ObjectiveTo determine the steady-state plasma and epithelial lining fluid concentrations of cefepime administered in continuous infusion in critically ill patients with severe bacterial pneumonia.DesignProspective, open-label study.SettingAn intensive care unit and research ward in a university hospital.PatientsTwenty adult patients with severe nosocomial bacterial pneumonia on mechanical ventilation were enrolled.InterventionsAll subjects received a 30-min intravenous infusion of cefepime 2 g followed by a continuous infusion of 4 g over 24 hrs. The concentrations of cefepime in plasma and epithelial lining fluid were determined at steady state after 48 hrs of therapy with high performance liquid chromatography.Measurements and Main ResultsThe mean ± sd steady-state plasma and epithelial lining fluid concentrations of cefepime 4 g in continuous infusion were 13.5 ± 3.3 &mgr;g/mL and 14.1 ± 2.8 &mgr;g/mL, respectively, with a mean percentage penetration of cefepime into epithelial lining fluid of about 100%.ConclusionsThe administration of 4 g of cefepime in continuous infusion in critically ill patients with severe nosocomial pneumonia appears to optimize the pharmacodynamic profile of this &bgr;-lactam by constantly providing concentrations in excess of minimal inhibitory concentration of most of susceptible organisms over the course of therapy in both serum and epithelial lining fluid.