Necrotizing Fasciitis in Switzerland: Risk Factors and Clinical Outcomes Based on a 12-Year Retrospective Study

Background: Necrotizing fasciitis (NF) is a rapidly progressing and life-threatening soft tissue infection. It commonly affects the extremities and is triggered by trauma, surgical wounds or compromised skin integrity. Although there have been advancements in diagnosis and treatment, NF continues to be a complex condition due to comorbidities and the wide range of involved pathogens. The aim of this study was to assess the epidemiology, risk factors, and outcomes of NF in Switzerland, focusing on the distinction between polymicrobial and monomicrobial infections and their associated management. Methods: This monocentric retrospective study analyzed 75 patients treated for intraoperatively confirmed NF from 2010 to 2022. Data collection included demographic and clinical variables, comorbidities, and laboratory results. Univariate and multivariate statistical tests were conducted to assess associations between mortality and different infection types. Results: NF was most commonly localized in the lower extremities (52% of cases). Nearly all patients (99%) had at least one comorbidity, with coronary heart disease, kidney disease, and liver disease being most frequently observed. Advanced age was associated with higher in-hospital mortality (OR (odds ratio) 3.80, p = 0.033, q = 0.500, 16 of 44 patients over 60 died), and the overall in-hospital mortality in the cohort was 27%. Kidney disease and smoking were associated with polymicrobial infections, with an OR of 6.60 (p = 0.016, q = 0.130) and 5.60 (p = 0.009, q = 0.130), respectively. Trauma was associated with monomicrobial streptococcal infections (OR 3.40, p = 0.029, q = 0.500), and showed a significant association with Streptococcus pyogenes infections (OR 8.10, p < 0.001, q = 0.004). Conclusions: This study highlights advanced age, trauma, kidney disease and smoking as factors associated with worse outcomes and specific infection patterns in patients with NF. These findings, derived from a Swiss patient population, underscore the importance of early identification of high-risk individuals to improve clinical outcomes. Recognizing these risk profiles may support clinicians in prioritizing rapid escalation of care for the patients most likely to benefit from early and aggressive intervention.