28th July 2023

Aetiology

The most common cause of gastroenteritis in the UK is Campylobacter species. They generally contaminate chicken, with poor food hygiene increasing the risk of infection. Barbecues are a common ‘exposure’ event, often seen in MRCP questions.

Salmonella food poisoning is another important cause of gastroenteritis. Cases have decreased after a successful vaccination campaign, but it may still cause outbreaks which are often related to specific venues with catered food, such as weddings. Salmonella species are an important cause of septic arthritis in sickle cell patients.

Typhoid, or enteric fever, is an important Salmonella complication, most associated with the typhi and paratyphi species. High fever, relative bradycardia and rose spots are classical findings.

Bacillus cereus is said to have a short incubation period of only a few hours and classically comes from reheating rice, with vomiting a key feature.

There are four species of Shigella – two endemic in the UK in S. sonnei and S flexneri, and two imported in S. bodyi and S. dysenteriae. The endemic forms may be spread by sexual contact, with prevalence high in men who have sex with men. Shigellosis outbreaks have also been described in nursery settings.

Escherichia coli O157:H7, sometimes called STEC (Shiga toxin-producing Escherichia coli), is associated with animal contact. A common case scenario is farms or petting zoos. Hemolytic uraemic syndrome (HUS) is an important complication. Generally seen in children, it causes nephrotic syndrome and is associated with anaemia and thrombocytopenia. Characteristic features are vomiting, bloody diarrhoea, fever, confusion, and purpura/petechiae.

Listeria monocytogenes can affect any individual, usually causing non-specific diarrhoea and vomiting. Soft cheese, unpasteurised milk, smoked meats, and unwashed produce have all been linked to the acquisition of Listeria. Risk factors for the disease include pregnancy, extremes of age, alcohol excess and immunodeficiency. Listeria also affects sheep, where it can cause spontaneous abortion, and farmers are hence at increased risk of the disease. It is important to be aware of especially in the context of pregnancy, as Listeria can cause meningitis in neonates. For this reason, pregnant women are advised to avoid high risk foods.