Enterobacteriaceae in the Human Gut: Dynamics and Ecological Roles in Health and Disease

Simple Summary The human gastrointestinal tract harbors a complex and dynamic population of microorganisms (mostly bacteria and viruses) that are called the gut microbiota. This microbial community is known to exert a marked influence on the host health. Among the different bacterial families present in the gut microbiota, Enterobacteriaceae represents only a small fraction of total bacteria in healthy individuals, whereas it can abnormally proliferate in the gut of individuals affected by intestinal or extra-intestinal diseases such as obesity, inflammatory bowel disease or metabolic disorders. Our review explores the recent knowledge discussing the dynamics of Enterobacteriaceae in the human gut in healthy or disease-associated conditions. We also describe emerging mechanistic studies that could explain how Enterobacteriaceae proliferate in cases of gut microbiota imbalance in patients as well as the consequences such expansions could have on host health. Abstract The human gut microbiota plays a crucial role in maintaining host health. Our review explores the prevalence and dynamics of Enterobacteriaceae, a bacterial family within the Proteobacteria phylum, in the human gut which represents a small fraction of the gut microbiota in healthy conditions. Even though their roles are not yet fully understood, Enterobacteriaceae and especially Escherichia coli (E. coli) play a part in creating an anaerobic environment, producing vitamins and protecting against pathogenic infections. The composition and residency of E. coli strains in the gut fluctuate among individuals and is influenced by many factors such as geography, diet and health. Dysbiosis, characterized by alterations in the microbial composition of the gut microbiota, is associated with various diseases, including obesity, inflammatory bowel diseases and metabolic disorders. A consistent pattern in dysbiosis is the expansion of Proteobacteria, particularly Enterobacteriaceae, which has been proposed as a potential marker for intestinal and extra-intestinal inflammatory diseases. Here we develop the potential mechanisms contributing to Enterobacteriaceae proliferation during dysbiosis, including changes in oxygen levels, alterations in mucosal substrates and dietary factors. Better knowledge of these mechanisms is important for developing strategies to restore a balanced gut microbiota and reduce the negative consequences of the Enterobacteriaceae bloom.