Necrotizing Soft-Tissue Infections
Authors:   , Suijker Jacob 
Published: February 2024

Necrotizing soft tissue infections (NSTIs) are rare, severe infections that spread through the deep tissue layers (subcutis; fascia; muscle). Approximately half are mono-microbial infections, mostly due to group A streptococcus (GAS), while the rest are poly-microbial infections. Initially, symptoms are nonspecific (redness, swelling, pain), making early recognition difficult. Treatment always consists of antibiotics, surgical debridement, and hemodynamic support. Two approaches to acute surgical debridement have been described. En bloc debridement involves removing all skin overlying the affected deep tissue layers, while a skin-sparing approach aims to spare as much overlying skin as possible.

Part 1 - The interplay of patient and disease characteristics, recognition, and clinical outcomes

Chapter 2 describes 80 patients treated in three Dutch hospitals with a burn center. Patients referred to a burn center had larger skin defects, longer hospital stays, and were more likely to have Group A streptococcus (GAS) as the causative agent than regular admissions with NSTI. In 53% of cases, the diagnosis of NSTI was not recognized upon admission (misdiagnosis), leading to significant delay in the time to the first debridement.
Chapter 3 expanded this research to 216 patients across 11 different hospitals. The misdiagnosis rate was 54%, with a mortality rate of 23%. Misdiagnosis, older age, and septic shock were positively associated with mortality, while GAS infection was negatively associated with mortality. Septic shock was associated with larger skin defects, while a skin-sparing debridement was associated with smaller skin defects. Therefore, outcomes of NSTI treatment can potentially be improved through better recognition, adequate treatment of septic shock, and skin-sparing surgical debridement.
Chapter 4 introduces a clinical decision support tool (CDSS) based on AI for predicting 30-day mortality in a cohort of 409 NSTI patients (INFECT Cohort), which outperforms traditional prediction systems. This forms the basis of a clinical decision support model, to which other outcomes will also be added.

Part 2 - The patient perspective

Chapter 5 describes the long-term quality of life (QoL) in survivors of NSTI, as measured with the Short Form 36 questionnaire. It shows that after a median follow-up of 4.1 years, there is reduced QoL in physical aspects. No difference was found in mental aspects compared to the general population.
Chapter 6 was a qualitative study, conducting semi-structured interviews within focus groups or individual interviews, with a total of 25 survivors of NSTI. This study shows that NSTI, in addition to physical consequences (scars; cognitive problems; fatigue; sleep problems; recurrent infections), also had psychological (post-traumatic stress symptoms; fear of recurrence; shame about changed appearance; sexual problems), social (misunderstanding; change in social contacts), and work-related (dismissal; financial decline) consequences. Psychological trauma in relatives, such as partners or children, was also frequent. Many expressed hope that the mistakes made in their case of misdiagnosis would be prevented in the future.

Part 3 - Approaches to acute debridement

Chapter 7 provides an overview of the literature on skin-sparing versus en bloc debridement. A total of 10 studies were included, 1 pseudo-randomized study, and 9 case series. Based on these studies of moderate quality, there is evidence that skin-sparing surgery leads to smaller scars without resulting in higher mortality or more complications.
Chapter 8 reports the results of a survey among Dutch general surgeons and plastic surgeons, showing a variety of opinions on the amount of skin that should be resected in the acute treatment of NSTI. To achieve more consensus, more insight into the outcomes of the different approaches seems important.