Necrotizing fasciitis, commonly called “flesh-eating bacteria,” is a rare, invasive bacterial infection that has a rapid onset and quickly leads to systemic infection and overwhelming shock. A patient with necrotizing fasciitis will quickly decline into septic shock and eventually death without early identification and surgical intervention. Incidence is reported to be between 0.3 and 15 cases per every 100,000 people, but it varies by location and population. Mortality remains high; an estimated 25% to 30% of cases result in death. Early identification and emergent surgical intervention are keys to meaningful patient outcomes.
Patients at highest risk for necrotizing fasciitis are those with underlying chronic illness and older patients. The most common chronic illnesses seen in conjunction with necrotizing fasciitis are diabetes and immunocompromise, including patients with HIV/AIDS, organ transplant recipients, and those receiving chemotherapy or taking immunosuppressive medications for autoimmune disease.
Exposure to contaminated water can increase risk, especially when other risk factors exist such as diabetes and/or immunosuppression. Trauma or breaks in the skin while in contact with contaminated water can cause infection even in a healthy patient. For example, Vibrio vulnificus is often found in warm saltwater and Aeromonas hydrophila is found in fresh water. These bacteria have been identified as causes in patients with reported water exposure.
There are two types of necrotizing fasciitis. Caused by a combination of two or more bacteria, type I, or polymicrobial, is the most common type. Type II, or monomicrobial, is most commonly caused by group A streptococcus (see Common bacterial causes of necrotizing fasciitis).
Fournier gangrene is a subtype of necrotizing fasciitis that affects the perineum. It's most often seen in men and involvement can include the scrotum and penis. In women, areas of infection include the labia, perineum, and rectum. Patients often report that the infection started as a small “bump” that got progressively larger. Like any other necrotizing infection, Fournier gangrene can progress quickly from the area of origin to adjacent areas, including the muscles of the abdominal wall and the buttocks. Morbid obesity and poorly controlled diabetes are often contributing factors for the development of Fournier gangrene.
Signs and symptoms
Patients with necrotizing fasciitis usually present with severe pain to the affected area. This pain is often disproportionate to the appearance of the presenting injury. Most patients present with an area of redness and what appears to be a simple soft tissue infection or cellulitis. On the surface, the area may appear to be a small bruise or reddened area that doesn't seem significant. Below the surface, however, progressive damage to the tissues and fascial plane is taking place (see Necrotizing fasciitis in a 59-year-old woman).
The fascia is a layer of connective tissues that helps enclose body cavities and helps with overall body stability. This area is poorly vascularized, which makes fighting off infection difficult. Poor vascularization also makes the healing process challenging.
Necrotizing fasciitis most commonly affects the lower extremities. Patients most often present with sudden onset of erythema, pain, and edema to one of the lower extremities. Both edema and severe pain will extend beyond the area of erythema. You may also see fluid-filled blisters or bullae, and the skin beyond the area of erythema may be cool, pale, and/or mottled. If the infection has progressed, you may also see areas of blackened or necrotic skin. On palpation, you may be able to feel crepitus, which feels like crunching under the fingertips. The patient may report areas of numbness. Patients with necrotizing fasciitis may appear toxic and sicker than a patient generally does with a simple soft-tissue infection such as cellulitis.
Lab evaluation is important and certain findings can be helpful in decision-making. One of the most common lab findings is an elevated white blood cell count with elevated bands on the differential. Other commonly seen abnormal labs may include an elevated lactic acid level, C-reactive protein, and creatine kinase. Hyponatremia with a serum sodium level below 135 mEq/L is highly suggestive of a necrotizing infection, as well as a predictor of inpatient mortality.
Useful imaging techniques include X-ray and computed tomography scan. Both may show gas formation in the tissues, but obtaining imaging shouldn't delay surgical intervention. Gas in the tissues is highly suggestive of a necrotizing infection, but absence of gas doesn't rule it out. Expedient surgical intervention is associated with the best patient outcomes. Guidelines recommend taking the patient with high clinical suspicion of necrotizing fasciitis to the OR as soon as possible.
Treatment is focused on surgical intervention and requires both medical and nursing management for positive patient outcomes. Surgical debridement of all necrotic tissue is a priority to control the continued spread of infection. Patients will generally require an initial surgical debridement to open the area involved and evaluate the extent of the infection. This initial surgical intervention allows for drainage of any fluid collection and removal of obvious necrotic tissue. Most patients will then require serial surgical debridement to remove any progressive tissue necrosis and contain the spreading infection.
Surgery is the hallmark treatment for patients with a necrotizing infection, but all patients will need broad-spectrum antibiotics to control the bacterial infection and keep bacteria from multiplying. Blood cultures should be obtained before initiation of antibiotic therapy to evaluate the patient for bacteremia. Most patients will have symptoms of septic shock and may require hemodynamic support, including vasopressors. Other organ support includes mechanical ventilation and renal replacement therapy for respiratory and renal failure. Most patients will need to stay in the ICU during their initial hospital course.
Patients with a necrotizing infection require intensive skilled nursing care for a range of needs. Pain and shock management are key during the acute phase. Pain control can be difficult due to soft tissue and nerve damage. Patients often require multimodality pain control with opioids, nonopioids, and medications for nerve pain. Dressing changes can be extensive and extremely painful. Patients may experience anxiety before dressing changes. A care plan should be in place specific for dressing changes that may need to include sedation or medication for anxiety, as well as quick-acting pain medication.
Surgical intervention that requires debridement of dead tissue often leads to large defects, open wounds, and possibly amputations. Large wounds may need surgical closure or skin grafting for full resolution. Wounds may not be fully healed before discharge, so wound care education for the patient and family is an important part of discharge planning. Demonstration to the patient and/or family during dressing changes should start early to help assist with this transition. If an ostomy is present, the patient should start performing ostomy care before discharge if he or she is able to participate. Preparing the patient for discharge days or even weeks before allows him or her to develop the needed skills to transition from the hospital to home.
Wound management may include wound vacs (also known as negative pressure wound therapy), specialty dressings, biologic dressings such as temporary skins, and basic dressing changes. The type of dressing being used will determine when and how the dressing is changed. However, the basic principles of wound care apply. Goals of wound management include control of drainage (exudate) and promotion of granulation tissue to help with healing.
Almost all patients who survive necrotizing fasciitis are impacted by body image issues. Nurses need to be prepared to address these concerns during the recovery phase. Amputations may also be performed to both upper and lower extremities, leading to a whole new self-perception, as well as physical challenges and potential loss of independence. Patients with infections that involve the perineum and rectum often won't be able to participate in sexual activity for an extended time period, which may lead to feelings of loss and shame. Others may require a diverting ostomy to allow wounds to heal. These can be traumatic life changes that require patient teaching and coping skills. Often, patients will require counseling or psychiatric evaluation for depression.
Patients with necrotizing infections will often need to return for multiple surgeries after discharge. They may require physical and/or occupational therapy regardless of amputations. Given the critical nature of necrotizing fasciitis, patients are often weak and deconditioned after their hospital stay. Most will require strength training to regain their previous level of activity. Those with amputations will need to learn how to care for themselves with new disabilities.
Emergency action required
Necrotizing fasciitis is a rare but devastating infection that requires quick identification, surgical management, and broad-spectrum I.V. antibiotics. Patients often require ICU-level care due to septic shock, which can lead to respiratory and/or renal failure. Mortality remains high, but patients who survive often need multiple surgical interventions and have large wounds that may take weeks to months to heal or surgically close. Necrotizing fasciitis is a surgical emergency that requires skilled nursing care to maximize patient outcomes.
- Traumatic injury
- Gynecologic procedures
- Advanced age
- Chronic lesions
- I.V. drug use
- Fresh or saltwater lacerations
Bonne SL, Kadri SS. Evaluation and management of necrotizing soft tissue infections. Infect Dis Clin North Am
Burnham JP, Kirby JP, Kollef MH. Diagnosis and management of skin and soft tissue infections in the intensive care unit: a review. Intensive Care Med
Bystritsky R, Chambers H. Cellulitis and soft tissue infections. Ann Intern Med
Gelbard RB, Ferrada P, Yeh DD, et al Optimal timing of initial debridement for necrotizing soft tissue infection: a practice management guideline from the eastern association for the surgery of trauma. J Trauma Acute Care Surg
Kobayashi L, Konstantinidis A, Shackelford S, et al Necrotizing soft tissue infections: delayed surgical treatment is associated with increased number of surgical debridements and morbidity. J Trauma
Stevens DL, Bryant AE. Necrotizing soft-tissue infections. N Engl J Med