Necrotizing Fasciitis (aka Flesh-Eating Bacteria) Part II: Diagnosis and Treatment by Dorcas M Eaves, M.D., M.S.S.

Board Certified General Surgeon

INTRODUCTION:

In Part I of Necrotizing Fasciitis, my article focused on the history of the disease to include the first reported cases in medical journals and the longevity of the disease that dates back to the Civil War and before. The worst outbreaks of this disease were found on battlefields, war-torn areas, and military hospitals. While not a common disease in the U.S., the disease still exists with a high incidence of morbidity and mortality in many war-torn countries outside the U.S.  Necrotizing Fasciitis is caused by different types of bacteria which enter a wound.

PART II:

Theoretically, anyone with an infection has a small risk of getting necrotizing fasciitis. Individuals who are immune-suppressed, such as diabetics, the elderly, infants, persons with liver disease, or patients taking immunosuppressant medication, are at higher risk. Often a preliminary diagnosis of necrotizing fasciitis is based on the patient’s symptoms. Visible infections of the skin, hair follicles, fingernails, or visible trauma sites are more likely to be noticed and treated than deeper infections. Patients who have any deep infections such as muscle, bone, joint, gastrointestinal, are at a somewhat higher risk for the disease because the initial infection and subsequent spread is usually not as noticeable as more visible infections. A recent case of necrotizing fasciitis was found in an otherwise healthy 24-year-old female after she incurred a deep laceration on her arm that was contaminated with Aeromonas bacteria. As a rule of thumb, pregnant women rarely develop necrotizing fasciitis. The exception can be seen in the postpartum period especially if the mother has diabetes and has a procedure such as cesarean section or episiotomy. Necrotizing enterocolitis occurs mainly in premature infants or sick infants which may be a variant of this disease. The demographics of necrotizing fasciitis are very interesting. More males are affected than females in a ratio of one in three for the organism Vibrio Vulnificus. Infections with this organism seem to be limited to coastal areas with warm water where the organisms are found associated with seafood and contaminated water.

Untreated necrotizing fasciitis has a poor prognosis. Death or severe morbidity is the frequent outcome. It is estimated that there are between 500-1,000 cases per year seen in the United States. Even with appropriate treatment the mortality can be as high as 25%. In general, the bacteria that cause necrotizing fasciitis utilize similar methods to cause and advanced the disease. Most produce toxins that inhibit the immune response, damage or kill tissue, produce tissue hypoxia specifically, dissolve connective tissue, or do all of the above. In polymicrobic infections, one bacterial genus may produce a toxic factor of E. Coli (for example) causing tissue hypoxia while different types of co-infecting bacteria may produce other toxins that lyse damaged tissue cells or connective tissue. In general this disease is not contagious but the organisms that may lead to its development are contagious, usually by direct contact between people or items that can transfer the bacteria.

When a preliminary diagnosis is made, the patient needs to be hospitalized and started on intravenous antibiotics. The initial antibiotic choice can be based upon the types of bacteria that cause necrotizing fasciitis. In most cases, the causative organism is methicillin-resistant Staphylococcus Aureus or capital (MRSA). Since most infections are polymicrobial, usually more than one antibiotic is used in the initial treatment until culture results isolate the offending organism. When the diagnosis is made, a surgeon needs to be involved with the care immediately. Debridement of the necrotic tissue and collection of tissue samples needed for culture is done by the surgeon.  The area affected will determine what type of surgeon is needed by the patient. For instance, if the area of infection is in the scrotum, then a urologic surgeon would be needed. If the infection is in other areas of the body, a general surgeon would be needed. Early surgical treatment and immediate antimicrobial therapy can reduce the morbidity and mortality associated with this disease.

Many patients with necrotizing fasciitis are very sick and require admission to intensive care. Sepsis and organ failure (renal, pulmonary, and cardiovascular systems) need to be treated aggressively to increase the patient’s chance of recovery. These treatments can include breathing tube insertion and administration of IV intravenous fluids and drugs to support the cardiovascular system can be required. Hyperbaric oxygen therapy is sometimes used to treat this condition as oxygen can inhibit anaerobic bacterial growth and promote tissue recovery. This addition does not preclude treatment with antibiotics or surgical debridement of necrotic tissue. Hyperbaric oxygen treatment, in some research studies, has decreased the morbidity and mortality by 10 to 20% when used in conjunction with surgery and antibiotic therapy.

The combined morbidity and mortality including limb loss, scar formation, renal failure, and sepsis, for all cases of necrotizing fasciitis has been reported as high as 70 to 80%. Cases of Fournier’s gangrene have been reported as high as 75% mortality rates, while cases of Vibrio Vulnificus-associated necrotizing fasciitis is about 50%. While this organism is relatively uncommon in the U.S. the incidence is increasing and the Centers for Disease Control and Prevention in 2007 made Vibrio Vulnificus a reportable disease.

References:  Necrotizing Fasciitis, C.P. Davis, MD, PhD medicine.com; M.C. Stoppler, MD, medicine.com

Necrotizing Fasciitis, WebMD.com/a-to-z guides