1.2 Gastro-Enteritis Flashcards
What is the difference between Diarrhoea and Gastroenteritis?
- Diarrhoea - subjective (A change in pattern indicated Diarrhoea)
- Gastroenteritis - objective (Diarrhoea + other symptoms)
What changes during Diarrhoea?
- Fluidity of the stool
2. Frequency of the stool
What are the features of Gastroenteritis?
- 3+ loose stools per day
2. Accompanying features
Is a positive stool culture needed to have Gastroenteritis?
No, but need to have 3+ loose stools per day the other symptoms
Note - It is an objective finding but clinical, not always biological
What is Dysentery?
Large bowel inflammation due to infection
What is present with Dysentery?
- Bloody stools
- A lot of pain
Note - it is quite obvious when someone has contracted Dysentery
What is the name of the chart which stools are measured against?
The Bristol Stool Chart:
1 - Separate hard lumps, hard to pass
4 - Sausage / Snake like, smooth and soft
7 - Watery, no solid pieces, entirely liquid
What is the Aetiology of Gastroenteritis?
- Contamination of foodstuffs (intensity of farming - e.g. Chicken and Campylobacter)
- Storage of produce (Bacterial proliferation at room temperature)
- Salmonella in outbreaks (also imported from abroad in Travel Related Infections)
- Campylobacter in isolated cases (can also be imported)
What is the Epidemiology of Gastroenteritis?
- 25% of the population have an infectious intestinal disorder each year
- 2% of the population visit the GP because of GI infection
- For every reported case, there are an unreported:
- a) 10 GP consultations
- b) 147 community cases
What is the most common cause of Gastroenteritis?
- Viruses (e.g. Norovirus)
2. Campylobacter (most common bacterial pathogen with 280,000 cases per year)
- How many cases of food poisoning are there per year?
2. How many are linked to poultry meat?
- 500,000
2. 244,000
What is the bacterial pathogen of Gastroenteritis, which causes the most hospital admission each year?
Salmonella
What are the number of cases (in Scotland) of Gastroenteritis caused by:
- Campylobacter?
- Salmonella?
- E. Coli O157?
- 6,366
- 736
- 253
Note - E. Coli O157 is not a big organism but it is important as it has more complex complications
What is the best defence against Gastroenteritis?
- Hand Hygiene
- Decrease Stomach pH - Taking PPI’s make you more susceptible to bacterial infection
- Normal Flora - taking antibiotics alter normal flora (e.g. C. Diff infection)
- Immunity - Immunosuppression leaves you more susceptible to infection
How is Gastroenteritis treated?
- Rehydration therapy:
- a) Oral salt/sugar solution
- b) IV saline
- Antimicrobials
- Treatment of complications
Why is a salt/sugar solution used in Oral Rehydration?
The salt is being lost from the gut lining, so the salt is replaced.
Glucose is used as well as they share a transporter and so increased absorption
Should routine antidiarrhoeals be given in Gastro-enteritis?
No
How long can those with Campylobacter Gastroenteritis be incubated for?
Up to 7 days, so dietary history may be inreliable
How long will it take for stool sample to be negative?
6 weeks
What clinical feature is associated with Campylobacter Gastroenteritis?
Severe abdominal pain
Can Campylobacter Gastroenteritis be invasive?
Yes, but it is not common (<1%)
Note - if it becomes invasive you should suspect something is wrong with the immune system
What “Post-infection sequaelae” can occur from Campylobacter Gastroenteritis?
- Guillain-Barre Syndrome
2. Reactive Arthritis
Why is a routine bacterial culture of stools used?
- It can be difficult to find a pathogen in the midst of complex normal flora
- It allows for selective and enrichment of the cultures necessary - only 4 pathogens are actually looked for
If the routine bacterial culture of stools comes back negative, does that mean there isn’t a cause?
No, as the test only looks for 4 common pathogens, it could easily be something less common
How long does it take to do a routine bacterial culture?
3 days to complete all tests
What is looked for in a routine bacterial culture?
- Campylobacter
- Salmonella
- E. Coli O157
- Shigella
What are the 2 types of Campylobacter bacteria being tested for under the specialised culture conditions?
- Campylobacter Jejuni
- Campylobacter Coli
But there are many other species of this
Does Campylobacter Gastroenteritis occur in isolated cases, or outbreaks?
Although this is the commonest cause of bacterial food poisoning, this occurs in isolated cases, rather than outbreaks
How long does the onset of Salmonella Gastroenteritis usually take?
Less than 48 hours
How long does Salmonella Gastroenteritis usually last?
Less than 10 days
What is it hard to differentiate Salmonella Gastroenteritis with?
Campylobacter Gastroenteritis
- What percentage of Salmonella Gastroenteritis cases have positive blood cultures?
- What is suggested if this is the case?
- Less than 5%
2. Underlying immune function pathology
In cases of Salmonella Gastroenteritis, how common is it to have positive stool cultures 20 weeks after symptoms go away?
Quite common - 20% of patients will still have positive stool cultures at 20/52
What can prolonged carriage of Salmonella Gastroenteritis be associated with?
Gallstones
What is a common post-infectious problem of Salmonella Gastroenteritis?
Post-infectious Irritable Bowel Syndrome is common
How is Salmonella Gastroenteritis screened for in a routine bacterial culture?
It is screened out as lactose non-fermentors
Which, of the bacteria studied in a routine bacterial culture, is associated with complex complications?
E. Coli O157
How can E. Coli O157 Gastroenteritis infection spread?
- Contaminated meat
2. Person - person spread
What characterizes E. Coli O157 Gastroenteritis infection?
Frequent bloody stools
What is the pathology of E. Coli O157 Gastroenteritis?
E. Coli O157 produces a (verocyto-)toxin which enters the blood whilst the E. Coli O157 bacteria stays in the gut
What can the (verocyto-)toxin, caused by E. Coli O157 Gastroenteritis, cause?
Haemolytic-Uraemic Syndrome (HUS)
What is Haemolytic-Uraemic Syndrome (HUS) characterized by?
- Haemolytic anaemia
- Renal failure
- Thrombocytopenia
What is the pathology of Haemolytic-Uraemic Syndrome (HUS)?
- Toxin produced by E. Coli O157 binds to globotriaosylceramide
- Platelet activation is stimulated
- Micro-angiopathy (clotting) occurs
- The clot’s attach to Endothelial, Glomerular tubule and Mesingial cells in the Kidney
What is the treatment for Haemolytic-Uraemic Syndrome (HUS)?
Supportive - antibiotics are not indicated
Note - If you get past 10 days without getting HUS, you’re probably not going to get it
What other forms of E. Coli Gastroenteritis cause Diarrhoea?
- Enteropathogenic
- Enterotoxic (Traveller’s Diarrhoea)
- Enteroinvasive
Note - these other strains of E. Coli can’t be routinely diagnosed, only distinguished from “Ordinary” E. Coli O157
What is the most common Shigella species to cause outbreaks?
Shigella Sonnei
What are some occational causes of food poisoning outbreaks?
- Staph. Aureus (toxin)
- Bacillus Cereus (re-fried rice)
- Clostridium Perfringens (toxin) - can cause gangrene
When are antibiotics indicated in Gastroenteritis?
- Immunocompromised patients (Steroids, HIV, etc.)
- Severe Sepsis or invasive infection
- Valvular Heart Disease
- Chronic Illness
- Diabetes
What is the mainstay of treatment for Gastroenteritis?
Rehydration therapy
For Gastroenteritis, are antibiotics indicated for a healthy patient with a non-invasive infection?
No
