Lung infections are commonly caused by the following bacteria: 1, bacterial infections: such as Streptococcus pneumoniae, Streptococcus hemolyticus, Staphylococcus, and negative bacteria, such as Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae; 2, atypical pathogens: such as Mycoplasma, Chlamydia, Legionella; 3, viruses: such as rhinovirus, adenovirus, syncytial virus; 4, fungi: such as mold, fungi; 5, parasites: such as Pneumocystis carinii of AIDS; 6, chemotherapy: radiation-induced radiation pneumonia; 7, gastroesophageal reflux: gastric acid aspiration into the lungs causes pneumonia.