The ventilator-associated pneumonia (VAP) is responsible for almost half of infections acquired in intensive care, affecting up to 28% of mechanically ventilated patients with a mortality rate ranging from 25 to 50%. The majority of these VAP originate in the sub-glottic juice that accumulates just above the endotracheal tube cuff. Many preventive measures exist and are applied in this institution, including oropharyngeal aspiration every 4 hours and tracheal aspirates every 8 hours. Currently, these aspirates are simply discarded. However, a French study evaluating the colonization and infection of the respiratory tract of patients with acute respiratory distress syndrome (ARDS) has highlighted that the causative agent of VAP is selected in more than 2/3 of the cases in tracheal aspirates several days before the VAP. This suggest that "microbiological surveillance" of daily aspirates may permit the identification of a selected respiratory pathogen later responsible of VAP.