Ertapenem is an antibiotic that is highly bound to plasma protein (> 95%). The effects of this high protein binding on tissue distribution of antibiotics have been few evaluated yet.

In this study, two groups of subjects will be compared: 6 healthy volunteers and 6 critically ill patients (patients with infection due to an Ertapenem susceptible bacteria). Indeed, these 2 populations show changes in binding capacity of drugs to plasma proteins due to a decrease of protidaemia and of the affinity of drugs to transport proteins.

It seems therefore important to clarify the consequences of a modification in protein binding on distribution of antibiotics. That's why we have decided to characterize tissue distribution of ertapenem in healthy volunteers and critically ill patients by assessing: free and total concentrations in plasma and free concentrations in muscle by microdialysis.

Inclusion Criteria:

• Age: from 18 to 80 years
• Patients with infection due to ertapenem susceptible bacteria.

Exclusion Criteria:

• Patients who received ertapenem within 7 days prior to inclusion
• Known allergy to ertapenem or any excipients
• Neutropenia < 500/mm3
• Hemoglobin concentration < 9g/dl
• Renal failure (creatinin clearance < 30ml/min/1.73m²)
• Decompensated heart failure
• Patients receiving vasopressor (adrenalin, noradrenalin), > 0.5µg/kg/min
• Known hypersensitivity to Elma®
• Positive pregnancy test or currently lactating