EAECs

Enteroaggregative Escherichia coli (EAEC) refers to a pathotype of Escherichia coli characterized by a distinctive aggregative adherence to intestinal mucosa and the ability to form biofilms. EAEC were first recognized as a cause of persistent diarrhea in children and travelers, with symptoms ranging from acute watery diarrhea to prolonged illness. The hallmark in laboratory studies is an “aggregative” or stacked-brick adhesion pattern observed on HEp-2 cell assays, reflecting a mechanism of colonization and biofilm formation on the intestinal epithelium.

Typical EAEC strains carry a collection of virulence determinants on the pAA plasmid, including the regulator aggR and genes for aggregative adherence fimbriae (AAF variants), dispersin (aap), and the dispersin transporter (aatA). Atypical EAEC strains lack aggR and related pAA-encoded virulence genes but may still cause illness. The pathogenesis involves mucosal adherence, biofilm formation, and secretion of toxins and mediators that disrupt absorptive and secretory processes, contributing to watery diarrhea and, in some cases, persistent diarrhea, especially in children in developing countries and in immunocompromised individuals.

Diagnosis commonly relies on stool testing for EAEC-associated virulence genes by PCR, particularly aggR and aatA, in combination with clinical presentation. The HEp-2 adherence assay is used mainly in research settings rather than routine diagnostics.

Treatment emphasizes supportive care, including oral or intravenous rehydration. Antibiotics are selectively used, often for persistent cases or in specific settings, with choices guided by local resistance patterns. Prevention focuses on standard diarrheal disease measures: safe drinking water, good hygiene, and proper sanitation.