Regarding ETEC, true is
**Core Concept**
ETEC (Enterotoxigenic Escherichia coli) is a type of bacterial pathogen that causes traveler's diarrhea, particularly in individuals visiting developing countries. This bacterium produces heat-labile (LT) and/or heat-stable (ST) enterotoxins, which stimulate the intestinal epithelial cells to secrete water and electrolytes, leading to diarrhea.
**Why the Correct Answer is Right**
The correct answer is related to the mechanism of action of ETEC toxins. Heat-labile enterotoxin (LT) activates the adenylate cyclase enzyme in intestinal epithelial cells, increasing intracellular cyclic AMP (cAMP) levels. This leads to the secretion of water and electrolytes into the intestinal lumen, causing diarrhea. The heat-stable enterotoxin (ST) also stimulates adenylate cyclase activity, but through a different mechanism involving guanylate cyclase.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct mechanism of action of ETEC toxins. While ETEC does cause diarrhea, the correct answer should relate to the specific biochemical pathway involved.
**Option B:** This option is incorrect because it does not accurately describe the primary mechanism of ETEC toxins. The LT toxin primarily acts through adenylate cyclase activation, not through inhibition of prostaglandin synthesis.
**Option C:** This option is incorrect because it does not provide a clear mechanism of action for ETEC toxins. While the toxin does cause diarrhea, the correct answer should specify the biochemical pathway involved.
**Clinical Pearl / High-Yield Fact**
ETEC is a common cause of traveler's diarrhea, particularly in individuals visiting developing countries. The use of bismuth subsalicylate and antibiotics such as rifaximin can help prevent and treat ETEC infections.
**Correct Answer:** C.