Background Necrotizing soft-tissue infections (NSTI) are life-threatening conditions often caused by β-hemolytic streptococci, group A Streptococcus (GAS) in particular. Optimal treatment is contentious. The INFECT cohort includes the largest set of prospectively enrolled streptococcal NSTI cases to date. Methods From the INFECT cohort of 409 adults admitted with NSTI to 5 clinical centers in Scandinavia, patients culture-positive for GAS or Streptococcus dysgalactiae (SD) were selected. Risk factors were identified by comparison with a cohort of nonnecrotizing streptococcal cellulitis. The impact of baseline factors and treatment on 90-day mortality was explored using Lasso regression. Whole-genome sequencing of bacterial isolates was used for emm typing and virulence gene profiling. Results The 126 GAS NSTI cases and 27 cases caused by SD constituted 31% and 7% of the whole NSTI cohort, respectively. When comparing to nonnecrotizing streptococcal cellulitis, streptococcal NSTI was associated to blunt trauma, absence of preexisting skin lesions, and a lower body mass index. Septic shock was significantly more frequent in GAS (65%) compared to SD (41%) and polymicrobial, nonstreptococcal NSTI (46%). Age, male sex, septic shock, and no administration of intravenous immunoglobulin (IVIG) were among factors associated with 90-day mortality. Predominant emm types were emm1, emm3, and emm28 in GAS and stG62647 in SD. Conclusions Streptococcal NSTI was associated with several risk factors, including blunt trauma. Septic shock was more frequent in NSTI caused by GAS than in cases due to SD. Factors associated with mortality in GAS NSTI included age, septic shock, and no administration of IVIG.

Background: Skin and soft tissue infections (SSTIs) are increasing. Frequent over-and under-treatment has been reported, including non-purulent SSTIs where cases demanding surgery or broad-spectrum therapy often are hard to identify. Our aim was to measure the predictive power of a modified severity score and use it to identify areas of improvement in antimicrobial therapy of non-purulent SSTIs. Methods: We prospectively included adult patients admitted to hospital with non-purulent SSTIs. A modified Dundee score at admission was calculated retrospectively, and associations between severity and outcomes were analysed. We evaluated appropriateness of treatment in relation to severity scores, and assessed adverse effects of broad-spectrum therapy. Results: We included 200 cases with cellulitis and 19 cases with necrotising soft tissue infections (NSTIs). Thirty-two per cent were categorised as severity class I, 15% as class II, 28% as class III and 25% as class IV (most severe). In class I, 66 out of 69 cases did not have a complicated course. All but one NSTI case were identified by the class IV criteria. Over-treatment was common and mostly seen in class I. Broad-spectrum antibiotics or clindamycin use was associated with an increased risk of diarrhoea. Prolonged treatment (>14 days) was associated with age, severity and surgery. Conclusions: The modified Dundee score proved valuable in identifying those with the lowest risk of complication and the most severe infections, and could serve as a useful clinical tool in the emergency department. Frequent over-treatment and associated adverse effects were confirmed, underscoring the need for improved risk assessment.

Our findings indicate that BHS are the leading cause of facial cellulitis. Most patients exhibit sharply demarcated lesions and systemic symptoms. Narrow-spectrum β-lactam antibiotics and short hospital stay appear sufficient. Few complications and low recurrence rates were seen.

No abstract

These infections are infrequent, but are associated with a significant health burden due to high mortality and risk of severe long-term disability as a consequence of extensive tissue loss or amputations (3)(4)(5). The progression of the disease is rapid, and early identification is therefore pivotal for improving the prognosis of affected patients. Currently, the initial diagnosis of NSTI is challenging due to the often vague symptoms during early stages, a heterogeneous patient group, and lack of specific diagnostic tools (6), which lead to misdiagnoses of NSTI in many cases (7). Still, doctors are advised that in case of NSTI suspicion, patients should be referred to surgical evaluation immediately (8). Previous efforts to improve the diagnosis of NSTIs led to the proposal of the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) CONCLUSIONS. This study identifies predictive biomarkers for NSTI clinical phenotypes of potential value for diagnostic, prognostic, and therapeutic approaches in NSTIs. TRIAL REGISTRATION. ClinicalTrials.gov NCT01790698.