The first keynote speaker at the ESCP Annual Meeting in Nice this year was world renowned expert in microbial pathogenesis of infections which occur post-surgery, Dr John Alverdy, Professor of Surgery and Executive Vice-Chair of the Department of Surgery at the University of Chicago. As well as his Executive Vice-Chair of surgery role, he is also co-associate director of the Digestive Disease Research Center Core (DDRCC) and Past President of the Surgical Infection Society (North America).
The session was chaired by Linda Ferrari (Italy) and Des Winter (Ireland). According to Des Winter, the insights Dr Alverdy shared in ‘Microbiomic and metagenomic influences on colorectal patients’ are set to change the way we think.
Dr Alverdy started by explaining that he’s been studying the microbiome for 25 years and views it as the ‘unaccounted for’ dimension in human biology applied to patient wellness and disease management. He said there are ‘n’ dimensions of interactions between the microbiome and the host’s physiology/function but that we have previously dismissed the relevance of the microbiome in surgical complications because we did not know how to measure its effect on a host’s function.
He pointed out that Ileus and infection account for more than 50% of readmissions - effectively becoming the new proxy for being a good surgeon. He then asked, is postoperative ileus an infection? Dr Alverdy queried whether the immune system is not just a puppet of the microbiome?
He spoke about the nature of infection. Is it correct to say that it is when a pathogen overwhelms host clearance mechanisms and causes systemic illness or is it more accurate to say it is the perturbation in host function that occurs as a result of a complex interconnectivity between various species of microbes (i.e a community) and host physiology.
Dr Alverdy explained that systems interconnectivity is ‘context dependent’ and develops from a bidirectional molecular dialogue between the host and its microbiota. Complex interactions produce emergent bacterial phenotypes unique to the environmental context. As such how we operate is ‘sensed’ by microbiota who then ‘respond’ accordingly. This means every aspect of surgery is important!
Host ‘cues’ are gathered, processed and transduced by the microbiota. So, when bacteria get the nutrients they need, they do not respond to incoming host activation ‘cues’.
He therefore went on to look at whether Enhanced Recovery Programs (ERAS) improve outcomes due to their influence on the microbiome given the focus of these initiatives are to establish ‘peace’ between the microbiome and host. He referenced research he’d done with Kristi Guyton looking at whether the recovery of the microbiome matters? This has led to the understanding that the loss of the microbiome impairs systemic immune function.
Their studies have found that restoring the microbiome with a fecal microbiota transplant (FMT) drives a recovery directed systemic immune response. He revealed that peritoneal cultures demonstrate near total clearance of the injected pathogens in mice treated with an FMT - with no antibiotics!
Given this Dr Alverdy went on to say that, as diet has such a profound effect on the microbiome, it can potentially ‘rescue’ a patient. Diet, antibiotics and the microbiome all influence anastomotic leak pathogenesis. And it is about the right kind of diet - they researched the effect of typical western diet – polyunsaturated fatty acid (PUFA) as well as high fibre low fat.
He went on to conclude that, as a result of his studies into gut microbiota and gastrointestinal surgery, we need ‘point-of-care’ diagnostics to assess whether our patients’ microbiome is optimised to give the resilience needed to withstand the stress of surgery.
Such a test would inform the best way to prepare the bowel effectively for surgery. This is in contrast to the current approach which is to stun the microbiome then hope it recovers rapidly.
Dr Alverdy suggested that while ERAS is important, it may be that Enhanced Rehabilitation Before Surgery (ERBS) may be equally important. It will require high resolution microbiome analyses to further reduce postoperative infections and cancer recurrence rates.