Coughing up purulent sputum with foul odor suggests obvious infection in the respiratory tract, and the pathogen of infection is purulent bacteria, which can be accompanied by anaerobic infection, the more common ones are staphylococcus aureus, Klebsiella, Pseudomonas aeruginosa combined with anaerobic infection. Clinically, it can be seen in acute lung abscess, pneumonia, and bronchiectasis combined with severe infection, generally through the X-ray film of both lungs, CT or MRI to clarify the condition and cause of the disease, and if necessary, you can also take the pus sputum to find pathogens, or do the drug sensitivity test of pathogens, culture, to clarify the cause of the disease, as well as to clarify the treatment plan.