Introduction Staphylococcus aureus is the main causative agent of bone and joint infections (BJI). More than 80% of the strains isolated in France are methicillin-susceptible (MSSA). During the early phase of MSSA BJI management national and international guidelines recommend the use of intra-venous type M penicillin with a dosage ranging from 100 to 200 mg/kg/day. Pharmacological properties of this class of penicillin require 4 to 6 infusions by day. Continuous infusion of beta-lactams is increasingly used especially in intensive care units. It allows an improvement of pharmacokinetic/pharmacodynamics (PK/PD) parameters and a reduction in time dedicated to infusion preparations by the nurses. However pharmacological data regarding such administration is required for type M penicillin.