The added benefit of prolonged antibiotic prophylactic treatment in patients undergoing breast reconstruction who have drains placed for several days after surgery is controversial. In this study we aim to compare two prophylactic regimens: 1. 24 hour antibiotic treatment prior to surgery with cefazolin 2. a prolonged antibiotic regimen consisting of 48 hours cefazolin treatment followed by oral therapy with cephalexin until the removal of the drains. Patients will sign an informed consent form prior to the surgery and will be randomized to one of the antibiotic regimens. Patients will be closely followed up to one year after surgery. The number of surgical site infections according to the NNIS criteria and loss of breast implants will be compared between the two groups.