Overview
Gastroenteritis describes the inflammation of the stomach and intestines and is often due to infection. In general, diarrhoea is defined as the passage of ≥3 loose/liquid stools within 24 hours. Most cases are self-limiting and caused by viruses, with nearly half of them lasting <1 day.
Definitions
Dysentery describes bloody diarrhoea with pain, fever, mucus, and tenesmus often due to bacterial, parasitic, or protozoan infections.
Food poisoning describes vomiting/diarrhoea that is caused by food that is contaminated with microorganisms or toxins (e.g. poisonous mushrooms). This tends to cause symptoms due to enterotoxins produced by the microorganism, rather than the microorganism itself.
Travellers’ diarrhoea describes travelling abroad with diarrhoea developing at the destination with at least one additional symptom including abdominal cramps, nausea, vomiting, fever, faecal urgency, or tenesmus.
Antibiotic-associated diarrhoea describes an infection resulting from the disturbance of the normal gut flora due to antibiotic use, resulting in certain strains of Clostridioides difficile growing and producing toxins.
Prolonged diarrhoea is defined as acute-onset diarrhoea that has persisted over 14 days.
Bacterial Causes
Campylobacter species:
- The most common bacterial infection of the intestines in the UK
- Associated with contaminated food, especially undercooked poultry
- Features: flu-like prodrome (e.g. fever, malaise, myalgia) followed by diarrhoea that may be bloody, abdominal cramps, nausea, and vomiting.
- Usually self-limiting within 2-3 days and resolves within 7 days
Escherichia coli:
- Commonly associated with foreign travel
- Transmitted through contaminated food via the faecal-oral route
- Features: watery stools, abdominal cramps, nausea
- Certain strains can cause haemolytic uraemic syndrome
- Usually self-limiting and resolves within 10 days
Staphylococcus aureus:
- Transmitted through contaminated food, particularly meat and dairy
- Features: short incubation period (within ~6 hours) followed by acute severe vomiting, abdominal cramps, nausea, and sometimes diarrhoea
- Usually self-limiting and resolves within a day
Bacillus cereus:
- Transmitted through contaminated food that has been undercooked, classically undercooked reheated rice
- Features either acute vomiting within ~6 hours (emetic syndrome) or diarrhoea within ~6 hours (diarrhoeal syndrome) however they can overlap
- Usually self-limiting and resolves within a day
Clostridioides difficile:
- Usually caused by recent broad-spectrum antibiotic use, most commonly due to cephalosporins, but also clindamycin
- Features: diarrhoea, abdominal pain, pseudomembranous colitis
Shigella:
- Transmitted via the faecal-oral route, often from person-to-person and usually seen in young children (<5 years old)
- features: bloody diarrhoea and mucus, along with fever, abdominal cramps, and may have nausea and vomiting.
- Usually resolvers within 7 days
Cholera:
- Associated with poverty and may be seen in returning travellers, particularly drinking untreated water, eating contaminated food, or unsanitary living conditions
- Features: profuse, watery diarrhoea (‘rice water’ stools that are greyish, cloudy, with mucus) – litres are often lost causing severe dehydration
- Other details:
Yersinia enterocolitica:
- Rare and more common in children, transmitted by the faecal-oral route and through contaminated food, particularly undercooked pork
- Features: bloody, watery diarrhoea, abdominal pain, and fever
- Symptoms can from 2 days to 6 weeks
Parasitic Causes
Cryptosporidiosis:
- The most common protozoal intestinal infection in the UK and associated with foreign travel, transmitted via contaminated food/water
- Features: watery diarrhoea, abdominal cramps, nausea, vomiting, and fever
- Symptoms usually last 1-2 weeks
Entamoeba histolytica (amoebiasis)
- Transmitted via the faecal-oral route, usually seen in foreign travel, and has a long incubation period (>1 week)
- Features: can cause amoebic dysentery (bloody diarrhoea and fever) and possibly an amoebic liver abscess (right upper quadrant pain, constitutional symptoms, and hepatomegaly)
Giardiasis:
- Transmitted via the faecal-oral route and has a long incubation period (>1 week)
- Features: chronic non-bloody diarrhoea that is initially watery but can lead to steatorrhoea over time, malabsorption, weight loss, and lactose intolerance
- Giardiasis should be considered in someone with chronic diarrhoea associated with malabsorption and weight loss.
