Reduced bactericidal activity against Staphylococcus aureus and Pseudomonas aeruginosa of blood neutrophils from patients with early adult respiratory distress syndrome.

This study investigated the bactericidal capability of circulating neutrophils from blunt trauma patients admitted to an Intensive Care Unit against Staphylococcus aureus and Pseudomonas aeruginosa. Among those patients, two groups were considered and compared: patients who developed adult respiratory distress syndrome (ARDS) and patients who developed only pneumonia. Peripheral blood samples were drawn as soon as a diagnosis of pneumonia or ARDS was made, followed by the isolation of neutrophil cells and assessment of bacteria phagocytosis and killing. The results demonstrated that in patients with ARDS, phagocytosis and killing efficiency were significantly impaired in comparison with patients with pneumonia and healthy controls. A possible dysregulation of reactive oxygen species production involving the release of humoral mediators in early ARDS may be involved.