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 |