Prognostic factors and monomicrobial necrotizing fasciitis: gram-positive versus gram-negative pathogens

Forty-six patients with monomicrobial necrotizing fasciitis were examined retrospectively from November 2002 to January 2008. All patients received adequate broad-spectrum antibiotic therapy, aggressive resuscitation, prompt radical debridement and adjuvant hyperbaric oxygen therapy. Eleven patients were infected with a gram-positive pathogen (Group 1) and 35 patients with a gram-negative pathogen (Group 2).Group 2 was characterized by a higher incidence of hemorrhagic bullae and septic shock, higher APACHE II scores at 24 h post-admission, a higher rate of thrombocytopenia, and a higher prevalence of chronic liver dysfunction. Gouty arthritis was more prevalent in Group 1. For non-survivors, the incidences of chronic liver dysfunction, chronic renal failure and thrombocytopenia were higher in comparison with those for survivors. Lower level of serum albumin was also demonstrated in the non-survivors as compared to those in survivors.Pre-existing chronic liver dysfunction, chronic renal failure, thrombocytopenia and hypoalbuminemia, and post-operative dependence on mechanical ventilation represent poor prognostic factors in monomicrobial necrotizing fasciitis. Patients with gram-negative monobacterial necrotizing fasciitis present with more fulminant sepsis.Necrotizing fasciitis is characterized by a rapidly spreading necrosis of the superficial fascia and subcutaneous tissue and is associated with a high mortality despite aggressive surgical treatment and adequate parenteral antibiotic therapy [1]. This disease is generally classified into the following categories: Type 1 (polymicrobial infection), Type 2 (infection with a Group A β-haemolytic Streptococcus or Staphylococcus aureus), and Type 3 (infection with a gram-negative bacillus such as Vibrio) [2-4]. The incidence of monomicrobial necrotizing fasciitis has recently increased [5-8]. The soft tissue necrosis that typifies these infections is attributable to the release of endotoxins, exotoxins and proteases th