Enteroaggregative E. coli (EAEC) causes disease by which mechanism?

Enteroaggregative E. coli (EAEC) causes disease by which mechanism?

• A. It forms a biofilm on the small intestine mucosa and aggregates to itself and cell surfaces without invading, producing toxins.
• B. It invades enterocytes and spreads systemically.
• C. It solely releases endotoxins causing fever.
• D. It is nonpathogenic.

Answer: (A)

Enteroaggregative E. coli causes disease mainly through adherence to the intestinal lining in an aggregative, stacked-brick pattern and by forming a biofilm on the mucosal surface. This biofilm keeps bacteria attached to the enterocytes, disrupts normal absorption, and leads to persistent watery diarrhea. The bacteria stay on the surface and do not invade the intestinal cells or spread systemically. Some EAEC strains produce toxins, such as EAST1 or Pet, that amplify diarrheal symptoms, but invasion and systemic infection are not part of its mechanism. This makes the mechanism described—biofilm formation with aggregative adherence and toxin production, without invasion—the best description of how EAEC causes disease.

Enteroaggregative E. coli causes disease mainly through adherence to the intestinal lining in an aggregative, stacked-brick pattern and by forming a biofilm on the mucosal surface. This biofilm keeps bacteria attached to the enterocytes, disrupts normal absorption, and leads to persistent watery diarrhea. The bacteria stay on the surface and do not invade the intestinal cells or spread systemically. Some EAEC strains produce toxins, such as EAST1 or Pet, that amplify diarrheal symptoms, but invasion and systemic infection are not part of its mechanism. This makes the mechanism described—biofilm formation with aggregative adherence and toxin production, without invasion—the best description of how EAEC causes disease.