Powerpoint 7: Salmonella Flashcards
What is the optimum growth temperature?
35-37
But can grow at 5-54 (mesophilic)
Are they killed by pasteurization?
yes
Are they sensitive to low pH?
yes
What pH do they grow in?
4.5 - 9.5
What is the lowest aw they can tolerate?
0.94
What happens to heat resistance as water activity decreases?
Heat resistance increases (logic : when its hot, the tolerable water it can grow in decreases because heat removes water)
What can affect heat resistance?
Types of solute in food
Can cells survive in frozen and dried states for a long time? (ex: chicken nuggest, breaded chicken strips, chocolate)
Yes
What is the Aw like in chclate?
lw
Why can’t yu inactivate salmnella using heat?
-gives it a burned taste
lw aw makes the heat resistance even greater
Hw much time can salomonela survive in chcolaote?
years
How many species des the geonus have?
2 species
Salomnela enetrica is gruped int hw many subspecies?
six subspecies
Which subspecies is the nly onoe that causes disease in humans?
Salmonella enterica enterica
Hw many types fo serovars exist fr the subspecies s.enterica enterica
> 2000
Which 2 ser0vars are m0st c0m0nloy ass0ciated t0 f00dbrn illness?
Thyphymurium and Entiriditis
What is the meth0d to ser0type?
- reacti0ns with antisera
- wh0loe gen0me typing
Wh0 carries the ser0var Typhymurium?
-many pets, f00d animals
What can servara entiriditis infect?
-0varies 0f chicken -> infect the egg
meth0d t0 av0id sickness: highly c00king
H0w many h0urs after infecti0n d0 sympt0ms 0ccur?
8-72 h0urs
Is it self-limiting?
yes
D0es it have blo0dy diarhea?
n0
In h0w many days d0 sympt0ms res0lve?
5 days
What c0mplicati0n can happen in imun0c0mpr0mised individuals with n0n-typh0idal salm0nella?
- invasive disease
- bacteremia
- high m0rtality rate
Where d0es salom0nella remain lo0caloized?
intestinal tissue
What is resp0nsible f0r the sympt0ms 0f gastr0-entiritis?
h0st inflammat0ry resp0nse t0 invading pathgens
-> the number is n0t many th0ugh
Where d0 m0st salm0nella bacteria remain after infecti0n?
gastr0-intestinal lumen
Despite it being able t0 invade the cellos wh0 will clear s.typhymurium?
neutr0phils
where are the virulence fact0rs lo0cated?
SPAI
H0w d0es salom0nella survive the acidic pH 0f the st0mach?
-activates acid t0lerance resp0nse t0 maintain intracellular pH
what is enc0ded in SPAI 3 and 4 that all0ws adherence t0 epithelium?
adhesins
What are the 2 things enc0ded by SPAI 3?
1) MisL : binds fibr0nectin 0n epithelial cells
2) Mgt CB: intramacr0phage survival
Which things are enc0ded by SPAI 4?
c0ntains 0nly 6 ORF enc0ded in 0ne 0per0n.o
1)SiiE : mediates attachment t0 epithelial cells
What d0es SPI 1 enc0de?
A T3 SS : delivers a c0h0rt 0f virulence effect0r pr0teins int0 the h0st cell
What d0 the effect0rs secreted by SPI 1 d0?
2 manipulate h0st cell signalling pathway (i.e. inflammat0ry resp0nse)
#1 drive f0rce uptake 0f bacteria by n0n-phag0cytic cells -induce actin cytoskelet0n rearrangement in h0st, creating large pr0trusi0ns 0n membrane called ruffles
What are membrane ruffles?
result due t0 h0st cell rearanging actin cyt0skelet0n (due t0 effect0rs secreted by T3 SS)
What d0 ruffles d0?
engulf the path0gen int0 large vesicles called Salm0nella c0ntaining vesicles
What d0 salom0nella c0ntaining vesicles d0?
hoang 0ut near g0lgi apparatus t0 intercept vesicles and 0btain nutrients
What causes diarrhea?
H0st resp0nse and inflammati0n due t0 bacterial invasi0n 0f the intestinal cells
T/F in healthy individuals salom0nela c0ntaining vesicles can migrate t0 the bas0lateral side enter the bl00d and cause systemic infecti0n
F: this happens in immu0c0mpr0mised individuals
what is a type 3 secreti0n system?
- pr0tein appendage
- f0und in gram - bacteria
- needle like structure is used as a sens0ry pr0be t0 detect eukarytic cells
- can inject effect0r pr0teins (help survive + escape immune system)
What is pry0pt0sis?
highly inflamat0ry f0rm 0f pre-pr0grammed cell death
-in intracellular path0gens
Functi0n 0f SPI 1 genes ?
1) inhibiti0n 0f ap0pt0sis and macr0phage pry0pt0sis
2) stabilizati0n / lo0caloizati0n 0f actin filaments during invasi0n
3) adhesin 0f epithelialo cells
4) disrupti0n 0f actin cyt0skelet0n
Functi0n 0f SPI 2?
intrace//u/ar rep/icati0n
Functi0n 0f SPI 5?
cytskelet0n rem0de//ing + inducti0n 0f inflammat0ry resp0nse
- rendundant
- enc0des S0pE, S0p E2, Sig D
What causes gastr0intestina/ dysbi0sis?
inflammati0n
H0w d0es inflammati0n fav0r salom0nella gr0wth?
since respirat0ry electr0n accept0rs are 0ver pr0duced pr0vides an energetic gr0wth advantage t0 facultative anaer0bes loike salom0ne//a
What 0per0n d0es Spi2 enc0de, and what is its functi0n?
enc0des ttr 0per0n: a//0ws sa/m0ne//a t0 use tetrathi0nate as TEA, 0utgr0w anaer0bic c0mpetit0rs
Wh0 disrupts the tight juncti0ns?
intra and extra cellular path0gens
H0w are ruffling re/ated t0 tight juncti0ns?
pr0teins f0r ruff/ing are essential t0 alter tight juncti0ns
What 4 effect0rs are used t0 disrupt the tight juncti0ns?
Sip A, S0p B, S0p E and S0p E2 (research still 0ng0ing)
Are antibi0tics administered?
Yes if bl00d b0rn infecti0n
Why are strains resistant t0 antibi0tics?
Rutinely used in feed and godo animals and birds
T/F : Genes for virulence factrs and antibi0tic resistance can 0ccur 0n the same ploasmid
True
What is the difference bewteen thyph0id and n0n-typh0id?
Typhi / paratyphi : human restricted ; causes human fever
N0n tyhph0id (typhimuirum, entiriditis): br0ad range; causes gastr0-entiritis (abdminalo pain, inflammat0ry diarrhea, vmiting)
Gr0uped acc0rding t0 ser0var l00king at what?
- 0 antigen 0n LPS
- H antigen (flagellar)
T/F It is a leading cause 0f f00db0rn illness in humans?
True
What 2 0ther meth0ds can be used t0 gr0up it?
- wh0le gen0me sequencing
- pulsed field gel electr0ph0resis
Which ser0type can cause systemic inflammati0n in immun0cmpr0mised individuals?
typhi and parathyphi
Is antimicr0bial resistance a pr0blem?
yes!!
