A Multi-center, Randomized, Double-blind, Double-dummy Clinical Study to Evaluate the Safety and Efficacy of Prulifloxacin Film-coated Tablet for the Treatment of Acute Exacerbations of Chronic Bronchitis With Levofloxacin Hydrochloride Tablet as Active Control

Inclusion Criteria: 1. Patient is willing to participate in the study and gives the signature of informed consent; 2. In and out-patients (aged 18-70 years old), male or female; 3. Patient receives no effective antibacterial therapy or the therapy has no remarkable efficacy, or positive bacterial test result in the past 72 hours; 4. Diagnosed as mild to moderate acute exacerbation of chronic bronchitis patients (see \<Severity Evaluation Criteria Table\>) 5. Within 48 hours prior to the study, women of child-bearing age have a negative urine pregnancy test and is willing to use efficient measures of contraception to avoid pregnancy during the study. Exclusion Criteria: 1. Patient hypersensitive to quinolones or with allergic constitution; 2. Patient with severe condition which need combination with other antibacterial agents; 3. Concurrent infections in other organs or system; 4. Patient with severe heart, liver or kidney disease, or Q-T prolongation of over 450 ms, serum AST or ALT more than twice as high as the upper limit of normal or Cr over the upper limit of normal; 5. With any of the following diseases: active tuberculosis, bronchiectasis, lung abscess, aspiration pneumonia, lung cancer, non-infectious interstitial lung disease, pulmonary edema, atelectasis, pulmonary embolism, pulmonary addicted acidic granulocyte infiltration and pulmonary vasculitis syndrome; 6. Patient with severe hematologic disease or central nervous system disease or convulsion history, with mental status unable to coordinate; 7. Patient with malignant tumor or other severe background disease; 8. Patient with severe immunodeficiency; 9. A history of tendon; 10. Known pregnancy or lactation; 11. Prulifloxacin contains lactose, therefore, patients with a rare genetic disease such as galactose intolerance, Lapp lactase deficiency or glucose - galactose malabsorption cannot be enrolled; 12. Participation in other clinical trials within 3 months before screening or currently on any investigational therapy.