Pneumonia is an inflammatory disease caused by bacteria, viruses and other pathogenic microorganisms that invade the lungs. The cause of pneumonia can be caused by a variety of pathogens, such as microbes, viruses, fungi, parasites, etc. Other factors such as radiation, chemicals and allergies can also cause pneumonia. Pneumonia caused by pathogens is the most common. Immune defense mechanisms such as filtration and humidification of inhaled gases, coryza and cough reflexes, bronchial ciliary mucus excretion system, humoral and cellular immune functions keep tracheal, bronchial and alveolar tissues sterile. Immune function is impaired (such as cold, hunger, fatigue, intoxication, coma, gas inhalation, hypoxemia, pulmonary edema, uremia, malnutrition, viral infections and the application of glucocorticoids, artificial airway or into the lower whistle pathogenic bacteria are more virulent or in greater numbers, then prone to pneumonia. 1, bacterial pneumonia A variety of bacteria can cause pneumonia, the majority of which are pneumococcus, which is the most pathogenic type III. The pneumococcus is a gram-positive cocci with pods, and its pathogenicity is due to the invasive effect of the pods of polymeric polysaccharides on the tissue. A few are pneumococci, Staphylococcus aureus, Streptococcus haemolyticus, Haemophilus influenzae, etc. (1) Aerobic Gram-staining positive cocci, such as pneumococci, Staphylococcus aureus, hemolytic streptococcus A, etc. (2) Aerobic Gram-staining negative bacteria, such as Klebsiella pneumoniae, Haemophilus influenzae, Escherichia coli, Pseudomonas aeruginosa, etc. (3) anaerobic bacilli such as rod-shaped bacilli, clostridium difficile, etc. 2, viral pneumonia such as adenovirus, whistling syncytial virus, influenza virus, measles virus, cytomegalovirus, herpes simplex virus, etc. are the causes of pneumonia. 3, mycoplasma pneumonia caused by Mycoplasma pneumoniae. 4, fungal pneumonia Pneumonia caused by causes such as Candida albicans, Aspergillus, Actinomyces, etc. 5, pneumonia caused by other pathogens such as rickettsia (such as Q fever rickettsia), chlamydia (such as Chlamydia psittaci), toxoplasma (such as Toxoplasma gondii), protozoa (such as Pneumocystis carinii), parasites (such as pulmonary encystment, pulmonary schistosomes, pulmonary schistosomes), etc. People with low immunity (such as AIDS patients) are prone to lung infections such as Pneumocystis carinii, Legionella, Mycobacterium avium, Mycobacterium tuberculosis, and Toxoplasma gondii.