Infectious Diarrhoea Flashcards
How is diarrhoea defined?
- Subjective
- By fluidity and frequency
How is gastro-enteritis defined?
- Objective
- Three or more loose stools/day with accompanying features
How is dysentery defied?
- Obvious
- Large bowel inflammation with bloody stools
Describe the Bristol stool chart.
- Type 1: separate hard lumps
- Type 2: sausage shaped but lumpy
- Type 3: sausage with cracks on the surface
- Type 4: smooth and soft sausage shaped
- Type 5: soft blobs with clear cut edges
- Type 6: fluffy pieces with ragged edges
- Type 7: watery, entirely liquid
What can cause gastro-enteritis?
- Contamination of foodstuffs (chicken and campylobacter)
- Poor storage of produce (bacterial proliferation at room temperature)
- Travel-related infections (salmonella)
- Person to person spread (particularly viruses such as norovirus)
What is the commonest cause of infectious diarrhoea?
- Viruses
- The commonest bacterial pathogen is campylobacter
What is the most common foodborne pathogen?
Campylobacter
What pathogen is responsible for the most hospital admissions each year?
Salmonella
Give 3 examples of isolated pathogens found in Scotland.
- Campylobacter
- Salmonella
- E.coli O157
What defences are there against enteric infections?
- Good hygiene
- Stomach acid
- Normal gut flora
- Immune system
How can diarrhoeal illness present?
- Non-inflammatory or secretory such as cholera
- Inflammatory such as shigella dysentery
- Mixed picture such as C. difficile
How does non-inflammatory diarrhoea present?
Frequent watery stools with little abdominal pain
How is non-inflammatory diarrhoea mediated?
- It is secretory toxin-mediated
- Cholera increases cAMP levels and Cl secretion (loss), increasing osmotic pressure
- Enterotoxigenic E.coli (traveller’s diarrhoea)
What is the mainstay of therapy for non-inflammatory diarrhoea?
Rehydration
How does inflammatory diarrhoea present?
- Inflammatory toxin damage and mucosal destruction
- Pain and fever
- Bacterial infection, amoebic dysentery
How is inflammatory diarrhoea treated?
Antimicrobials may be appropriate but rehydration alone is often sufficient
How should a patient presenting with diarrhoea be assessed?
- Symptoms and their duration (i,e, >2/52 unlikely to be infective gastro-enteritis)
- Could it be food poisoning? (diet, contact, travel history)
- Assess hydration status (postural BP, skin turgor, pulse)
- Are there features of inflammation? (SIRS) (fever, raised WCC)
What potential fluid and electrolyte loss with diarrhoea?
- Fluid loss can be severe 1-7 litres
- Hyponatraemia due to sodium loss with fluid replacement by hypotonic solutions
- Hypokalaemia due to K loss in stool
What investigations should be carried out for diarrhoea?
-Stool culture
-Renal function
Blood count (neutrophilia, haemolysis)
-Abdominal x-ray if the abdomen is distended and tender
What is the differential diagnosis for diarrhoea?
- IBD
- Spurious diarrhoea
- Carcinoma
- Sepsis outside of the gut
What is the treatment for gastro-enteritis?
Rehydration
- Oral with salt/sugar solution
- IV saline
How does campylobacter gastroenteritis present?
-Up to 7 days incubation so dietary history may be unreliable
-Stools negative within 6 weeks
-Abdominal pain can be severe
-<1% invasive
Post-infection sequelae can occur
What post infection sequelae can occur with campylobacter gastroenteritis?
- Guillain barre-syndrome
- Reactive arthritis
Why does it take 3 days for a routine bacterial culture?
- Difficult to find pathogen in the midst of complex normal flora
- Selective and enrichment methods of culture necessary - variety of media and incubation conditions
What campylobacter species are found on routine culture in gastroenteritis?
- C. jejuni
- C. coli