Enterobacteriaceae (Escherichia coli, Attaching-Effacing E. coli, Salmonella Serotypes, Klebsiella, Enterobacter)

• Attaching and Effacing E. coli (AEEC):
• AEEC strains are defined by their ability to induce characteristic 'attaching and effacing' (A/E) histopathological lesions on intestinal enterocytes, driven by genes on the Locus of Enterocyte Effacement (LEE) pathogenicity island. This involves intimin (eae) binding to the Translocated Intimin Receptor (Tir), triggering host actin polymerization into attaching pedestals and effacing microvilli.
• Members of AEEC: Enterohemorrhagic E. coli (EHEC), typical Enteropathogenic E. coli (EPEC), and atypical EPEC.
• Enterotoxigenic E. coli (ETEC) Distinction: ETEC adheres to intestinal epithelial cells using colonization factor antigens (fimbriae/pili such as F4, F5, F6, F41) without effacing brush-border microvilli, exerting pathogenicity via heat-labile (LT) and heat-stable (ST) enterotoxins.

Correct option: (2) Entero-toxigenic Escherichia coli (ETEC)