Inclusion Criteria:

• Adult patients hospitalized in an ICU
• Under mechanical ventilation for at least five days
• Microbiologically confirmed VAP preferably on a distal lung sample (bronchoalveolar lavage or protected distal specimen) otherwise endotracheal aspiration
• Enterobacteriaceae susceptible to cotrimoxazole, and for polymicrobial VAP, all bacteria susceptible to cotrimoxazole
• 5) Treated for at least 24 hours by an appropriate empiric antibiotic therapy (at least one effective antibiotic from the initiation of treatment for this VAP episode), and for polymicrobial VAP, all bacteria susceptible to empiric antibiotic therapy
• Stability of haemodynamic (stability or decrease in catecholamine dose) and respiratory (stability or improvement of FIO2) parameters

Exclusion Criteria:

• Haemodynamic instability (increasing dose of a catecholamine in the last 24 hours)

• Contra-indication to cotrimoxazole:

  • allergy,
  • advanced liver insufficiency,
  • renal dysfunction with clearance <15 mL/min/1.73 m² without hemodialysis
  • G6PD deficiency
  • history of hypersensitivity to one of the components (in particular, hypersensitivity to sulphonamides
  • known macrocytic anemia defined by VGM >
  • treatment with methotrexate

• Infection requiring prolonged antibiotic-therapy (pleural empyema, lung abscess, necrotizing pneumonia, etc…)

• Cystic fibrosis

• Immunosuppression (neutropenia, HIV with CD4 lymphocytes below 200/mm3, immunosuppressive therapy or corticosteroid therapy >0.5 mg/kg/j before ICU admission)

• Cardiac arrest without awakening

• Moribund state (patient likely to die within 24h)

• Limitation of life support (comfort care applied only) at the time of screening

• Enrolment to another interventional study on VAP care/management

• Pregnancy or breastfeeding

• Subject deprived of freedom, subject under a legal protective measure

• No affiliation to any health insurance system

• Refusal to participate to the study (patient or legal representative or family member or close relative if present)

• Patients previously included in the study