Digestive Infections

• Stomach ulcers are inflamed and damaged areas in the stomach wall, typically caused by exposure to gastric acids
• There is a strong positive correlation between Helicobacter pylori infection and the development of stomach ulcers
• Helicobacter pylori is a bacterium that can survive the acid conditions of the stomach by penetrating the mucus lining
• H. pylori anchors to the epithelial lining of the stomach, underneath the mucus lining
• An inflammatory immune response damages the epithelial cells of the stomach, including the mucus-secreting goblet cells
• This results in the degradation of the protective mucus lining, exposing the stomach wall to gastric acids and causing ulcers
• The prolonged presence of stomach ulcers may lead to the development of stomach cancer over many years (20 – 30 years)
• H. pylori infections can be treated by antibiotics
• Vibrio cholerae is a bacterial pathogen that infects the intestines and causes acute diarrhea and dehydration
• Cholera can kill within hours unless treated with oral rehydration therapies
• V. cholerae releases a toxin that binds to ganglioside receptors on the surface of intestinal epithelium cells
• This toxin is internalized by endocytosis and triggers the production of cyclic AMP (a second messenger) within the cell
• Cyclic AMP (cAMP) activates specific ion channels within the cell membrane, causing an efflux of ions from the cell
• The build-up of ions in the intestinal lumen draws water from cells and tissues via osmosis, causing acute diarrhea
• Dehydration will result if left untreated as water is being removed from body tissues