The diagnosis of pneumonia is challenging in Intensive Care Unit. The auto-fluorescence of white corpuscles is altered during pneumonia. In presence of bacterial growth on lung samples, the measure of autofluorescence of white corpuscles could help the clinicians to discriminate bacterial colonization from acute infection.

Inclusion Criteria:

• Hospitalization in intensive care units
• Mechanical ventilation
• Age > 18 years
• Collection of a lung sample for bacteriological analysis for the suspicion of a first episode of lung infection.

Exclusion Criteria:

• Refuse to participate

Patients in intensive care units