The surgical site infection is one of the most important causes of postoperative morbidity. The appropriate antibiotic prophylaxis is one of the most effective way to prevent surgical site infections. The beta-lactam are the most frequent antibiotics recommended for surgical prophylaxis and patients known to be allergic to beta-lactam are more likely to presented surgical site infection, probably due to use of others antibiotic such as vancomycin or clindamycin.

The main objective of the study is to describe the tissu and plasma pharmacokinetics of vancomycin, clindamycin and gentamicin using as surgical antibiotic prophylaxis in patients with beta-lactam hypersensivity and to predict the probability of target attainment for usual bacteria.

Inclusion Criteria:

• Adult patient between 18 and 80 years old
• Patient with history of beta-lactam hypersensitivity
• Patient who underwent abdominal or orthopedic surgery whose forseeable time exceeds 1 hour and requires a surgical antibiotic prophylaxis by vancomycin or clindamycin + gentamicin

Exclusion Criteria:

• morbid obesity (BMI > 35 kg/m2)
• mild to severe renal impairment (clearance creatinine < 60 ml/min)
• vancomycin, clindamycin or gentamicin hypersensitivity
• pregnancy