Necrotizing fasciitis and myositis caused by group A streptococci. Epidemiology, diagnosis, and treatment of "flesh-eating bacteria".

Despite the absence of conclusive proof, the incidence of necrotizing fasciitis and myositis due to GAS may be increasing, possibly related to shifts in the proportion of GAS isolates of M-Types 1 and 3. These M-types (or the production of exotoxins and proteases associated with them) may lead to severe GAS infections in individuals who lack immunity. Recent television and newspaper reports underscore the potential virulence of GAS even in young and previously well individuals although they do this at the expense of raising fear in the general population. It is unfortunate that these reports often fail to emphasize the rarity with which GAS causes myositis and fasciitis. The overall incidence of these dreadful diseases is very low. In fact, by extrapolating the CDC estimates, we suspect that only 14-40 cases of GAS-induced myositis or fasciitis occur annually in North Carolina. Each of these infections is a true calamity for the affected patients and their physicians, but together they represent only a tiny fraction of all GAS infections that occur in North Carolinians each year. It is relatively easy to separate uncomplicated streptococcal cellulitis from GAS-induced fasciitis and/or myositis by bedside exam and old-fashioned clinical judgment. Prompt and aggressive surgical debridement and antibiotic therapy are needed for all patients with myositis and/or fasciitis due to GAS; others can be treated with simple beta-lactam antibiotics and careful observation.