E.coli Flashcards
(29 cards)
Characteristics of e.coli
Enterobacteriacae
Gram -
Facultative anaeobe
Is E.coli lactose fermenting?
Yes
Where is E.coli found?
Flora of man (non harmful)
Faecal contamination
What are the 2 types of E.coli?
Intestinal and extraintestinal
Intestinal E.coli
Cause diarrhoea
Lactose negative
Cause disease 6 ways
What is ETEC?
Enterotoxigenic E.coli
Symptoms of ETEC
Watery stools and diarrhoea (non blood)
Spread by water/human-human
Self limiting (4-6d)
How many cells are needed for ETEC contamination?
10^6-10^8
How does ETEC cause pathogenicity?
Cells colonise surface of bowel
Produce enterotoxins in gut
How do heat liable toxins cause intoxication?
AB5 binds to GM1 on cell surface to target adenylate cyclase
Cl- secretion and inhibition of NaCl
Water moves into lumen (watery diarrhoea)
How do heat stable toxins cause intoxication?
Same as heat liable but increased cGMP
What is EIEC?
Enteroinvasive E.coli
Characteristics of EIEC
Non-mobile
L-serine, D-xylose and mucate fermentation
10 cells needed
EIEC mechanisms of pathogenicity
Destroy epithelial cells lining colon
Same mechanism of invasion as Shigella
What is EAggEC?
Enteroaggregative E.coli
What does EAggEC do?
Bacteria in stacked-brick formation to enhance mucus to trap bacteria in
EAggEC mechanism of pathogenicity
aggR regulates aggregative adherence fimbrial expression
Chromosome induces intestinal secretion and has Shigella enterotoxin 1
EAggEC foods
Salsa, unpasteurised cheese, handlers
What is DAEC?
Diffusely adherent E.coli
How does DAEC cause pathogenicity?
Expresses the aidA gene and encodes an adhesins involved in diffuse aherence
What is EPEC?
Enteropathogenic E.coli
Characteristics of EPEC
Profuse watery diarrhoea with vomiting
Highly infectious in infants
10^8-10^9 needed in adults
How does EPEC cause pathogenicity?
Adherence via BFP through intimate attachment