Chronic obstructive pulmonary disease (COPD) is one of the most common diseases in the world. Acute exacerbation of COPD (AECOPD) refers to an exaggeration of the symptoms of the disease. Currently, the 3 Anthonisen criteria appear to be most satisfactory in defining the AECOPD: The increase in the volume of sputum, the alteration of its appearance which becomes purulent and The increase in dyspnea. Our recent study, showed that administration of levofloxacin is superior to placebo in the treatment of AECOPD; it is accompanied by a substantial reduction in mortality and a significant reduction in the residence time in hospital.The choice of antibiotic to be used in this situation is challenging to the clinician who must choose between traditional antibiotics (cyclins, aminopenicillins, cotrimoxazole...) and new antimicrobial agents. Antibiotic treatment duration was not based on a strong scientific rationale. Yet at the time of the dramatic emergence of bacterial resistance, reducing the selection pressure by reducing the exposure to antibiotic should be a major issue. In addition, the decrease in costs and associated side effects reinforces the interest of short treatments.

Unfortunately, few studies with a satisfactory methodology are available in the literature. In fact, we present the rational and the interest in shortening the durations of antibiotic treatment of AECOPD by levofloxacin in patients admitted to the emergency for exacerbation of COPD and to study the epidemiology of viral and bacterial AECOPD.

This study is a randomized prospective double-blind, accomplished with sealed envelopes ,with two groups :

• Group A: Short treatment duration: 1 tablet Levofloxacin 500mg / day for two days completed by 1 tablet Placebo Levofloxacin 500mg / day for the remaining 5 days.
• Group B: Standard treatment duration (control group): 1 tablet Levofloxacin 500mg / day for 7 days.

The study is conducted by recruiting AECOPD patients to collect their blood samples and sputum samples. These samples will be used for the inflammatory analyses and the study of bacterial and viral serology. The results were seized by the SPSS.20.0 software.

Inclusion Criteria:

45 years or older; had a smoking history of at least 10 pack-years; had a clinical diagnosis of mild-to-severe COPD, defined as a postbronchodilator forced expiratory volume in 1 s (FEV1 ) to forced vital capacity ratio of 0·7 or lower and a postbronchodilator FEV1 of at least 30%, according to Global Initiative of Chronic Obstructive Lung Disease (GOLD).

Exclusion Criteria:

Patients were excluded if they presented one of the following conditions: clinical evidence of hemodynamic compromise with need to vasoactive drugs, Glasgow coma scale <7.20, pneumonia, previous adverse reactions to study drug, antibiotic treatment in the previous days, pregnancy or lactation, severe renal (creatinineclearance 40 mL/min) or hepatic impairment, or lung disease other than COPD that couldaffect the clinical evaluation of the treatments. Patients with active alcohol or drug abuse were also excluded.