Which statement best describes enterotoxigenic E. coli (ETEC) pathogenesis?

Which statement best describes enterotoxigenic E. coli (ETEC) pathogenesis?

• A. It invades the intestinal mucosa.
• B. It attaches via adhesins without invading and produces toxins that cause malabsorption.
• C. It produces endotoxin LPS that leads to diarrhea.
• D. It causes systemic illness with fever.

Answer: (B)

ETEC causes diarrhea through a toxin-mediated secretory mechanism that does not invade the intestinal lining. It first adheres to enterocytes with specific adhesins (colonization factors), creating a stable colonization without penetrating the mucosa. Once attached, it releases enterotoxins—heat-labile and/or heat-stable—that disrupt ion transport in enterocytes, leading to increased chloride secretion and impaired absorption. This results in watery diarrhea with some malabsorption, rather than invasive inflammation or systemic illness. Endotoxin (LPS)–driven effects and fever are not the primary drivers of ETEC disease, and invasion of the mucosa is not part of its typical pathogenesis. Therefore, a description focusing on adhesion without invasion plus toxin production causing diarrheal malabsorption best fits ETEC.

ETEC causes diarrhea through a toxin-mediated secretory mechanism that does not invade the intestinal lining. It first adheres to enterocytes with specific adhesins (colonization factors), creating a stable colonization without penetrating the mucosa. Once attached, it releases enterotoxins—heat-labile and/or heat-stable—that disrupt ion transport in enterocytes, leading to increased chloride secretion and impaired absorption. This results in watery diarrhea with some malabsorption, rather than invasive inflammation or systemic illness. Endotoxin (LPS)–driven effects and fever are not the primary drivers of ETEC disease, and invasion of the mucosa is not part of its typical pathogenesis. Therefore, a description focusing on adhesion without invasion plus toxin production causing diarrheal malabsorption best fits ETEC.