Gastroenterology

Question 1

Things impacting GI diseases

Answer 1

• 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

Question 2

GI infection risk factors

Answer 2

Malnutrition/deficiency, closed/semi-closed communities, exposure to contaminated food/water/travel, immunosuppression

Question 3

Diarrhoea

Answer 3

> 3 unformed stools a day, stools hold shape of the container

Question 4

Bristol stool chart

Answer 4

• 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)

Question 5

Dysentery

Answer 5

Inflammation of the intestine, particularly the colon, causing diarrhoea associated with blood or mucus

Question 6

Bacteria causing dysentery

Answer 6

Shigella, campelobacter

Question 7

Symptoms of dysentery

Answer 7

Fever, abdominal pain, tenesmus

Question 8

What do bacteria need to multiply?

Answer 8

• Time
• Temperature
• Food source
• Moisture

Question 9

Gastroenteritis

Answer 9

Illness caused by eating food contaminated with microorganisms, toxins, poisons etc

Question 10

Symptoms of gastroenteritis

Answer 10

Diarrhoea, blood, mucous, vomiting, abdominal pain

Question 11

Questions to ask when taking a history relating to gastroenteritis

Answer 11

Travel, contacts, food history, medication history

Question 12

Bacillus cerues:

• Gram negative or gram positive?
• What foods is it found in?
• Describe the spores
• What can it cause?
• Incubation period

Answer 12

• Gram positive bacillus
• Starchy foods - can get it from reheated rice
• Spores are heat resistant
• Profuse vomiting
• 1-6 hours

Question 13

Staph aureus:

• Gram positive or gram negative?
• Which foods is it found in?
• What does it act on?
• Incubation period

Answer 13

• 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

Question 14

Bacillus cereus:

• What type of pathogen is it?
• What foods can it come from?
• What can it cause?
• Incubation period

Answer 14

• Diarrhoeal toxin
• Meat, stew, gravy, vanilla sauce
• Abdominal cramps, watery diarrhoea, nauseua
• 8-16 hours

Question 15

Clostridium perfringens:

• What type of pathogen is it?
• What foods can it come from?
• What can it cause?
• Incubation period

Answer 15

• Toxin
• Meat, poultry, gravy, dried or precooked foods, time and/or temperature-abused food
• Watery diarrhoea, nausea, abdominal cramps
• 8-16 hours

Question 16

What is the most common bacteria?

Answer 16

Campylobacter jejuni

Question 17

What tests do all stool cultures get?

Answer 17

Salmonella/shigella/campylobacter/O 157 and cryptosporidium, all >4 years old get C.difficile

Question 18

Types of Shigella

Answer 18

• Shigella dysenteriae (group A)
• Shigella flexneri (group B)
• Shigella boydii (group C)
• Shigella sonnei (group D)

Question 19

What does the shiga toxin in shigella bind to?

Answer 19

Receptors found on renal cells, RBC and inhibits protein synthesis causing cell death

Question 20

What does E.coli do?

Answer 20

Adhere to intestinal epithelial cells and elaborate shiga toxin

Question 21

How does shiga toxin cause disease in E.coli?

Answer 21

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

Question 22

How do shiga toxins cause death of vascular endothelial cells?

Answer 22

Shiga toxins enter bloodstream via damaged intestinal epithelium and cause death of vascular endothelial cells by inhibiting protein synthesis

Question 23

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?

Answer 23

• 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

Question 24

Presentation of haemolytic uraemic syndrome

Answer 24

• 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

Question 25

Investigations for haemolytic uraemic syndrome

Answer 25

- 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

Question 26

How is haemolytic uraemic syndrome diagnosed?

Answer 26

Microbiologically

Question 27

Pathotypes of E.coli

Answer 27

Enterotoxigenic, enteropathogenic, enteroinvasive, enteroaggrative

Question 28

Enterotoxigenic E.coli: - What type of toxin does it produce? - What is it related to?

Answer 28

- Heat labile and heat stable toxin | - Travel

Question 29

Enteropathogenic E.coli: - What does it do? - Who does it occur in?

Answer 29

- Synthesises, secretes and inserts its own receptor into membranes - Non-breastfed children

Question 30

Enteroinvasive: - What symptoms does it cause? - What test can be done to diagnose this?

Answer 30

- Watery diarrhoea, rare dysentery | - Sereny test

Question 31

Campylobacter: - Incubation period - Which foods is it present in? - Symptoms

Answer 31

- 16-48 hours - Poultry and raw milk - Pain, blood, fever

Question 32

Salmonella enteriditis: - Incubation period - Where is it found? - Symptoms

Answer 32

- 12-48 hours - Animal guts and multiplies in food, e.g. poultry, meat, raw egg - Diarrhoea and vomiting, blood in stool or vomit, fever

Question 33

Most common groups of salmonella

Answer 33

B, C, D

Question 34

Listeria monocytogenes: - Incubation period - Symptoms - Where is it found?

Answer 34

- 9-48 hours - Fever, muscle aches, diarrhoea - Unpasteurised milk products, deli counter

Question 35

Diagnosis of listeria monocytogenes

Answer 35

Easier from sterile site, gram positive rod

Question 36

Rotavirus: - Who does it affect? - How does it spread? - Clinical presentation - Infectious dose - How long does it last? - Diagnosis - Management

Answer 36

- 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

Question 37

Rotavirus vaccine: - How is it given? - What type of vaccine is it? - How is it secreted? - Who gets it?

Answer 37

- Orally - Live attenuated - Faeces - 2 doses at 2 and 3 months old, not >24 weeks

Question 38

Norovirus: - How is it spread? - Infectious dose - Symptoms - Incubation - Diagnosis - Management

Answer 38

- 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