Blunt trauma as a risk factor for group A streptococcal necrotizing fasciitis

PURPOSE: Anecdotal reports suggest that blunt trauma and seemingly innocuous musculoskeletal injuries (e.g., muscle strains) are risk factors for developing necrotizing fasciitis (NF) and myositis caused by group A Streptococcus and other bacteria; however, this hypothesis has not been tested in analytic epidemiologic studies of invasive group A streptococcal (GAS) disease. We conducted two case-control studies to determine whether nonpenetrating trauma is a risk factor for either NF or severe cellulitis caused by GAS. METHODS: A secondary analysis of patients who were hospitalized throughout Florida for invasive GAS disease during a 4-year period was conducted. Two case series were used. The first series comprised patients who had severe GAS cellulitis. The second were patients who had GAS NF. Case-patients were compared to a single control series composed of patients with invasive GAS disease not including either NF or cellulitis (e.g., primary bacteremia, septic arthritis). RESULTS: After we adjusted for age, race, and clindamycin usage, GAS NF cases were 5.97 times as likely as controls to have a recent history of blunt trauma (p = 0.04). Patients with severe cellulitis were not more likely than controls to have associated blunt trauma. CONCLUSIONS: Nonpenetrating trauma is significantly associated with the development of GAS NF.