Deciphering the Implications of Escherichia coli in Inflammatory Bowel Disease: From Symbiont to Pathogen

Aceto, Gitana Maria; Falasca, Katia; Berardinucci, Desirèe; Cavallo, Ludovica; Mangiò, Alessio; Mancuso, Giuseppe; Muraro, Raffaella; Ciccocioppo, Rachele; Catalano, Teresa

doi:10.3390/pathogens15050548

Open AccessReview

Deciphering the Implications of Escherichia coli in Inflammatory Bowel Disease: From Symbiont to Pathogen

by

Gitana Maria Aceto

^1,*

,

Katia Falasca

²

,

Desirèe Berardinucci

³,

Ludovica Cavallo

⁴,

Alessio Mangiò

⁵,

Giuseppe Mancuso

⁵

,

Raffaella Muraro

⁶,

Rachele Ciccocioppo

⁷

and

Teresa Catalano

^8,*

¹

Department of Sciences, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy

²

Clinic of Infectious Diseases, Department of Medicine and Science of Aging, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy

³

Department of Sciences, Medical School Student, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy

⁴

Department of Sciences, Chemistry and Pharmaceutical Technology Student, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy

⁵

Department of Human Pathology, University of Messina, 98125 Messina, Italy

⁶

Department of Innovative Technologies in Medicine & Dentistry, University “G. d’Annunzio” of Chieti-Pescara, 66100 Chieti, Italy

⁷

Department of Medicine and Ageing, “G. d’Annunzio” University of Chieti-Pescara, 66100 Chieti, Italy

⁸

Department of Clinical and Experimental Medicine, University of Messina, 98125 Messina, Italy

^*

Authors to whom correspondence should be addressed.

Pathogens 2026, 15(5), 548; https://doi.org/10.3390/pathogens15050548

Submission received: 13 March 2026 / Revised: 6 May 2026 / Accepted: 13 May 2026 / Published: 19 May 2026

(This article belongs to the Special Issue Virulence and Resistance Mechanisms in Multidrug-Resistant Gram-Negative Bacteria: 2nd Edition)

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Abstract

Inflammatory bowel disease (IBD) is a chronic inflammatory condition resulting from complex interactions between the immune system, genetic predisposition, and the gut microbiota. In this context, Escherichia coli (E. coli) plays a dual role in the human gut, ranging from harmless commensal strains to pathobionts capable of promoting intestinal inflammation. A growing body of evidence suggests that specific E. coli pathotypes, such as adherent-invasive E. coli (AIEC) and diffusely adherent E. coli (DAEC), contribute to the development and progression of IBD. This narrative review critically examines the microbiological, immunological, and clinical evidence supporting the role of E. coli in IBD, with particular emphasis on mechanisms of mucosal colonization, host–microbe interactions, and persistence within the inflamed intestinal environment. Furthermore, the lack of a standardized operational definition and the limited reproducibility of the AIEC phenotype are addressed, as well as uncertainty about the role played by E. coli as a primary initiator of the disease or as an opportunistic amplifier of intestinal inflammation, and the varying strength of evidence supporting associations with Crohn’s disease versus ulcerative colitis. Diagnostic implications, antimicrobial resistance, and therapeutic aspects are addressed as downstream and context-dependent consequences of E. coli–host interactions, with relevance for disease management and therapeutic response in patients with established IBD. By integrating data from experimental models, clinical studies, and translational research, the review identifies areas of consensus, ongoing controversy, and major knowledge gaps in IBD pathophysiology and clinical practice.

Keywords: inflammatory bowel disease; Escherichia coli; pathobionts; adherent-invasive E. coli; diffusely adherent E. coli; gut microbiota; host–microbe interactions; mucosal colonization; antimicrobial resistance; clinical management

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MDPI and ACS Style

Aceto, G.M.; Falasca, K.; Berardinucci, D.; Cavallo, L.; Mangiò, A.; Mancuso, G.; Muraro, R.; Ciccocioppo, R.; Catalano, T. Deciphering the Implications of Escherichia coli in Inflammatory Bowel Disease: From Symbiont to Pathogen. Pathogens 2026, 15, 548. https://doi.org/10.3390/pathogens15050548

AMA Style

Aceto GM, Falasca K, Berardinucci D, Cavallo L, Mangiò A, Mancuso G, Muraro R, Ciccocioppo R, Catalano T. Deciphering the Implications of Escherichia coli in Inflammatory Bowel Disease: From Symbiont to Pathogen. Pathogens. 2026; 15(5):548. https://doi.org/10.3390/pathogens15050548

Chicago/Turabian Style

Aceto, Gitana Maria, Katia Falasca, Desirèe Berardinucci, Ludovica Cavallo, Alessio Mangiò, Giuseppe Mancuso, Raffaella Muraro, Rachele Ciccocioppo, and Teresa Catalano. 2026. "Deciphering the Implications of Escherichia coli in Inflammatory Bowel Disease: From Symbiont to Pathogen" Pathogens 15, no. 5: 548. https://doi.org/10.3390/pathogens15050548

APA Style

Aceto, G. M., Falasca, K., Berardinucci, D., Cavallo, L., Mangiò, A., Mancuso, G., Muraro, R., Ciccocioppo, R., & Catalano, T. (2026). Deciphering the Implications of Escherichia coli in Inflammatory Bowel Disease: From Symbiont to Pathogen. Pathogens, 15(5), 548. https://doi.org/10.3390/pathogens15050548

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Deciphering the Implications of Escherichia coli in Inflammatory Bowel Disease: From Symbiont to Pathogen

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