Antibiotic prophylaxis with vancomycin and gentamicin and the occurrence of acute kidney injury after cardiac surgery with cardiopulmonary bypass

BACKGROUND Vancomycin combined with gentamicin (VGA) is used as an alternative antibiotic prophylaxis in cardiac surgery when cephalosporins are contraindicated. However, the nephrotoxic potential of this combination raises concerns regarding postoperative acute kidney injury (AKI). OBJECTIVE This study aimed to evaluate the association between VGA prophylaxis and AKI occurrence in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB), while accounting for preoperative risk factors. DESIGN Retrospective single-centre study. AKI was defined according to KDIGO criteria within 7 postoperative days. PATIENTS Of the 8895 eligible patients between April 2013 and December 2021, 8198 were included. Subgroup analyses were performed according to preoperative AKI risk status (high-risk: insulin-dependent diabetes, cirrhosis, acute endocarditis, preoperative critical state, emergency surgery, or cardiac transplantation). RESULTS In our cohort, 7469 (91%) received cephalosporins and 729 (9%) received VGA. The overall AKI incidence was 16%. AKI occurred more frequently in the VGA group (29% vs. 15%, P < 0.001). After multivariable adjustment, VGA remained independently associated with AKI [odds ratio (OR) 1.29, 95% confidence interval (CI) 1.03 to 1.62, P = 0.024], confirmed by propensity score analysis (OR 1.32, 95% CI 1.09 to 1.60, P = 0.005). In subgroup analyses, VGA was significantly associated with AKI in high-risk patients (OR 1.53, 95% CI 1.14 to 2.04, P = 0.004), but not in low-risk patients (OR 1.19, 95% CI 0.87 to 1.64, P = 0.285). CONCLUSION In this large retrospective cohort, VGA antibiotic prophylaxis was independently associated with increased AKI risk following cardiac surgery with CPB. This association was driven primarily by patients with preoperative risk factors for AKI. Alternative prophylactic regimens should be considered in high-risk patients when possible.