Ceftidoren Versus Levofloxacin in the Treatment of Patients With Acute Exacerbations of Chronic Bronchitis (AECB)

Inclusion Criteria: 1. Male or female outpatients with age between 40 and 75 years with no limitation of race. 2. Patients with a diagnosis of Acute Exacerbations of Chronic Bronchitis\* characterized by the presence of the following three symptoms, or at least two including purulence: * increased dyspnoea; * increased of sputum volume; * increased of sputum purulence, that had to be confirmed macroscopically by the investigator. * Chronic bronchitis is characterized by cough and excessive secretion of mucus and is diagnosed when patients report production of sputum on most days over at least three consecutive months for 2 or more consecutive years (American Thoracic Society 1995). 3. FEV1 \>50% of the predicted value. 4. Availability of a valid sputum specimen of broncho-pulmonary origin for microbiological evaluation obtained by either expectoration, suction, bronchoscopy or bronchial lavage. Valid samples will be characterized by \< 10 squamous epithelial cells and \> 25 polymorph nuclear leucocytes per low-power magnification 100x field (Wilson 2004). 5. Negative chest radiography to rule out pneumonia and active tuberculosis. 6. Written informed consent to the trial signed and dated by the patient according to the local regulations, obtained prior to all activities related to the trial. Exclusion Criteria: 1. Hypersensitivity or allergy to antibacterial betalactams or fluoroquinolones and/or to any component of the study medications. 2. Underlying asthma. 3. Systemic corticosteroids (treatment since ≤ 2 weeks before trial drug administration) are excluded, unless patients are chronically treated (treatment for \>2 weeks before trial drug administration). Corticosteroid nasal spray administration is allowed in the first 3 days of the study drug administrations only. 4. Childbearing potential where pregnancy is not excluded by pregnancy test in urine (HCG), or lactation. 5. History of tendinopathy. 6. Recent or past history of psychiatric illness or epilepsy. 7. Recent or past history of cardiac disease or rhythm disorders or clinically significant ECG abnormalities. 8. Latent or known deficiencies for the glucose-6-phosphate dehydrogenase activity. 9. Known severe hepatic and/or renal insufficiency (AST, ALT and/or creatinine levels more than twice as high as the Upper Laboratory Norm, ULN). Should laboratory data not be available when treatment is required, the patient may be conditionally enrolled. 10. Other lower respiratory tract illness: severe bronchiectasis, cystic fibrosis, or pulmonary malignancy. 11. Concurrent infections and /or neoplasm. 12. Concomitant treatment with hypoglycemic drugs. 13. Patients under treatment with fenbufen and xanthines. Patients treated with xanthines could however be recruited if plasma levels were monitored; if plasma levels exceeded concentrations of 10-15 micrograms/ml, the daily dosages of xanthines should be lowered by the Investigator (Hendels 1983); 14. Treatment with antibiotics or antibacterials within the previous week 15. Treatment with experimental drugs in the previous 4 weeks