In colorectal surgery, efforts have focused on improving the surgical technique and postoperative care to reduce the risk of complications and recurrences. The most common complications include postoperative ileus and surgical site infections. However, the most feared one is still anastomotic leakage. Several factors have been identified, such as inadequate bowel perfusion, treatment with neoadjuvant therapies, and technical defects. However, the intestinal microbiome has not been considered as a robust, active participant.
The gut microbiome is affected by multiple factors, including environment, genetics, diet, the host’s immune system, and antibiotic exposure. For example, the host releases cytokines and opioids, among other factors, during surgical stress. They affect the gut microbial community, with interspecies and intraspecies signal exchanges, resulting in dysbiosis with new bacterial phenotypes that are unique to the environmental context. Such dysbiosis can cause a loss in bacterial balance, with a proliferation of potentially harmful species, which might impair immune function or anastomotic healing.
Since the 1950s, it has been known that specific antibiotic therapies might protect from anastomotic leakage. Thus, scientists have performed several studies focused on demonstrating that anastomotic leak can be considered an infectious disease. Modern trials have concluded that specific factors are related to microbe-mediated pathology. Morphine, an excess of oxygen, and wrong antibiotic exposure can collapse the microbiome and activate enterococcus faecalis virulence. This fact is followed by the amplification of tissue inflammation (through collagenolytic activity, for example), generating the clinical manifestations of leakage.
Dr. John Alverdy can be regarded as one of the fathers of microbiome study. He has spent years analyzing the microbial pathogenesis of infections that develop following surgical stress. In this valuable lecture, he provides an update on the role of bacterial community in the development of wound infection and anastomotic leakage.