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GI Infections
Infections of the Gastrointestinal Tract
Term | Definition |
---|---|
E. coli | The most common organsim in the gut. Is an opportunistic pathogen of the urinary tract (urinary tract infections). |
Viruses | Responsible for 50 - 70% of GI infections. |
Small intestine infections characterised by | Watery diarrhoea and vomiting |
Large intestine infections characterised by | Dysentery (low faecal volume and many cases of blood) |
Intoxication | Due to the ingestion of preformed toxins. Symptoms occur within 30 minutes of intake. |
Infection | Due to the ingestion of viable micro-organisms Symptoms occur after 24 hours. Can be enteric (local infection) or non-enteric (invades other organs) |
Toxicoinfection | Caused by sporeformers (C. perfringens) and Gram - organisms (in which only a small number of organisms are required) |
Short incubation (within 1 day) | Emetic or diarrhoeal syndrome S. aureus, B. cereus, C perfringens |
Intermediate incubation(1-3 days) | Bacterial or viral agents Large or small bowel enteritis |
Long incubation (3-5 days) | Haemorrhagic colitis |
Staphylococcus Aureus | INTOXICATION Heat stable and heat resistant enterotoxins in fatty foods (custard, cream). Symptoms occur after 6 hours. Complications include scalded skin syndrome, TSS, carbuncles and pustular impetigo. |
Clostridium botulinum | INTOXICATION Endospores found in inadequately prepared canned food. AB toxin A - blocks cholinergic neurotransmission at the NMJ B - protects the A portion from stomach acid Death may result from respiratory failure. DON'T FEED HONEY TO BABIES |
Bacillus cereus | TOXICOINFECTION A sporeformer that produces heat resistant and heat stable spores in normal conditions.'Fried rice syndrome' - Emetic toxin (Type 1) - high carb foods - Diarrhoeal form (Type 2) - high protein foods Can cause tissue and blood damage. |
Clostridium perfringens | TOXICOINFECTION A sporeformer that releases a heat labile protein when vegetative cells become spores. Protein binds to brush border in small intestine resulting in watery diarrhoea. Large numbers need to be ingested. Implicated in cellulitis. |
Clostridium difficile | TOXICOINFECTION The most common cause of diarrhoea in hospitalised patients or those with excessive antibiotic use - opportunistic infection. Can lead to diarrhoea, pseudo-membranous colitis and toxic megacolon. Associated with PPIs |
Vibrio cholerae | TOXICOINFECTION Gram - bacteria. The majority are killed by gastric acid but some can infect the small intestine. Exotoxin doesn't penetrate the mucosa.Causes a net release of ions from the gut wall causing abrupt watery diarrhoea |
Enteropathogenic E. Coli | TOXICOINFECTION The toxin causes the destruction of the microvilli on cells of the small intestine. It can cause death in infants. |
E. Coli Gastroenteritis | INFECTION Is often called traveller's diarrhoea |
Campylobacter jejuni | INFECTION The no. 1 food borne pathogen in Australia - associated with poultry. Causes enterotoxin mediated diarrhoea or inflammatory invasive diarrhoea. Complications are seizures, meningitis and Guillain Barre Syndrome. |
Salmonella | INFECTION Gram - motile anaerobe. Resistant to bile salts and produces the smell of rotten eggs. Causes acute gastroenteritis and Typhoid fever |
Salmonella Typhi | Causes Typhoid fever. Transmitted person-person by chronic carrier or faecal contaminated food/water. The gall bladder is the reservoir in humans. Can lead to sepsis/bacteraemia. |
Helicobacter Pylori | INFECTION 50% of the world's population is carriers. It is implicated in 90% of duodenal ulcers and 70% of gastric ulcers. Treated via triple therapy (amoxicillin, macrolide and an antacid) |
Shigella | INFECTION A dysentery syndrome. Has a small inoculum. Causes ulceration of the intestine, diarrhoea, malabsorption of electrolytes and shuts down cellular metabolism (NAD glycohydrolase). |
Listeria monocytogenes | INFECTION A Gram + rod that can survive at cold temperatures. Is asymptomatic in adults but can cross the placental and blood-brain barrier. It can cause meningitis in the newborn, gastroenteritis and respiratory distress. Pregnant women at risk. |
Viral Gastroenteritis | INFECTION Caused by the Norwalk virus, rotavirus, adenovirus and astrovirus. |
Hepatitis A | INFETION A mild intestinal infection that will lead to hepatocellular jaundice. Immunisation is available |
Hepatitis E | INFECTION Implicated in many epidemics. Has a high fatality rate in pregnant women. |
Amoebiasis | INFECTION Caused by the ingestion of mature cysts of this parasite from contaminated food, water or faecal exposure during sexual contact. Causes dysentery, diarrhoea, appendicitis and abscess formation. |
Giardia | INFECTION The most common water-borne infection. Symptoms include diarrhoea, abdominal pain, cramps, flatus and steatorrhoea. |
Cryptosporidiosis | INFECTION Responsible for persistent chronic diarrhoea in immunocompromised individuals. |
Ascariasis (Round Worm) | INFECTION The most common intestinal helminth. Are transmitted by contaminated food and penetrate the intestine to invade the liver, lung and heart. |
Tape Worm | INFECTION Segmented worms in which the adult lives in the GIT. Larvae are found in almost every organ. Can grow up to 25m in length |