Lecture 19 Pathogenic shigella and E coli Flashcards
(39 cards)
What species are part of your normal flora of your stomach?
- E. coli non-pathogenic species
- Klebsiella
- Enterobacter
- Proteus
- Serratia
What is not part of the human flora?
- Salmonella
- Shigella
- Yer sinia
- Pathogenic E. coli
What type of diseases are caused by bacteria not part of the human flora.
•Cause a wide variety of disease •endotoxic shock, UTI, diarrhea, HUS
How is E. Coli identified,
- Gram negative
- Lactose fermentation.
- indole positive
- most are normal colonic flora
What are the type of diseases caused by E. coli?
- Urinary Tract Infection (UTI)
- Gastroenteritis
- Septicemia - usually following UTI or gastroenteritis
- Neonatal meningitis
What E. Coli infections are not caused by a person’s own flora?
gastroenteritis and neonatal meningitis
What plates can be used to identify E. Coli?
- CHROMagar
- MacConkey
What is unique about CHROMagar?
Has a unique specific metabolism for multiple organisms, can grow multiple organism on plate and identify the different types.
What is a common theme between pathogenic E. Coli?
-secretion and new DNA. Not normal flora. Uses different mechs to cause disease.
What are the surface structures of E. Coli?
- O antigen
- H antigen (flagella)
- BFP pili
- CFA pili
- Type 1 pili
- K antigen capsule
- P pili
What are BFP pili?
bundle forming pili: found in EPEC strains
What is CFA pili?
colonization factor antigen: pili used by ETEC strains for binding to host cells
What are type 1 pili?
common pili binds via FimA to mannose residues on epithelial cells
How does EPEC cause diarrheal disease?
BFP used to form cluster of cells, injects effector proteins, causes pedestal formation.
How does EHEC cause diarrhea?
causes pedestal formation and injects Stx-shiga toxin into the cells.
How does EHEC cause disease?
uses CFA pili to bind then secretes two types of enterotoxins: ST (heat stable) and LT (heat labile).
How does EAEC cause disease?
forms a biofilm on the surface of the cells, produces cytotoxins and enterotoxins to cause diarrhea.
How does EIEC cause diarrhea?
binds, then invades cells, then escapes into the cytoplasm. Similar to Shigella.
How does DAEC cause diarrhea?
binds as single cells.
What is UPEC E. Coli?
- Uropathogenic E.coli:
- causes most cases of Pyelonephritis (kidney infection)
- infection starts from spreading to colon to bladder
What makes UPEC so good at causing infection?
-P pili and FimH
What are some characteristics of ETEC?
- prevalent in developing world (traveler’s diarrhea and infantile diarrhea
- spread via food
- attacks small bowel causing watery diarrhea
- no histological or inflammatory changes to GI tract.
- treatment is hydration
What are the toxins produced by ETEC?
- LT - Heat Liable (similar to cholera) .
- ST - heat stable
What are characteristics of EPEC?
- Most prevalent in the developing world
- Attacks small bowel
- Causes severe watery diarrhea, nausea and vomiting, dehydration
- Treatment: hydration
- EPEC has been used to study the interaction of a bacterial pathogen with the host target cell
