- Title
- The microbiota of the abdominal wall surgical site in colorectal surgery
- Creator
- Vishnoi, Veral
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2023
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Colorectal incisional surgical site infection remains a significant postoperative complication. Whilst infection is a multi-factorial process, the role of bacteria has been scrutinised for over a century. Culture-based microbiological studies in the postoperative period when the infection has already ensued, has led us down the pathway of pathogenic inoculation of the surgical site during the operation as the source and cause for infection. Yet, strategies to mitigate this in colorectal surgery have failed to control rates of infection in modern practice. This suggests that there are alternative pathways of infection which are poorly understood. Investigating the intraoperative surgical site presents a unique opportunity to better understand the role of bacteria in surgical site infection, however culture-based methods are starting to become outdated. Genomic sequencing has introduced the concept of microbiota into clinical medicine, which through translational studies has shown us that the microbiota plays a fundamental role in disease causation. The goal of this thesis was to use genomic sequencing to characterise the microbiota of the surgical site in patients undergoing colorectal resection to better understand the role of microbes with a view to tailor more effective preventative strategies. Through a series of phases, the surgical site of patients undergoing elective colorectal resection was opportunistically sampled at different points in their surgical pathway. Following DNA extraction, 16S rRNA amplicon sequencing was performed through a next generation sequencing platform to characterise the microbiota of the surgical site. The results show that the native subcutaneous space prior to resection of the bowel is a low biodiversity gram-positive aerobic community which, following resection, reflects a high biodiversity anaerobic profile in all patients. Alpha diversity is significantly increased in patients with an eventual infection, and this is likely due to microbial load from the lumen of the bowel. Bacteroidacaea and Lachnospiraceae dominate the intraoperative surgical site at the end of the case, yet infection does not result from these families. Functionally, it appears this microbiota primes the incision by suppressing inflammation, rendering it susceptible to known pathogens. In our small cohort we have shown that infection occurs because of known pathogens such as Staphylococaceae and Enterobacteriaceae. Interestingly, these pathogens are not amongst the most dominant families of bacteria usually seen at the end of the operative case. The culmination of these findings would suggest that a dual process is required for infection in colorectal patients; luminal contamination does not cause infection but instead, it propagates an environment which favours the proliferation of known pathogens Staphylococaceae and Enterobacteriaceae. In this thesis we have shown, for the first time, an aberrant microbiota that is associated with colorectal surgical site infection. The findings suggest that microbial ecology is more important in determining the outcome of the wound than a simplistic pathogenic inoculation pathway. Pending validation studies, this provides potential targets for interventions to reduce the burden of not only colorectal, but all forms of surgical site infection.
- Subject
- microbiota; colorectal surgery; surgical site infection; intervention
- Identifier
- http://hdl.handle.net/1959.13/1485787
- Identifier
- uon:51696
- Rights
- Copyright 2023 Veral Vishnoi
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 5 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 225 KB | Adobe Acrobat PDF | View Details Download |