Exam 3 (Enteric Bacteria) Flashcards
Are enteric bacteria G- or G+?
G-
What does the H antigen do for enteric bacteria?
peritrichous flagella = motility
Shigella, Klebsiella, and Yersinia are all ___________ enteric bacteria.
non-motile
K and Vi antigens on ___________ bacteria form a _________.
- enteric
- capsule
What enteric bacteria species have a capsule?
Klebsiella, enterobacter, E. coli
ALL enteric bacteria have ______ with enterobacterial common antigen and serotype-specific __ _______.
- LPS
- O antigen
Cholera toxin causes….
watery diarrhea
Shiga toxin causes…
blood in diarrhea
Pathogen E. coli strains that cause inflammation and neutrophils in the stool cause…
puss in diarrhea = dysentery
What is heat-stable enterotoxin?
LPS
What structures form the enterobacterial common antigen?
The outer and inner core sugars of LPS
What is the Type III secretion system?
20 protein system that looks like a short, hollow flagellum to inject a variety of species specific toxins into host cells
A translocated intimin receptor is inserted via….
Type III secretion system
Escherichia coli are G+ or G-?
G-
E. coli is spread in what three ways?
- person-to-person
- contaminated food
- human and animal feces
What is the mechanism of action of E. coli’s heat-labile enterotoxin?
- ADP-ribosylation of G protein
- incr cAMP
- loss of water + electrolytes
- watery diarrhea
Mechanism of action of E. coli’s shiga toxin?
- inactivation of 60s ribosome subunit by removal of adenine base from nucleotide of 28s rRNA
- stop translation
- cell death
- bloody diarrhea
Symptoms of enterohemorrhagic E. coli (EHEC) and treatment?
Symptoms: bloody diarrhea, hemorrhagic colitis, hemolytic uremic syndrome
Tx: replenish fluids antibiotics contraindicated
Symptoms of Uropathogenic E. coli?
cystitis (bladder infection)
What is responsible for 70-90% of bladder infections?
E. coli
What are the virulence factors of Shigella dysenteriae?
- Shiga toxin: bloody/watery diarrhea
- Cell invasion: neutrophils = pus
Epidemiology of shigella dysenteriae?
fecal-oral route (fecally contaminated food/water, humans usually only source
What are the 5 Steps of Shigella dysenteriae infection?
- shigellas taken up by M cells, taken up by macrophages that die and release them
- shigella enter epithelial cells via endocytosis and lyse endosomes
- actin filament tails push shigella into next cell
- shigellas multiply
- infected cells die, acute inflammatory response from neutrophils, apoptosis and abscess formation
What salmonella strain causes typhoid fever and has a high mortality?
S. enterica
4 virulence factors of Salmonella/
- Type III secretion system
- intracellular endosome growth in macrophages (prevents fusion of pagosome + lysosome)
- invasive into diff tissues and organs via macrophages
- destruction of Peyer’s Patches (intestinal rupture)
What bacteria is known to destroy Peyer’s Patches and cause intestinal rupture?
Salmonella
4 Steps of Salmonella invasion?
- M cell uptake through ruffles
- electrolyte release to lumen (diarrhea/gastroenteritis)
- release of inflammatory exudate
- transport to lymph nodes/transient diarrhea
Be able to draw diagram of Typhoid Fever Pathogenesis from 3.6 - Slide 14
3.6 - Slide 14
Is Enterobacteriaceae G+ or G-?
G-
ID: gram- curved rods, salt tolerant, found in marine environments
Vibrio cholerae
How do vibrio cholerae adhere to cells?
toxin co-regulated pilus (tcp)
How do vibrio cholerae cause diarrhea?
heat labile exotoxin: protein A causes cAMP rise
OR
ST (toxin) raises cGMP levels with similar effect
What does neurminidase do?
incrases cholera toxin binding
TCP production by cholera is only produced….
in the intestine
What genes encode the proteins for cholera toxin?
ctxA and ctxB
What is the common epidemic strain of cholera?
serovar O1
What was the new strain that started the newest cholera pandemic in the 90’s? Did the O1 vaccine protect?
- serovar O139 with a capsule
- no
4 virulence factors of Vibrio cholerae?
- cholera toxin
- toxin-coregulated pili
- toxins
- neuraminidase
How is V. cholerae self limiting? What is the treatment?
- intestinal cells with surface bacteria are shed
- rehydration + electrolytes
What bacteria can be spread by undercooked coastal crabs?
V. cholerae
Where does Campylobacter jejune grow?
-inside or beneath intestinal epithelial cells
Is campylobacter G+ or G-? What is its shape?
- G-
- vibrio (curved), short S or comma shaped rods
What is the reservoir of C. jejune? Transmission? Diseases (3)?
- zoonotic (intestinal**)
- contaminated food (>89% poultry), milk
- gastroenteritis, diarrhea, dysentery
What is the treatment for Campylobacter jejune?
NONE
-disease resolves in about 1 week and get protective immunity
