Clinically, some patients can have recurrent infections over a long period of time, and these patients are commonly found in three types. The first type, immunocompromised. In the first case, the patient’s own constitution is weak, and such patients have a reduced ability to tolerate the disease. In the second case, the patient has certain tumor diseases or blood system diseases, and their immune function is affected, and such patients are immunocompromised. Therefore some people can be infected for a long time. Finally, they go to the hospital for examination, which may be cancer or some kind of blood system disease. In the second category, some primary diseases predispose patients to recurrent infections, such as cerebrovascular disease, stroke, long-term bed rest, or chronic respiratory diseases, such as patients with chronic obstructive pulmonary disease or patients with weak constitution. They are prone to recurrent infections because they are bedridden for a long time or have poor coughing ability and cannot easily cough up sputum. In the third category, patients who use broad-spectrum antibiotics for a long time. These patients have dysbiosis in their bodies and are prone to secondary infections, or some non-pathogenic bacteria grow like crazy later, leading to some specific infections.