Gastroenterology Flashcards
Things impacting GI diseases
- Poor sanitation
- Commercialisation of food production
- Import of food from other countries
- Increase in day care/care home
- International travel
- Acid suppression
- Healthcare associated infections of the GI tract
GI infection risk factors
Malnutrition/deficiency, closed/semi-closed communities, exposure to contaminated food/water/travel, immunosuppression
Diarrhoea
> 3 unformed stools a day, stools hold shape of the container
Bristol stool chart
- Type 1 – separate hard lumps, like nuts
- Type 2 – sausage-shaped but lumpy
- Type 3 – sausage shaped, but with cracks on the surface
- Type 4 – sausage or snake like, smooth and soft
- Type 5 – soft blobs with clear-cut edges (easy to pass)
- Type 6 – fluffy pieces with ragged edges, mushy
- Type 7 – watery, no solid pieces (entirely liquid)
Dysentery
Inflammation of the intestine, particularly the colon, causing diarrhoea associated with blood or mucus
Bacteria causing dysentery
Shigella, campelobacter
Symptoms of dysentery
Fever, abdominal pain, tenesmus
What do bacteria need to multiply?
- Time
- Temperature
- Food source
- Moisture
Gastroenteritis
Illness caused by eating food contaminated with microorganisms, toxins, poisons etc
Symptoms of gastroenteritis
Diarrhoea, blood, mucous, vomiting, abdominal pain
Questions to ask when taking a history relating to gastroenteritis
Travel, contacts, food history, medication history
Bacillus cerues:
- Gram negative or gram positive?
- What foods is it found in?
- Describe the spores
- What can it cause?
- Incubation period
- Gram positive bacillus
- Starchy foods - can get it from reheated rice
- Spores are heat resistant
- Profuse vomiting
- 1-6 hours
Staph aureus:
- Gram positive or gram negative?
- Which foods is it found in?
- What does it act on?
- Incubation period
- Gram positive coccus
- Foods left at food temperature e.g. milk, meat, fish
- Acts on vomiting centre in brain causing vomiting and abdominal pain
- 1-6 hours
Bacillus cereus:
- What type of pathogen is it?
- What foods can it come from?
- What can it cause?
- Incubation period
- Diarrhoeal toxin
- Meat, stew, gravy, vanilla sauce
- Abdominal cramps, watery diarrhoea, nauseua
- 8-16 hours
Clostridium perfringens:
- What type of pathogen is it?
- What foods can it come from?
- What can it cause?
- Incubation period
- Toxin
- Meat, poultry, gravy, dried or precooked foods, time and/or temperature-abused food
- Watery diarrhoea, nausea, abdominal cramps
- 8-16 hours
What is the most common bacteria?
Campylobacter jejuni
What tests do all stool cultures get?
Salmonella/shigella/campylobacter/O 157 and cryptosporidium, all >4 years old get C.difficile
Types of Shigella
- Shigella dysenteriae (group A)
- Shigella flexneri (group B)
- Shigella boydii (group C)
- Shigella sonnei (group D)
What does the shiga toxin in shigella bind to?
Receptors found on renal cells, RBC and inhibits protein synthesis causing cell death
What does E.coli do?
Adhere to intestinal epithelial cells and elaborate shiga toxin
How does shiga toxin cause disease in E.coli?
Bind to absorptive enterocytes on the luminal surface of the small and large intestines, enter the cell and irreversibly inhibit protein synthesis causing cell death
How do shiga toxins cause death of vascular endothelial cells?
Shiga toxins enter bloodstream via damaged intestinal epithelium and cause death of vascular endothelial cells by inhibiting protein synthesis
E.coli 0157:
- When should it be suspected?
- What can it cause?
- Infectious dose
- Which food is it found in?
- How is it spread?
- Incubation period
- What toxin does it produce?
- In bloody diarrhoea or blood per rectum
- Haemorrhagic colitis
- Very low infectious dose
- Found in beef mostly, but wide range
- Spread person-to-person or animal contact
- 1-14 days
- Verotoxin
Presentation of haemolytic uraemic syndrome
- Abdominal pain, fever, pallor, petechiae, oliguria
- Most cases in <16 years old
- Patients will have high white cells, low platelets, low haemoglobin, red cell fragments, LDH>1.5 x normal
Investigations for haemolytic uraemic syndrome
- Send stool culture samples
- Send U&E, FBC, film, LFT, clotting, urine, lactate dehydrogenase
- Close monitoring
- Admission is usually needed
- Check for acute renal failure, thrombocytopaenia, haemolytic anaemia
How is haemolytic uraemic syndrome diagnosed?
Microbiologically
Pathotypes of E.coli
Enterotoxigenic, enteropathogenic, enteroinvasive, enteroaggrative
Enterotoxigenic E.coli:
- What type of toxin does it produce?
- What is it related to?
- Heat labile and heat stable toxin
- Travel
Enteropathogenic E.coli:
- What does it do?
- Who does it occur in?
- Synthesises, secretes and inserts its own receptor into membranes
- Non-breastfed children
Enteroinvasive:
- What symptoms does it cause?
- What test can be done to diagnose this?
- Watery diarrhoea, rare dysentery
- Sereny test
Campylobacter:
- Incubation period
- Which foods is it present in?
- Symptoms
- 16-48 hours
- Poultry and raw milk
- Pain, blood, fever
Salmonella enteriditis:
- Incubation period
- Where is it found?
- Symptoms
- 12-48 hours
- Animal guts and multiplies in food, e.g. poultry, meat, raw egg
- Diarrhoea and vomiting, blood in stool or vomit, fever
Most common groups of salmonella
B, C, D
Listeria monocytogenes:
- Incubation period
- Symptoms
- Where is it found?
- 9-48 hours
- Fever, muscle aches, diarrhoea
- Unpasteurised milk products, deli counter
Diagnosis of listeria monocytogenes
Easier from sterile site, gram positive rod
Rotavirus:
- Who does it affect?
- How does it spread?
- Clinical presentation
- Infectious dose
- How long does it last?
- Diagnosis
- Management
- Children, most common <3 years old
- Person-to-person, faecal oral
- Fever, vomiting, diarrhoea (watery but not bloody)
- Low infectious dose
- About a week
- PCR on faeces
- Supportive care - hydration is key
Rotavirus vaccine:
- How is it given?
- What type of vaccine is it?
- How is it secreted?
- Who gets it?
- Orally
- Live attenuated
- Faeces
- 2 doses at 2 and 3 months old, not >24 weeks
Norovirus:
- How is it spread?
- Infectious dose
- Symptoms
- Incubation
- Diagnosis
- Management
- Faecal-oral, droplets, person-to-person or contaminated food/water
- Low infectious dose
- Explosive and sudden diarrhoea and vomiting
- <24 hours, lasts 2-4 days
- PCR on stool takes 6 hours, PCR on vomit using red copan viral swabs
- Supportive - hydration
