What are the incentives for pneumonia

Under normal circumstances, the human respiratory tract defense mechanisms, pathogens enter the body does not necessarily cause disease, some factors may decline to defenses, pathogens take advantage of the body lead to disease. These incentives include:
⑴ upper respiratory tract infections: viral infection can damage the integrity of bronchial mucous membrane, the impact of mucus - cilia activities, leading to bacterial infection.
⑵ by a sudden, hunger, fatigue, drunkenness, weakened body resistance, so that phagocytic role may be weakened immune function, leading to disease.
⑶ coma, anesthesia overdose of sedatives, vulnerable to foreign body aspiration, cause of bacterial infection.
⑷ suffering from some diseases, such as immune deficiency, diabetes, renal failure, and so on, are also susceptible factors.