Which feature distinguishes EIEC from other E. coli strains?

Enteroinvasive Escherichia coli (EIEC) is specifically characterized by its ability to invade the intestinal mucosa and cause symptoms similar to those of Shigella infection. The primary feature that distinguishes EIEC from other strains of E. coli, such as enterotoxigenic E. coli (ETEC) or enterohemorrhagic E. coli (EHEC), is its capacity to cause bloody diarrhea due to direct epithelial invasion, rather than through the production of toxins alone.

EIEC invades the intestinal cells, leading to cell death and inflammation, which can result in bloody diarrhea. In contrast, other strains like ETEC primarily cause watery diarrhea through the secretion of enterotoxins, while EHEC produces toxins that can also cause bloody diarrhea, but the mechanism is due to toxin-mediated damage and not direct invasion.

Thus, the defining distinction of EIEC is its ability to cause bloody diarrhea via invasion of the intestinal mucosa, rather than through toxin production.