombophlebitis, etc. Decreased defense function of the organism and pathogen invasion into the lungs is the occurrence of infection, which can occur, bacterial pneumonia, viral pneumonia, atypical pathogen pneumonia, fungal pneumonia, caused by other illegal infectious factors.