wk 4 9/10 gastroenteritis 1/2 Flashcards
which bacteria is the most commen pathogen of gastroenteritis
campylobacter
t/f most people with gastroenteritis do not require antibiotics
true
associated risk factors for GI infection
malnutrition deficiency closed/semi-closed communities contaminated food winter congregating summer floods age <5, not breastfed older age
likely bacterias to develop if acid suppressed (PPIs)
h.pylori
yersinia enterocoliticia
salmonella
campylobacter
shigella
infective if you are…
immunosuppressed
more likely to get cholera if u are blood group
0
aspects which bacteria can alter
adherence to mucosa cellular invasion production of exotoxins changes in epithelial cell physiology loss of brush border digestive enzymes increased intestinal motility, net fludi secretion, iflxu of inflam cells and/or intestinal haemorrhage
define inoculum size
median infecting dose required to cause disease in 50%
lower =spreads easier
pH affects required dose
diarrhoea
> 3 unformed stools/day
no other causes (caffeine,laxatives))
stools hold shape of container
dysentry
inflammation of intestine (colon mainly)
diarrhoea with blood and mucus
associated with fever, ab pain, rectal tenesmus (incomplete defaecation)
which bacteria may cause dysentry
shigella
campylobacter
acute duration of gastroenteritis
<2weeks
diarrhoea associated with cholera
rice water - clear vvv liquidy
assocated history questions for diarrhoea 6
diarrhoea - freq,blood,mucous,time other symptoms travel, contacts, animals food history - time,type,storage medication
recent antibiotics increases what yype of infection
c.difficile
bacillus cereus (gram+ bacillus) is associated with what type of food
starchy food - reheated rice
leads to profuse vomiting
staph auerus contains a preformed toxin in food, leading to rapid absorption. It is a gram + coccus, what types of food does it typically infect
milk
meat
fish
viral pathogens use what type of test
PCR
which enteric pathogen is most infective
shigella
due to shiga toxin
what does shiga toxiin do
binds to receptors in renal, RBC and others
inhibits protein synthesis
STEC
shiga-like toxin (producing) e.coli
shigella produces 2 toxins - type 1 and 2, which is more infective
2 (bacteriaa produce similar - shiga like)
outline how shiga-toxin producing e.coli infect
compete with normal bacterial bowel flora
adhere to intestinal epithelial
toxins bind to absorptive enterocytes, enter cell, inhibit protein synthessi = death
toxins can then enter bloodstream via damaged intestinal epithelium = death of vascular cells
endothelial cell lysis leads to platelet activation + aggregation, cytokines, vasoconstriction = fibrin
microangiopathy propagates as toxins carried to kidneys - hematuria and renal failure
t/f e.coli 0157 most likely to e STEC
true
can also be called VTEC
r.coli0157 can lead to Haemolytic Ureamic Syndrome, clinical presentation of this
ab pain fever pallor petechiae (purple spot) oliguria (low urine output) bloody diarrhoea (this may have stopped)
likely results from stool culture of HUS
high WC
low platelets
low Hb
red cell fragments
outline characteristics of campylobacter (most common bacteria)
16-48hrs incubation sporadic poultry (raw) small pathogen numbers invasive signs - pain, blood fever
which type of antibiotic is given for campylobacter
macroslide
(only if vvv severe and quite sure on bacteria)
careful tho
associated foods for salmonella enteriitidis
poultry,meat,raw egg
t/f salmonella typhoidal leads to gastroenteritis
false
non-typhoidal
listeria monocytogenes is found
in fridge
listeria monocytogenes can lead to gastroenteritis or invasive, outline difference
gastro - fever,myalgia,diarrhoea
pregnant
unpasteurised milk products, cold meats (foodies)
invasive - immunosuppressed
>50 yrs
pregnant
meningitis/bacteraemia
how is listeria diagnosed
gram +ve rod
cold environment (frigde)
difficulty culturing
2 main viruses causing gastroenteritis
rotavirus
norovirus
t/f treatment differs iif virus gastro
false
only treating symptoms
most common virus for diarrhoea in kids <3yrs
rotavirus
rotavirus or norovirus is more infective
norovirus
how is norovirus diagnosed, what is key for treatment
PCR
hydration
e.coli pathotypes group symptoms that are related to the disease. 4: Enterotoxigenic (ETEC) enteropathogenic (EPEC), enteroinvasive (EIEC) eneraggregative (EAIC)
ETEC- produces heat, similar to cholera and yersinia toxins,travel
EPEC - attachins, no toxin no invasion, synthesises and secretes own receptor in cell membrane, non breastfed children, asymptomatic
EIEC- watery diarrhoea, dysentery rare, invasion,
EAIC - travellers diarhoea, cytogenic secretogenic, proinflammatory
