OVERVIEW
• Necrotizing fasciitis (NF) is an extremely uncommon but potentially fatal infection of the skin and subcutaneous connective tissue.
• It is commonly referred to as flesh-eating disease although the causative bacteria do not actually “eat” flesh, but release toxins that damage and destroy adjacent tissue.
The condition can start from a relatively minor injury, such as a small cut or wound, or insect bite and rapidly become lethal if not diagnosed in time and managed appropriately
• It causes severe morbidity and mortality if not recognized and treated in the early stages. However, it is difficult to distinguish it from other superficial skin infections such as cellulitis.

CAUSES OF NECROTIZING FASCIITIS
Many types of bacteria can cause necrotizing fasciitis. The most common culprit is Group A Streptococcus. Other microbial organisms that can cause necrotizing fasciitis include:
• Clostridium
• Klebsiella
• Staphylococcus aureus
• E. coli
• Aeromonas hydrophila

RISK FACTORS FOR NECROTIZING FASCIITIS
• Persons with a weak immune system or on immunosuppressive therapy (such as anti-cancer drugs or anti-rejection drugs)
• Diabetes
• Long term steroid therapy
• Bone marrow cancers
• Underlying heart or lung disease
• IV drug or alcohol abuse
• Chronic skin lesions

PATHOPHYSIOLOGY
The bacterial organisms spread into the deeper planes of tissues helped by bacterial enzymes and toxins. Infection in the deeper portions causes vascular occlusion and ischemic death and necrosis of tissues. Also there is injury of superficial nerves resulting in localized numbness. Important factors in the pathogenesis include bacterial proteins that increase adherence to host tissues and prevent phagocytosis by neutrophils

CLINICAL FEATURES OF NECROTIZING FASCIITIS
Early symptoms include the following
• History of small cut or scratch on the skin
• intense pain of the wound out of proportion to size of injury or damage to skin
• High temperature (fever)
• Generalized fatigue and malaise

Within a few hours to days, there may be
• Swelling and redness of affected part
• Vomiting and diarrhea
• Dark blotches on the skin which become fluid filled blisters
• Dizziness, confusion, coma and death due to organ failure if not treated promptly

DIAGNOSIS OF NECROTIZING FASCIITIS
• Physical examination of the affected area of skin
• Blood tests (to confirm presence of acute infection, evidence of muscle damage)
• Imaging – MRI and CT scan
• Diagnosis can only be confirmed by removing the affected tissue and sending for histopathological examination (HPE)

MANAGEMENT OF NECROTIZING FASCIITIS
The mainstay of management includes
• Surgery to remove infected portions of skin and subcutaneous tissue completely. Amputation of affected limbs may be necessary to save the patient’s life in some cases
• Broad spectrum antibiotics intravenously
• Supportive treatment to control your blood pressure, acid base balance and fluid levels and function of vital organs

People with necrotizing fasciitis often need to remain in the intensive care unit for several weeks. Isolation from other patients is important to reduce the risk of spreading the infection.

PROGNOSIS
• Even with treatment, reports suggest a 20-40% fatality in necrotizing fasciitis
• People who survive often have disability due to the amputation or extensive surgery
• Further surgery to improve cosmetic appearance of the affected area
• Rehabilitation support to cope with disability

PREVENTION OF NECROTIZING FASCIITIS
• Keep wounds clean and dry
• Treat with antibiotics at the first sign of infection, especially in persons at high risk
• Maintain good hand hygiene by frequent washing with soap and water