Purpose

The investigators hope to learn 1) if the addition of prophylaxis with vancomycin will decrease the rate of cefazolin non-susceptible surgical site infections (SSI), in high risk population 2) to develop better understanding of vancomycin and cefazolin pharmacokinetics in children undergoing cardiopulmonary bypass (CPB) 3) to assess the barriers to vancomycin dosing peri-operatively 4) to assess side effects and risks associated with peri-operative vancomycin administration. This will allow us to improve patient care by better understanding the benefits or the risks of peri-operative vancomycin administration and potentially decrease cefazolin-resistant surgical site infections. In addition, this study gives us the opportunity to evaluate cefazolin and vancomycin pharmacokinetics (pK) on children on CPB. The investigators will take blood samples from 20 patients. In 10 patients the investigators will do Cefazolin pK analysis and in the other 10 the investigators will do pK Vancomycin analysis. For the remainder of 292 patients, only prospective chart review will be done to determine the incidence of SSIs. This data will be compared with 936 controls who received only Cefazolin pre-operatively as prophylaxis for SSI's. --------------------------------------------------------------------------------