E. coli Virotypes
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- Traveler's diarrhea
- Infant diarrhea
- Bloody diarrhea
- Hemorrhagic colitis
- Infant Diarrhea
- Traveler's Diarrhea
EPEC attaches to epithelial cells of __________
Major histological characteristic of EPEC is?
Effacement (destruction) of microvilli in small intestine (attachment/effacement [A/E] pathology)
Which strand of E. coli causes A/E pathology?
E. coli genes involved in A/E are encoded on a ______
What type of pili do EPEC have? What type of attachment is this?
Bfp pili, allow for loose attachment
What type of secretion system does EPEC use to secrete Tir?
Type III Secretion System
Type III Secretion System of EPEC secretes?
Tir (Translocated intimin receptor)
What type of E. coli secretes Tir and what does this do?
- EPEC secretes Tir (translocated intimin receptor).
- Tir goes into host cell dimerizes and then localized to the membrane where it serves as a receptor for intimin (which is on E. coli surface). This is a TIGHT attachment!
- Then this causes a cascade which causes rearrangment of host actin and loss of microvilli.
What two proteins produced by EPEC mediate host cell apoptosis?
Tir and ESPF
Main cause of traveler's diarrhea?
How do you acquire ETEC?
Consumption of fecally contaminated water or food
Name the 3 virulence factors of ETEC.
- CFA: Colonization factor antigens
- ST: Heat-stable toxins
- LT: Heat-labile enterotoxins
Unlike EPEC, ETEC has _______
No inflammation or histological changes to the mucosa
ETEC presents clinically with?
ETEC: Heat-Labile Toxin (LT-1)
1) What type of toxin?
2) Endocytosed to?
3) Which subunit detaches? Where does it go?
4) What does it do?
5) Phosphorylated GS regulates? Leads to?
6) _____ secretion increases and ____ absorption decreases.
- 1) A-B toxin (1A, 5B subunits)
- A= active
- B= binding
- 2) ER/ GA
- 3) A subunit detaches and leaves the compartment.
- 4) Transfers the ADP-ribose from NAD to GDP subunit of Gs.
- 5) Adenylyl cyclase --> Increase in intracellular cAMP.
- 6) Chloride increases, sodium decreases
- 7) Results in watery diarrhea
What toxin from what strain of E. coli is similar to cholera toxin in that they both have the same # of subunits?
LT-1 from ETEC (1A, 5B subunits)
What ETEC virulence factor allows attachment of bacteria to epithelial cells?
CFA (colonization factor antigens)
ETEC: Heat-Stable toxin (STa)
1) What type of toxin?
2) Secreted and binds to?
3) Activated guanylyl cyclase catalyzes _____ to _____.
4) Stimulates secretion of _____
- 1) Small monomeric toxin
- 2) Binds to host guanylyl cyclase
- 3) GTP --> cGMP
- 4) chloride
- 5) watery diarrhea
Labile in the Air, Stable on the Ground
- Heat labile toxin = Adenylyl Cyclase
- Heat stable toxin = Guanylyl Cyclase
ETEC: Heat labile or heat stable?
1) Which one leads to increased chloride secretion and decreased sodium absorption?
2) Which one leads to increased chloride secretion?
- 1) Heat-labile toxin (LT-1)
- 2) Heat-stable toxin (STa)
Chloride secretion is done by the ?
E. coli 0157:H7 is what type of E. coli?
What virotype of E. coli is the most common to produce diseases in developed countries?
HUS is what type of E. coli virotype?
Name the main toxin of EHEC.
Shiga (Stx-1, Stx-2, or both)
What EHEC toxin is identical to the Shigella dysenteriae toxin? How much in common is the other one?
Stx-1 is identical. Stx-2 is 60% homologous.
How are Stx-1 & Stx-2 viruses acquired by EHEC?
Describe the structure of Stx-1 and Stx-2 toxins on EHEC.
Both are A-B toxins (1A, 5B)
What two types of E. coli have a Type III Secretion System?
Describe pathogenesis of EHEC.
1) Express ____ secretion system, ____, and _____ for binding
2) Secretes ___which crosses the epithelium and is carried by the blood
3) The _____ subunits of Stx bind to host__________, also known as____.
4) After endocytosis of Stx, the ____ subunit leaves the compartment and binds to/ cleaves the _____ of the ____ subunit.
5) This disrupts ______
6) Endothelial cell death occurs and can lead to coagulation in the microvasculature, platelet consumption, red cell fragmentation, decreased glomerular filtration, and renal failure
- 1) Type III SS, Tir, intimin (A/E phenotype on epi.)
- 2) Stx
- 3) B subunit, Globotriaosylceramide, GB3
- 4) A subunit, 28S rRNA, 60S
- 5) Protein synthesis
Which E. coli is rare in the US and uncommon in developing countries?
Name the 3 pathogenic strains of EIEC.
Invade and destroy colonic epithelium
O124, O143, O164 are virulent strains of what E. coli virotype? They are very closely related to?
- Very closely related to Shigella
EIEC's strains are characterized by invasion and destruction of what?
EIEC causes dysentary. What does that consist of?
Fever, abdominal cramps, blood and pus in stool
EIEC becomes internalized within a phagocytic-like vacuole, escapes into the cytoplasm, replicates, and spreads to adjacent cells via ______
host actin tails
Which E. coli virotype spreads to other cells via host actin tails?
What carries the genes for EIEC's invation into epithelial cells?
Large plasmid (invasion plasmid antigens- ipa)
Causes diarrhea in adults in both developing and developed countries.
Chronic diarrhea in children in developing countries is associated with____
EAEC auto-agglutinate into a "stacked-brick" arrangement mediated by__________
bundle-forming fimbriae (aggregative adherence fimbriae I and II)
EAEC stimulates _______, which traps the bacteria ina biofilm on the epithelium of the small intestine.
Which E. coli virotype stimulates mucus secretion?
How does hemorrhage occur in EAEC?
Microvilli become shortened, mononuclear cells infiltrate, and hemorrhage can occur
Characterized by a uniform but diffuse attachment of the bacteria to the epithelium; mediated by a Dr-like fimbrial adhesion.
Associated with Brazilian children
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