Severity assessment of skin and soft tissue infections: cohort study of management and outcomes for hospitalized patients

Skin and soft tissue infections (SSTIs) are caused by bacterial invasion of the skin and underlying soft tissues and can present with a wide spectrum of signs, symptoms and illness severity. They are a common indication for antimicrobial therapy. However, there are few data on treatment outcomes or the validity of clinical severity scores. Two hundred and five adult patients admitted to Ninewells Hospital, Scotland in 2005, and treated with antibiotics for SSTI, were identified. They were stratified into four classes of severity (class IV = most severe) based on sepsis, co-morbidity and their standardized early warning score (SEWS). Empirical antimicrobial therapy by severity class was compared with the recommendations of a UK guideline. Thirty-five different empirical antimicrobial regimens were prescribed. Overall, 43% of patients were over-treated, this being particularly common in the lowest severity class I (65% patients). Thirty-day mortality was 9% (18/205) and 17 patients (8%) died during their index admission. Mortality (30 day) and inadequate therapy increased with severity class: I, no sepsis or co-morbidity (45% patients, 1% mortality, 14% therapy inadequate); II, significant co-morbidity but no sepsis (32% patients, 11% mortality, 39% therapy inadequate); III, sepsis but SEWS < 4 (17% of patients, 17% mortality, 39% therapy inadequate); and IV, sepsis plus SEWS >= 4 (6% of patients, 33% mortality, 92% therapy inadequate). SSTI in hospital is associated with significant mortality. Choice of empirical therapy is not evidence based, with significant under-treatment of severely ill patients.