Perineal necrotizing fasciitis is a less common and serious soft tissue infection that differs from streptococcal necrosis in that it is often a mixture of multiple bacteria. The causative organisms include Gram-positive hemolytic streptococci, Staphylococcus aureus, Gram-negative bacteria and anaerobic bacteria. In the past, anaerobic bacteria were often not detected due to poor anaerobic culture techniques. Depending on the condition, necrotizing fasciitis can be divided into two types: one in which the causative organism spreads through trauma or the primary lesion, causing a sudden deterioration and rapid necrosis of soft tissue. The other type has a slower progression and is predominantly cellulitis, with multiple skin ulcers, thin and oddly smelly pus, a dishwater-like appearance, extensive subterranean skin around the ulcers, and a twisted pronunciation and local sensation of numbness or pain, characteristics that are not common in cellulitis. Patients often have significant toxemia with chills, hyperthermia, and hypotension. Hypocalcemia may occur in cases of extensive subcutaneous tissue necrosis, and bacteriological examination is of particular importance for diagnosis, especially smear examination of wound pus. The key to the treatment of necrotizing fasciitis is early and thorough dilation surgery with adequate incision of the subcutaneous margin and excision of necrotic tissue, including necrotic subcutaneous fatty tissue or superficial fascia, but the skin can usually be preserved. The wound is left open and irrigated with 3% hydrogen peroxide or 1:5000 potassium permanganate solution, loosely filled with gauze, or several polyethylene catheters are inserted for postoperative irrigation. Baxter recommends irrigation with saline containing neomycin 100 mg/L and polymyxin B 100 mg/L, while others recommend carbenicillin or 0.5% metronidazole solution. The drug change should be done to speed up the removal of necrotic tissues, and the necrotic tissues found need to be re-invasive. Bacterial cultures should be repeated at the time of dressing change for early detection of secondary bacteria such as Pseudomonas aeruginosa, Serratia marcescens, or Candida. The causative agents of necrotizing fasciitis include Enterobacter spp, Enterococcus spp and anaerobic Streptococcus and Bacteroidetes spp and should be combined with ampicillin to control Enterococcus and anaerobic Streptococcus.