Lecture 5 - Ecoli 0157 Flashcards
(46 cards)
Where doe ecoli fall phylogenetically
Proteobacteria gamma
Name some general characteristics of enterobacteriaceae
- gram - Straight rods Motile (Peritrichous) or non motile Non sporulating Facultative anaerobes Production of acid from glucose Catalase positive oxidase negative
Name some major genera of enterobacteriaceae
Escherichia Salmonella Shigella Citrobacter Proteus
Who noticed e coli in diarrhoea ofchildren
theodore Erlich
Name general characteristics of Ecoli
Gram - Facultative anaerobe Non spiorulating Peritrichous Growth - temp 10-55 . O 37 deg PH 4.5-9. O 7-7.5 Aw 0.96 (7% Nacl)
Why doesnt e coli satisfy Koch postulates
Both in healthy and diseased organism
Where does e coli live
Commensal - human and warm blooded animals eg, cattle
How quickly does e coli colonise gut
Babies almost pure culture - one of first organisms to colonise gut from mother
Once take in food this reduce as get more organisms
Main groups of pathogenic e coli
Enteropathogenic ecoli (EPEC) - infantile diarrhoea (adults immune)
Enterotoxigenic (ETEC) - on holiday e.g Egypt. Endemic population usually resistant
Enteroinvasive (EIEC) - produce symptoms similar to dysentery
Enterohaemmorhagic (EHEC) - verocytotoxin ecoli (VTEC/STEC) 0157 model strain
What is ETEC associated with
Ice salad
Travel
Why is enteroinvasive like shigella dysentery
Invasive ecoli penetrate through gut wall and into peritoneum so gut come troug hole created into faeces and out
Red blood in faeces
Where as EHEC first isolated
Canada
How is EHEC different to other types of ecoli
Non invasive like EIEC
Not produce enterotoxin like ETEC
Clinically different to EPEC
What are main serogroups for EHEC
Big 5 - 026, 0103, 011, O157
What caused it be recognised as foodborne pathogen
Jack in a box outbreak - chain of burger restaurants in US. Ask for burger to be poked how wanted it to be done
Who made concept of serotyping
Kauffmann White
What is O157
Antibody reaction with LPS on cell wall - antigenically distinct
Antibody 157 recognise antigen 157 which is certain configuration of sugars and lipids on outer cell wall
How many possibility are there for O and H antigens
173 o antigen
55 possibilities of H - flagella
Why are 0157 not all vtec
- vtec can be not 0157 r.g. O26
- some 0157 don’t produce toxin
NOT ALL INTERCHANGABLE
What are risk factors for ecoli 0157
Assumptomatic carrier.- cattle
Vehicles - food - MILK (unpasteurised) and vegetables grown in faeces and eating meat directly risk
Person to person - when symptomatic shed massiv number in own faeces- large congregation of people, e,g. Nursery, swimming etc
Contact animals - open farms - young children exposrd via faeces on fence etc
What is main annual case of 0157 in uk
900 and 1000 cases
What country has most e coli cases
Scotland unknown why
What are symptoms of EHEC
- could get diarrhoea disease (nicest option)
If get worse can get Haemoragic colitis - haemmoraghing of colom - blood in faeces - 10% of children under 5 or 6 cab get haemolytic ureamic syndrome = most susceptible cause complications of kidney - lead to kidney failure. Not well to treat so either need dialysis or transplant
- older patients can get thrombotic thrombocytopaenic pupura (TTP) - blood clots, bruising and internal bleeding as result of toxin mopping up plateletsa
What is duration of EHEC 0157
2-9days
