When a patient is diagnosed with left lower lung pneumonia, routine blood tests, C-reactive protein, calcitoninogen, mycoplasma antibodies, virus antibodies, and other related tests should be completed. If the patient has a significant increase in leukocytes and a significant increase in C-reactive protein and calcitoninogen, the patient is considered to have a bacterial infection and needs to be treated with antibiotics, such as cefixime, azithromycin, levofloxacin, moxifloxacin, etc. If the patient’s pneumonia is interstitial with normal or below normal white blood cells and below normal lymphocytes, the patient is considered to have viral pneumonia and needs to be treated with relevant antiviral drugs such as oseltamivir. If the patient’s mycoplasma antibodies have recently increased more than 4-fold, then mycoplasma pneumonia is considered, and treatment with macrolides such as azithromycin and erythromycin, or quinolones such as levofloxacin and moxifloxacin, and other related drugs is required.