Enteric Bacteria Flashcards
(25 cards)
heat-labile enterotoxin “LT”
(cholera-like AB-exotoxin): ADP-ribosylation of G protein ► cAMP
►
loss of water + electrolytes ► watery diarrhea (e.g. foodborne enterotoxigenic ETEC E.coli)
In Shigella dysenteriae this set of symptoms “diarrhea with blood” is combined with
intestinal cell invasion, apoptosis and neutrophilia (► “pus”) to define “dysentery”.
Traveller’s diarrhea
Shiga toxin
(AB-exotoxin cytotoxin): inactivation of 60S ribosome subunit by removal of a
specific adenine base from a nucleotide of 28S rRNA ► stop translation ► cell death ►
bloody diarrhea (e.g. foodborne enterohemorrhagic EHEC E.coli O157:H7)
In addition: ► hemolytic uremic syndrome ► kidney damage
Shigella dysenteriae
In Shigella dysenteriae this set of symptoms “diarrhea with blood” is combined with
intestinal cell invasion, apoptosis and neutrophilia (► “pus”) to define “dysentery”.
E.coli Virulence Factors
heat-labile enterotoxin “LT” Shiga toxin (AB-exotoxin cytotoxin):
Shigella dysenteriae Virulance Factors
Shiga toxin: bloody watery diarrhea
Ø Cell invasion ►neutrophils ► pus dysentery
Shigella dysenteriae are taken up by…..
M-cells
Shigella dysenteriae enters through
the inferior and lateral aspects of epithelium cells
Typhoid Fever
Salmonella
Salmonella Virulence
Type III
Salmonella invasion of intestinal epithelia
M cell uptake through ruffles: transport through epithelial layer.
• Electrolyte release to lumen (diarrhea/gastroenteritis).
• Release of inflammatory exudate.
• Transport to lymph nodes / transient bacteremia
Tranport to lymph nodes
Salmonella
Human Reservoir
Salmonella stored in gallbladder Typhoid May
Salt Tolerant
Found in Marine Enviroments
Vibro Cholerae
Vibro Cholerae
Virulance Factors
toxin co-regulated pilus (tcp): adhesion to small intestinal epithelia
Ø cholera toxin (heat-labile exotoxin “LT”): protein A causes cAMP rise + watery diarrhea
Ø an additional toxin “ST” can raise cGMP levels with a similar effect
toxin co-regulated pilus (tcp): adhesion to small intestinal epithelia
Vibrio cholerae
TCP production is induceed (..................), while production in other environments appears to be (....................)
TCP production is induced within the intestine, while production in other environments appears to be minimal
CTXφ (a bacteriophage)
Virbo cholerae
ctxA and ctxB encode the
proteins that comprise
cholera toxin
formalinized whole-cell vaccine:
several doses; partial protection for 2-3 yrs
Cholera Toxin
Common epidemic strain Vibro Cholerae
serovar O1
Vibro Cholerae O1 vaccine (India 1992) does not protect
O139 with capsule
Campylobacter Jejune
Growth in intestinal tract:
§ invade intestinal epithelial cells or
grow below epithelial layer.
§ inflammatory respons
Disease resolves without treatment in <1 week
Creates protective immunity
Campylobacter Jejune
Zoonosis: animal reservoir (intestinal)
Transmission: contaminated food (poultry, milk)
(e.g. in >89% of raw chicken)
Disease: gastroenteritis, diarrhea, dysentery
Campylobacter Jejune
