Gastroenteritis

Question 1

Definition

Answer 1

Acute inflammation of the lining of the GI tract, manifested by nausea, vomiting,
diarrhoea and abdominal discomfort

Question 2

Aetiology (viral)

Answer 2

o Rotavirus
o Adenovirus
o Astrovirus
o Calcivirus
o Norwalk virus
o Small round structures viruses

Question 3

Aetiology (bacterial)

Answer 3

o Campylobacter jejuni
o Escherichia coli (particularly O157)
o Salmonella
o Shigella
o Vibrio cholerae
o Listeria
o Yersinia enterocolitica

Question 4

Aetiology (protozoal)

Answer 4

o Entamoeba histolytica
o Cryptosporidium parvum
o Giardia lamblia

Question 5

Aetiology (toxins)

Answer 5

o Staphylococcus aureus
o Clostridium botulinum
o Clostridium perfringens
o Bacillus cereus
o Mushrooms
o Heavy metals
o Seafood

Question 6

Aetiology (contaminated food)

Answer 6

o Improperly cooked meat
o Old rice
o Eggs and poultry
o Milk and cheeses
o Canned food 

Faecal-oral route

Question 7

Epidemiology

Answer 7

• COMMON

* Serious cause of morbidity and mortality in the developing world

Question 8

Presenting symptoms

Answer 8

• Sudden onset nausea, vomiting, anorexia
• DIARRHOEA (bloody or watery)
• Abdominal pain or discomfort
• Fever and malaise

• IMPORTANT: enquire about recent travel, antibiotic use and recent food intake (how
the food was cooked, sourced and whether anyone else is ill)

• Time of Onset:
o Toxins = early (1-24 hours)
o Bacterial/viral/protozoal = 12+ hours

• Pay attention to the other effects of toxins:
o Botulinum causes paralysis
o Mushrooms can cause fits, renal or liver failure

Question 9

Signs on physical examination

Answer 9

• Diffuse abdominal tenderness
• Abdominal distension
• Bowel sounds are often INCREASED
• In SEVERE gastroenteritis: pyrexia, dehydration, hypotension and peripheral shutdown

IMPORTANT: ANY DIARRHOEAL CONDITION CAN LEAD TO DEHYDRATION so assess and
address the patient’s hydration status immediately

Question 10

Investigations

Answer 10

• Bloods: FBC, blood culture (identify bacteraemia), U&Es (dehydration)

• Stool: faecal microscopy and analysis for toxins (particularly for the toxin causing
pseudomembranous colitis (C. difficile toxin)

• AXR or ultrasound: exclude other causes of abdominal pain (e.g. bowel perforation)

• Sigmoidoscopy: usually unnecessary unless inflammatory bowel disease needs to be
excluded

Question 11

Management plan

Answer 11

• Bed rest
• Fluid and electrolyte replacement with oral rehydration solution (contains glucose and
salt)
• IV rehydration may be necessary in those with severe vomiting
• Most infections are self-limiting (so will go away with time)
• Antibiotic treatment is only used if severe or if infective agent has been identified

• NOTE: if botulism is present (due to Clostridium botulinum) treat with botulinum
antitoxin (IM) and manage in ITU

• NOTE: this is often a notifiable disease and is an important public health issue

Question 12

Possible complications

Answer 12

• Dehydration
• Electrolyte imbalance
• Prerenal failure (due to dehydration)
• Secondary lactose intolerance (particularly in infants)
• Sepsis and shock
• Haemolytic uraemic syndrome (associated with toxins from E. coli O157)
• Guillain-Barre Syndrome may occur weeks after recovery from Campylobacter
gastroenteritis

• NOTE: botulism can lead to respiratory muscle weakness or paralysis

Question 13

Prognosis

Answer 13

Good prognosis because most cases are self-limiting