Salmonella Flashcards
What are the two possible modes of transmission of Salmonella?
Fecal-oral
Respiratory route
What are the three possible manifestations of a Salmonella infection?
Enteritis resulting in diarrhea
Septicemia
Nothing!
Name the host-adapted strain of Salmonella which is ONLY seen in humans
Salmonella typhi
How do is typhoid (disease of Salmonella typhi) transmitted?
Fecal-oral
Mostly a water-borne infection in the developing world
In older human women what disease is generally associated with infection of Salmonella typhi?
Biliary diseases (cholecystitis and cholelithiasis)
Disease is characterized by septicemia and enteritis whereby the biliary tract is persistently seeded
What is the Salmonella which is generally associated with swine?
This Salmonella contains a host-restricted and host-adapted strain which is which?
Salmonella choleraesuis kunzendorf variety
Host-restricted: Salmonella choleraesuis kunzendorf variety
Host-adapted: Salmonella choleraesuis non-kunzendorf variety
What diseases are generally seen with Salmonella choleraesuis kunzendorf variety?
Respiratory disease
Button ulcers of the intestines (see photo)
What is the host-adapted strain of Salmonella found in cattle?
Salmonella dublin
What clinical signs are associated with Salmonella dublin?
Septicemia and enteritis (pseudomembranosis colitis) (leading to hemorrhagic enterocolitis)
What are the HOST-ADAPTED strains of Salmonella found in poultry?
- Salmonella gallinarum*
- Salmonella anatum*
- Salmonella arizonae*
What is the HOST-RESTRICTED strain of Salmonella found in chickens?
Salmonella pullorum
What clinical sign can be seen with an avian infected with Salmonella pullorum?
Bacillary white diarrhea
What clinical sign can be seen with an avian infected with Salmonella gallinarum?
Fowl typhoid
What clinical sign can be seen with an avian infected with Salmonella anatum?
Keel disease in ducklings
What clinical sign can be seen with an avian infected with Salmonella arizonae?
Septicemia
Salmonella can be found in the normal flora of what species
Reptiles (esp. turtles)
This is the reason pet stores cannot cell turtles under certain sizes for fear of children placing them in their mouths
Host specificity of Salmonella occurs because of two reasons what are they?
Adherence of Salmonella to host epithelial cells
Ability of Salmonella to survive inside macrophages
What Salmonella is the most common cause of salmonellosis in mammalian hosts
Salmonella typhimurium
_________ is with in the normal gut flora of poultry so is allowed in small numbers in USDA inspection of poultry. But is not allowed during inspection of other meats (beef, pork)
Salmonella typhimurium
What is a Strain DT104 Salmonella?
A multiple antibiotic resistant gene which has been inserted into Salmonella
Which was acquired by a phage through one INTEGRON
Why is Salmonella Strain DT104 more virulent in cattle?
Because of the integron associated multiple antibiotic resistance as well as, the protozoa within the rumen which help select for more the more virulent Salmonella leading to reduced competition for binding sites.
What serovars has strain DT104 been found in?
- Salmonella typhimurium*
- Salmonella choleraesuis*
- What is the broad range Salmonella which is the second most common serotype isolated from human cases?
- How is it contracted?
- Salmonella enteritidis It is within the normal flora of chickens and resides inside the ova.
- It is contracted by the consumption of raw or undercooked eggs
What are the three mechanisms of Salmonella virulence?
Intestinal colonization
Invasion of intestinal cells
Diarrhea
What cell type do Salmonella prefer to adhere to and why?
M cells
They prefer M cells because they contain shorter and less dense glycocalyx and do enterocytes.
Think of the parachuting into the forest analogy
Briefly explain Salmonella’s mechanism invasion of intestinal cells
Salmonella attach to the outside of M cells –> they then release bacterial proteins –> these proteins rearrange actin w/in the plasma membrane –> invasion of the plasma membrane by Salmonella
True or False
Salmonella are not able to invade plant cells because of the lignin within in the cell wall prevents bacterial rearrangement and subsequent entry
False!
Salmonella can also invade plant cells and form a “ruffle” after the rearrangement of actin. They then will reside within a plant cell and await ingestion by a mammal or bird
Briefly explain how Salmonella causes diarrhea
Salmonella attach to the outside of M cells –> they then release bacterial proteins –> these proteins cause inflammatory process to occur within the cell and results in fluid and electrolyte loss
How do normal flora help in the prevention of salmonellosis?
Normal flora compete for receptor binding sites
Normal flora also produce compounds which inhibit/kill Salmonella
List the ways one can diagnose Salmonella
Fecal culture for enteritis
Spleen culture for septicemia
Immunodiagnostics (serogrouping and serotyping)
Diagnosing a Salmonella serovar using immunodiagnostics serogrouping is based upon what part of the Salmonella?
The O-antigens on the surface
Diagnosing a Salmonella serovar using immunodiagnostics serotyping is based upon what part of the Salmonella?
The H antigen flagellar
Define a monophasic and diphasic H antigen
Monophasic H antigen can either have phase 1 OR phase 2 flagellins
Diphasic H antigen can make BOTH phase 1 and phase 2 flagellins
Immunity to Salmonella is mostly ______ and is generally ______
Immunity to Salmonella is mostly CMI and is generally LIFELONG
What does SRP stand for and how do these vaccines act?
Siderophore receptor protein (SRP) vaccine.
Act by causing antibodies to be made against SRP. Resulting in an anamnestic response during infection which STOPS THE IRON INTAKE into Salmonella. Leading to the death of the Salmonella.
Why are killed bacterins not as effective against Salmonella?
They generally do not elicit a CMI response and the epitopes are usually the O antigens. The O antigens are serogroup-specific leading these killed bacterins bacterins to be monovalent.
Salmonella can also readily shed its O antigens if needed removing the Ab against them.
List two other preventative methods besides vaccination which may be effective against salmonellosis
LPS toxoid
Defaunation (elimination of rumen parasites)
Extra note: Sanitation and improved management practices are also very effective as preventative measures
Name when antibiotic treatment against Salmonella is warranted. What treatment would one use in each case?
Cases of enteritis and systemic infection.
Enteritis- know which antibiotic is susceptible and treat with that antibiotic
Systemic infection- treat with Ceftiofur intravenously
In what instances are virulence genes for Salmonella hyperactivated?
At microgravity
