Necrotizing soft tissue infection is a severe and very rare type of bacterial infection which destroys the muscles, skin, and underlying tissue. The word “necrotizing” means something that causes body tissue to die.
Necrotizing fasciitis (flesh-eating disease) information:
- Necrotizing fasciitis is a rapidly spreading infection, usually located in fascial planes of connective tissue that results in tissue death (necrosis). ). Fascial planes are bands of connective tissue that surround muscles, nerves, and blood vessels. Fascial planes can bind structures together as well as allow body structures to slide over each other effectively.
- Different types of bacterial infection can cause necrotizing fasciitis. Necrotizing Fascitis is mainly caused by group A beta-hemolytic streptococci (Streptococcus pyogenes), most investigators now agree that many different bacterial genera and species, either alone or together (polymicrobial), can cause this disease. Occasionally, mycotic (fungal) species cause necrotizing fasciitis.
- The majority of cases begin with an existing infection or a wound most frequently on an extremity. It can occur in almost any area of the body.
- Necrotizing fasciitis is a serious condition that is often associated with sepsis and extensive organ failure.
- Treatment involves antibiotics and surgical debridement of the wound areas as well as supportive measures such as insertion of a breathing tube, intravenous administration of fluids, and drugs to support the cardiovascular system.
- Currently, there are many names that have been used for necrotizing fasciitis:flesh-eating bacterial infection or disease; suppurative fasciitis; dermal, Meleney, hospital, or Fournier’s gangrene; and necrotizing cellulitis.
- Important in understanding necrotizing fasciitis is the fact that the infecting organism(s), once it reaches and grows in connective tissue, the spread of the infection is so fast (some organisms can progress about 3 centimeters per hour) that the infection becomes hard to stop with both antimicrobial drugs and surgery.
Mortality (death) rates have been reported as high as 75% for necrotizing fasciitis associated with Fournier’s (testicular) gangrene. Patients with necrotizing fasciitis have an ongoing medical emergency that often leads to death or disability if it is not rapidly and effectively treated.
What are the Causes of Nectrotizing Fascitis:
Different types of bacteria can cause this infection. A very severe and usually deadly form of necrotizing soft tissue infection is due to Streptococcus pyogenes, which is sometimes called “flesh-eating bacteria.”
Necrotizing soft tissue infection develops when the bacteria enters the body, usually through a minor cut or scrape. The bacteria begins to grow and release harmful substances (toxins) that kill tissue and affect blood flow to the area. As the tissue becomes dead the bacteria enters the blood and rapidly spreads throughout the body.
What are Necrotizing Fasciitis Symptoms and Signs?
This disease begins with an already existing infection, most commonly on an extremity or in a wound. The initial infection can be from almost any cause (e.g., cuts on the skin, puncture wounds, surgical incisions, insect bites). Instead of healing, the infected site can show erythema (redness) and swelling. The site is very sensitive to pain, even across the area of erythema and may sting. At the same time, patients often experience fever and chills. Early symptoms resemble those of cellulitis, but progressive skin changes such as bullae (thin-walled fluid-filled blisters) formation, ulcerations on the skin, necrotic scars (black scabs), gas formation in the tissues, and fluid oozing from the site can occur rapidly as the infection progresses. Some patients can become septic (the infection spread to the bloodstream and throughout the body) before the skin changes become evident, especially when necrotizing fasciitis begins in deep facial planes.
What are the types of Necrotizing Fasciitis?
- Type 1 often occurs after trauma or surgery and may form little or undetectable amounts of gas.
- Type 2 usually occurs after more simple skin trauma (cuts, abrasions, and insect bites) and infects more superficial facial planes with almost no gas formation.
- Type 3 usually occurs after trauma or after wounds become contaminated with dirt that contains Clostridium spp, which produce gas in tissues (gangrene) and necrotic eschars.
However, symptoms for types 1-3 are not specific
One set of patients that is being recognized with a more specific set of symptoms and health history are those infected with Vibrio vulnificus. The organisms occur in the warmer waters in the U.S. (Gulf of Mexico and southern coastal states) and other parts of the world with similar water conditions. Ths infection is caused by either ingesting the organisms or getting Vibrio vulnificus from contaminated seawater into skin abrasions or cuts. This infection commonly occurs in immunocompromised patients or chronic liver disease patients (alcoholic liver disease, hepatitis, or cirrhosis). Bullae formation and rapid progression of the disease (within hours) on the extremities are hallmarks of Vibrio vulnificus wound infections. Even though a single type of bacteria causes this infection, some investigators classify it as a variant of type 1 necrotizing fasciitis.
Necrotizing enterocolitis (also termed NEC; necrosis of gastrointestinal tissue) occurs mainly in premature or sick infants. It is known to be another variant of necrotizing fasciitis.
How is Necrotizing Fasciitis Diagnosed?
Often initial diagnosis of necrotizing fasciitis is based on the patient’s symptoms, including the medical and exposure history as mentioned above. Initial treatment is often started based upon a preliminary diagnosis because waiting for a definitive diagnosis can delay treatment and result in increased morbidity and mortality.
- Gram staining of exudates (fluid from the infection site) or biopsied tissue can determine what organism(s) are causing the infection. For example, the stain can distinguish between Gram-negative and Gram-positive organisms and further distinguish their shapes (coccus or round, rod, or comma-shaped like Vibrio). Definitive diagnosis depends on isolation of the organism(s) from the patient using both aerobic and anaerobic isolation techniques, and rarely, fungal culture methods.
- Organisms isolated from necrotizing fasciitis are investigated for antibiotic resistance, because many organisms causing the disease are multidrug resistant. A surgeon needs to be consulted early to help obtain tissue samples and to be involved with potential treatment protocols (debridement, amputation).
- Doppler, CT, or MRI studies are done to look for gas in tissues and to help demarcate the extent of the infection.
- White blood cell (WBC) counts (elevated in necrotizing fasciitis),
- BUN (blood urea nitrogen),
- Sodium (both decreased in necrotizing fasciitis)
Your doctor can diagnose this condition by looking at your skin. You may be diagnosed in an operating room by a surgeon.
What is the Treatment of Necrotizing Fasciitis?
Patients needs to be hospitalized and started on intravenous antibiotics immediately. The initial choice of antibiotics can be made based upon the types of bacteria suspected of causing the infection, but many doctors believe that multiple antibiotics should be used at the same time to protect the patient from methicillin-resistant Staphylococcus aureus (MRSA), as well as infections with anaerobic bacteria, and polymicrobic infections. Antibiotic sensitivity studies are done in the laboratory after the infecting organism(s) has been isolated from the patient. Then best antibiotic is given to the patient.
A surgeon needs to be consulted immediately for the debridement of necrotic tissue and collection of tissue samples for lab tests. Early surgical treatment of most cases of necrotizing fasciitis can reduce morbidity and mortality.
Many patients with necrotizing fasciitis are very critical and need to be treated in intensive care unit. Sepsis and organ failure (renal, pulmonary, and cardiovascular systems) should be treated aggressively to increase the patient’s chance for recovery. Supportive treatment such as insertion of endotracheal tube, intravenous administration of fluids, and drugs to support the cardiovascular system may be required. Hyperbaric oxygen therapy (oxygen given under pressure with the patient in a chamber) is sometimes used in treatment as the oxygen can inhibit anaerobic bacterial growth and promote tissue recovery. This therapy does not replace antibiotics or surgical treatment. However, hyperbaric oxygen therapy has been shown by researchers to further reduce morbidity and mortality by about 10%-20% in some patients when used in conjunction with antibiotics and surgery.
How can Necrotizing Fasciitis Prevented?
Necrotizing fasciitis does not begin unless an infection has already started in tissue; immediate effective treatment of any infection is likely to prevent the disease. Practices such as hand washing, checking extremities for cuts or wounds if you have diabetes, avoiding physical contact with people who carry MRSA, and good hygiene practices help prevent initial infections that may lead to necrotizing fasciitis.
Immunocompromised patients should be very vigilant not to get infections, and people with liver disease should avoid eating seafood and should not have any infections or cuts in the skin exposed to warm seawater to avoid necrotizing fasciitis caused byVibrio vulnificus.
Physicians, surgeons play an important role in prevention. Cases of necrotizing fasciitis may occur when surgical sites become infected. Sterile techniques should be used when doing surgery and adhere to hospital practices such as glove and gown coverage to help prevent infection spread in hospitalized patients. Bowel surgery, episiotomy (surgically enlarging the vaginal outlet), and debridement with closure of traumatic wounds are the easily infected areas, so special care should be taken.
Is Necrotizing Fasciitis Contagious?
Necrotizing fasciitis is not usually contagious. However, it is possible for uninfected people to physically come into contact with some patients with the disease and become infected with an organism that may eventually cause necrotizing fasciitis. Transmission from one person to another usually requires direct contact with a patient or some item that can transfer organisms like MRSA to another person’s skin; infection usually requires a skin break (cut or abrasion) for the organisms to establish an infection.
What is the Prognosis of Nectrotizing Fasciitis?
Untreated necrotizing fasciitis has a poor prognosis; death or severe morbidity (for example, limb loss) is the frequent outcome. Data on the number of cases per year are estimated between 500-1,000 per year in the U.S. Even with appropriate treatment, the mortality (death) rate can be as high as 25%. Combined mortality and morbidity (for example, limb loss, scar formation, renal failure, and sepsis) for all cases of necrotizing fasciitis has been reported to be 70%-80%. Cases of Fournier’s gangrene have as high as 75% mortality rates, while cases ofVibrio vulnificus-associated necrotizing fasciitis have about a 50% mortality rate.
What are the Complications of Necrotizing Fasciitis?
- Tissue loss.
- Amputation of limb,
- Kidney failure.
- Extensive scarring.
Who are the High Risk Patients?
Anyone with an infection has a small risk of getting necrotizing fasciitis.High risk patients include;
- Immunosuppressed individuals (diabetics, elderly, infants, those with liver disease, or those taking immunosuppressive drugs such as chemotherapy for cancer).
- Patients who have any deep infections (muscle, bone, joint, gastrointestinal)
- Postpartum period, especially if the mother has diabetes and has procedures such as cesarean delivery(C-section) or episiotomy.