Diarrhoea illness Flashcards
what is gastro-enteritis?
3 or more loose stools per day with accompanying features such as:
- fever
- abdo pain
- bloody stool
what is dysentry?
large bowel inflammation with bloody stools
what can cause gastroenteritis?
contamination of foodstuffs aka. food poisoning
poor storage of foodstuffs
travel related infection
person to person spread
what is the most common cause of gastroenteritis?
viruses
what’s the most common bacterial pathogen responsible for gastroenteritis?
campylobacter
what are the 4 defences against enteric infections?
hygiene
stomach acid
normal gut flora
immunity
how does cholera cause diarrhoea?
increases cAMP levels and Cl secretion
increases secretion of Cl along with Na and K which causes osmotic effect = massive loss of water from the gut
how would you initially assess a patient with diarrhoea?
symptom duration: <2 weeks is unlikely
risk of food poisoning (diet, travel)
assess hydration (pulse, skin turgor, postural BP)
features of inflammation: SIRS (fever, raised WCC etc)
what investigations would you carry out if someone presented with diarrhoea?
stool bacterial culture (molecular or Ag testing) blood culture renal function blood count abdominal X-ray/ CT if distended/tender abdominal
what are the differential diagnoses of gastroenteritis?
IBD
spurious diarrhoea secondary to constipation
carcinoma
what is the difference in the onset of campylobacter vs salmonella?
campylobacter has 7 day incubation period whereas salmonella is < 48 hours after exposure
what are the 2 most common species of campylobacter that cause gastroenteritis?
C. jejuni
C. coli
what is the difference in the stool tests with campylobacter vs salmonella?
campylobacter will be negative after 6 weeks
salmonella may still show positive up to 20 weeks
what are the 2 most common salmonella infections?
salmonella enteritis
salmonella typhimurium
how is E.coli contracted?
contaminated meat or from person to person spread
what toxin does E.coli O157 produce?
shinga toxin
what is haemolytic uraemia syndrome and what causes it?
caused by E.coli O157
renal failure, haemolytic anaemia and thrombocytopenia (low platelets)
what is the treatment for HUS?
supportive
don’t give antibiotics as this makes the haemolytic worse
how is E.coli distinguished from other strains of E.coli?
it is non-sorbitol fermenting
what are causes of food poisoning outbreaks?
staph aureus
bacillus cereus
clostridium perfringes
when would you give antibiotics for gastroenteritis?
immunocompromised
severe sepsis or invasive infection
chronic illness i.e. malignancy
if a patient presents with diarrhoea and had been on co-amoxiclav 2 weeks ago, what is the most likely cause of the diarrhoea?
clostridium difficile
what is the treatment for c.diff?
vancomycin
metronidazole
what is the treatment for giardia lamblia?
metronidazole
what amoeba causes invasive extra intestinal symptoms?
entamoeba histolytica
what is the treatment for intestinal disease causes by entamoeba histolytica?
metronidazole + luminal agent to clear colonisation
what is the difference between rotavirus and norovirus?
rotavirus found in children under 5 in the winter usually
norovirus is the ‘winter vomiting disease’ found in adults usually in hospitals, schools etc
how is norovirus diagnosed?
PCR
what is an example of an inflammatory and non-inflammatory diarrhoea illness?
non-inflammatory = cholera inflammatory = shigella dysentery
what are the 3 most common parasites that cause diarrhoea illness?
giardia lambia / duodenalis
cryptosporidium parvum
entamoeba histolytica
what investigation should be carried out for diagnosis of a parasitic infection causing diarrhoea?
stool microscopy
what investigations should be carried out to exclude c.difficile as the cause of diarrhoea?
toxin testing
what investigation should be carried out for diagnosis of a viral infection causing diarrhoea?
viral PCR/ antigen testing
what diarrhoea illness is toxic megacolon a complication of?
clostridium difficile
what is responsible for the cause of entamoeba histolytic?
foreign travel and poor hygiene
what is responsible for the cause of guardia lambia?
contaminated water supply
