Reason Evaluation of Initial Treatment Failure in Patients With CAP

Inclusion Criteria: 1. Age\>=18y. 2. Diagnosed with CAP. 3. Need hospitalization. 4. Receive Moxifloxacin Hydrochloride and Sodium Chloride Injection or β-lactam antibiotics for injection +/- Azithromycin for Injection as initial treatment. 5. Signed informed consent form. Exclusion Criteria: Patients who meet any of the following criteria will not be included in the study: 1. Pneumonia is aquired more than 48h after admission or the patient was admitted to hospital within 30 days prior to admission. 2. Start antibiotic treatment before admission. 3. Gestational period or suckling period. 4. Admitted to ICU. 5. Immunocompromised patients. 6. Pneumonia is the terminal event of a serious disease. 7. Tuberculosis, lung cancer, non-infectious interstitial lung disease, pulmonary edema, atelectasis, pulmonary embolism, pulmanory eosinophilia, pulmonary vasculitis. 8. Allergic to the antibiotics of the study.