Which mechanism is responsible for secretory diarrhea via heat-labile enterotoxins?

Which mechanism is responsible for secretory diarrhea via heat-labile enterotoxins?

• A. Enteroadherence
• B. Enterotoxin production
• C. Mucosal invasion
• D. Submucosal invasion

Answer: (B)

Secretory diarrhea from heat-labile enterotoxins happens because the bacteria make a toxin that directly drives the intestinal lining to secrete fluid and electrolytes. The heat-labile enterotoxin produced by some strains (notably enterotoxigenic E. coli) acts on enterocytes to ADP-ribosylate the Gs protein, which keeps adenylate cyclase activated and raises intracellular cAMP. This surge in cAMP opens the CFTR chloride channel, pushing chloride (and water) into the gut lumen and producing large volumes of watery stools. Because the effect is toxin-mediated secretion rather than tissue invasion, there’s typically little or no blood or inflammatory response. Other mechanisms like adherence or mucosal/submucosal invasion cause different diseases and don’t explain the watery secretory diarrhea driven by heat-labile toxins.

Secretory diarrhea from heat-labile enterotoxins happens because the bacteria make a toxin that directly drives the intestinal lining to secrete fluid and electrolytes. The heat-labile enterotoxin produced by some strains (notably enterotoxigenic E. coli) acts on enterocytes to ADP-ribosylate the Gs protein, which keeps adenylate cyclase activated and raises intracellular cAMP. This surge in cAMP opens the CFTR chloride channel, pushing chloride (and water) into the gut lumen and producing large volumes of watery stools. Because the effect is toxin-mediated secretion rather than tissue invasion, there’s typically little or no blood or inflammatory response. Other mechanisms like adherence or mucosal/submucosal invasion cause different diseases and don’t explain the watery secretory diarrhea driven by heat-labile toxins.