What is the main mechanism by which Vibrio cholera causes diarrhea?

What is the main mechanism by which Vibrio cholera causes diarrhea?

• A. Invasion of the intestinal mucosa
• B. Cholera toxin impairs intestinal electrolyte transport
• C. Overgrowth of gut flora
• D. Increased gastrointestinal motility

Answer: (B)

Vibrio cholerae is known to cause diarrhea primarily through the action of cholera toxin, which is a potent enterotoxin. This toxin affects the intestinal epithelial cells by binding to cell surface receptors and entering the cells, where it catalyzes the activation of adenylate cyclase. This leads to an increase in cyclic AMP (cAMP) levels, which subsequently disrupts normal electrolyte and water transport. The mechanism involves the inhibition of sodium (Na+) absorption and the stimulation of chloride (Cl-) secretion in the intestines. As a result, there is an increase in the secretion of water into the lumen of the intestine, leading to the characteristic watery diarrhea associated with cholera. This loss of electrolytes and fluids can lead to severe dehydration and subsequent complications if not treated promptly. The choice regarding invasion of the intestinal mucosa is not relevant to Vibrio cholerae since it does not invade tissues but rather acts on the intestinal lumen. Similarly, overgrowth of gut flora and increased gastrointestinal motility are not mechanisms associated with the pathogenesis of cholera. Instead, the disease is primarily due to the actions of the cholera toxin on electrolyte transport, which is why the answer related to cholera toxin impeding intestinal electrolyte transport

Vibrio cholerae is known to cause diarrhea primarily through the action of cholera toxin, which is a potent enterotoxin. This toxin affects the intestinal epithelial cells by binding to cell surface receptors and entering the cells, where it catalyzes the activation of adenylate cyclase. This leads to an increase in cyclic AMP (cAMP) levels, which subsequently disrupts normal electrolyte and water transport.

The mechanism involves the inhibition of sodium (Na+) absorption and the stimulation of chloride (Cl-) secretion in the intestines. As a result, there is an increase in the secretion of water into the lumen of the intestine, leading to the characteristic watery diarrhea associated with cholera. This loss of electrolytes and fluids can lead to severe dehydration and subsequent complications if not treated promptly.

The choice regarding invasion of the intestinal mucosa is not relevant to Vibrio cholerae since it does not invade tissues but rather acts on the intestinal lumen. Similarly, overgrowth of gut flora and increased gastrointestinal motility are not mechanisms associated with the pathogenesis of cholera. Instead, the disease is primarily due to the actions of the cholera toxin on electrolyte transport, which is why the answer related to cholera toxin impeding intestinal electrolyte transport