Mycoplasma pneumoniae is a common causative agent of acute bronchitis, and has the following characteristics: 1. It is relatively common in young people, but relatively rare in older adults. 2. Cough symptoms are often prominent, usually without significant coughing sputum. 3. The treatment is not effective. Azithromycin or respiratory quinolone antibiotics are effective in the treatment of acute bronchitis caused by Mycoplasma pneumoniae, when the patient with bronchitis has the above characteristics suggesting the presence of mycoplasma infection.