This study was performed to confirm that a single 2.0-g dose of azithromycin SR is at least as effective as 7 days of levofloxacin 500 mg/day in adults with acute exacerbation of chronic bronchitis Secondary objectives: To assess safety and the bacteriologic efficacy of both treatment regimens

Inclusion Criteria:

Adult patients with a history of chronic bronchitis (i.e., chronic cough and sputum production on most days for 3 consecutive months for more than 2 years) and current evidence of an acute bacterial exacerbation of their disease, as demonstrated by production of purulent sputum and the presence of at lest 2 of the following signs and symptoms, were included: increased sputum production, increased dypsnea, increased cough, or increased sputum purulence.

Exclusion Criteria:

Key exclusion criteria were treatment with any systemic antibiotic within the previous 7 days, or the likelihood of receiving other systemic antibiotics during participation in the study; a chest radiograph consistent with pneumonia; and previously diagnosed conditions which tend to mimic or complicate the course and evaluation of the infectious process (e.g., bronchiectasis, lung abscess or empyema, active TB, pulmonary malignancy, cystic fibrosis).