Antibiotic prophylaxis in (sub)normothermic organ preservation: in vitro efficacy and toxicity of cephalosporins

Bacterial contamination during cold organ preservation occurs without major complications. However, with organ preservation steering toward (sub)normothermic temperatures, bacterial contamination may be detrimental with limited evidence to support the choice of antibiotic. This study aimed to determine the effective antibiotic prophylaxis for (sub)normothermic preservation by investigating whether Staphylococcus epidermidis was capable of growing in a subnormothermia-compatible preservation solution Polysol (PS) and in solutions designed for cold preservation (University of Wisconsin solution, histidine-tryptophan-ketoglutarate solution, and Belzer-machine perfusion solution). Various S. epidermidis and Staphylococcus aureus strains were exposed to ceftriaxone and cefazolin at concentrations from 0 to 1000 μg/mL under subnormothermic and normothermic conditions in PS. To mimic procedural conditions, the effect of cefazolin was determined after exposure of bacteria to 20-hr incubation at 28°C in the presence of cefazolin and subsequent incubation at 37°C in the absence of cefazolin. The toxicity of cefazolin was assessed by cell viability and caspase activation assays in porcine kidney endothelial cells. Without antibiotics, PS sustained bacterial growth under sub(normothermic) conditions, whereas growth was absent in cold preservation solutions. Cefazolin exhibited greater bactericidal effect on S. epidermidis than ceftriaxone. However, after inoculating PS with 10 colony-forming units/mL, only a cefazolin concentration of 1000 μg/mL was able to exert a complete bactericidal effect on S. epidermidis and S. aureus strains and maintain sterility after removal of cefazolin. Finally, 1000 μg/mL cefazolin showed no adverse effects on porcine kidney endothelial cells. Based on these findings, we recommend that high-dose cefazolin be used for prophylaxis in (sub)normothermic organ preservation with PS.