Penetration of meropenem into pneumonic human lung tissue as measured by in vivo microdialysis.

Until recently, information on antibiotic pharmacokinetic properties in infected human lung tissue was limited. We therefore studied a microdialysis-based approach for measurement of the penetration of meropenem into the extracellular space fluid of human pneumonic lung parenchyma. The lung penetration of meropenem was determined for seven patients with pneumonia and metapneumonic pleural empyema treated by decortication. Intraoperatively, two microdialysis probes were inserted into pneumonic lung tissue and one was inserted into healthy skeletal muscle for reference values. Serum and microdialysis samples were collected at 20-min intervals for at least 8 h following a single intravenous dose of 1 g of meropenem. The maximum free interstitial concentration (mean and standard deviation) of meropenem in infected lung tissue was 11.4 +/- 10.9 mg/liter, and that in serum was 47.3 +/- 21.0 mg/liter. The areas under the curve for infected lung tissue (36.2 +/- 17.9 mg. h/liter) and serum (95.4 +/- 46.6 mg. h/liter) revealed a significant difference. This technique enabled quasi-continuous tissue pharmacokinetic measurements of free, unbound antibiotic in pneumonic lung tissue of patients with pneumonia. The present data corroborate the use of meropenem in the treatment of lung infections caused by extracellular bacteria, demonstrating the excellent distribution profile for meropenem in the interstitial space of human pneumonic lung tissue.