Infection context: Necrotizing fasciitis

Abstract

The deep skin and soft tissue infections (SSTIs) mainly caused by group A streptococcus are composed of necrotizing fasciitis and muscle necrosis. Necrotizing fasciitis is a deep–tissue infection of the subcutaneous tissue that results in the rapidly progressive destruction of fat and fascia. Necrotizing fasciitis (NF) may be monomicrobial (type II), where group A streptococcus (GAS) alone or accompanied with Staphylococcus aureus is the most common cause, or polymicrobial (type I), in which a mixture of Gram–positive and Gram–negative aerobes and anaerobes is identified. In monomicrobial, NF is more frequently seen in “community–acquired” or “idiopathic” cases, while after head and neck or Fournier's gangrene (genitourinary tract) surgeries, more polymicrobial causes are typical. Risk factors for invasive group A streptococcus SSTIs are multiple including minor traumas, most recent initial varicella zoster virus infection (with this, the lesion becomes superinfected), diabetes, and use of nonsteroidal anti–inflammatory agents, even though this can be happening to healthy individuals [1]. Group A streptococcus necrotizing fasciitis was once considered very uncommon, but population–based studies estimate as many as 1,500–3,000 cases per annum of necrotizing fasciitis [2]. In addition to increasing incidence, very rapid and dramatic clinical manifestations and high morbidity and mortality rate of the NF have been paid attention to in the study of pathogenesis. Despite vigorous studies, essential questions to group A streptococcus pathogenesis in NF remain unanswered [3].