Inclusion Criteria:

• Invasive mechanical ventilation for longer than 48 hours

• Respiratory sample collection taken less than two hours ago (at physician discretion, according to local protocol) for a first episode of suspected ventilator-associated pneumonia (meeting the following prespecified criteria) :

  • new or changing chest X-ray infiltrates

  • plus at least two of the following:

    • body temperature ≥38.3°C or ≤35.5°C,
    • blood leukocyte count >12 000/µL or <4000/µL,
    • purulent tracheobronchial aspirate.

• Age ≥18 years

• Informed consent from the patient or next of kin to participation in the trial, or emergency procedure if no next of kin is available

• Patients affiliated to a social security system

Non-inclusion Criteria:

• Criteria for severe ventilator-associated pneumonia defined as:

  • Vasopressor therapy for onset of septic shock around the time of ventilator-associated pneumonia suspicion
  • Onset or severe worsening of hypoxemia (PaO2/FiO2<150 with 60% FiO2 and 10 mm H2O peak expiratory pressure, or patient on veno-venous extracorporeal membrane oxygenation)

• Immunosuppression defined as :

  • leukocytes <1G/L or neutrophils <0,5 G/L
  • within the last 3 months
  • hematopoietic stem-cell transplant or organ transplant with chronic immunosuppressant therapy
  • HIV infection with CD4<50/mm3
  • chronic corticosteroid use (>0.5 mg/kg day for at least one month within the last three months).

• Patient already on Antibiotic Therapy of predicted duration ≥4 weeks (endocarditis, spondylodiscitis, abscess...)

• Previous ventilator-associated pneumonia suspicion with sampling and/or Antibiotic Therapy for suspected ventilator-associated pneumonia

• Previous inclusion in the trial

• Patient included in an interventional study on ventilator-associated pneumonia management with the same primary endpoint.

• Pregnancy, recent delivery, or breastfeeding

• Correctional facility inmate, adult under guardianship

• Patient under legal protection

• Life expectancy less than 48 h and/or decision not to treat potential pneumonia acquired under mechanical ventilation in the context of limiting/discontinuing treatment.

• Organ donor reanimation