In ETEC infections, which component contributes to malabsorption?

In ETEC infections, which component contributes to malabsorption?

• A. Adhesin-mediated attachment only.
• B. Invasion of enterocytes.
• C. Toxins (heat-labile and heat-stable).
• D. Endotoxin produced by bacteria.

Answer: (C)

ETEC causes malabsorption mainly through its enterotoxins that disrupt enterocyte ion transport, leading to a secretory, malabsorptive diarrhea. The heat-labile toxin acts like cholera toxin, ADP-ribosylating the Gs alpha subunit to raise cAMP inside enterocytes. This activates protein kinase A, opens the CFTR chloride channel, and drives chloride and water secretion into the lumen while impairing absorption. The heat-stable toxin raises intracellular cGMP by activating guanylate cyclase C, which also reduces absorptive capacity and promotes secretion. The combined effect is a watery diarrhea with malabsorption, driven by toxins rather than invasion or endotoxin effects. Adhesins help with attachment but don’t directly cause malabsorption; invasion of enterocytes is typical of invasive pathogens and not ETEC; endotoxin can cause systemic symptoms but isn’t the primary mechanism of malabsorption in ETEC infection.

ETEC causes malabsorption mainly through its enterotoxins that disrupt enterocyte ion transport, leading to a secretory, malabsorptive diarrhea. The heat-labile toxin acts like cholera toxin, ADP-ribosylating the Gs alpha subunit to raise cAMP inside enterocytes. This activates protein kinase A, opens the CFTR chloride channel, and drives chloride and water secretion into the lumen while impairing absorption. The heat-stable toxin raises intracellular cGMP by activating guanylate cyclase C, which also reduces absorptive capacity and promotes secretion. The combined effect is a watery diarrhea with malabsorption, driven by toxins rather than invasion or endotoxin effects. Adhesins help with attachment but don’t directly cause malabsorption; invasion of enterocytes is typical of invasive pathogens and not ETEC; endotoxin can cause systemic symptoms but isn’t the primary mechanism of malabsorption in ETEC infection.