Bioresources: IBIS (cohort), Nantes, France. Patients were enrolled from 31st January 2017 to 5th May 2020 in two French Surgical Intensive Care Units of one university hospital (Nantes, France). The collection of human samples has been declared to the French Ministry of Health (Programme de recherche Immunologie, DC2014-2206, authorization renewed DC-2017-2987), and was approved by the Comite de Protection des Personnes Ouest IV (7/04/2015 and 08/10/2020). Inclusion criteria were brain injury (Glasgow Coma Scale below or equal to 12 and abnormal brain-CT scan) and receiving invasive Mechanical Ventilation. Exclusion criteria were cancer in the previous five years, immunosuppressive drugs, and pregnancy. All patients were clinically followed up for 90 days. Endotracheal aspirates were collected on days 0, 4, and 7 after ICU admission, frozen at -80c, and stored until sequencing.