Which organism produces a potent enterotoxin associated with severe diarrhea in outbreaks?

• A. Enterobacter aerogenes
• B. Escherichia coli
• C. Proteus mirabilis
• D. Vibrio cholerae

Answer: (D)

Vibrio cholerae is known for producing the cholera toxin, a potent enterotoxin that drives massive watery diarrhea during outbreaks. The toxin is an AB toxin that ADP-ribosylates the Gs alpha subunit in intestinal cells, keeping adenylate cyclase activated and causing a surge of cyclic AMP. This leads to extensive secretion of chloride and other electrolytes into the gut, with water following osmotically, producing the characteristic voluminous “rice-water” stools and rapid dehydration seen in cholera.

Outbreaks typically occur in areas with contaminated water and poor sanitation, and prompt, aggressive fluid and electrolyte replacement is crucial for treatment. Antibiotics may shorten illness in severe cases.

Other organisms can have enterotoxins and cause diarrhea, but the classic association with a potent toxin causing severe outbreaks is Vibrio cholerae.