The human large intestine is host to an incredibly complex ecosystem of prokaryotic and eukaryotic microorganisms. It is estimated that there are at least 10-fold more microbial cells in the large gut than host cells in the entire adult human body. The genetic and metabolic diversity of this microflora far outstrips that of the host.
In normal conditions, the microflora exists in symbiosis with the host and contributes to defence against pathogens by occupying available niches and stimulating host immune system. It has more recently been shown to have a role in immune response modulation and even, through the gut-brain axis, in host neurological function.
The microflora is a highly dynamic system that differs between individuals and changes within the same person in response to diet, stress, antibiotic use, physiological disease, GI infection and many other factors. Geographic location also affects the composition. This may be due to dietary and genetic factors and to the acquisition of microflora from parents.
Disruption of the microflora by antibiotic use, dietary change, physiological disease or other factors may lead to establishment of pathogens in the gut. Clostridium difficile is a defining and serious example of this. Once established, it causes debilitating and life-threatening disease that is extremely difficult to treat with conventional medication.
Experimental studies have shown that re-establishment of a normal microflora in patients with C. difficile infection by infusion of gut contents from normal individuals can ameliorate the symptoms and reduce the bioburden of C. difficile in patients.
Many other GI diseases such as food poisoning, traveller’s diarrhoea, IBD and even IBS are associate with disruption of the microflora and are targets for treatments that aim to maintain or re-establish the normal microflora.
And here’s a thought - given the genetic and metabolic complexity of the microflora, is evolution driven by the need to assure continuance of the microbial biome by providing more sophisticated hosts?
In this presentation, we will review the acquisition, composition and metabolic activity of micro-organisms in the gut, look at the influence of these organisms on human health, and examine attempts to beneficially modify the composition of the large intestinal microflora.
Our Speaker Stewart Gibson is who has a first degree in biochemistry from Glasgow University in Scotland and a PhD in the role of the macrophage system in low density lipoprotein metabolism in humans (1984). This was followed by a post doc at the Dunn Clinical Centre in Cambridge, England [masked]) where his interest in the gut microflora began.