Ventilation-associated pneumonia (VAP) is the main site of healthcare-associated infections in the brain injured patients, with an incidence rate of 22% to 58%. VAP increases morbi-mortality, length of stay in intensive care and overall management costs. The prevention of ICU nosocomial infections depends on several measures : orotracheal intubation route, maintaining tube cuff pressure between 25 and 30 cm of water (H2O), maintaining a semi-seated position >= 30°, nasal and oropharyngeal care at regular intervals, striving to avoid unscheduled extubation, and use of a written sedation-analgesia algorithm allowing for early weaning from ventilation. Two randomized study show that administration of antibiotic therapy after intubation reduces the risk of early VAP incidence. However, in clinical practice, its administration solely purposes of limiting VAP occurence is not presently recommended. Indeed, to date no placebo blind controlled study was been realized and the fear of development of bacterial resistance remains stronger than the efficiency of this prevention measure. This aim of the present study is to show by a placebo randomized study that 2g of Ceftriaxone within 8 hours post-intubation after a brain injury decrease the risk of occurence an early VAP.

Ancillary study An ancillary study is performed in 2 centres which routinely practice rectal swabs at admission and discharge of ICU, to survey intestinal flora (CHU of Angers and CHU of Rennes). The goal of this study is to compare the incidence of acquired cephalosporin resistant gram negative bacteria at the discharge of ICU between the 2 groups of patients, receiving or not ceftriaxone.

Inclusion Criteria:

• Brain injured patients with a Glasgow scale score ≤ 12 who require ventilation more than 48 hours

Exclusion Criteria:

• Patient with a high risk of death within the 48 first hours after admission,
• Patient intubated for more than12 hours
• Intubation after the 48th hours after admission
• Coverage to cardiopulmonary arrest
• Coma due to a tumor, an infectious disease or a cardiac arrest
• Previous hospitalisation within the last month before admission for coma
• béta-lactamines allergy
• Patient who receive already antibiotics at the admission for a previous infection
• Prophylactic antibiotic due to be done within 24 hours following the randomisation
• Patient Intubated through a tracheal tube with subglottic secretion aspiration
• Patient with a tracheotomy
• Patient or family refuse to be involved in the study
• Use of Ceftriaxone within 2 days before enrolment
• Participation in another research protocol focusing on an anti-infective treatment or on a measure decreasing the risk of infection
• Patients not affiliated to a social security scheme, Pregnant woman or breast-feeding mother, Patients deprived of their liberty by judicial or administrative decision