Augmentation mammoplasty using autologous fat transfer has been widely practiced. However, this procedure is not exempted from complications even after technique refinements. These complications include excessive bruising, edema, hematoma formation, infections, fat necrosis, oil cyst formation, and donor site complications. The development of infection and abscess formation deserve the most attention. In case of delayed infection, a high suspicion of unusual bacteria should be considered. Case Presentation: We report the case of a 32-year-old female patient underwent breast augmentation using autologous fat graft; the patient demonstrated delayed right sided breast abscess caused by a rare etiology identified by culture as peptostreptococcus. This anaerobic bacterium is commensal organisms in humans and under normal conditions does not cause postoperative infection, and its pathogenicity is low. The patient was treated properly and recovered fully with no complications. Conclusion: Abscess formation and infection development are not common complications in the breast after fat transfer, but deserve attention and emergent management. As all grafts including fat graft are non-vascularized during the first days postoperatively, these can be the host of unusual bacteria and cause severe infection. The sterile technique should be considered at all time. In case of delayed infection, a high suspicion for anaerobic peptostreptococci or other unusual bacteria should be considered.

Keywords : Fat Graft; Fat Transfer; Breast Abscess; Anaerobic Infection; Breast Lipofilling; Peptostreptococcal.