Homeostasis vs. Dysbiosis: Role of commensal Escherichia coli in disease

Abstract

Since the beginning, life on Earth has been influenced by the association between organisms and this continuous co-evolutionary process, led in life as we know it today. In this process, humans and microorganisms developed an intimate relationship known as the human microbiome. Any disturbance in our resident microbial community such as a shift away from homeostasis likely expresses itself in a pathological state. In this context, the term dysbiosis is used to describe a state of imbalance between the microbial population and the host species. E. coli, as part of our normal microbiome play an important role in homeostasis and it also has been linked to dysbiotic process. In the present chapter, we describe the role of different E. coli strains that have been linked to homeostasis and dysbiosis. Adherent Invasive E. coli (AIEC), lacking the known virulence factors of other pathogenic strains, is involved in inflammatory bowel disease (IBD). Enterohemorrhagic E. coli, together with the by-products of other members of the microbiome, colonize the human colon and E. coli Nissle is involved in maintaining homeostasis between host and its associated microbiome. The most recent studies in all Americas are also included in the present work.