Fig. 5. After wound VAC therapy, a patient with necrotizing fasciitis demonstrates healthy granulation tissue reading for skin grafting

Synergistic necrotizing cellulitis

Synergistic necrotizing cellulitis (SNC) is a variant of necrotizing fasciitis that extends beyond the fascial borders causing myonecrosis and is most commonly seen in immunocompromised patients or those with chronic diseases[65]. This disease process is perpetuated through a symbiotic relationship between aerobic Gram-negative and facultative anaerobes. Cultures from these patients are usually polymicrobial with the most commonly isolated organisms being: Clostridia, anaerobic Streptococcus, and Bacteroides with synergistic bacteria including aerobes such as E. coli, Klebsiella, Proteus, and Pseudomonas [66, 67].

Patients commonly present with small superficial ulcerations that drain a malodorous reddish brown fluid. Ulcerations are surrounded by varying degrees of skin erythema and necrosis with approximately 25% of patients presenting with subcutaneous emphysema. Affected areas are exquisitely tender to palpation despite the occasional benign appearance of the overlying lesions. A major difference between SNC and NF is that many patients with SNC may have experience some of the above symptoms for 2 weeks or more before seeking medical attention. SNC tends to have a more prolonged and indolent course when compared to the rapid onset and quickly progressing disease process seen in NF [67]. Treatment for these patients however is similar to those with NF, including care in a burn center, cor-

rection of electrolyte and hemodynamic abnormalities, prompt initiation of broad-spectrum antibiotics and wide surgical debridement [65–67]. Because of its slower clinical course, if the SNC patient does show a clinical response with the initiation of antibiotics, then conservative treatment may continue as long as positive clinical progress continues; any signs of worsening disease mandates surgical debridement.

Purpura fulminans

Purpura Fulminans (PF) is another necrotizing disease of the soft tissue characterized by widespread intravascular thrombosis of the skin with eventual hemorrhagic infarction, septicemia, and disseminated intravascular coagulation (DIC) occurring after acute infections [52, 68]. When associated with adrenal hemorrhage, it is also known as WaterhouseFriderichsen syndrome [69]. It is believed that PF is initiated through the release of specific endotoxins from inciting bacteria leading to a cascade of septic shock with associated DIC and full thickness skin loss [70]. An additional aspect of the disease pathogenesis is associated with a relative genetic deficiency of Protein C and/or Protein S, leading to vascularthrombosisfromaninherentcoagulopathy [71–73]. Three types of PF have been identified: inherited (neonatal) PF from abnormalities with Protein C/S, acute infectious PF, and idiopathic PF [52, 74]. The immaturity of the neonatal hepatic system leads to a relative deficiency of Protein C/S as birth, placing them at an increased risk of PF [72, 74].

The onset of this disease commonly occurs after acute bacterial infections and usually leads to full thickness skin loss with the likely need for extremity amputations[75]. Neisseria meningitidis is the causative bacteria most commonly seen in infants and pediatrics while the adults are affected most often by Streptococcus species [69, 76]. There are reports of PF occurring as a result of other infections such has Haemophilus influenzae, varicella, and Legionella pneumonia [77–79].

Clinical presentation

Patients will often be in the process of recovering from a benign infection when they develop a pe-