Here is the design of a clinical trial:

Official Title: "Antibioprophylaxis for Excision-graft Surgery in Burn Patient: a Multicenter Randomized Double-blind Study: A2B Trial"

Included conditions:
- Burns Surgery

Study Armgroups:
- {'label': 'active group', 'type': 'ACTIVE_COMPARATOR', 'description': 'The antibiotic prophylaxis will be cefazolin 2 g powder for solution for injection diluted in 50mL of NaCl 0.9%, IV infusion on 30 minutes with syringe pump, in case of absence of colonization to Pseudomonas aeruginosa prior to the surgical procedure.\n\nThe dose administer is 2g.\n\nAntibiotic prophylaxis will be piperacilline-tazobactam 4 g powder for solution for injection diluted in 50mL of NaCl 0.9%, IV infusion on 30 minutes with syringe driver in patients with burn wound colonized to Pseudomonas aeruginosa.\n\nThe dose administer is 4g.', 'interventionNames': ['Drug: active intervention']}
- {'label': 'Placebo group', 'type': 'PLACEBO_COMPARATOR', 'description': 'The control group will received, as placebo NaCl 0.9% solution for injection diluted in 50mL of NaCl 0.9%, IV infusion on 30 minutes with syringe pump.', 'interventionNames': ['Other: placebo intervention']}

Interventions:
- {'type': 'DRUG', 'name': 'active intervention', 'description': 'The antibiotic prophylaxis will be cefazolin 2 g, or piperacilline-tazobactam 4 g, powder for solution for injection diluted in 50mL of NaCl 0.9%, IV infusion on 30 minutes with syringe pump.', 'armGroupLabels': ['active group'], 'otherNames': ['Cefazolin or piperacilline-tazobactam 4 g']}
- {'type': 'OTHER', 'name': 'placebo intervention', 'description': 'The control group will received, as placebo NaCl 0.9% solution for injection diluted in 50mL of NaCl 0.9%, IV infusion on 30 minutes with syringe pump.', 'armGroupLabels': ['Placebo group'], 'otherNames': ['NaC 0,9%l']}

Primary Outcomes:
- {'measure': 'Post-operative infection defined as Post-operative sepsis and/or Surgical site infection, and/or Graft lysis requiring a new graft within 7 days after surgery.', 'description': 'Postoperative infection will be collected by the intensivists or infectious disease specialist consultant blinded to the interventional or control arm. Skin infection and skin graft lysis requiring a new graft procedure will be assess by a surgeon blinded of the arm of the study.', 'timeFrame': '7 days after surgery'}
- {'measure': 'Post-operative sepsis', 'description': 'Sepsis is defined as life-threatening organ dysfunction (defined by an increase of Sepsis related organ failure assessment \\[SOFA\\] score of 2 points or more) in response to infection. The minimum value is 0 and maximum value is 24. 0 meaning no organ dysfunction and 24 the maximum organ dysfunction.', 'timeFrame': '7 days after surgery'}
- {'measure': 'Surgical site infection', 'description': 'Surgical site (operated skin) infection with general signs is considered as a systemic infection originated from skin (Presence of a local or loco-regional inflammatory reaction; Unfavourable and unexpected local evolution; Lysis of grafts; Necrosis of fat located under the graft)', 'timeFrame': '7 days after surgery'}
- {'measure': 'Graft lysis needing a new graft procedure', 'description': 'Graft lysis is defined as a skin graft lysis in the 7 days post operative, and needing a new skin graft assessed be a surgeon blinded of the randomization group.', 'timeFrame': '7 days after surgery'}

Please estimate the sample size based on the assumption: 
Alpha risk is set at 4.9% (adjusted for interim analysis) and power is set at 80%.
Sample size determination
        The incidence of the primary endpoint is estimated to be 25% (based on investigatorsâ personal data). With an alpha risk of 4.9% (adjusted for interim analysis) and powerâ=â80%, the number of patients to include to show an absolute reduction of 10% of the primary endpoint, we need to enroll 506 patients (253 in the intervention group and 253 in the control group).