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63 Cards in this Set

  • Front
  • Back
What are the biochemical characteristics of Ecoli?
gram negative rod
90% lactose +
indole +!!!
What are the 4 serotype antigens of e. coli?
What is the O Ag for E. coli?
somatic antigen
LPS oligosaccharide side chain
What is the H Ag for E. coli?
flagellar Ag
What is the K Ag for E. coli?
capsular Ag
acidic polysaccharides
What is the F Ag for E. coli?
fimbrial antigens (protiens)
What causes 90% of UTIs in anatomically normal unobstructed urinary tracts?
e. coli
What is usually present in stool and colonizes periurethral adn vaginal areas?
UPEC - uriopathogenic strains of e. coli
E.coli ascends to the bladder
invasion of mucosa, inflamation
passage up ureters and replication in teh renal pelvis and parenchyma
UPEC possesses a pathogenicity island that...
is located on the same chromosome as a PI encoded by e.coli causing diarrhea
Adhesions associated with urinary tract e. coli infections
Type I finbriae, pili
Type I fimbriae, pili...
mannose sensitive - recognizes cells that contain surface glycoprotiens with mannose
allows colonization of intestinal, vaginal, urethral and bladder mucosal cells
Ecoli that cause kidney infections produce what?
p or pap pili that bind to glycolipid on the surface of bladder and kidney cells
Neonatal Meningitis
synth K1 capsule
What is K1 capsule?
homopolymer of silic acid that is similar antigenically to fetal neuronal tissues that evade phagocytosis and complement adn cause meningitis
K1 is immunologically and chemically identical to what?
the capsular polysaccharide of N. meningitidis group B
ALL e.coli causing diarrhea have...
atleast one virulence determinatant carried on a plasmid
Diarrhagenic e.coli has chromosomal virulence factors organized in clusters called
pathogenicity islands
diarrhagenic e. coli has individual traits that can be encoded on ...
transposons ST
phage Stx 2
What are the 3 phatogenic paradigms for diarrheagenic e. coli?
1. enterotixin production
2. intracellular invasion
3. intimate adherace & membrane signaling
Colonization factors for ETEC?
multiple protein fimbriae that are plasmid encoded
What is the epidemiology of ETEC?
associated with food/water
traveler's diarrhea
Clincial considerations for ETEC?
abrupt onset of watery diarrhea with no blood
What are the 2 toxins of ETEC?
What is LT?
toxin of ETEC
heat labile
What does the A subunit of ETEC LT toxin do?
ADP-ribosylates Gs stim subunit of adenylate cyclase that elevates intracellular cAMP
What is CFTR?
in ETEC LT toxin
stim secretion of Cl-
inhibition of Na absorption
water efflux
osmotic diarrhea
What is ST?
toxin in ETEC
heat stable
What is ST in ETEC encoded on?
plasmids and transposons
What does ST do?
ETEC toxin
binds guanylate cyclase to stim cGMP to make CFTR
What is the end result of ST toxin of ETEC?
osmotic diarrhea due to CFTR same as LT toxin
What is enteropathic e.coli associated with?
infant diarrhea
What group does EPEC belong to?
intimate adherance and membrane signaling
what is the major histopathology of EPEC?
attaching and effacing lesion
-effacement of microvilli
-intimate attatchment
-cytoskeletal changes
What is the diagnositic test for EPEC?
FAS - fluorescent actin staining test
Local adherence in EPEC?
plasmid encoded bundle forming pili (bfp)
Signal transduction in EPEC?
change intracell Ca and release IP3 to P myosin light chain activation of PKC which causes inc perm of tight junctions and migration of polymorphonulcear leukocytes adn up reg of NF-kB to cause an inflammatory response
Intimate adherence in EPEC...
mediated by intimin encoded on the eae gene
What does intimin do
part of EPEC
binds to Tir
What is Tir?
part of EPEC
delivered by type III
P in euk intestinal cells
causes pedestal formation
What does Wiskott-Aldrich Syndrome have to do with anything?
family of proteins (WASP) and actin nucleating factor Arp2/3 cause pedestal formation
What group is enterohemorrhagic e.coli a part of? (EHEC)
intimate adherence and membrane signalling
Hemorrhagic colitis HC is assoicated with?
consumption of undercooked hamburgers
Sporatic HUS is associated with?
fecal cytotoxin
Sx of enterohemorrhagic e. coli (EHEC)?
severe crapmy ab pain
watery diarrhea followed by grossly bloody stool
little or no fever
the really bad stuff associated with enterohemorrhagic e. coli (EHEC)...
renal failure!
microangiopathic hemolytic anemia
Typically EHEC strains:
produce Stx
A/E lesions
60-MDa plasmids
What is the histopathology of EHEC?
hemorrhage & edema of lamina propria
thumbprinting pattern on barium enema
focal necrosis, infiltrating neutrophils
cytotoxicity of EHEC could be neutralized by?
antibodies to Stx 1
The A subunit of shiga toxin is?
RNA N-glycosidase
removes single adenine residue form teh 28S rRNA of eukaryotic ribosomes
The B subunit of the shiga toxin is?
binds globotriasylceramide Gb3
Why is there bloody diarrhea with HUS?
toxins effect endothelia cells
receptor density onf renal cel
contrib of LPS
contrib of cytokines
inflammatory response
Where is the reservoir for EHEC?
intestinal tract of cattle
What is EIEC?
enteroinvasive e. coli
what group is EIEC in?
intracellular invasion
Characteristics of EIEC?
lactose negative!
related to shigella
What is the pathogenesis of enteroinvasive e. coli?
epithelial cell penetration
lysis of endocytic vacuole
intracellular multiplication
move through cytoplasm
invasion into adjacent cells
What causes the ulceration of the colonic mucosa in EIEC?
strong inflammatory response
Clinically, what does enteroinvasive ecoli look like?
period of watery diarrhea occassionally followed by teh onset of scanty stool containing blood and mucus
What is the epidemiology of EIEC?
infectious dose is higher than shigella
foodborne/water/person to person