Study to Evaluate Two Diagnostic Strategies for the Treatment of Severe Community Acquired Pneumonia (SCAP)

Main hypothesis: microbiological diagnossis off severe community acquired pneumonia can be performed by non invasive or semi invasive microbiological tools, semi invasive tools including protected distal bronchial samplings by the mean of Fiber optic bronchoscopy (FOB). A microbiological diagnosis could improve antibiotic therapy efficacy and improve patient\'s outcome. These Two strategies have never been prospectivally evauated. * Aim of the study: To evaluate 2 diagnostic strategies: non invasive or semi invasive including protected distal bronchial samplings by the mean of Fiber optic bronchoscopy (FOB)for the care of patients admitted in intensive care for severe community acquired pneumonia and receiving an empirical antibiotic therapy as recommanded by 2001 American thoracic guidelines * Type of study randomized multicentric controlled open study