Question

Identify toxins important to GI tract diseases. What role(s) do toxins play in GI tract infections?

Answer 1

Several patogenic organisms cause infection and food poisoning affecting the gastrointestinal tract. The pathogens include bacteria, virus and protozoa etc. The GI tract infections are mainly caused by food and water contamination and unhygienic conditions of food preparation and food consumption. The major infections of GI tract include gastroenteritis, diarrhea, dysentery and enterocolitis. Important pathogens causing GI tract diseases include E. coli, Salmonella. Shigella, Compylobacter, Vibrio, Clostridium perfringes, Bacillus cereus, Yersinia enteocolitica and viruses like rota virus etc.

Many of these pathogens release different types of toxins like heat labile toxins, heat stable toxins and subunit toxins etc. These pathogens cause infections with common symptoms such as diarrhea, nausea, vomitting, abdominal crapms and fever etc.

Heat labile toxin of E. coli strain is similar to the cholera toxin and heat stable toxin causes profuse diarrhea by activation of guanylyl cyclase and producing increased amounts of GMP that causes huge fluid secretion to intestine lumen. The enterotoxins bind to te intestinal cells and cause necrosis. These enterotoxin are produced by gram positive C. perfringens and B. cereus. C. difficile is known to cause antibiotic associated diarrhea. The antibiotics eliminate some beneficial bacteria colonizing intestines along with pathogens. In such cases, C. difficile causes opportunistic intestinal infection. Rota viruses cause diarrhea in children due to contamination of water mostly. C. botulinum produces exotoxin causing food poisoning and affecting nervous system.