Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
43 Cards in this Set
- Front
- Back
|
What is the structure of Salmonella?
|
It is a gram negative rod that is flagellated and thus highly motile.
|
|
|
What are some special characteristics of Salmonella bacteria?
|
It is lactose negative and H2S producing
|
|
|
What antigen is used to determine Salmonella serotypes?
|
O antigen (LPS)
|
|
|
What is special about S. typhi?
|
It contains a Vi capsule (other Salmonella are NOT encapsulated)
|
|
|
What type of media is Salmonella grown on?
|
Hectoen Enteric agar- this is a selective and differential agar. It will turn Salmonella blue-green (indicating it is a nonlactose fermenter) and generates black centers in the colonies (indicating it produces H2S)
|
|
|
What are the 2 species of Salmonella?
|
S. bongori and S. enterica
|
|
|
Within the S. enterica species that are 6 subspecies. What are these?
|
subsp. enterica, subsp. arizonae, subsp. diarizonae, subsp. houtenae, subsp. indica, and subsp. salame.
|
|
|
Which subspecies of Salmonella enterica are found within cold blooded animals and the environment?
|
subsp. arizonae, subsp. diarizonae, subsp. houtenae, subsp. indica, and subsp. salame.
|
|
|
Which subspecies of Salmonella enterica is found in humans and warm-blood animals and what are some of its characteristics?
|
Subsp. enterica can infect humans and warm-blood animals. There are MANY different serotypes with different O, H and K antigens. One example of the Typhimurium serotype.
|
|
|
How is Salmonella usually transmitted?
|
It is a foodborne illness. It is common in dairy products. it is transmitted through fecal contamination.
|
|
|
Within the US, where has Salmonella infections been seen?
|
Almost EVERYWHERE
|
|
|
What is the full name of Salmonella typh?
|
S. typhi is Salmonella enterica subsp. enterica serotype Typhi
|
|
|
What 3 diseases are caused by Salmonella?
|
Gastroenteritis, Focal systemic infections and Typhoid fever
|
|
|
What are some characteristics of Gastroenteritis caused by Salmonella?
|
It can result in nausea, vomiting and diarrhea. A VERY high dose of the bacteria is needed to cause disease due to the bacteria being acid-sensitive (stomach acid is protective). It is a self-limited disease. It is most often caused by S. enteritidis.
|
|
|
What species and subspecies do most pathogenic Salmonella belong to?
|
Salmonella enterica enterica (ALL Salmonella bacteria we talk about are a part of this group just different serotypes)
|
|
|
What are some focal systemic infections caused by Salmonella?
|
Endocarditis and Osteomyelitis.
|
|
|
Which serotype of Salmonella enterica enterica usually cause focal systemic infections?
|
S. Typhimurium and S. choleraesius
|
|
|
What are some characteristics of typhoid fever caused by Salmonella?
|
It is a systemic infection with bacteremia. It causes damage to the tissue and can be carried for a long time.
|
|
|
What serotypes of Salmonella enterica enterica usually cause typhoid fever?
|
S. typhi and S. paratyphi.
|
|
|
What are the 2 ways the bacterial group S. enterica is split up clinically?
|
Typhoid and non-typhoid Salmonella
|
|
|
What is the bacteria in the Typhoid class of Salmonella and what does it cause?
|
S. Typhi is considered a typhoid Salmonella and it causes Typhoid fever which is a systemic syndrome with enteric fever.
|
|
|
What type of disease is common for non-typhoid Salmonella to cause?
|
Diarrhea with inflammation
|
|
|
What are some characteristics of S. Typhi and the disease it causes?
|
S. typhi causes Typhoid fever which is a systemic syndrome. Diarrhea is not a prominent feature of this disease. The bacteria can cause disease ONLY in humans and can be carried in humans asymptomatically. It It is a MAJOR world health problem and causes mortality and morbidity.
|
|
|
What was done to the water supply that greatly reduced the amount of Typhoid fever in the US?
|
The water was chlorinated
|
|
|
What are some main differences between typhoid and non-typhoid Salmonella?
|
Non-typhoid Salmonella is acquired by ingestion just like S. typhi (they are foodborne or fecal-oral transmission pathogens)
Unlike S. typhi, non-typhoid Salmonella has animal hosts, causes a self-limiting diarrhea disease, and should NOT be treated with antibiotics. |
|
|
What is the pathogenesis of Salmonella bacteria?
|
They are ALL invasive and inflammatory. They get into the epithelial cells and can get into the blood.
The infection begins in the small intestine. Non-typhoid Salmonella stops there whereas S. typhi passes through the mucosa to enter the systemic circulation. They are ALL GREAT at evading the immune response. |
|
|
How does Salmonella get engulfed by host cells?
|
They are engulfed via cell ruffling of the host cell. It binds to the host cell membrane and causes the transient disruption of the host cell membrane by injection of protein through a Type III secretion system #1. This affects actin dynamics and causes the host cytoskeleton to rearrange and generate the ruffling that engulfs the Salmonella into the host cell where it remains in a vacuole in the cytoplasm. Some of the toxins/proteins injected affect actin, the plasma membrane and activate GTPases.
|
|
|
Where is Salmonella found within host cells and how does it get its toxins into the host cell?
|
Salmonella are found within vacuoles in the host cell and use a Type III secretion system #2 to inject their toxins into the cytoplasm.
|
|
|
What are the virulence factors of Salmonella?
|
Salmonella has 2 Type III secretion systems encoded on a pathogenicity island. Type III secretion system #1 is required for bacterial uptake into the host cell. Type III secretion system #2 is required for intracellular survival and immune evasion within the host cell (it results in vacuolar remodeling and prevents lysosomal fusion to the vacuole).
Salmonella has virulence regulators (turn on virulence genes once the bacteria is inside the host cell) and adherence fimbriae. ONLY Salmonella Typhi has a Vi capsule. |
|
|
What is one main way (with regards to DNA content) that Salmonella and E. coli differ?
|
Salmonella and E. coli have about 85% of their genome that is the SAME. Salmonella has many more pathogenicity islands than E. coli though that encode for its unique traits.
|
|
|
Once inside the host cell, what is the pathogenesis of Salmonella?
|
It multiples within the vacuole. Then the bacteria escape and infect other cells via leaving the epithelial cells out of the basolateral side.
|
|
|
What doe Salmonella do to the host cell machinery?
|
It utilizes it to do what it needs to survive.
|
|
|
What is the effect of S. typhi on the innate immune response and does S. typhimurium have the same effects?
|
S. typhi can blunt the local innate immune response that keeps the infection within the gut allowing it to become a systemic infection. No, S. typhimurium cannot do this.
|
|
|
What are the following traits for S. typhimurium:
Reservoir? Incubation period? Disease? Host cells recruited? Type III secretion system? Microbe-associated molecular patterns? Capsule? |
S. Typhimurium:
Reservoir= animals Incubation period= 1-3 days Disease= local, self-limiting Host cells recruited= neutrophils Type III secretion system= YES Microbe-associated Molecular patterns= flagellin and LPS Capsule= NO |
|
|
What are the following traits for S. typhi:
Reservoir? Incubation period? Disease? Host cells recruited? Type III secretion system? Microbe-associated molecular patterns? Capsule? |
S. Typhi:
Reservoir= humans Incubation period= week Disease= systemic, chronic Host cells recruited= monocytes Type III secretion system= YES Microbe-associated Molecular patterns= flagellin and LPS Capsule= YES |
|
|
What are the similarities between S. typhi and S. typhimurium?
|
Both S. typhi and S. typhimurium have Type III secretion systems and have microbe-associated molecular patterns (flagellin and LPS).
|
|
|
What is the effect of Salmonella on macrophages?
|
Macrophages can recognize Salmoneall via their Toll-like receptors. LPS interacts with TLR4 and Flagellin interacts with TLR5. It results in chemokine production, phagocytosis of the bacteria into the macrophage (which is not killed by the bacteria), PMN recruitment, the eventual development of an adaptive immune response by T cells, and resulting macrophage activation.
|
|
|
What are some of the features of disease caused by S. typhimurium?
|
S. typhimurium causes acute enteritis. It results in an inflammatory infiltrate that is primarily PMNs. It causes the necrosis of the uppermost mucosa in the terminal ileum and colon resulting in bloody diarrhea.
|
|
|
What are the mechanisms that cause disease used by S. typhimurium?
|
S. typhi's virulence factors Type III #1 secretion system, LPS and flagellin bind to TLRs and NODs and result in the production of proinflammatory mediators. Fluid is lost due to the host inflammation (NOT due to chloride secretion) and the host response results in damage to the tissue.
|
|
|
What can S. typhi cause disease-wise in an individual after ingestion?
|
After ingestion S. typhi is in the small intestine. It can cause inflammation resulting in diarrhea, hemorrhage and potential perforation of the gut. From the small intestine it can infect the lymphatics and cause swollen lymph nodes. It can travel into the blood and cause bacteremia. From there it can get inside macrophages within the liver, spleen and bone marrow and multiply. It can lead to septicemia which results in fever and infection of organs throughout the body. Finally it can get into the bile and then into the gallbladder causing cholescystitis. It can remain in the gallbladder and result in patients that are carriers of this bacteria.
|
|
|
What happens when Salmonella is put in bile?
|
It secretes a polysaccharide matrix and forms biofilms on gallstones. Thus, people with gallstones are MORE LIKELY to be carriers of Salmonella. The adherence of the bacteria to a solid surface likely prevents its flushing from the body.
|
|
|
Where does Salmonella infect the body?
|
It attaches to epithelial cells in the small intestine.
|
|
|
What type of host response does Salmonella cause?
|
Inflammation and an influx of PMNs
|
