Gastroenteritis and Infectious Colitis

Question 1

Define gastroenteritis

Answer 1

Inflammation of the GI tract (stomach and small bowel) typically resulting from bacterial
toxins or viral infections. Transmission may occur due to eating improperly prepared foods,
drinking contaminated water or through close contact with an infected individual.
Incubation period typically lasts 16-24h.

Question 2

What are the causes/risk factors of gastroenteritis?

Answer 2

Infectious
Viral
• Rotavirus
• Norovirus
• Adenovirus

Bacterial
• Campylobacter (chicken)
• Salmonella (eggs, poultry)
• Shigella
• E.coli (contaminated meat)

Parasitic
• Giardia – Eastern Europe/Russia
• Entamoeba – tropical regions

Non-infectious
• Drugs e.g. NSAIDs
• Food e.g. (lactose intolerance, coeliac disease)

Risk Factors:
• Young
• Old
• Travellers
• Crohn’s disease

Question 3

What are the symptoms of gastroenteritis?

Answer 3

• Diarrhoea
• Dysentery (CHESS – Campylobacter, Haemorrhagic E. coli, Entamoeba histolytica,
Salmonella, Shigella)
• Vomiting (viral gastroenteritis, Staphylococcus aureus, Bacillus cereus)
• Abdominal pain/cramping
• Bloating, foul smelling eructation/
flatus (Giardia)

Question 4

What are the signs of gastroenteritis?

Answer 4

Signs of dehydration
• Prolonged capillary refill
• Reduced skin turgor

Question 5

What is the management of gastroenteritis?

Answer 5

• Oral rehydration therapy
• Antibiotics only if <3 months, >50
years, immunosuppressed, internal
prostheses

Question 6

Define infectious colitis

Answer 6

Inflammation of the colon caused by an infective agent

Pseudomembranous colitis – an infectious colitis caused by C. difficile
characterised by large bowel inflammation, mucosal destruction and
pseudomembranes (layer of exudate resembling membrane)

Question 7

What are the causes/risk factors of infectious colitis?

Answer 7

• Bacteria
o Clostridium difficile –
enterotoxin A + cytotoxin B
-  Shigella
- Campylobacter
- Salmonella
- Yersinia enterolytica
- E.coli (enteroinvasive and
enteroaggregative)
• Viruses
- Rotavirus
- CMV
• Parasites
- Entamoeba histolytica

Risk Factors
• Antibiotic use - especially clindamycin, ampicillin and broad spectrum
cephalosporins
• IBD
• Serious acute illness
• GI procedures
• Age

Question 8

What are the symptoms of infectious colitis?

Answer 8

Diarrhoea (3 or more loose stools per day)
• Bloody diarrhoea(dysentery)
• Abdominal pain/cramps
• Rectal bleeding
• Tenesmus
• Fever

Question 9

What are the signs of infectious colitis?

Answer 9

Localized or generalized abdominal tenderness

• Rebound tenderness

Question 10

What investigations are carried out for gastroenteritis and infectious colitis?

Answer 10

• FBC - high WBC with most inflammatory/invasive pathogen associated diarrhoea.
- low WBC are associated with typhoid fever and some viruses.
- Anaemia and thrombocytopaenia may indicate HUS in EHEC infections.
• CRP - elevated
• ABG - to assess whether there is a metabolic acidosis.
• U&Es - hypokalaemic metabolic acidosis secondary to diarrhoea.
- Hyper-or-hyponatraemia and elevated urea secondary to dehydration.
- Severe dehydration may lead to AKI.
• Blood Culture - blood culture is performed to exclude bacteraemia if the patient is notably febrile and there are signs of sepsis.
• Stool - faecal microscopy for polymorphs, parasites, oocysts.
- Stool Culture.
- Electron Microscopy for viral gastroenteritis.
- Toxin analysis –especially for pseudomembranous colitis (C. diff)
- PCR of stool.
• AXR - can help to assess colonic inflammation and to exclude toxic dilatation but it does not identify the cause.
• USS Abdomen - to exclude other causes of abdominal pain.
• Sigmoidoscopy - to exclude other causes of abdominal pain