Exam 3 Lecture 21 Flashcards
True or false: Salmonella has many polar flagella
False: peretrichous flagella
What types of food has Salmonella been carried in?
leafy green veggies, malt&meal, chicken pot pie, ice cream (dairy), peanut butter
True or false: rapid use of antibiotics have increased the number and frequency of multi-drug resistant strains of Salmonella
true
What are some commonalities between Salmonella and Yersinia? (6)
- gram-negative rods
- facultative anaerobes
- can cause enteritis and systemic disease
- both use T3SS encoded on pathogenicity islands
- both adhere to M-cells of Peyer’s patches
- both interact w/ macrophages
True or false: Salmonella is usually only found in poultry
false; ubiquitous organism (has been found in seeds and spices)
There are over ___ different types of Salmonella, and ___ are associated with humans and mammals.
2250; 1435
True or false: the vast majority of salmonella serotypes are found in cold-blooded animals
false - warm blooded
Salmonella does not form ___ and does not ferment ____. (also: what is one exception?)
spores; lactose
S. Arizona is an exception
___ formation in indicator media is used to differentiate Salmonella
H2S
What are 4 commonly used medias to isolate Salmonella?
- SS agar
- Hektoen
- XLT
- MacConkey
What surface markers in Salmonella can we use for serotype description? (2)
- H-antigen
2. O-antigen
S. Typhi contains __-____, which is a polysaccharide capsule
Vi-antigen
True or false: there is no vaccine available for S. Typhi
False - there are 2 (Ts21a live oral vaccine, Vi-antigen injectable)
How long does the Vi-antigen vaccine last?
1-1.5 years
___ ___ that are present in media inhibit the growth of __-___ organisms like streptococcus and staphylococcus
bile salts; gram-positive
S. Arizona can look like:
E. coli
Symptoms of non-typhoidal Salmonella infection
fever, abdominal cramps, diarrhea (sometimes bloody)
occasionally establish localized infection like septic arthritis or progress to sepsis
How is non-typhoidal Salmonella transmitted?
ingestion of contaminated food, water, or contact with infected animals
Non-typhoidal Salmonella affects which age group? Who is most at risk for severe disease?
affects all ages; most at risk include infants, elderly, immunocompromised
50% of all salmonellosis cases in the US are due to either: (3)
S. Typhimurium, S. Enteritidis, S. Newport
likely due to the way poultry operations are run
An estimated 1.4 million cases of non-typhoidal Salmonella occur annually in the US, but this number is likely ___-____
under-reported
True or false: Salmonella is an enteric pathogen, and all spp are capable of infecting a wide variety of vertebrate hosts.
False - not all of them. S. Typhi only infects/replicates in humans
Salmonella is a ____ ____ ____, so it can survive both intra/extracellularly
facultative intracellular pathogen
Non-typhoidal Salmonella serotypes cause:
enteritis and occasional systemic infection
Typhoidal Salmonella cause:
enteric fever with little enteritis
True or false: Regarding S. Typhi, diarrhea is a common symptom along with enteric fever
False, usually don’t get diarrhea (little enteritis) but you can get enteric fever
Salmonella cannot survive anything below pH __. Therefore, in order to cause infection, the bacterial dose has to be ___.
4.5; large
Infectious dose of Salmonella is reduced if you eat ice cream because:
milk proteins buffer stomach acid
When ingested, Salmonella travel to the ___ ___. Uptake of Salmonella is mediated by _-___ and ____ cells
distial ileum; M-cells; CD18+
Salmonella invasion into M-cells is mediated by ____
SPI-1
Salmonella SPI-1 encodes?
Type 3 Secretion System effector proteins
Once across the intestinal epithelial cell layer, Salmonella encounters ____ ___ in the ____ ___.
phagocytic cells; lamina propria
Survival of Salmonella in professional phagocytic cells is needed for ____ ____. ___ gene products are needed for this step.
systemic infection; SPI-2
In the intestine, Salmonella expresses ___.
SPI-1
In macrophages, Salmonella expresses ___.
SPI-2
True or false: Salmonella have over 7 pathogenicity islands. Some have a plasmid
True
What is a hallmark of pathogenicity islands?
High A/T content (higher than the rest of the chromosome)
True or false: Expression of island genes are tightly controlled by multiple regulatory systems
true
True or false: Island genes are required for in vitro growth
False
___ is required for virulence of Salmonella by the oral route of infection for animal models and humans.
SPI-1
SPI-2 encodes products that are injected into the cytoplasm of the ____ from inside the ____.
macrophage; phagosome
What do SPI-2 effector proteins do?
interrupt the formation of enzyme complexes, preventing the accumulation of toxic products in the phagosome containing Salmonella
What additional pathogenicity island does S. Typhi contain, and what does it encode?
SP17; encodes the Vi-antigen which is not found in other serotypes
When Salmonella is invading intestinal epithelial cells, it induces …..
ruffling of target cell membrane, which facilitates bacteria to invade into the cell
SPI-1 is needed to get into intestinal epithelial cells. What else does SPI-1 induce?
neutrophil migration
When neutrophils migrate to site of Salmonella entry, what happens?
inflammation increases, which messed up chloride/water secretion, which is responsible for diarrhea
SipA
needed for membrane ruffling by binding to actin filaments
SipC
nucleates the actin and causes condensation of the actin to form ruffles
SopD/B
act to promote chloride and fluid secretion
Presence of intracellular bacteria is sensed by ___-____ ___
TLR5-recognition pathway
Stimulation of TLR5 induces production of ___, which in turn stimulates the migration of ____ which causes ____ and ___ ___
IL8; neutrophils; inflammation; tissue damage
Salmonella reside in the ____ of infected macrophage
phagosome
Macrophages kill things via:
respiratory burst
What is a respiratory burst?
rapid release of H2O2 and other ROS which is meant to kill bacteria
Respiratory burst induces ____ ___ ___ that go on to damage __ and ___
secondary chemical compounds; DNA and protein
True or false: SPI-2 prevents peroxides from being deposited into the phagosome containing salmonella
True
Respiratory burst induces production of NO which is an ____
antimicrobial
True or false: dumping of peroxides is the main mechanism of directly killing bacteria
false - peroxides just slow growth while NO kills bacteria
True or false: proteins encoded on SPI-2 are easy to purify
False - very difficult because they’re meant to work from inside a membrane (they work inside to out)
Salmonella ____ resident microbiota in the gut
outcompetes
Salmonella use ____ and ____ as electron acceptors, thus grow even better in the presence of __
ethanolamine; tetrathionate; ROS
definition of enteritis
inflammation of the intestinal lumen and induction of neutrophils
definition of enteric fever
bacteria cross intestinal cell barrier and live in extra/intracellular sites
True or false: Salmonella-mediated enteritis is not due to a toxin or enterotoxin
True - mediated by SPI-1 gene products
Typhoid fever symptoms
fever, headache, constipation, malaise, chills, myalgia
Which symptom of Typhoid fever is unique compared to other Salmonella infection symptoms?
constipation
Where can S. Typhi be recovered from?
bloodstream, bone marrow, stool, urine
S. Typhi cases mostly occur among:
travelers
How long does S. Typhi illness last without treatment?
3-4 weeks with high death rate (12-30%)
S. Typhi is transmitted through:
contaminated water or food, especially street vended foods
True or false: almost all clinical isolates of S. Typhi produce Vi-antigen encoded on SPI-7
True
How does Vi-antigen function in immune evasion?
shields S. Typhi frmo stimulating TLR5 and TLR4 signaling pathways of the innate immune system
S. Typhi has over __ pseudogenes
200
pseudogene definition
nonfunctional sections of DNA that no longer express anything
Salmonella Typhi Infection Cycle (in order)
- ingestion of S. Typhi
- small intestine (leads to inflammation/ulceration)
- mesenteric lymph nodes
- transient bacteremia
- multiplication in macrophages
- gallbladder (which produces bile which circles back to small intestine)
Yersinia spp cause similar disease as ___
Salmonella
Which species of Yersinia are human pathogens and found in variety of animals and environments?
Y. enterocolitica; Y. pseudotuberculosis
Major animal reservoir of Yersinia
swine
Major source of Yersinia infection
- pork products, raw and undercooked chitterlings (small intestine)
- also milk products, turkey, chicken
True or false: swine frequently succumb to infection by Yersinia
false
Yersinia infection in humans mimics:
appendicitis
Y. enterocolitica is acuired by:
ingestion of contaminated food
Y. enterocolitica adheres to and invades:
M-cells of the Peyer’s patches (like Salmonella)
Y. enterocolitica grows in:
regional lymph nodes, spleen, liver
True or false: Y. enterocolitica commonly causes septicemia
False
Which people are more susceptible to Y. enterocolitica mediated septicemia?
Immunocompromised people, people who are iron-overloaded, those who are being trated with deroxamine (iron chelation)
Yersinia has ___ secretion system
Type 3
True or false: once Yersinia has infected, they grow within macrophages
false - they grow extracellularly
True or false: Y. enterocolitica can survive and resist antibody mediated killing
true
Yersinia Virulence factors
- invasin
- Yops
- Yersiniabactin
Function of Yersinia invasin
facilitates uptake by host cells
Function of Yersinia Yops
produced on virulence plasmids, secreted into host cells via T3SS to disrupt host macrophage function and keep Yersinia from being phagocytosed
Function of Yersinia Yersiniabactin
siderophore that binds and transports extracellular iron into the cell
YopE and YopT
depolymerizes actin
YopO
phosphorylates host proteins & disrupts cell signaling
YopH
dephosphorylation of signal transduction proteins
YopP
inhibits macrophage apoptosis and prevents TNF-alpha release
Yersinia infection can lead to:
abscesses in the intestines at the M-cells
True or false: temperature, calcium, and iron levels regulate virulence gene expression for Yersinia
true
