micro 6 Flashcards
what is shiga toxin producing e.coli also known as?
•Verocytotoxin producing E. coli
what is a subset of shiga toxin producing e.coli?
- A subset of these can be called EnterohemorrhagicE. coli (EHEC)
- All EHEC are STEC but not all STEC are EHEC
how infectious is STEC?
- STEC infectious dose is low
* Believed to be <100 cells (some say <10)
what are the two main variants of STEC?
2 main variants Stx1 andStx2
are the STEC variants the same?
•Antigenically different but same mechanism of action
what are the STEC variants used for?
Used as markers for identification (PCR/multiplex PCR
what is STEC associated with?
Associated with hemorrhagic colitis and hemolytic-uremic syndrome.
what was the first iscolated STEC?
E.coli 0157:H7
how can E.coli 0157:H7 be spread?
- Major foodborne pathogen
* Can be spread person-person through faecal shedding
what are STEC 0157 ?
refers to EC strains which are 0157 but not necessarily H7 variants
what are shiga toxins and where are they most commonly found?
- Family of toxins that are most commonly found in Shigella dysenteriae and some STEC serotypes
- Extremely potent bacterial toxin
what are the two units which shiga toxins are composed of?
- Comprised of 2 units
* A (1 copy)•B (5 identical copies)
how does shiga toxin producing e.coli work?
- Bacteria binds to cell surface a)Intimin protein
- B subunit binds to glycolipic globotriaosylceamide (Gb3)
- Internalised within an endosome
- Transported to Golgi a)A1 subunit is cleaved from B pentamer
- Inhibits protein synthesis
- Cell death
what was clostridioides difficile known as?
•Was originally Clostridium difficile•Technically renamed in 2016
what is c. difficle known for?
One of the most important healthcare associated MDR pathogens- NOT TRAVLERS DIAHORREA