Pathological changes include congestion stage, red liver stage, gray liver stage and dissipation stage. The manifestations are congestion and edema of lung tissue, exudation of serous fluid in alveoli, infiltration of red blood cells and white blood cells, phagocytosis of bacteria by white blood cells, dissolution and absorption of fibrin exudate, and reinflation of alveoli. In fact, there is no exact boundary between the pathological stages of liver cirrhosis. This typical pathological stage is rare after early application of antibacterial drugs. After the focus disappeared, the lung tissue structure was basically intact and there was no fibrous scar. Very few patients have incomplete absorption of fibrin in alveoli, and even formed fibroblasts, forming organized pneumonia. Infections in the elderly and infants can be distributed along the bronchi (bronchopneumonia). If antibiotics are not used in time, 5% ~ 10% patients may be complicated with empyema, and 10% ~ 20% patients may be infected with meningitis, pericarditis, endocarditis, arthritis and otitis media due to bacteria entering the blood circulation through lymphatic vessels and thoracic ducts.