Microorganisms. 2021 Mar 27;9(4):697. doi: 10.3390/microorganisms9040697.

Valerio Baldelli ¹, Franco Scaldaferri ^2 3, Lorenza Putignani ⁴, Federica Del Chierico ¹

Author information

• ¹Multimodal Laboratory Medicine Research Area, Unit of Human Microbiome, Bambino Gesù Children's Hospital, IRCCS, 00147 Rome, Italy.
• ²CEMAD, Unità Operativa Complessa di Medicina Interna e Gastroenterologia, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, 00168 Rome, Italy.
• ³Dipartimento Universitario di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, 00168 Rome, Italy.
• ⁴Department of Diagnostic and Laboratory Medicine, Unit of Parasitology and Multimodal Laboratory Medicine Research Area, Unit of Human Microbiome, Bambino Gesù Children's Hospital, IRCCS, 00165 Rome, Italy.

Abstract

Inflammatory bowel diseases (IBDs) are a group of chronic gastrointestinal inflammatory diseases with unknown etiology. There is a combination of well documented factors in their pathogenesis, including intestinal microbiota dysbiosis. The symbiotic microbiota plays important functions in the host, and the loss of beneficial microbes could favor the expansion of microbial pathobionts. In particular, the bloom of potentially harmful Proteobacteria, especially Enterobacteriaceae, has been described as enhancing the inflammatory response, as observed in IBDs. Herein, we seek to investigate the contribution of Enterobacteriaceae to IBD pathogenesis whilst considering the continuous expansion of the literature and data. Despite the mechanism of their expansion still remaining unclear, their expansion could be correlated with the increase in nitrate and oxygen levels in the inflamed gut and with the bile acid dysmetabolism described in IBD patients. Furthermore, in several Enterobacteriaceae studies conducted at a species level, it has been suggested that some adherent-invasive Escherichia coli (AIEC) play an important role in IBD pathogenesis. Overall, this review highlights the pivotal role played by Enterobacteriaceae in gut dysbiosis associated with IBD pathogenesis and progression.