L49 Flashcards
Salmonella GN or GP Motile? Grow on MacConkey Lactose -/+ Glucose ferment yes or no?
GN Motile b/c of flagella Yes on MacConkey Lactose - No glucose fermentation
How are salmonella strains typed?
O & H antigens = serotyping
Salmonella transmission
Food (undercooked chicken)
- For all types of salmonella disease this is true (w/ or w/o GI symptoms)
Cold blooded animals - turtles
What are the 2 classifications of salmonella? Diseases caused by each.
Non-typhoid = inflam diarrhea
- Issue in AFRICA where causes bactermia in kids!!
Typhoid = typhoid fever, life threatening
Treatment for salmonella food poisoning
NONE
Which patients should you worry about if they get non-typhi salmonella food poisoning?
Immunocompromised - may progress to systemic bacteremia
Which strains of salmonella cause typhoid fever?
S. typhi
S. paratyphi
Typhoid fever clinical presentation
Look sick
Rose spots on stomach
Constipation - pea soup diarrhea (not prominent feature)
How can you be a carrier of salmonella?
Asymptomatic if carried in gall bladder
- Remove gall bladder = no longer a carrier
Typhoid Mary
Complications of untreated typhoid fever
Intestinal hemorrhage –> death
How do you treat typhoid salmonella?
Indicated but unclear due to multidrug resistance
What is the salmonella vaccine?
Vs. s.typhi strain
- Oral, live attenuated
- Polysaccharide of Vi capsule
Where does a salmonella infection start in the body?
SI
Non-typhoid - stops here, causes GI symptoms
Typhoid - invades mucosa –> circulation
How does typhoid salmonella get into the SI mucosa?
T3SS (SPI 1)- changes actin –> induce own update
A different T3SS (SPI 2) X PL fusion
Multiple inside protected phagosome
Escape –> inflammation
Which type of salmonella do you see significant inflammation (vs. minimal)?
Non-typhoidal
Does this via surface LPS & flagella
Which type of salmonella do you see large neutrophil response?
Non-typhoidal
What virulence factors are unique to typhoid salmonella?
Vi capsule - decreased inflam response (why typhoid has little inflam)
- Prevents interaction of LPS w/ host PRRs
Can downregulate flaeglla
Why is it adventageous that salmonella cause some inflammation?
Competitive advantage
Can secrete lipocalin to inhibit host antimicrobial peptides
BUT normal gut flora can’t!
Salmonella > other gut microbes
Shigella GN or GP Shape Motile? Grow on MacConkey Ferment lactose? Ferment glucose?
GN Rods Non-motile Grow on MacConkey NO lactose fermentation YES glucose fermentation (Same GN flowchart path as salmonella)
What is unique about how shigella is transmitted?
SMALL infectious dose
Therefore, transmitted person-person via fecal-oral
Symptoms of shigella infection
- Abdominal cramps
2. Dysentery = mucous, bloody diarrhea w/ WBCs
What are the complications of untreated shigella?
Colitis –> hemorrhage
Malnutrition –> cognitive defects in kids
Rectal prolapse
Reiter’s syndrome
Shigella pathogenesis
Infects M cells sampling lumen contents Into macrophages --> kills them - Via T3SS Apoptosis triggers inflam rxn (IL 8) Invades other GI epithelial cells from BL side via vacuoles --> use host cell actin to move and infect neighboring cells
What surface protein does shigella use to infect cells from BL side?
VirG
Where are most of shigella’s virulence factors contained? What virulence factor is it lacking?
VF on plasmids + PI in chromosomes
Lacking Avl –> why this strain is so pathogenic vs E.Coli which still has this gene
Treat shigella infection
Fluids
Antimicrobials can be helpful - but immune system will eventually clear the bug, question is how long/how severe are symptoms
Which strain of shigella is more virulent than the others? Why?
S.dysenteriae
+ shiga toxin –> cleaves host rRNA
Associated with HUS complications in kids
Why does s.dysenteriae often become epi/pandemic?
No baseline level of immunity for this
