Dynamic 16S rRNA Sequencing of the Abdominal Wall Surgical Site Highlights Potential Pathways of Incisional Surgical Site Infection in Colorectal Surgery

Understanding the microbial changes within the surgical site may enhance our understanding of the origin and subsequent role of microbes in the causation of incisional surgical site infections (SSIs). In this study we used 16S rRNA sequencing to establish the dynamic microbiota of the surgical site in patients undergoing bowel resection.

The surgical site of patients undergoing bowel resection was sampled at four different time points: on initial incision of the surgical site prior to peritoneal breach; on completion of the operation following fascial closure; from the lumen of the resected segment of bowel; and from the superficial skin of the surgical site in the follow-up period. DNA was extracted and used for 16S rRNA amplicon gene sequencing to establish the dynamic microbiota changes that occur within the surgical site.

A total of 250 samples were collected from 50 patients. The native subcutaneous abdominal plane is a low biodiversity Gram positive aerobic community, which following resection of the bowel, reflects a high biodiversity obligate anaerobic community, suggestive of contamination from the GI lumen. The follow-up sampling shows resilience of skin commensals, depletion of the most abundant luminal microbes with emergence of Enterobacteriaceae and Staphylococaceae. These two families thrive to colonise the follow up wound in all patients, highlighting potential pathways of infection in colorectal surgery.

Whilst this study does not demonstrate causality, it does add to the body of literature in deciphering the poorly understood pathogenesis of SSIs in colorectal patients. This study should be used as a platform to perform further multiomics-based investigations to try and underpin the exact mechanisms behind SSIs in this form of surgery, thus allowing us to improve preventative strategies in the future.