Lecture 3 Gastroenteritis PDF

Gastroenteritis Pixabay.com 1. Introduction Gastroenteritis Acute Persistent Chronic Etiology Wikimedia Commons, 2025 Norovirus, Rotavirus E. coli, Clostridium...

Gastroenteritis Pixabay.com 1. Introduction Gastroenteritis Acute Persistent Chronic Etiology Wikimedia Commons, 2025 Norovirus, Rotavirus E. coli, Clostridium difficile, C. perfringens, Shigella spp., Salmonella spp. Giardia lamblia, Entamoeba histolytica, Cryptosporidium spp. Non-infectious gastroenteritis Transmission Contaminated food or water, surfaces, person-to person (virus! Aerosolized vomitus!) Epidemiology (acute, persistent and chronic)  2. Pathogenesis – Bacterial Gastroenteritis Three Mechanisms: 1. Bacteria that make a toxin in the food before it is consumed E.g., S. aureus, B. cereus (heat-stable enterotoxins) No person-to-person transmission 2. Bacteria that make a toxin in the gastrointestinal tract E.g., Clostridium perfringens, Enterotoxigenic E. coli E coli Wikimedia Commons, 2025 3. Bacteria that invade the intestinal wall causing inflammatory diarrhea E.g., Enterohemorrhagic E coli (EHEC) (shiga toxin producing) Found in undercooked meat, raw milk, etc. Cell destruction, hemorrhagic colitis, no fever (or low grade) No antibiotic recommended 2.* Antibiotic-associated diarrhea C. difficile colitis (cell apoptosis, ulceration, neutrophils chemotaxis) DOI: https://doi.org/10.3949/ccjm.83a.14183 Pseudomembranes 2. Pathogenesis – Viral Gastroenteritis Impact on enterocytes Interference with brusher border enzyme Wikimedia Commons, 2025 production (e.g., maltase, lactase) Malabsorption and osmotic diarrhea Viral toxins lead to cell lysis – loss of fluid Electrolyte abnormalities Virus is shed Feces and occasionally vomitus Peaks at 24 to 48 hs after symptomatology Wikimedia Commons, 2025 3. Clinical Manifestations Vomiting Diarrhea Abdominal cramping Fever Blood in stool Pixabay.com 4. Complications Most cases are self-limiting Dehydration and electrolyte imbalances Hypovolemia Metabolic acidosis Wikimedia Commons, 2025 Hemolytic uremic syndrome (HUS) Associated with Shiga toxin (6 to 9% of cases EHEC) Microthrombi Hemolysis Uremia Thrombocytopenia  5. Management Principles Most gastroenteritis Supportive care (rehydration strategies) Antibiotics (specific cases of bacterial gastroenteritis) Instructions on proper handling of food Public health measures Wikimedia Commons, 2025 Sanitation Hygiene Vaccinations