Broad-spectrum Antibiotic Prophylaxis in Tumor and Infected Orthopedic Surgery - the prospective-randomized, microbiologist-blinded, stratified, superiority Trials - BAPTIST trials

Abstract Background: The perioperative antibiotic prophylaxis with 1st or 2nd-generation cephalosporins is evidence-based in orthopedic surgery. There are, however, situations with a high risk of prophylaxis-resistant surgical site infections (SSI). Methods: We perform a superiority randomized-controlled trial with a 10% margin and a power of 90% in favor of the broad-spectrum prophylaxis. We will randomize orthopedic interventions with a high risk for SSI (open fractures, surgery under therapeutic antibiotics, tumor surgery, spine surgery with ASA-Score ≥ 3 points) in a prospective-alternating scheme (1:1, standard prophylaxis with mostly cefuroxime versus a broad-spectrum prophylaxis of a combined single-shot of vancomycin 1 g & gentamicin 5 mg/kg parenterally). The primary outcomes are "remission" at 6 weeks; or at 1 year for surgeries with implant. Secondary outcomes are the risk for prophylaxis-resistant SSI pathogens, revision surgery for any reason, change of antibiotic therapy, adverse events and the incidence of non-SSI infections within 6 weeks (e.g. urine infections). With event-free surgeries to 95% in the broad-spectrum versus 85% in the standard arm, we need 2 x 207 orthopedic surgeries among all groups. Discussion: In selected patients with a high risk for prophylaxis-resistant SSI, a broad-spectrum combination might prevent SSIs better than the standard prophylaxis. Trial registration: ClinicalTrial.gov NCT05502380. Registered on 12 August 2022. Protocol version: 2 (3 June 2022)