Inclusion Criteria:

• Outpatients with chronic bronchitis
• Male or female subjects, >=60 years old
• Post bronchodilator forced expiratory volume in one second (FEV1) less than or equal to 60% predicted and FEV1 / forced vital capacity (FVC) less than 70% at enrollment
• Documented history of 2 or more AECB episodes, within 12 months of study enrollment, requiring a course of systemic antibiotics and/or systemic corticosteroids

• All symptoms/signs must be present and confirmed by the Investigator:

  • increase in dyspnea
  • purulent sputum
  • increase in sputum volume
• Current or past cigarette smoker with equal to or greater than 20 pack year smoking history
• Subjects must be exacerbation free for at least 30 days prior to enrollment
• Subjects must be willing and able to complete the questionnaires and subject booklet without assistance

Exclusion Criteria:

• Known hypersensitivity to quinolones, ß lactams, or to any of the excipients of the study drugs
• Known to have congenital or acquired QT prolongation
• Known to have clinically relevant bradycardia
• Known to have clinically relevant heart failure with reduced left ventricular ejection fraction
• Known to have previous history of symptomatic arrhythmias
• Taking QT prolonging drugs, for example Class Ia or III antiarrhythmic agents or other QT prolonging drugs
• Known electrolyte disturbances that are not controlled, particularly uncorrected hypokalemia
• Known history of hereditary problems of galactose intolerance, the Lapp lactase deficiency, or glucose galactose malabsorption
• History of a tendon disease/disorder
• Known history of liver dysfunction (Child-Pugh C), including known elevated transaminase levels (alanine aminotransferase [ALT] and/or aspartate aminotransferase [AST] >5 times the upper limit of normal [5 x ULN])
• Known severe renal impairment with glomerular filtration rate of <30 mL/min
• Known neutropenia (neutrophil count <1000/mm3) caused by immunosuppressive therapy or malignancy
• Known to have Acquired Immunodeficiency Syndrome (AIDS) (CD4 count of <200/mm3), or be human immunodeficiency virus (HIV) positive and receiving highly active anti retroviral therapy (HAART) (testing for HIV is not mandatory)
• Known chronic asthma (>15% reversibility or at least 200 mL), bronchial carcinoma, active pulmonary tuberculosis, known diffuse bronchiectasis, cystic fibrosis, or pneumonia (a chest x ray is not mandatory)
• Known history of chronic colonization of pathogenic organisms resistant to moxifloxacin and/or amoxicillin clavulanic acid (eg, P. aeruginosa, methicillin resistant Staphylococcus aureus)
• Receiving long term (>4 consecutive weeks) systemic corticosteroid treatment (>10 mg/day of prednisolone or equivalent)
• Received short course of systemic corticosteroid treatment within 30 days prior to enrollment
• Life expectancy of less than 6 months
• Receiving systemic antibacterial therapy within 30 days prior to study enrollment
• Requiring concomitant systemic antibacterial agents
• Requiring home ventilatory support (subjects requiring home/portable oxygen therapy or continuous positive airway pressure (CPAP) for sleep apnea are not excluded) and/or those who have a tracheotomy in situ
• History of liver function disorders following previous treatment with amoxicillin-clavulanic acid
• Receiving disulfiram therapy