The severity of bacterial infections in the lungs depends on the specific type of bacteria. In general, for most bacterial pneumonia, such as lobar pneumonia caused by Streptococcus pneumoniae, a week of treatment with penicillin as the drug of choice can completely cure it. For other pneumonia such as Staphylococcus aureus, Klebsiella and Pseudomonas aeruginosa pneumonia is relatively serious because of the relatively strong toxicity of the bacteria and the obvious damage to the lung mucosa, which can lead to lung abscess, pneumothorax and even bronchopleural fistula respectively. For this type of pneumonia it is necessary to standardize the choice of two or more sensitive antibiotics and a sufficient course of treatment to achieve complete cure.