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24th July 2023
Gastroenteritis
Gastroenteritis (colloquially known as “stomach flu”) refers to enteric infections which are usually transient and self-limiting, characterised by an acute diarrhoeal illness, which may be associated with vomiting, abdominal pain and fever.
Food poisoning is a subset of gastroenteritis, in which the causative organism has been spread through the consumption of contaminated food or water.
Most cases of gastroenteritis are caused by viruses and generally resolve within 48-72 hours with no specific interventions. Bacterial infections may cause more significant illness and are more associated with systemic upset.
The most important causative organisms are summarised in the table below.
| Organism | Clinical features | Investigation and diagnosis | Management and complications |
|---|---|---|---|
| Escherichia coli (E. coli) | Bacterial infection, presents with watery diarrhoea, and abdominal cramps
Commonest cause of travellers’ diarrhoea |
Stool culture, microscopy and sensitivity can be used to confirm diagnosis
E. coli 0157 (also known as VTEC) is the most common serotype |
Supportive treatment
Haemolytic uraemic syndrome (HUS) is a key complication – causes triad of haemolytic anaemia, thrombocytopenia, and AKI |
| Campylobacter species | Most commonly Campylobacter jejuni
Presents initially with a prodrome of fever, headache and malaise, and then progresses into watery diarrhoea which may contain blood Associated with crampy abdominal pain, often in right iliac fossa (may be confused with appendicitis) |
Stool culture, microscopy and sensitivity can be used to confirm diagnosis – bacteria have an appearance of curved rods or a ‘gull-wing’ formation
|
Generally managed supportively
Macrolide antibiotic can be used in severe cases Associated with Guillain-Barre syndrome and reactive arthritis as complications |
| Shigella species | Causes a bloody diarrhoeal illness, associated with abdominal pain | Stool culture, microscopy and sensitivity | Generally managed supportively
Antibiotics can be given in severe cases or immunocompromised patients/extremes of age. Antibiotics may shorten the duration of symptoms. Pivmecillinam and ciprofloxacin are amongst the first line options. Associated with HUS as a complication |
| Giardia species | Most commonly Giardia duodenalis (also known as G. lamblia). Disease caused by Giardia species are known as giardiasis. Presents as profuse watery diarrhoea, associated with abdominal pain and bloating
Prolonged symptoms may lead to malabsorption, and weight loss |
Stool culture, microscopy and sensitivity | Generally managed supportively
In severe cases, first line antibiotic treatment is with metronidazole |
| Staphylococcus aureus | Causes an acute illness characterised by profuse vomiting – rather than diarrhoea
Very short incubation period – symptoms can occur only a few hours after infection – and symptoms tend to last less than 24 hours |
Stool culture, microscopy and sensitivity | Supportive treatment |
| Bacillus cereus | Generally due to food poisoning – with uncooked rice a common sauces
Causes an acute diarrhoeal illness which generally presents within 8-16 hours of exposure, associated with abdominal cramps, nausea and vomiting |
Stool culture, microscopy and sensitivity | Supportive treatment |
| Norovirus | Acute illness, within 24 to 48 hours of exposure, of diarrhoea, nausea and vomiting, abdominal pain, myalgia and malaise
Also known as “winter vomiting illness”, and spreads rapidly through institutions like hospitals and care homes |
Diagnosis confirmed through RT-PCR testing of stool sample
Enzyme immunoassays can be used for antigen detection |
Generally managed supportively – no indication for antiviral
Hospitalisation may be required if significant dehydration, intractable vomiting, or if electrolyte derangement or renal dysfunction occurs |
Table 4: Important causative organisms in gastroenteritis
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