Combined Use of a Respiratory Multiplex PCR and Algorithm-based Therapy to Improve Early Optimization of Antibiotic Therapy in Critically Ill Patients With Ventilator-associated Pneumonia

Inclusion Criteria: * Adults (≥18 years) with VAP (mechanical ventilation and hospitalization ≥ 48 hours) and deep respiratory sample by mini BAL \< 12 hours. The diagnosis of pneumonia includes two clinical criteria among fever (≥38.3°C), purulent sputum or aspiration, hyperleukocytosis (\>12,000 WBC/mm³) or leukopenia (\<4,000 WBC/mm³), hypoxemia, auscultatory signs in the affected area, and a newly-appeared parenchymal infiltrate * Patient receiving initial probabilistic antibiotic therapy for VAP suspicion * Informed consent or emergency procedure * Patient affiliated with or beneficiary of a health insurance plan. Non inclusion Criteria: * Pregnancy * Congenital immunodeficiency; * HIV infection with the lymphocyte CD4 count below 200/mm3 or unknown in the last year; * Acute hematologic malignancy; * Neutropenia (\<1 leucocyte/mL or \< 0.5 neutrophil/mL); * Immunosuppressive drugs within the previous 30 days, including anti-cancer - Chemotherapy and anti-rejection drugs for organ/bone marrow transplant * Corticosteroids ≥ 20 mg/d of prednisone equivalent for more than 14 days * Known allergy to beta-lactams * Moribund patient or death expected from underlying disease during the current admission; * Patient deprived of liberty or under legal protection measure; * Participation in another interventional trial. Exclusion criteria : * mPCR non available