Inclusion Criteria:  Patient under MV Diagnosis of microbiologically confirmed of first episode of VAP Initial appropriate empiric antibiotic therapy Written informed consent from the patient or a legal representative if appropriate. If absence of a legal representative the patient may be included in emergency procedure  Definitive diagnosis of pneumonia (in agreement with international guidelines) is defined by association:  Patient under MV>48 hours New pulmonary infiltrate of which an infectious origin is strongly suspected Worsening oxygenation  Have the following clinical criteria within the 24 hours prior to the first dose of antibiotic therapy  Purulent tracheal secretions And at least 1 of the following : documented fever (body temperature >38,3°C) or hypothermia (body temperature <35°C) or white blood cell (WBC) count >10,000 cells/mm3 or <4,000 cells/mm3 Microbiological criteria (positive quantitative culture of a lower respiratory tract (LRT): bronchoalveolar lavage fluid (BAL) (significant threshold ≥10^4 colony-forming units/mL) or plugged telescopic catheter (PTC) (significant threshold ≥ 10^3 colony-forming units/mL) or quantitative endotracheal aspirate (ETA) distal pulmonary secretion samples (significant threshold ≥10^5 colony-forming units/mL)  Exclusion Criteria:  Patient under selective decontamination of the digestive tract Concomitant extra-respiratory infection requiring antibiotic therapy at the moment of inclusion Inclusion in another interventional study concerning antimicrobial strategies Moribund (IGS II>80) Thoracic trauma with Abbreviated Injury Scale (AIS) thorax ≥ 3 Severely immunocompromised patients (such as congenital immunodeficiency, neutropenia (<1leucocyte/ml or <0.5 neutrophil/ml) or acute hematologic malignancy or stem cell transplant, HIV infection with CD4 count below 200/mm3 Patients undergoing immunosuppressive therapy and long term corticotherapy > 0.5 mg/kg VAP due to: Pseudomonas aeruginosa, Carbapenem-resistant Acinetobacter spp, Carbapenem-resistant Enterobacteriaceae Bacterial VAP in a context of COVID-19 or other confirmed viral pneumonia Patients with empyema, necrotizing and abscessed pneumonia Pregnant women No health insurance coverage