Gastroenteritis Flashcards
What id the definition of Travellers’ diarrhoea and the most common cause?
- Defined as at least 3 loose to watery stools in 24 hours +/- abdominal cramps, fever, nausea, vomiting or blood.
- The most common cause is E.coli
Describe acute food poisoning and its most common causes
- It is the sudden onset of nausea, vomiting and diarrhoea after the ingestion of a toxin.
- Common causes are S. aureus, Bacillus cereus and clostridium perfringes
What are the bacterial causes of gastroenteritis?
- Staphylococcus aureus,
- Bacillus cerus (reheated rice)
- Clostridium perfringes (reheated meat)
- Campylobacter
- E.coli (inc. E.coli 0157)
- Salmonella
- Shigella
What are the viral causes of gastroenteritis?
- Rotovirus (mainly in children)
- Norovirus (across all ages)
- Adenovirus (often causes resp illnesses)
What are the parasitic causes of gastroenteritis?
- Giardia intestinalis,
- Cryptosporidium
- Schistosoma
- Entamoeba
What are the investigations for gastroenteritis?
- History and examination
- Bloods (FBC, UEs - look for dehydration, LFTs, CRP, pregnancy test) and blood film,
- Sigmoidoscopy
- Abdominal x-ray
- Stool cultures x3
Describe features of Salmonella infections and its presentation
- Acquired via contaminated food. Incubation is 12-72 hours
- It presents with watery orbloody diarrhoea, vomiting and fever. Can last up to 1 week
What is the treatment for salmonella infections
- Fluid replacement is sufficient for most cases
- Antibiotics, first line is ciprofloxacin, are for severe infections or bacteraemia.
What are the features and presentation of Campylobacter
- Commonest foodborne bacterial infection in UK. Especially chicken. Incubation is 2-5 days.
- Presents with bloody diarrhoea, cramping abdominal pain and fever. NOT vomiting. Can last up to 10 days.
- Can mimic appendicitis
What is the treatment for campylobacter gastroenteritis
- Fluid replacement is normally sufficient
- In severe cases or immunocompromised patients; Clarithromycin is first line. (macrolides)
What is a complication of Campylobacter?
Guillian Barre Syndrome
What are the features of enteropathogenic and enterotoxigenic E.coli
- Enteropathogenic causes attaching and effacing lesions mediated by intimin and Tir, causing microvili disrtuption. Incubation is 1-2 days
- Enterotoxigenic releases heat labile and heat stable toxins. Incubation is 1-7 days
- Both present with watery diarrhoea, abdominal pain and vomiting
Describe features of enterohaemorrhagic E.coli
- E.coli 0157. It produces shiga like toxins. Incubation is 1-7 days.
- It presents with bloody diarrhoea, abdominal pain and vomiting.
- May cause haemolytic uraemic syndrome 5 days after diarrhoeal infection (in 5-10% of cases)
What is the treatment for enterohaemorrhagic e.coli?
Supportive management only as antiboitcs increases the risk of developing HUS.
What is the presentation of haemolytic uraemic syndrome?
Intravascular blood clots cause this triad of symptoms:
- Acute kidney injury,
- Microangiopathic haemolytic anaemia
- Thombocytopenia
This presents as low urine output, haematuria, abdo pain, confusion, hypertension and bruising.
What are the investigations for haemolytic uraemic syndrome?
- FBC: Microangiopathic haemolytic anaemia is a Hb < 80 with a negative coomb’s test. It will also show thrombocytopenae
- Blood film: Schistocytes and helmet cells
- U&E’s - AKI
- Stool culture: PCR for shiga toxin.
What is the treatment of haemolytic uraemic syndrome?
- Supportive: fluids, blood and dialysis if needed. NO ABx or loperamide
- Plasma exchange for severe cases not associated with diarrhoea. With C5 monoclonal antibody
What is a direct and indirect coombs test?
Direct - Detects if there are antibodies on the surface of RBCs. When mixed with coombs reagent it will cause a thrombus.
Indirect - Patient’s plasma (which contains any potential antibodies) is mixed with donor blood.
When do you use the Direct coombs test and the indirect coombs test?
Direct - Autoimmune haemolytic anaemia, HUS, haemolytic disease of the newborn.
Indirect - Pre-transfusion testing ot pre-natal antibody screen
Describe features of Shigella
- It causes bloody diarrhoea, abdominal cramps and fever.
- Incubation is 12hr-3 days
- Produces shiga toxic so can cause HUS
- Severe cases can be treated with azithromycin
Describe features of bacillus Cereus
- Grows on rice. Reheating can kill the bacteria but not toxin.
- Cereulide toxin causes abdompinal cramping and vomiting within 5 hours of ingestion and diarrhoea within 8 hours of ingestion. Resolution in 24 hours.
Describe features of Yersinia Enterocolitica
- Pigs are key carriers. Incubation is 4-7 days. Typically affects kids
- It causes watery/bloody diarrhoea, abdominal pain and fever.
- In older children and adults it can cause right sided abdo pain due to mesenteric lymphadenitis which can mimic appendicitis
What are the incubation periods for the following infections:
- S.Aureus,
- Salmonella,
- Shigella,
- Amoebiasis,
- Bacillus cereus,
- E.coli,
- Campylobactoor
- Giardiasis
1-6 hrs: Staphylococcus aureus, Bacillus cereus
12-48 hrs: Salmonella, Escherichia coli
48-72 hrs: Shigella, Campylobacter
> 7 days: Giardiasis, Amoebiasis
Describe featurs of the norovirus
Symptoms occur 24-48 hours after innoculation. Usually self limiting vomiting bug but can cause AKIs in the elderly population.
Describe features of Giardiasis
- Parasitic infection which is transmitted via the faecal-oral route.
- Can cause chronic diarrhoea, steatorrhoea, flactulence, malabsorption, bloating and abdominal pain
- Investigated via stool sampling (NAAT)
- Treated with tinidazole or metronidazole
What are the general principles of managing gastroenteritis?
- Send faeces sample for microscopy, culture and sensitivities.
- Ensure hydration via oral rehydration salts or IV fluids
- Antidiarrhoeal drugs (loperamide) and anti-emetics are generally avoided as they may worsen infection.
- Antibiotics are only used in systemically unwell, elderly and immunosuppressed patients
What are possible complications following gastroenteritis
- Lactose intolerance,
- IBS
- Reactive arthritis
- Guillian-Barre syndrome
- HUS
