19.2 Evidence for antimicrobial prophylaxis perioperatively In earlier studies, antimicrobial prophylaxis was broad spectrum and given for a prolonged duration. Two published multicentre surveys reported a wide variation in the different types of antimicrobial prophylaxis used in MCS implant surgery [476, 477]. More recently, MCS centres follow more general cardiac surgery prophylaxis guidelines and do not include broad spectrum gram-negative or fungal coverage. Cardiac surgery prophylaxis guidelines usually recommend a cephalosporin (cefazolin or cefuroxime) for 24–48 h, which can provide sufficient gram-positive and gram-negative coverage [26, 478–481]. Routine antifungal prophylaxis is not recommended [26].