Clinical Research Directory

Inclusion Criteria: 1. AECOPD patients admitted to hospitals 2. The exacerbation has lasted for at least 24 hours but equal to or less than 21 days 3. ≥40 years of age but no more than 80 years old 4. With at least 10 pack-year history of smoking 5. Able to provide written informed consent and ensure the completion of the trial Exclusion Criteria: 1. Axillary temperature≥38°C 2. Acute pneumonia identified by X-Ray or CT of the chest 3. Severe respiratory failure requiring admittance to ICU 4. Comorbidities require antibiotic therapy (i.e. infection at another site, systematic infection, active chronic inflammatory condition, specific viral infection) 5. Immunosuppression status (i.e., patients with HIV infection, with malignant tumor of blood system, receiving chemotherapy) 6. Concurrent diseases requiring corticosteroids (equivalent to 60mg prednisone/day or more than 30 days) 7. Antibiotic use in the previous four weeks 8. Current tracheotomy status 9. Bronchiectasis of origin other than COPD 10. Invasive mechanical ventilation 11. Patients diagnosed malignant tumors 12. Pregnant or lactating women, or women of childbearing age not using an acceptable method of contraception. 13. Newly diagnosed pulmonary embolism 14. Participation in another clinical trial