Necrotising Fasciitis - Causes, Symptoms and Treatment

Necrotizing fasciitis is commonly known as flesh-eating bacteria. It is a rare infection of the deeper layers of skin and subcutaneous tissues and easily spreading across the fascial plane within the subcutaneous tissue. The bacteria multiply and release toxins and enzymes that result in thrombosis (clotting) in the blood vessels. The result is destruction of the soft tissues and fascia. Necrotizing fasciitis is very rare but serious. Around 30% of those who develop necrotizing fasciitis die from the disease. Many people who get necrotizing fasciitis are in good health prior to the infection A few distinct NF syndromes should be recognized. Necrotizing fasciitis is caused by several kinds of bacteria. The 3 most important are type I, or polymicrobial; type II, or group A streptococcal; and type III gas gangrene, or clostridial myonecrosis. A variant of NF type I is saltwater NF, in which an apparently minor skin wound is contaminated with saltwater containing a Vibrio species. The most common cause is infection by a group A streptococcal (GAS) bacterium, most often Streptococcus pyogenes , which also causes other common infections such as strep throat or impetigo . Usually the infections caused by these bacteria are mild. In rare cases, however, the bacteria produce poisons (toxins) that can damage the soft tissue below the skin and cause a more dangerous infection that spreads through the blood to the lungs and other organs. The disease also may be caused by Vibrio vulnificus . Infection with this bacterium can occur if wounds are exposed to ocean water or the drippings from raw saltwater fish, or through injuries from handling marine crustaceans such as crabs. These infections are more common in people who have chronic liver diseases such as cirrhosis .

NF may occur as a complication of a variety of surgical procedures, including cardiac catheterization. A person may have pain from an injury that lessens over 24 to 36 hours and then suddenly becomes much worse. Other symptoms may include fever, chills, and nausea and vomiting or diarrhea. The skin commonly becomes red, swollen, and hot to the touch. Serious illness and shock can develop in addition to tissue damage. Necrotizing fasciitis can lead to organ failure and, sometimes, death. Important bacterial factors include surface protein expression and toxin production. M-1 and M-3 surface proteins, which increase the adherence of the streptococci to the tissues, also protect the bacteria against phagocytosis by neutrophils. NF tends to begin with constitutional symptoms of fever and chills. After 2-3 days, erythema is noted, and supralesional vesiculation or bullae formation ensues. Serosanguineous fluid may drain from the affected area. NF may develop after skin biopsy; at needle puncture sites in those use illicit drugs; and after episodes of frostbite, chronic venous leg ulcers, open bone fractures, insect bites, surgical wounds, and skin abscesses. Many NF risk factors devlop afrter sin biopsy, needle puncture sites in intravenous drug abusers and associated with chronic venous leg ulcers, open bone fractures and surgical wounds. In many cases, there is no association with any underlying factor. Other predisposing factors include age over 50, diabetes mellitus , alcohol abuse , peripheral vascular disease and immunosuppression. However, approximately 50% of cases of streptococcal necrotising fasciitis occur in young, previously healthy individuals.

Causes of Necrotising Fasciitis

Common Causes and Risk factors of Necrotising Fasciitis

Haemophilus aphrophilus.
S aureus.
Diabetes mellitus.
Immunosuppression predispose.
Clostridium perfringens.
Clostridium septicum.
Peripheral vascular disease.

Sign and Symptoms of Necrotising Fasciitis

Common Sign and Symptoms of Necrotising Fasciitis

Pain.
Fever.
Chills.
Nausea.
Vomiting.
Diarrhea.

Treatment for Necrotising Fasciitis

Common Treatment for Necrotising Fasciitis

Antibiotics: Gram staining of the exudate may provide a clue as to whether type I or type II infection is present; the type influences antibiotic therapy. Broad-spectrum antibiotics should be administered immediately.
Combination therapy: This approach involves the use of 2 or 3 antibiotics. To cover aerobes (usually gram-negative organisms), ampicillin and gentamicin are useful. For anaerobes, clindamycin or metronidazole has been used. In group A streptococcal infections, clindamycin has been used, specifically in combination with beta-lactam antibiotics.
Antimicrobial therapy is important but remains secondary to the removal of diseased and necrotic tissues
Single antibiotic coverage: Broad-spectrum beta-lactam drugs such as imipenem cover aerobes, including Pseudomonas species. Ampicillin sulbactam also has broad-spectrum coverage, but it does not cover Pseudomonas species.
Vancomycin: The use of vancomycin to treat methicillin-resistant S aureus is often discussed and may depend on the clinical situation.
Amputation of the affected organ(s) may be necessary. Repeat explorations usually need to be done to remove additional necrotic tissue.

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