Characteristics and differences in necrotizing fasciitis and gas forming myonecrosis: a series of 36 patients.

BACKGROUND AND AIMS Necrotizing fasciitis (NF) and gas forming myonecrosis (GFM), both being subtypes of necrotizing soft tissue infection (NSTI), are life threatening conditions sharing certain similarities. Despite the necessity of early and radical surgical debridement in necrotizing infections, the distinction between these entities is of clinical relevance since gas forming myonecrosis in a number of cases results from an underlying abdominal cause and the focus of infection can be missed. This study was to evaluate the incidence and risk factors as well as the mortality rate in patients with NSTI and GFM. MATERIAL AND METHODS All patients with NSTI treated in the authors' hospital between January 2005 and Decem-ber 2009 were enrolled in the study. Medical records, histological slides, microbiological and laboratory parameters as well as Computerized Tomography (CT) and magnetic resonance imaging (MRI) scans were reviewed for all patients. Differences between NF and GFM regarding hospital stay, number of surgical interventions and pre-existing comorbidities as well as mortality rate were analyzed. The laboratory risk factor for necrotizing fasciitis (LRINEC) score was calculated in all patients on admission. RESULTS AND CONCLUSIONS Thirty patients (17 female, 13 male) with necrotizing fasciitis with a mean age of 55 years (SD 15.5) were included in the study. There was no statistically significant difference between survivors and deceased patients comparing the LRINEC score (n.s.). Patients with necrotizing fasciitis secondarily involving the trunk had a significantly higher mortality rate (OR 11.2; 95% CI=1.7-72.3). In the majority of cases (12 cases), minor skin lesions were identified as the site of origin. Amongst all necrotizing soft tissue infections six patients (female n=3; male n=3) with a mean age of 61.5 years (SD 12.2) with non-clostridial gas forming myonecrosis were identified. Three patients had a history of malignancy and in three patients the infection was secondary to major surgery. The mean LRINEC score was 8.5 (SD 1). Three patients (50%) died due to GFM. Early diagnosis and appropriate intervention is critical to provide accurate treatment decisions. Eradicating the differing primary sources of infection in GFM and NF will have a positive impact on outcome.