Lung Microbiota and VAP Development (PULMIVAP) (PULMIVAP)

Several factors are involved in the pathogenesis of VAP: the presence of endotracheal tube, the creation of bacterial biofilms around the device, host characteristics (comorbidities, surgery, antibiotic exposure) and, finally, immunological factors (including modulation of cytokine expression). In this study, patients mechanically ventilated for non-pulmonary reasons, will be followed up to 15 days of ventilation, estubation or death (whichever comes first). For microbiota analysis, all patients who develop VAP in the first 15 days of MV will be selected and matched (1:1; by center, gender, age (+/- 10 years), reason for intubation, duration of intubation), with a patient who do not developed VAP during MV. The optimal matching algorithm will be used to identify the control group that minimizes the total intra-pair dissimilarity.

The investigators plan to enroll about 700 MV patients for non-pulmonary conditions in order to describe VAP and non-VAP patients' characteristics identify. The investigators estimate that at least 70 patients will develop VAP in the first 15 days of MV. Microbiota and immunological analysis will be longitudinally performed on tracheal aspirate samples and oro-pharyngeal swab. The investigators will performe microbiota analyses on tracheal aspirate and oropharyngeal swab according to the following time schedule:

• VAP patient, 3 times: intubation (T0), the 24h before VAP development (T pre-VAP) and at VAP development (T-VAP).
• non-VAP patient, 2 times: intubation (T0) and a second sample, selected at the time point (day), corresponding to T-VAP of his/her matched VAP-patient (T no-VAP).

The investigators will perform immunological analysis on tracheal aspirate for all patients at intubation and at T-VAP or T no-VAP time.