Daptomycin is validated as a treatment of bone and joint infections by the Infectious Disease Society of America. However, most of studies did not investigate daptomycin pharmacokinetics in this indication while it is known that efficacy and toxicity concentration studies show a close therapeutic margin.

Evaluation of P-Glycoprotein (P-gp), a transmembrane transport protein, has demonstrated its influence on the concentration and intracellular activity of daptomycin. Recent work has linked the genetic polymorphism of P-gp to the pharmacokinetics of daptomycin, which may explain inter-individual variability but requires further explorations. Previous studies demonstrated existence of interindividual variabilities as sex, renal function and p-glycoprotein polymorphism couple with an intraindividual variabilities unexplained yet.

A population approach will be used to determinate the pharmacokinetics factors, their intra and interindividual variabilities, the parameters associated to those variabilities (as the p glycoprotein).

The investigator's goal is to evaluate different posology and to try to increase daptomycin efficacy and security in bone and joint infection.

Inclusion Criteria:

Patients

• having had a bone or joint infection, with or without implant,
• having an antibiotherapy with daptomycin between December 2012 and December 2016 at the Croix-Rousse hospital
• are at least 18 years old

Exclusion Criteria:

• None

Patients having bone or joint infection, with or without implant, having an antibiotherapy with daptomycin