E. coli (Escherichia coli) A common bacterium in human/animal intestines; most strains are harmless, but some are pathogenic.
Diarrheagenic E. coli Pathogenic strains causing diarrhea. Major types:
- EPEC (Enteropathogenic E. coli) Attaches to intestine via intimin, encoded by eae gene.
- STEC (Shiga toxin-producing E. coli) Produces Shiga toxin (encoded by stx genes).
- EHEC (Enterohemorrhagic E. coli) Subset of STEC that also carries eae (e.g., O157:H7).
The eae gene Encodes intimin, an outer membrane protein that enables tight attachment to intestinal epithelial cells, causing “attaching and effacing” lesions.
Presence of eae helps differentiate EPEC/EHEC from other diarrheagenic E. coli.
Detection significance Identifying eae (and stx) allows surveillance of pathogenic E. coli in clinical, food, and environmental samples (e.g., wastewater).
