Most commonly known as " flesh-eating bacteria." necrotizing fasciitis is a progressive, rapidly spreading inflammatory infection of the deep fascia. It's also referred to as hemolytic streptococcal gangrene, acute dermal gangrene, suppurative fasciitis, and synergistic necrotizing cellulitis.
Necrotizing fasciitis destroys the fascia and fat tissues, with secondary necrosis of subcutaneous tissue. It's most commonly caused by the pathogenic bacteria. Streptococcus pyogenes also known as group A streptococcus (GAS), but other aerobic and anaerobic pathogens may be present. This severe and potentially fatal infection may begin at the site of a small insignificant wound or a surgical incision and is characterized by invasive and progressive necrosis of the soft tissue and underlying blood supply.
Causes and pathophysiology
In necrotizing fasciitis group A beta-hemolytic Streptococcus and Staphylococcus aureus, alone or together, are most often the primary infecting bacteria. There are more than 80 types of the causative bacteria. S. pyogenes, making the epidemiology of GAS infections complex. Other aerobic and anaerobic pathogens include Bacteroides, Clostridium, Peptostreptococcus, Enterobacteriaceae, coliforms, Proteus, Pseudomonas, and Klebsiella.
Risk factors for contracting necrotizing fasciitis include advanced age, human immunodeficiency virus infection, alcohol abuse, and varicella infection. Patients with chronic illness, such as cancer, diabetes, cardiac and pulmonary disease, and kidney disease requiring hemodialysis, are also at risk for contracting necrotizing fasciitis. Those using steroids are more susceptible to GAS infection due to debilitated immune responsiveness.
The infecting bacteria in this disorder enter the host through a local tissue injury or a breach in a mucous membrane barrier. Wounds as minor as pinpricks, needle punctures, blisters, and abrasions or as serious as a traumatic injury or surgical incision can provide an opportunity for bacteria to enter the body.
The organisms proliferate in an environment of tissue hypoxia caused by trauma. recent surgery or a medical condition that compromises the patient. The end product of the invasion is necrosis of the surrounding tissue, which accelerates the disease process by creating a favorable environment for these organisms.
There are 2 important symptoms to watch out for:
The original site of infection may be a minor wound or injury such as a small cut or bruise. Or, it may follow a recent chickenpox infection. Sometimes there is no obvious skin wound or injury.
The appearance of the skin and underlying tissues, and the presence of gangrene (black or dead tissue) indicates a necrotizing soft tissue infection. Imaging tests, such as CT scans, are sometimes helpful.
Often a patient will be diagnosed in the operating room by a surgeon. A gram stain and culture of drainage or tissue from the area may find which bacteria is causing the infection.
Prompt and aggressive exploration and debridement of suspected necrotizing fasciitis is mandatory to provide an early and definitive diagnosis and enhance the patient's prognosis. Ninety percent of patients that present with clinical signs and symptoms need immediate surgical debridement, fasciectomy, or amputation.
Penicillin, clindamycin (Cleocin), metronidazole (Flagy!), ceftriaxone (Rocephin), gentamicin (Garamycin), chloramphenicol (Chloromycetin), and ampicillin (Omnipen) are some of the medications used orally. I.V., or intramuscularly to combat the organisms involved with necrotizing fasciitis. The particular drugs used are determined by the sensitivity of the organisms in culture. Medications in combination must be used when the infection is polymicrobial. Drug recommendations continue to change as new antibiotics are developed and new resistance emerges.
Hyperbaric oxygen therapy (HBO) may decrease the mortality rate and significantly improve tissues' defense against infection. HBO prevents necrosis from spreading by increasing the normal oxygen saturations of infected wounds by a thousand-fold, causing a bactericidal effect. Typical treatment involves HBO started aggressively after the first surgical debridement and continuing for 10 to 15 sessions.
Clean any skin injury thoroughly. Watch for signs of infection such as redness, pain, drainage, swelling around the wound, and consult the health care provider promptly if these occur.
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