Current Insights On The Multidisciplinary Treatment Of Necrotizing Fasciitis
This author presents a multidisciplinary approach to diagnosing and treating a 54-year-old patient with diabetes who presented with intense pain and a toe that was turning black.
Necrotizing soft tissue infections are rare but potentially fatal. They are generally divided into three categories based upon anatomical involvement: crepitant cellulitis, necrotizing fasciitis and myonecrosis.
Crepitant cellulitis is characterized by infection limited to the skin. Typically, this infection involves ample soft tissue crepitus, limited pain and minimal systemic symptoms. Necrotizing fasciitis extends beyond the skin into the subcutaneous tissue and fascia. Usually, there is less air present in the soft tissue but pain is more pronounced and systemic symptoms are prominent. Myonecrosis includes muscle involvement, pronounced pain, systemic symptoms and further risk for loss of limb.
Despite these distinctions, one should note there is often significant overlap between these entities, depending upon the amount of tissue involved and the pathogens present.
Necrotizing soft tissue infections are characterized by rapidly developing tissue destruction due to the presence of bacterial enzymes and toxins. Vascular ischemia and tissue necrosis result from the combination of virulent factors present in the tissue. Typically, these infections are polymicrobial. There is usually the presence of an anaerobic organism (Bacteroides fragilis, Clostridium species, Peptostreptococcus species) with one or several members of the Enterobacteriaceae family (E. coli, Proteus species, Klebsiella species). Beta hemolytic streptococci such as Streptococcus pyogenes (Group A strep) may be present with either an anaerobe or an Enterobacteriaceae. Clostridium species can act alone to create a rapidly progressive illness, especially in cases of myonecrosis.
Necrotizing soft tissue infection is typically more severe in patients with an underlying immunodeficiency. Examples include poorly controlled diabetes mellitus, organ transplant recipients, chronic steroid use and the use of immune modulators, alcohol abuse with liver disease, and patients undergoing chemotherapy for malignancies.
In most cases, the anaerobic bacteria proliferate in an environment of local tissue hypoxia. Due to lower oxidation reduction potential, these bacteria produce gases such as hydrogen, nitrogen, hydrogen sulfide and methane, which accumulate in the soft tissue spaces because of reduced solubility in water.