Gastroenteritis

Question 1

Define Gastroenteritis

Answer 1

Inflammation of the stomach and intestines, typically resulting from bacterial toxins or viral infection and causing vomiting and diarrhoea.

Question 2

Define Diarrhoea

Answer 2

> 3 bowel motions per day with looser than normal stools.

Question 3

Causes of Acute Gastroenteritis

Answer 3

• Viral (80%)
  * Rotavirus (developed countries)
  * Adenovirus
  
  • Bacterial
    
    • Common causes
      
      • Campylobactor jejuni
      • Salmonella spp
    • Less commonly
      
      • Escherichia coli
      • Shigella sp
    • Post antibiotics
      
      • Clostridium difficile (Psuedomembranous colitis)
  • Protozoa
    
    • Giardia lamblia
    • Entamoeba histolytica
    • Cryptosporidium
  • Food poisoning
    
    • Staphylococcal toxin

Question 4

Chronic causes of Diarrhoea

Answer 4

• Chronic enteric infection
  
  • Coeliac Disease
  • Cystic Fibrosis
  • Lactose intolerance
  • Inflammatory bowel disease
  • Post infective irritable bowel
  • Giardiasis

Question 5

Mechanism of infective diarrhoea

Answer 5

• Mucosal adherence
  
  • Mucosal invasion
  • Toxin production

Question 6

Mucosal Adherence Mechanism of Infective Diarrhoea

Answer 6

• Damage surface causing secretory diarrhoea

Question 7

Mucosal invasion Mechanism of Infective Diarrhoea

Answer 7

• Penetration and destruction of mucosa

Question 8

Toxins produced causing Infective Diarrhoea

Answer 8

Enterotoxin
- released by an organism in the intestine

Cytotoxin
- the organism is toxic to the body

Pre-formed neurotoxin
- toxin released before it is eaten

Question 9

Mucosal Adherence Infective Diarrhoea Presentation and Causes

Answer 9

Presentation
- Watery diarrhoea
Examples
- Viral (rotavirus)
- Cholera
- E. coli (traveler’s)

Question 10

Mucosal invasion Infective Diarrhoea Presentation and Causes

Answer 10

Presentation
- Dysentery
Examples
- Campylobacter jejuni
- Shigella

Question 11

Enterotoxin Infective Diarrhoea Presentation and Causes

Answer 11

Presentation
- Watery diarrhoea
Examples
- Salmonella
- Campylobacter

Question 12

Cytotoxin Infective Diarrhoea Presentation and Causes

Answer 12

Presentation
- Dysentery (blood ++)
Examples
- Shigella
- Campylobacter

Question 13

Pre-formed neurotoxin Infective Diarrhoea Presentation and Causes

Answer 13

Presentation
- Variable D & V
Examples
- Staph aureus

Question 14

Define dysentery

Answer 14

Diarrhoea including blood and mucus that is of reduced volume and is less frequent

• > 10 bowel movements per day
• Lower abdominal pain (+/- rectal pain)

Question 15

Define watery diarrhoea

Answer 15

Diarrhoea of increased volume and reduced frequency.

• 4-8 bowel movements per day
• Upper abdominal pain (no rectal pain)

Question 16

Gastroenteritis clinical presentation

Answer 16

Clinical assessment centres around determining the degree of dehydration. Features are:

• Dehydration
• Diarrhoea or dysentery
• Fever
• Severe abdominal pain

Question 17

Timeline of infection

Answer 17

0-6hrs

• Staph aureus
• Bacillus

18-36 hrs

• Clostridium botuminum
• -> descending paralysis, resp failure & death

1-2 days

• Salmonella
• E. coli
• Shigella

2-4 days

• Campylobacter jejuni
• -> Guillain-Barre - ascending paralysis

Question 18

Investigations

Answer 18

Diagnostic tests are limited to those with more severe disease.

• Stool MCS
  
  • Faecal leucocytes (inflammatory diarrhoea)
  • Ova and parasites
  • Clostridium difficile toxin (most common nosocomial)
• FBE - anaemia
• U&Es - low K+
• Sigmoidoscopy/colonoscopy - useful for sustained diarrhoea

Question 19

Gastroenteritis Management

Answer 19

Mild
- Oral rehydration 2-3L/day
Severe
- IV fluids
- Antiemetics (ondansetron)
- Antimotility (loperamide- opioid)
Sepsis
- Ciprofloxacin

Usually empirical and based on history rather than positive cultures.
If diarrhoea persists for > 3 weeks the patient will need further investigation (scopes).

• Rehydration is the most important aspect of managing acute gastroenteritis.
• Use of inappropriate rehydration fluids can cause potentially fatal electrolyte imbalances.
• Antibiotics are of no benefit in most cases and may exacerbate diarrhoea.

Question 20

Antidiarrhoeals

Answer 20

Opioid agents
- Loperamide, codeine
- Activate opioid receptors in the gut
Bulking agents
- Fybogel, metamucil
- Absorb water in the colon to increase bulk and stimulate peristaltic activity