Salmonella + Shigella Flashcards
(25 cards)
Does Salmonella ferment lactose?
no
How can you identify a lactose negative bacteria
MacConkey or EMG agar
Three important characteristics of ALL enterbacteriaceae
1) ferment glucose
2) oxidase negative
3) reduce nitrate
Does Salmonella produce H2S?
yes
Is Salmonella motile?
yes
Is Salmonella urease negative or positive?
negative
Is Salmonella indole negative or positive?
negative
What is the most common species of shigella in the developing world?
dysenteriae
18% of shigella in the US are of this species:
flexneri
most common shigella species in the US
sonnei
a common shigella species on the indian subcontinent
boydii
how is shigella spread?
food, fingers, feces, flies
is there bacteremia in shigella?
rare
symptoms of shigella
- fever
- diarrhea
- bloody diarrhea with mucus
- abdominal cramps
- hemolytic uremic syndrome
what is the infectious dose of shigella
10-100 organisms
shigella incubation period
1-4 days
explain the pathogenesis of shigella
- invade intestine in terminal ileum and colon
- uptake by macrophages (T3SS dependent)
- escape and cell to cell spread (T3SS indep)
- apoptosis of macrophage
- IL-1 and TNF from monocytes lead to fever
- shiga toxin causes intestinal ulcerations
- shiga toxin subunit A interferes with 60S ribosomal RNA inhibiting protein synthesis
can shigella be diagnosed based on clinical symptoms?
no
does shigella produce gas with glucose fermentation?
no
does shigella ferment lactose?
no, like all other enterobacteriaceae
does shigella produce H2S?
no
is shigella motile?
no
shigella negative or positive for indole? urease?
negative for both
what antigens does shigella possess?
O only.
