Diarrhoea Flashcards
What are the 4 different types of diarrhoea
- Osmotic/malabsorptive diarrhoea
- Secretory diarrhoea
- Inflammatory/infectious diarrhoea
- Motility disorders
Describe Osmotic/malabsorptive diarrhoea
It results from the presence of unabsorbed or poorly absorbed solute (magnesium, sorbitol, and mannitol) in the intestinal tract that causes an increased secretion of liquids into the gut lumen
Give an example of an secretory diarrhoea
Cholera toxin
In osmotic diarrhoea the diarrhoea ____ when the patient fasts
Stops
In secretory diarrhoea the diarrhoea ____ when the patient fasts
does not stop
Describe secretory diarrhoea
There is an altered transport of ions across the mucosa, which results in increased secretion and decreased absorption of fluids and electrolytes from the GI tract
Give an example of an osmotic diarrhoea
Laxative abuse
Describe inflammatory diarrhoea
Diarrhoea occurs because of damage to the intestinal mucosal cell so that there is a loss of fluid and blood
In addition, there is defective absorption of fluid and electrolytes.
Name the bacterium that causes inflammatory diarrhoea
Salmonella, E. coli, Campylobacter
Name the viruses that causes inflammatory diarrhoea
rotaviruses, coronaviruses, norovirus
Name the protozoa that causes inflammatory diarrhoea
Cryptosporium, Giardia
Describe motility disorders that cause diarrhoea
Increased motility, decreased transmit time/motility
Can lead to bacterial overgrowth
Give examples of motility disorder diarrhoea
Diabetic, post-vagotomy and hyperthyroid diarrhoea
Concentration of bacteria in the small intestine is smaller than in the large intestine.
What prevents the bacteria from colonising the small intestine
- Gastric acid
- Bile acids
- Propulsive motility
- Pancreatic enzymes
What is the pH of the large intestine
pH 4.5- 7
Are the bacteria in the large intestine aerobic or anaerobic?
99% are anaerobic (not reuqiring oxygen)
What is the function of gut bacteria?
- Ferment carbohydrate
- Produce short chain fatty acids – many actions and influences
- Reduce colonic pH
- Inhibit pathogens
- Produce a range of vitamins
Define fermentation
Anaerobic metabolism of carbohydrate and protein in human colon by the microbiota
Which carbohydrates does the gut microbiota fementate?
- Resistant starch
- Non starch polysaccharides
- Wheat bran, oat fibre, other cereals, pectins, glucans
- Sugar alcohols
- Non absorbed oligosaccharides and sugars
- prebiotics
What is the product of the fermentation of carbohydrate and protein
Short chain fatty acids (SCFA)
What is the function of short chain fatty acids formed from the fermentation of carbohydrates and proteins
- Promote colonic absorption – reduce diarrhoea
- Provide energy, influence hormone release affecting satiety -Obesity
•Protect gut mucosa- IBD and cancer
•Influence lipid metabolism in different ways - coronary heart disease
Contrast the reabsorption of water in the large and small intestine
- In the SI, you absorb a lot of water by cotransported with electrolytes
- In the LI, it is the SCFA. Few electrolytes present so it’s the SCFA in the LI that drives the absorption of water
- High fibre diets- large increase in stool output, because the flora are used to carbohydrate and protein food.
Give examples of short chain fatty acids
- Acetate
- Propionate
- Butyrate
Describe acetate
- 60% of the total number of SCFA formed.
- Main SCFA to reach systemic blood
- Used for energy
- May increase hepatic lipogenesis
- May influence satiety but may increase energy salvage from food.
Describe propionate
- 2nd most important short chain fatty acid
- Seems to influence the release of hormones in the gut that effect the lectin, gut mobility and Influence insulins sensitivity
- Inhibits cholesterol synthesis.
- Inhibits lipid synthesis
- Increases insulin sensitivity
Colonic pH is ____ by colonic fermentation
Reduced
Why is it important that the pH of the large intestine is more acidic
- inhibits harmful enzymes
- 7 alpha hydroxylase
- precipitates harmful molecules
- Bile acids, sterols, fatty soaps
- Inhibits colonic cell proliferation
- Increases colonic calcium and magnesium absorption
- Inhibits pathogens and may influence other bacteria
Define the term “probiotic”
Live microorganisms which when administered in adequate amounts confer a health benefit on the host.
Name the vitamins that are formed by the colonic bacteria
Vitamin K and B12
Which gases produced by the colonic bacteria add to flatus
Carbon dioxide, hydrogen gas, and methane
Which virus is the most frequent viral cause of severe gastroenteritis in infants and children
Rotavirus
When seeing a patient with diarrhoea, the most important investigation is?
A clear history
When treating someone with gastroenteritis, the most important management is
Rehydration
Which important vitamin is made and absorbed in the large intestine?
Vitamin K
Viral gastroenteritis is the most common. Viral gastroenteritis is highly contagious.
Name the 3 most common viruses that can cause viral gastroenteritis
Rotavirus
Norovirus
Adenovirus is a less common cause and presents with a more subacute diarrhoea
Describe E.coli in regards to its ability to cause gastroenteritis
Escherichia coli (E. coli) is a normal intestinal bacteria. Only certain strains cause gastroenteritis. It is spread through contact with infected faeces, unwashed salads or water.
E. coli 0157 produces the Shiga toxin. This causes abdominal cramps, bloody diarrhoea and vomiting. The Shiga toxin destroys blood cells and leads to haemolytic uraemic syndrome (HUS).
The use of antibiotics increases the risk of haemolytic uraemic syndrome therefore antibiotics should be avoided if E. coli gastroenteritis is considered.
Enterohaemorrhagic E coli (EHEC) is:
A) Gram negative
B) Gram positive
A) Gram negative
Describe the clinical signs of E.coli gastroenteritis
Blood often present
Abdominal pain
Which viral gastroenteritis has a high rate in children and often seen spread in nurseries
Rotavirus
What is the typical culprit of E.coli gastroenteritis
Beef, pork, unwashed veg
Describe Campylobacter Jejuni
- Gram negative bacterium
- Symptoms include:
- Blood often present
- Severe abdominal pain
- Nausea but rarely vomiting
- fever
- Cause is often under cooked poultry
- Mechanism is INFLAMMATORY
- Associated with Guillain-Barre syndrome or reactive arthritis
Describe Salmonella
- Gram negative bacterium
- Clinical symptoms include:
- Nausea
- Abdominal pain
- fever
- Cause is often under cooked poultry
- Asymptomatically shed for on average 5 weeks- people who work in healthcare or food handling job is required to be tested before going back to work to prevent spread during asymptomic stage
Describe Clostridium Difficile
- Gram positive bacterium
- Clinical signs:
- High WCC (leucocytosis)
- Fever
- Often seen in hospital and care homes
- Can result in toxic mega colon- very dilated colon
The typical exam patient develops symptoms soon after eating leftover fried rice that has been left at room temperature. It has a short incubation period after eating the rice and they then recover within 24 hours..
Which kind of pathogen has caused this diarrhoea
Bacillus Cereus
The typical course is vomiting within 5 hours, then diarrhoea after 8 hours, then resolution within 24 hours.
Describe Staphylococcus Aureus
can produce enterotoxins when when growing in food such as eggs, dairy and meat. When eaten these toxins cause small intestine inflammation. This causes symptoms of diarrhoea, perfuse vomiting, abdominal cramps and fever. These symptoms start within hours of ingestion and settle within 12-24 hours. It is not actually the bacteria causing the enteritis but the staphylococcus enterotoxin.
What is the management of Clostridium difficle
Stop or change causative antibiotics, give ORAL Metronidazole +/ Vancomycin as per local guidance. A faecal transplant can be used to restore gut flora in recurrent infection
Name four organisms which commonly cause blood diarrhoea
- Escherichia coli*
- Shigella species*
- Salmonella species*
- Campylobacter species*
Name the two types of inflammatory bowel disease
ulcerative colitis and Crohn’s disease
What are the most common causes of chronic diarrhoea
- Lactose intolerance
- Celiac disease
- Inflammatory bowel disease
- Irritable bowel disease
Describe crohns disease
- Can affect any part of the GI tract from mouth to anus
- The lesions are not continous
- It affects all layers of the gut wall
- The goblet cells appear normal
- It causes inflammation of the GI, which can lead to abdominal pain (in the right quadrant), severe diarrhea, fatigue, weight loss and malnutrition.
Describe ulcerative colitis
- UC is caused by the inflammation and ulceration of the inner lining of the colon and rectum (the large bowel).
- In Colitis, ulcers develop on the surface of the bowel lining and these may bleed and produce mucus- causing bloodly stools.
- The inflammation affects only the rectum and colon.
- The inflamed colon is less able to absorb the liquid and this can lead to a larger volume of watery stools. Also, because the colon cannot hold as much waste as normal, very frequent bowel movements (six or more a day) may occur
- `The lesions are continous through the colon and rectum
- Depletion of goblet cell numbers
