5 - Salmonella and Shigella Flashcards
Are Enterobacteriaceae gram positive or gram negative?
Gram negative
What shape are Enterobacteria?
Rod
How do Enterobacteria respire?
Facultative aerobes
What are 3 examples of Enterobacteria?
- Salmonella
- Shigella
- E. coli
Are Enterobacteria oxidase positive or negative?
Oxidase negative
Are Enterobacteria catalase positive or negative?
Catalase positive
How do Salmonella and Shigella enter host cells?
Using Type III secretion system to deliver bacterial effector proteins into host cytosol
Bacterial effectors trigger host cytoskeletal reorganisation engulfing the bacteria
What bacterial effectors destabilize phagosome in Shigella?
TTSS, IpaB and IpaC
What bacterial effectors are present in Salmonella?
SPI-1 and SPI-2
How does Shigella cause actin polymerisation for motility?
- IcsA binds and activated N-WASP
- N-WASP activates Arp2/3 complex resulting in actin polymerisation
What are the exotoxins of Salmonella and Shigella?
Shiga toxin
Shigella enterotoxins - ShET1 and ShET2
Salmonella enterotoxin
Why does salmonella stimulate the inflammatory response but S. Typhi doesn’t?
Salmonella LPS triggers inflammatory response
S. Typhi masks LPS with Vi antigen on capsule
What metabolism gives salmonella a selective advantage in the host gut?
Tetrathionate metabolism
What antibiotics are used to treat Salmonella and Shigella?
Salmonella: Ceftriaxone
Shigella: Ciprofloxacin
What antibiotics are used to treat S. Typhi
Resistance uncommon: Ciprofloxacin
Resistance common: Cefotaxime
