Ofloxacin is a gold standard antibiotic for the treatment of bone and joint infections due to sensible staphylococcus strains. However, in the elderly, inter-individual variability of the pharmacokinetics may reduce the efficacy or increase toxicity. The occurrence of ofloxacin side effects is likely to be increased in case of higher exposition. However, the serum concentration-toxicity relationship has not yet been determined. The purpose of this project is to assess the association between the residual serum concentration of ofloxacin at day 3 and the occurrence of at least one adverse effect attributable to ofloxacin, and determine a threshold toxicity concentration if this association exists.

Inclusion Criteria:

• Patients aged over 65 years hospitalized at the University Hospital of Amiens for an uncomplicated bone and joint infections
• Indication for oral switch to ofloxacin

Exclusion Criteria:

• Patient refusing to participate in the study
• Patient under guardianship or curators or deprived of public rights
• Any liver or biliary injury
• Any contraindications to ofloxacin