Gastroenteritis Flashcards
(36 cards)
What is gastroenteritis?
Gastroenteritis is a transient disorder due to enteric infection with viruses, bacteria, or parasites. It is characterized by the sudden onset of diarrhoea, with or without vomiting.
Define food poisoning
Food poisoning is defined as ‘an illness caused by the consumption of food or water contaminated with bacteria and/or their toxins, or with parasites, viruses, or chemicals’.
How does acute and prolonged diarrhoea differ?
Acute diarrhoea is usually defined as three or more episodes of liquid or semi-liquid stool in a 24-hour period, lasting for less than 14 days, where the stool takes the shape of the sample pot.
Prolonged diarrhoea is acute-onset diarrhoea that has persisted for over 14 days.
What is dysentery?
Dysentery is an acute infectious gastroenteritis characterized by diarrhoea with blood and mucus, often with fever and abdominal pain.
Give examples of causes of gastroenteritis
Viruses
- Rotavirus
- Norovirus
- Adenovirus
Bacteria
- Campylobacter jejuni
- Escherichia coli (E. coli)
- Shigella
- Salmonella
- Bacillus Cereus
Parasites
- Cryptosporidiosis
- Entamoeba histolytica (amoebiasis)
- Giardia intestinalis or Giardia lamblia
What are the most common causes of gastroenteritis?
Most infectious diarrhoea is a self-limiting illness, caused by viruses (rather than bacteria or parasites), with nearly half of episodes lasting less than 1 day.
How is gastroenteritis transmitted?
Transmission of gastrointestinal infection from person-to-person may occur through one or more of a variety of different pathways, including faecal-oral, foodborne, environmental and airborne routes.
Briefly describe rotavirus
This is the most common cause of viral gastroenteritis in children, however, there has been a reduction in disease prevalence since the introduction of the rotavirus vaccine, as part of the UK national childhood immunization programme.
Most cases are transmitted by person-to-person spread by the faecal-oral route, or more rarely by contact with contaminated surfaces. Most cases in the UK occur in winter and spring.
Briefly describe norovirus
Norovirus is the commonest cause of gastroenteritis in England and Wales, with an increased prevalence during colder months.
Transmission is person-to-person, usually by the faecal-oral route. It can also be transmitted by consumption of contaminated food (such as oysters) or water, or contact with contaminated surfaces (such as toilets, soft furnishings, or floors), and outbreaks are common in semi-closed environments such as schools, hospitals, care homes, and cruise ships.
Briefly describe adenoviruses
These commonly cause respiratory tract infections, but can also cause gastroenteritis, particularly in children.
Briefly describe Escherichia coli (E. coli)
Escherichia coli (E. coli) is a normal intestinal bacteria. Only certain strains cause gastroenteritis. It is spread through contact with infected faeces, unwashed salads or water.
Briefly describe E. coli 0157
- E. coli* O157 is the most common serogroup of STEC causing infections in the UK.
- E. coli* 0157 produces the Shiga toxin. This causes abdominal cramps, bloody diarrhoea and vomiting. The Shiga toxin destroys blood cells and leads to haemolytic uraemic syndrome (HUS).
The use of antibiotics increases the risk of HUS therefore antibiotics should be avoided if E. coli gastroenteritis is considered.
What is haemolytic uraemic syndrome (HUS)?
Haemolytic uraemic syndrome (HUS) is characterised by microangiopathic haemolytic anaemia, thrombocytopenia, and acute kidney injury. Ninety percent of HUS cases occur in the paediatric population, due to Shiga toxin-producing Escherichia coli (STEC).
Briefly describe Shigella
Shigella is spread by faeces contaminating drinking water, swimming pools and food. The incubation period is 1-2 days and symptoms usually resolve within 1 week without treatment. It causes bloody diarrhoea, abdominal cramps and fever.
Shigella can produce the Shiga toxin and cause haemolytic uraemic syndrome.
Treatment of severe cases is with azithromycin or ciprofloxacin.
Briefly describe Salmonella
Salmonella is spread by eating raw eggs or poultry and food contaminated with infected faeces of small animals. Incubation is 12 hours to 3 days and symptoms usually resolve within 1 week. Symptoms are watery diarrhoea that can be associated with mucus or blood, abdominal pain and vomiting. Antibiotics are only necessary in severe cases and guided by stool culture and sensitivities.
Briefly describe Bacillus Cereus
Bacillus cereus is a gram positive rod that is spread through inadequately cooked food. It grows well on food not immediately refrigerated after cooking. The typical food is fried rice left out at room temperature.
Whilst growing on the food it produces a toxin called cereulide that causes abdominal cramping and vomiting within 5 hours of ingestion. When it arrives in the intestines it produces different toxins that cause a watery diarrhoea. This occurs more than 8 hours after ingestion. All of the symptoms usually resolves within 24 hours.
Therefore the typical course is vomiting within 5 hours, then diarrhoea after 8 hours, then resolution within 24 hours.
Briefly describe Campylobacter jejuni
Campylobacter is a common cause of travellers diarrhoea. It is the most common bacterial cause of gastroenteritis worldwide. Campylobacter means “curved bacteria”. It is a gram negative bacteria that is curved or spiral shaped.
It is spread by raw or improperly cooked poultry, untreated water and unpasteurised milk.
Incubation is usually 2-5 days. Symptoms resolve after 3-6 days. Symptoms are abdominal cramps, diarrhoea often with blood, vomiting and fever.
Antibiotics can be considered after isolating the organism where patients have severe symptoms or other risk factors such as HIV or heart failure. Popular antibiotic choices are azithromycin or ciprofloxacin.
Briefly describe cryptosporidiosis
Cryptosporidium is one of the most common protozoal causes of gastroenteritis in the UK.
Infection is transmitted by animal-to-human or human-to-human contact, by occupational or recreational exposure to contaminated land or water or by consuming contaminated water or food.
It typically causes profuse watery diarrhoea associated with abdominal cramps or pain, nausea, vomiting, fever, and loss of appetite. Symptoms usually last for 1–2 weeks.
Briefly describe Entamoeba histolytica (amoebiasis)
Transmission occurs through the ingestion of contaminated food or water. Person-to-person transmission may also occur between household. Most cases in the UK are imported by travellers to endemic areas.
90% of cases are asymptomatic. Symptoms are often mild diarrhoea and abdominal pain, but severe disease (amoebic dysentery) can occur, causing fever, severe abdominal pain, and blood and mucus in the faeces.
Briefly describe Giardia lamblia
Giardia lamblia is a type of microscopic parasite. It lives in the small intestines of mammals. These mammals may be pets, farmyard animals or humans. It releases cysts in the stools of infected mammals. These cysts then contaminate food or water and are eaten to infect a new host. This is called faecal-oral transmission.
Infection may not cause any symptoms or it may cause chronic diarrhoea.Symptoms include diarrhoea, malaise, abdominal pain, loss of appetite, flatulence, bloating, and rarely nausea. Malabsorption, weight loss, and faltering growth may occur in children.
Diagnosis is made by stool microscopy. Treatment is with metronidazole.
What are the risk factors for gastroenteritis?
- Contaminated food products
- Travel
- Poor hygiene
- Extremes of age (<5 and >60 years)
- Contact history
What are the symptoms of gastroenteritis?
- Sudden-onset diarrhoea, blood or mucus in the stool and faecal urgency
- Nausea or sudden onset of vomiting
- Fever or general malaise
- Abdominal pain or cramps
- Associated headache, myalgia, bloating, flatulence, weight loss and malabsorption
What are the signs of gastroenteritis?
- Volume depletion:
- Dry mucous membranes
- Reduced skin turgor
- Tachycardia
- Hypotension
What investigations should be ordered for gastroenteritis?
- Stool cultures
- FBC?
- Renal function and electrolytes?
