We've long known that most surgical site infections arise from the endogenous flora of the patient's skin, mucous membranes or hollow viscera, making antibiotic prophylaxis, skin antisepsis, draping and other preventive measures "Job #1" in surgical infection control. Unfortunately, our understanding of how to prevent these kinds of infections is still evolving. What we don't know about antimicrobial prep products, systemic antimicrobial prophylaxis and draping would fill volumes. Here's what experts advise based on our understanding so far.