The purpose of this study is to use oral prulifloxacin to treat patient with Acute Exacerbations of Chronic Bronchitis and compare the effect with Levofloxacin.

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.