7 - Salmonella Enterica Flashcards
What is a typical Salmonella outbreak?
Raw egg ziti pasta dish, temperature-abused
Salmonella enterica characteristics:
- gram -
- non-sporulating
- facultative anaerobe
- motile rods
What is the optimal temperature for Salmonella to grow?
Between 35-37C, but they have a growth range of 5-54C
Is salmonella easily killed by pasteurization?
Yes and salmonella is sensitive to low pH
Salmonella can grow between what pH range?
4.5-9.5
Salmonella does not multiply below Aw of ______
0.94
___________________ increases as the water activity decreases
Heat resistance
Cells can survive under _____________ states for a long time (chicken nuggets, breaded chicken strips, and chocolate can cause outbreaks)
frozen or dried
T OR F: It is the only pathogen directly referred to by name in the Canadian Food and Drugs Act
T
Why you cannot inactivate salmonella in chocolate by using heat?
The heat required to kill salmonella at the low water activity present in chocolate (high sucrose) would burn the sucrose containing chocolate
In the low aw in the chocolate, Salmonella can survive for ______ at room temperature
years
________________ is the only one to cause illness in humans
Salmonella enterica subsp. enterica
There are >2000 serovars of this subspecies based on the presence of ________________________ antigens
somatic, flagellar, and capsular antigens
Which serovars of Salmonella are most commonly associated with foodborne illness:
Serovars:
- Typhymurium
- Enteritidis
What is Salmonella Enterica serotyping:
making antibodies react with the different antigens present on the salmonella: flagella, somatic, capsule
T or F: Salmonella can be transmitted to humans via poultry animals or pet turtles
T
Serovars of Salmonella are generally named after the ______________
geographic origin
T or F: For the cases of recalls, if it has Salmonella present it is generally considered infectious
T
Many food animals and pets harbor serotype __________________ as carriers
Typhimurium
Serotype __________ can infect the ovaries of poultry and can be transmitted through eggs and undercooked poultry
Enteritidis
Name other vehicles of Salmonella infection:
- fish and shellfish
- fruits and vegetables
Talk about the symptoms and treatments associated with Salmonella:
- Symptoms generally occur 8-72 hrs after ingestion
- Illness is self-limiting, non-bloody diarrhea, and abdominal pain
- Symptoms generally resolve within 5 days
- Uncomplicated cases only require supportive therapy, such as fluids and electrolytes replacement
- Antibiotics prolong carrier state and increase AMR so they are not generally used
T or F: In immunocompromised people, non-Typhoidal Salmonella infection can manifest as an invasive disease, characterized by bacteremia and a high mortality rate
T
Salmonella invades phagocytic __ cells and non-phagocytic _________ cells
M intestinal epithelial (adheres to intestinal cells via fimbriae
Once across the epithelium,Salmonellacan efficiently invade further epithelial cells from the ______________ side
basolateral
Salmonellausually remain localized to ____________, where the host’s _______________ to the invading pathogen is responsible for the symptoms of ____________
intestinal tissues
inflammatory response
gastroenteritis
Although,S. ser. Typhimuriumcan survive and replicate within macrophages, the invading sub-population will eventually be cleared, likely by host __________.
neutrophils
*However, when this fails, ex in the immunocompromised, systemic spread, and bacteremia can occur
________________ contain the virulence factors that Salmonella requires during infection
Salmonella pathogenicity islands (SPIs)
What type of foodborne illness is Salmonella?
An infection
After ingestion Salmonella activates its _____________ to maintain intracellular pH in the acidic stomach
acid tolerance response
____________ increases the chance of encountering the epithelium
Motility via the Flagella
Explain the SPIs virulence factors adhesion and invasion:
1) When it gets to the epithelial cells SPI-4 secretes attachment proteins (T1SS) that allows for attachment + adherence to epithelial cells
2) SPI-1 encodes T3SS that inject effectors into eukaryotic cells, causing membrane ruffling which engulfs salmonella cells and allows the endocytic pathway to take fold and to ingest salmonella
3) Salmonella is contained inside a vacuole that can survive inside the cells in a number of ways
4) SPI-2 encodes a lot of genes that are needed for the survival inside the epithelial cells
SCV hangs out near the _________ apparatus to intercept vesicles and obtain nutrients
Golgi
T or F: Host response and inflammation due to bacterial invasion of the intestinal cells, caused by the immune-system leads to diarrhea
T
__________________ is a protein appendage found in several gram negative bacteria
T3SS or injectisome
What are the 2 SPI-1 genes involves in adhesion to epithelial cells:
SipB
SipC
What is pyroptosis:
a highly inflammatory form of programmed cell death that occurs most frequently upon infection with intracellular pathogens and is likely to form part of the antimicrobial response
AvrA is a SPI-1 gene that targets JNK and _________________
inhibits macrophage pyroptosis, so cells infected with salmonella don’t get killed as they should
______ is important for intracellular replication (epithelial cells and macrophages) inside the SCVs
SPI-2
What are the 2 SPI-2 genes that are important:
SSEF
SSEG
they promote SCV perinuclear migration
SPI-5 encodes SOPE2, SOPE and SigD that lead to cytoskeletal remodeling and induce the ____________ response
proinflammatory
Inflammation results in gastrointestinal _________
dysbiosis
Neutrophils release reactive oxygen species which react with thiosulfate in the gut to form a new electron acceptor:
tetrathionate
SPI-2 encodes the ____ operon which allows Salmonella to use ______________ as a terminal electron acceptor, this allows Salmonella to outgrow its anaerobic competitors
ttr
tetrathionate
How does Salmonella induce diarrhea?
Once Salmonella binds to epithelial cells and injects all the effectors that lead to actin rearrangement, tight juctions get disrupted because of actin rearragement and water is rushed out of the epithelial cells of GI tract and goes to the intestinal lumen = diarrhea
T or F: the genes for the virulence factors as well as for antibiotic resistance can occur on the same ______
plasmid
What are the 2 serovars associated with typhoid salmonella (human restricted): ______________
typhi and parathyphi
What is the difference between non-typhoid and typhoid salmonella
typhoid salmonella causes enteric fever and non-typhoid causes gastroenteritis
What are the 2 serovars associated with non-typhoid salmonella (broad-range): ______________
typhomurium
enteriditis
While non-typhoid Salmonella mostly stays in the _________________ Typhoid spreads wider and results in ______________________
gastrointestinal tract
systemic illness
Salmonella is spread via the _________________
fecal-oral route
An _____________________ state generally follows the active infection of typhoid salmonella
asymptomatic carrier
-allowing transmission from human-to-human
Name 2 antibiotics that can be used for typhoid salmonella in immunocompromised patients:
- ampicillin
- chloramphenicol
T or F: Salmonella enterica is the leading cause of foodborne bacterial illness in humans and is mostly linked to poultry and egg consumption
T
T or F: Salmonella are generally grouped according to serovar, based on antibody reactions with somatic (O) antigen (LPS), and the flagellar (H) antigens
T
