Skin graft scar on a woman's thigh, rear view. A skin graft has been used to cover and treat a wound caused by necrotising fasciitis, a rare bacterial infection of the subcutaneous tissues. It can be caused by a number of different bacteria, including Clostridium sp., Group A streptococcus and Staphylococcus sp. bacteria. Infected skin becomes painful, red and swollen. It progresses to blistering and necrosis (death) of subcutaneous tissues. It can be fatal. Treatment is with antibiotics. Skin grafts are performed when a wound is too large to heal naturally. The skin for grafts is generally taken from the patient to prevent rejection of the tissue by the immune system.