Flashcards in GI Infectious Diseases Deck (97):
What percentage of children under 5 dying is caused by diarrhoea? Pneumonia?
why does diarrhoea kill
1. fluid and electrolyte loss
Which bugs have a 20x higher death rate post infection?
ecoli, shigella, parasites
33% of all children deaths are caused by?
2 ways diarrhoea causes malnutrition?
1. increased energy loss
2. reduced energy intake
2 reasons for reduced energy intake in diarrhoea?
malabsorption post gut damage
withholding of food (moms think breast milk caused it)
how is Gut damage in kids different than adults?
kids guts repair slower
out of 10 litres of liquid consumed in 24 hours, how much is absorbed?
what is the reserve capacity of the GIT for fluids?
what happens if you surpass the reserve capacity of the GIT for fluid?
3 aetiological agents of diarrhoea?
What is the predominant cause of diarrhoea in developed countries?
What is the predominant cause of diarrhoea in developing countries?
Gastroenteritis generally just means?
vomiting and diarrhoea
dysentery needs to have?
blood, pus, mucous in the feces
enteroinvasive ecoli AKA:
shigella causes what kind of diarrhoea?
what does entamoeba histolytica cause? what is it?
protozoal cause of dysentery
Which foods do you find staph and salmonella poisoning in?
Mayonnaise (raw eggs)
Listeria outbreaks recently in which foods?
clostridium perfringes, bacillus, vibrio are from what kind of syndrome?
ciguatoxin si dangerous why?
Traveller's diarrhoea mainly caused by?
ETEC, bac, viruses, protozoa
What causes atibiotic-associated colitis?
What the difference between dysentery and haemorrhagic colitis?
No pus in the faeces
main bug that causes haemorrhagic colitis?
EHEC (entero-hemorrhagic e.coli)
What causes cholera-like symptoms?
vibrio cholerae, ETEC
enteric fevers are local or systemic?
Which 2 bugs cause enteric fever?
What is ETEC?
enterooxigenic E. coli
What is EPEC?
Enteropathogenic E. coli
What is EHEC?
enterohaemorrhagic E. coli
what is EIEC?
enteroinvasive E. coli
what is EAEC?
enteroaggregative E. coli
What are the adhesins for ETEC?
What are the adhesins for EPEC?
What are the adhesins for EHEC
intimin and Efa
EHEC evolved from?
What are the adhesins for EAEC?
Which ecoli can secrete shiga toxin?
shiga toxin is AKA?
which two ecoli cause watery diarrhoea?
which ecoli causes bloody diarrhoea?
what does EIEC cause?
5 levels of invasion of mucosa?
1. adhesive enterotoxigenic
2. adhesive with bush border damage
3. invasion restricted to muscosa
4. invasion of submucosa
5. systemic invasion
Bugs that are adhesive enterotoxigenic?
Bugs that are adhesive enterotoxigenic adhesive with bush border damage?
Bugs that are invasion restricted to muscosa
Bugs that are invasion of submucosa
Bugs that are systemic invasion?
What happens if immunocompromised patient has invasion of submucosa bugs like: salmonella
could turn systemic
EPEC has two stages of adherence they are?
1. plasmid mediated
2. chromosomal (attachment)
where do you find bundle forming pili?
stage one plasmid mediated adherence of EPEC only
Do mammals use Type III secretion systems?
Nope. ONLY pathogens
Why is Type III secretion system for pathogens special?
gets a protein DIRECTLY from bacterial cytoplasm to host cytoplasm via small 'syringe'
the Tir and Intimin combo is unique in nature for the following reason?
TIR = translocated intimin receptor
essentially e.coli secretes it's own receptor onto our cells so that their intimin can adhere to our cells
Which shigella is the worst and the only one that produces shiga toxin?
do ALL shigella dysenteriae produce shiga toxin?
Do ALL EHEC produce shiga toxin?
yes by definition
what does HUS stand for?
Haemolytic urea syndrome
Haemolytic urea syndrome caused by which toxin?
NEED shiga toxin
4 Virulence Determinants?
ability to resist killing
3 pathogens that are invasive?
2 kinds o adhesins?
2 kinds of exotoxins?
2 ways to resist killing?
resist phagocytes (eg. salmonella, macrophages)
are there microvilli on immature enterocytes?
after damage by rotavirus, what happens to intestinal architecture?
flattening of microvilli/improper absorption
do labs culture viruses?
only for the more common ones
5 things the lab does to diagnose pathogens?
detection of nucleic acid
Would you see bacteria with amoeboid infection? Why?
Nope, because amoebas eat bacteria!
Trophozoites of Giarbia lamblia are found where usually?
proximal small intestine, then let go an move down the gut making cysts along the way
In active trophozooite of Entamoeba histolytica, what the smoking gun in the diagnosis?
RBCs ingested by the amoeba on light microscope
Entamoeba histolytica can live as two things
commensal and pathogen
3 ways to culture faeces
direct plating on selective/indicator media
confirm suspicious colonies
3 ways to confirm suspicious colonies?
biochem tests (virulence typing)
serotyping (EHEC0157, salm.typhi)
What the last resort for viral infection diagnosis?
3 ways to diagnose viral infections
detection of nucleic acid
Eg. of when you would use capture assay for antigen?
rotavirus from a faeces sample
Viral nucleic acids by PCR revealed by?
2 best treatments for diarrhoea?
1. fluid and electrolyte replacement
2. reduce fluid loss
Why give electrolytes with fluid?
electrolytes help the body uptake water as water and other ions follow Na+
3 kinds of anti-diarrhoeals? (do they work?)
antimotility (still diarrhoea-ing on inside)
anti-secretory agents (doesn't work)
binding agents (does stop it, just looks better)
Is shiga toxin dangerous to non-humans?
Not as dangerous as they have the shiga toxin receptor and only destroys a few gut cells
Why is shiga toxin dangerous to humans?
we don't have a shiga toxin receptor so it can pass straight through and cause havoc on brain/heart etc.
Antibiotics for diarrhoea, what does it do for cholera?
shortens illness a smidge
which systemic infection MUST you treat with Antibiotics for diarrhoea?
Antibiotics for diarrhoea for immunocompromised patients?
treat shigella dystenteriae with antibiotics?
Would you treat someone with a protozoal infection even if they feel fine?
Yes. Always treat
Why is pseudomembranous colitis treatment paradoxical?
treatment is antibiotic (metronidazole)
caused by: antibiotics
WHO two best ways to reduce incidence of diarrhoea?
1. education: hygiene, breast-feeding
3 ways to prevent traveller's diarrhoea?
what's the function of bundle forming pili?
prevent washing away of pathogen due to peristalsis
LEE pathogenicity island stands for?
Locus of Enterocyte Effacement