Gastroenteritis Flashcards
what are common causative organisms of gastroenteritis
campylobacter (commonest)
salmonella
(outbreaks)
E coli 0157
C.diff, listeria, shigella, norovirus, rotavirus
how is gastritis mostly treated
supportive treatment- no antibiotics
how is it spread
faecal- oral transmission
what are the GI infection risk factors
malnutrition (micro nutrient deficiency), closed/ semi closed, exposure to contaminated food/ water/ travel, winter congregating, age <5, or elderly, acid suppression, immunosupression, microbiome, genetics
what organism is more common in acid suppression
C. diff
what bacterial factors allow them to infect patients
adherence/attachment to the gastrointestinal mucosa,
cellular invasion,
production of exotoxins,
changes in epithelial cell physiology,
loss of brush border digestive enzymes, and/or cell death,
increased intestinal motility, net fluid secretion, influx of inflammatory cells, and/or intestinal hemorrhage
what is the inoculum size
median infecting dose required to cause disease in 50%- low inoculum means easier spread
what affects inoculum size
pH and gastric mobility
what is diarrhoea
> 3 unformed stools a day (a departure from normal bowl habit) with no other cause (laxatives, drig abuse, stimulants) where the stool holds the shape of the container
what is dysnetry
gastroenteritis
what is gastroenteritis
An illness caused by eating food contaminated with micro-organisms, toxins, poisons etc
- inflammation of the intestine, particularly the colon, causing diarrhea associated with blood and mucus
what are the symptoms of gastroenteritis
diarrhoea with blood and mucus, fever, abdominal pain, rectal tenesmus (sense of incomplete defecation), frequent bowl movements
what is the acute duration of gastroenteritis
<2 weeks
how might yersinia enterocolitica mimic appendicitis
as it may envade mesenteric nodes
how can food cause gastroenteritis
cross contamination, waiting too long to eat, inadequate heating and cooling, contaminated environment, poor personal hygiene
why most spores be considered in cooking
as can survive the adverse conditions of many cooking methods
what does a large volume of bowl movements tent to mean
it comes from the small bowel- small volume= large bowel
describe the diarrhoea produced by cholera
large volume of rice water diarrhoea
what are factors that could mean a likelihood of gastroenteritis
foreign travel, recent camping or antibiotics, exposure to daycare or raw sea food, anal receptive sex, HIC positive status, outbreaks
why does gastroenteritis a very short incubation period
as pathogens pre form toxins
what organism cause gastroenteritis with an incubation period of 1-6 hours
bacillus cereus (gram +ve bacillus) found in starchy foods
staph aureus (pre formed toxin in food which acts on vomiting centre in the brain) gram +ve coccus- foods left at room temp
how does the lab identify the causative organism
traditional methods (culture), molecular methods (e.g. microarrays), viral pathogen PCR
why must you put details of the patients history on a stool sample
so lab can look for more specific causes
where is shigella common
refugees/ institutionalisation/ military
what does shiga toxin do
binds to receptors in renal cells, RBC and others- inhibits protein synthesis and causes cell death
what toxins does shigella produce
type 1 and type 2 (more potent)
what can produce shiga like toxins
other bacteria
what is a STEC
shiga like toxin producing e coli
what ecoli should be considered in association with shiga like toxin
e coli 0157
how can shiga toxin e coli cause blood clotting
Shiga toxins can then enter the bloodstream via damaged intestinal epithelium and cause the death of vascular endothelial cells by the same mechanism as absorptive enterocytes.
Endothelial cell lysis is accompanied by platelet activation and aggregation, cytokine secretion, vascular constriction contributing to fibrin deposition, and clot formation within the capillary lumen.
