Necrotizing fasciitis

Necrotizing fasciitis
SynonymsFlesh-eating bacteria, flesh-eating bacteria syndrome,[1] necrotizing soft tissue infection (NSTI),[2] fasciitis necroticans
Necrotizing fasciitis left leg.JPEG
Person with necrotizing fasciitis. The left leg shows extensive redness and tissue death.
Pronunciation
SpecialtyInfectious disease
SymptomsSevere pain, fever, purple colored skin in the affected area[3]
Usual onsetSudden, spreads rapidly[3]
CausesMultiple types of bacteria,[4] occasional fungus[5]
Risk factorsPoor immune function such as from diabetes or cancer, obesity, alcoholism, intravenous drug use, peripheral artery disease[2][3]
Diagnostic methodBased on symptoms, medical imaging[4]
Differential diagnosisCellulitis, pyomyositis, gas gangrene[6]
PreventionWound care, handwashing[3]
TreatmentSurgery to remove the infected tissue, intravenous antibiotics[2][3]
Prognosis~30% mortality[2]
Frequency0.7 per 100,000 per year[4]

Necrotizing fasciitis (NF), commonly known as flesh-eating disease, is an infection that results in the death of parts of the body's soft tissue.[3] It is a severe disease of sudden onset that spreads rapidly.[3] Symptoms include red or purple skin in the affected area, severe pain, fever, and vomiting.[3] The most commonly affected areas are the limbs and perineum.[2]

Typically, the infection enters the body through a break in the skin such as a cut or burn.[3] Risk factors include poor immune function such as from diabetes or cancer, obesity, alcoholism, intravenous drug use, and peripheral artery disease.[2][3] It is not typically spread between people.[3] The disease is classified into four types, depending on the infecting organism.[4] Between 55 and 80% of cases involve more than one type of bacteria.[4] Methicillin-resistant Staphylococcus aureus (MRSA) is involved in up to a third of cases.[4] Medical imaging is helpful to confirm the diagnosis.[4]

Necrotizing fasciitis may be prevented with proper wound care and handwashing.[3] It is usually treated with surgery to remove the infected tissue, and intravenous antibiotics.[2][3] Often, a combination of antibiotics is used, such as penicillin G, clindamycin, vancomycin, and gentamicin.[2] Delays in surgery are associated with a much higher risk of death.[4] Even with high-quality treatment, the risk of death is between 25 and 35%.[2]

Necrotizing fasciitis occurs in about 0.4 people per 100,000 per year in the US, and about 1 per 100,000 in Western Europe.[4] Both sexes are affected equally.[2] It becomes more common among older people and is rare in children.[4] It has been described at least since the time of Hippocrates.[2] The term "necrotizing fasciitis" first came into use in 1952.[4][7]

Signs and symptoms

Symptoms may include fever, swelling, and complaint of excessive pain. The initial skin changes are similar to cellulitis or abscess, thus making the diagnosis at early stages difficult. Hardening of the skin and soft tissue and swelling beyond the area of skin changes are commonly present in those with early necrotizing changes.[2] The redness and swelling usually blend into surrounding normal tissues. The overlying skin may appear shiny and tense.[8] Other signs which are more suggestive of necrotizing changes (but present in later stages in 7 to 44% of the cases) are: formation of bullae, bleeding into the skin which is present before skin necrosis[2] (skin turning from red to purple and black due to thrombosis of blood vessels),[8] presence of gas in tissues, and reduced or absent sensation over the skin[2] (due to the necrosis of the underlying nerves).[8] Rapid progression to shock despite antibiotic therapy is another indication of necrotizing fasciitis. Necrotizing changes affecting the groin are known as Fournier gangrene.[2]

However, those who are immunocompromised (have cancer, use corticosteroid, on radiotherapy, chemotherapy, HIV/AIDS, or prior organ or bone marrow transplantation) may not show normal symptoms. Immunocompromised persons also have twice the risk of death from necrotizing infections, so higher suspicion should be maintained in this group.[2]

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