The causes of pneumonia in the elderly are as follows: 1. Pneumonia in the elderly caused by mycoplasma, chlamydia, or bacterial or viral infections and other pathogenic bacteria. As the resistance of the respiratory tract of the elderly is poor, so it is easier to be infected, leading to the occurrence of pneumonia in the elderly; 2, mistakenly aspirated food easily caused by pneumonia in the elderly, commonly found in long-term bedridden patients. Therefore, for long-term bedridden patients, should try to sit and feed, do not lie down. 3, mixed infections, the elderly due to low immune function, often manifested as a variety of pathogens caused by mixed infections.