The treatment of Methicillin-sensitive Staphylococcus aureus bacteremia is based on the first-line use of cefazolin or M penicillins (oxacillin and cloxacillin). The use of the latter is recommended at high doses (150-200 mg/kg/24h). In a study on infectious endocarditis, 52 of 56 patients with staphylococcal endocarditis treated with (cl)oxacillin were overdosed with the recommended doses. Although the main mechanism of renal toxicity described for M penicillins is immunoallergic, a frequent overdose is observed in cases of acute renal failure with M penicillins. There is also a significant association between overdose and risk of neurological toxicity. The currently recommended treatment duration is a minimum of 14 days of IV treatment from the first negative blood culture, which leaves room for carrying out a plasma assay and possible dosage adjustment subsequently.

Overdose is a risk factor for nephrotoxicity and neurotoxicity. Plasma level could be predictive of clinical success. Systematic plasma dosing would reduce the risk of toxicity and improve the clinical cure rate.

Inclusion Criteria:

• Adult patient (≥18 years old)
• Having presented an infection with Staphylococcus aureus and treated at the University Hospitals of Strasbourg between January 1, 2019 and December 31, 2022.

Exclusion Criteria:

- Patient having expressed his opposition to the reuse of his data for scientific research purposes.

Adult patient (≥18 years old) having presented an infection with Staphylococcus aureus and treated at the University Hospitals of Strasbourg between January 1, 2019 and December 31, 2022.