Are anaerobes a major, underappreciated cause of necrotizing infections?

- NSTIs continue to cause high mortality and morbidity despite aggressive therapy.
- Polymicrobial NSTIs represent the majority of cases.
- Reliance on culture identification biases treatment towards cultivable etiology.
- 16S analysis reveals a larger role for anaerobes than previously realized.
- The steady rise of antibiotic resistance from anaerobes needs serious consideration.

Necrotizing soft tissue infections (NSTIs) are the most severe and rapidly progressing class of skin and soft tissue infections (SSTIs). They are a surgical emergency and are associated with high mortality and morbidity. While NSTIs remain relatively rare, their incidence is steadily rising. Earlier diagnosis and more focused antibiotic treatments can potentially improve patient outcome, but both of these solutions require a more accurate understanding of the microbial component of these infections. While molecular detection methods, namely 16S sequencing, have not been traditionally used to identify the causative microorganisms in NSTIs, they are becoming more commonplace for other types of SSTIs, especially for chronic wound infections. In chronic wound infections, 16S sequencing has revealed a higher than previously detected prevalence of obligate anaerobes. Therefore, it is possible that 16S sequencing may also detect a higher than expected proportion of obligate anaerobes in NSTIs. In this review, we discuss the current state of knowledge concerning the diagnosis and treatment of NSTIs and present reasons why the role of anaerobes may be significantly underestimated.