STEC Flashcards
List some of the different variants of E. Coli
Enteropathogenic E. Coli (EPEC)
Enterotoxigenic E. Coli (ETEC)
Diffusely adherent E. Coli (DAEC)
Enterohaemorrhagic E. Coli (EHEC)
Enteroinvasive E. Coli (EIEC)
Enteroaggregrative E. Coli (EAEC)
Uropathogenic E. Coli (UPEC)
Neontal meningitis E. Coli (NMEC)
EPEC, ETEC and DAEC cause infections where in the body?
Colonise the small bowel and cause diarrhoea
EHEC and EIEC cause infections where?
They cause disease in the large bowel
EAEC infects what part of the body?
Can colonise both the small and large bowels
Where does UPEC cause infection
Uropathogenic E. Coli enters the urinary tract and travels to the bladder to cause cystitis and if left untreated can ascend durther into the kidneys to cause pyelonephritis
It can also spread to blood and cause urosepsis
Where does NMEC cause infection
It can cause septicaemia
Neonatal meningitis E. Coli can cross the blood brain barrier into the central nervous system and cause meningitis
What E. Coli strains colonise the small bowel and cause diarrhoea
EPEC
ETEC
DAEC
What E. Coli strains cause disease in the large bowel
EHEC
EIEC
What E. Coli strains colonoise both the small and large bowel
EAEC
What E. Coli strains cause septicaemia
UPEC
NMEC
Who are most at risk of urosepsis
Elderly women -> UTIs progress into septicaemia
How do the E.coli strains differ from one another
They differ in terms of pathogenicity
some inherit toxins such as shiga toxin in EAHEC
What is VTEC
Verotoxigenic E. Coli
What are the genes for VTEC, what do they encode
Stx1 and Stx2
Verotoxins encoded on bacteriophages
What are the genes for EHEC and what is their function
vtx1, vtx2, eae genes
Haemorrhagic colitis hence enterohaemorrhagic E. Coli
How was E. Coli traditionally serotyped?
Traditionally classified on basis of the reaction of antibodies with three types of antigens: O, K and H antigens
According to this method there is over 170 O, 103 K and 56 H antigens -> this is always increasin
A combination of O and H antigens have been identified to type strains
NB: these arent useful predictors of virulence
Give some examples of E. Coli strains named according to O, H and K antigens
O157:H7
O104:H4
O26
O103
O111
Where did verotoxigenic E. Coli get its name
VTEC comes from the old assay that was used to identify verotoxin producing e. coli
Vero monkey cells
What two organisms produce shiga toxin
Shigella dynsentriae type 1
Shiga toxin-producing E. Coli
Traditionally how was functionally active shiga toxins detected?
Using vero cell toxicity test
What strains will be vero cell toxicity test positive?
Verotoxin or verocytotoxin-producing E. Coli (VTEC)
What does shiga toxin cause?
Diarrhoea
Haemorrhagic colitis
Haemolytic uremic syndrome (HUS)
Enterohaemorrhagic E. Coli (EHES)
Technically speaking Shiga toxin could be produced by any E. Coli why is this?
Since the gene for it is transferred via bacteriophage so technically any strain can take it up
Talk about STEC/Shiga toxin E. Colli, what is it, how many different types are there
These produce 1 or more types of shiga toxin (stx):
- stx 1 or stx2
There are over 400 E. Coli serotypes which harbour stx genes
270 serotypes have been associated with clinical infection
- virulence may differ between strains
Genes are located on distinct phage elements - mobile genetic elements