40 outpatients with exacerbations of Chronic Obstructive Pulmonary Diseases (COPD) will be enrolled in a multi-centre, open-label, randomised, pilot study. Two treatments will be compared, ceftidoren 200 mg bid for 5 days and levofloxacin 500 mg once daily for 7 days. Primary objective of the study is to evaluate the effects of the treatment on serum inflammatory biomarkers and the secondary objective is to evaluate the clinical and microbiological efficacy at the Test Of Cure visit (TOC), DAY 7-10 (end of treatment).