Steady-state plasma and intrapulmonary concentrations of piperacillin/tazobactam 4 g/0.5 g administered to critically ill patients with severe nosocomial pneumonia.

OBJECTIVE: To determine the steady-state plasma and epithelial lining fluid (ELF) concentrations of piperacillin/tazobactam (P/T) administered to critically ill patients with severe bacterial pneumonia.
DESIGN: Prospective, open-label study.
SETTING: An intensive care unit and research ward in a university hospital. PATIENTS: Ten adult patients with severe nosocomial bacterial pneumonia on mechanical ventilation.
INTERVENTIONS: All subjects received a 30-min intravenous infusion of P/T 4 g/0.5 g every 8 h. The steady-state plasma and ELF concentrations of P/T were determined by high-performance liquid chromatography.
MEASUREMENTS AND MAIN RESULTS: The mean+/-SD steady-state plasma trough, peak, and intermediate concentrations were 8.5+/-4.6 microg/ml, 55.9+/-21.6 microg/ml, and 24.0+/-13.8 microg/ml for piperacillin, and 2.1+/-1.0 microg/ml, 4.8+/-2.1 microg/ml, and 2.4+/-1.2 microg/ml for tazobactam, respectively. The mean+/-SD steady-state intermediate ELF concentrations were 13.6+/-9.4 microg/ml for piperacillin and 2.1+/-1.1 microg/ml for tazobactam, respectively, showing a mean percentage penetration of piperacillin and tazobactam into ELF of 56.8% and 91.3 %, respectively, with a P/T ratio of 6.5:1.
CONCLUSION: Our results show that during the treatment of severe nosocomial pneumonia, a regimen of P/T 4 g/0.5 g every 8 h might provide insufficient concentrations into lung tissue to exceed the MIC of many causative pathogens. This suggests that higher doses of P/T should be administered in order to maximize the antibiotic concentration at the site of infection, or that a second antimicrobial agent should be used in association.