Antimicrobial prophylaxis and the prevention of surgical site infection in cardiac surgery: an analysis of 21 007 patients in Switzerland†.

Objectives: Our goal was to determine the optimal timing and choice of surgical antimicrobial prophylaxis (SAP) in patients having cardiac surgery.

Methods: The setting was the Swiss surgical site infection (SSI) national surveillance system with a follow-up rate of >94%. Participants were patients from 14 hospitals who had cardiac surgery from 2009 to 2017 with clean wounds, SAP with cefuroxime, cefazolin or a vancomycin/cefuroxime combination and timing of SAP within 120 min before the incision. Exposures were SAP timing and agents; the main outcome was the incidence of SSI. We fitted generalized additive and mixed-effects generalized linear models to describe effects predicting SSIs.

Results: A total of 21 007 patients were enrolled with an SSI incidence of 5.5%. Administration of SAP within 30 min before the incision was significantly associated with decreased deep/organ space SSI [adjusted odds ratio (OR) 0.73, 95% confidence interval (CI) 0.54-0.98; P = 0.035] compared to administration of SAP 60-120 min before the incision. Cefazolin (adjusted OR 0.64, 95% CI 0.49-0.84; P = 0.001) but not vancomycin/cefuroxime combination (adjusted OR 1.05, 95% CI 0.82-1.34; P = 0.689) was significantly associated with a lower risk of overall SSI compared to cefuroxime alone. Nevertheless, there were no statistically significant differences between the SAP agents and the risk of deep/organ space SSI.

Conclusions: The results from this large prospective study provide substantial arguments that administration of SAP close to the time of the incision is more effective than earlier administration before cardiac surgery, making compliance with SAP administration easier. The choice of SAP appears to play a significant role in the prevention of all SSIs, even after adjusting for confounding variables.