Nebulized and Intravenous Colistin in Ventilator Associated-pneumonia

Inclusion criteria * Age older than 18 yr * Invasive mechanical ventilation for more than 48 h Tracheostomized patients receiving intermittent mechanical ventilation can be included * VAP caused by Gram-negative MDR bacteria resistant to all β-lactams and fluoroquinolones Exclusion criteria * Extrapulmonary Gram-negative MDR infection requiring intravenous colimycin * VAP associated with bacteremia requiring combined treatment by nebulized and intravenous colimycin * Hypersensitivity to colistimethate, colistin base, polymyxins and/or their excipients * Porphyria * Severe hypoxemia defined as PaO2 / FiO2\< 100; if veno-venous ECMO is initiated, the patient can be included * Severe brain injury (initial Glasgow coma score \< 8) during the first 7 days before randomization * Myasthenia * cystic fibrosis * Refusal to participate in the study * Participation in any clinical study of a therapeutic investigational product within 30 days prior to the first day of inclusion * No affiliation to social health insurance * Patient under guardianship * Pregnancy