The doctor in charge of the patient will fill a questionnaire with the help of the patients or the patient's family with several items as date of tracheostomy, history of respiratory infections, history of hospitalization, characteristics of ventilation (presence of a cannula, frequency of change of filter, type of water use in the humidifier…). Beside, a tracheal aspirate will be collected and send to the microbiology laboratory for bacterial culture. The tracheal aspirate will be supported as a usual clinical tracheal aspirate but each bacterial specie will be quantify and identify by mass spectrometry. Antimicrobial susceptibility testing will be performed only for potential pathogenic species with a cut-off at 105.