Randomized Controlled Trial to Evaluate the Optimal Timing of Surgical Antimicrobial Prophylaxis

Surgical site infections (SSI) are the most frequent hospital acquired infections in patients who underwent surgery. With regards to the increasing financial restraint in patient care, the socio-economic burden of SSI in the public health sector and its prevention gains in importance. The prophylactic application of antibiotics (surgical antimicrobial prophylaxis, SAP) prior to the skin incision significantly reduces the risk of SSI, but the correct time point of drug administration remains unclear. Most studies recommend application of SAP directly prior to skin incision. Other studies, however, suggest that this is too late and more time between administration of the SAP and skin incision is necessary for optimal SSI prevention. A large cohort study in Switzerland concluded that SAP should be applied between 74 and 30 minutes prior to skin incision. Due to the obvious importance of this controversy, we want to answer this question with a clinical study (randomized controlled trial, RCT) at the University Hospital of Basel and the Cantonal Hospital of Aarau. We plan to investigate two administration strategies according to the timing of the SAP. Strategy A will consist of SAP application in the anesthetic room located in front of the actual operating theatre, where the patient gets anesthesia. Therefore, the application of SAP will take place early, approximately between 75 and 30 minutes prior to skin incision. In strategy B we will apply SAP in the operating theatre, which on average occurs later (approximately within the last 30 minutes before skin incision). We test the hypothesis that strategy A is more effective in preventing SSI than strategy B. We will include a total of 5000 patients in abdominal, vascular and trauma surgery (2500 at each study site and 2500 per study group). All patients will be followed in the hospital for SSI occurrence. Additionally, all patients will be interviewed by telephone after hospital discharge at a defined follow-up period