Patients and Methods: Prospective, randomized, double-blind, placebo-controlled study. After randomization, 740 intubated patients with a predictive length of mechanical support of more than 48 hours will enterally receive either 10.10 cfu of probiotic (Ergyphilus, Nutergia, France) or a identical placebo daily until withdrawal of mechanical support. The main endpoint is the mortality rate in ICU. Secondary endpoints include hospital length of stay and mortality rate, VAP incidence and the number of days free from antibiotics. Length of the study 24 months.