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;
32 Cards in this Set
- Front
- Back
T/F
The majority of B.abortus induced abortion in cows occur during the second trimester of pregnancy |
True
|
|
T/F
B. abortus is an extracellular pathogen. Humoral immunity provides protection against the pathogen |
false - it is intracellular. Humoral immunity protects against abortion, not the pathogen.
|
|
T/F
B.abortus can penetrate intact mucosa and skin |
False - it can penetrate the mucosa, not the skin.
|
|
T/F
During the second gestation of a cow that had a previous B.abortus- induced abortion, it would give birth to health calves. |
True
|
|
How does Brucellosis stain? What shape are they? Are they spore forming?
|
• Brucella are small gram-negative coccobacilli, nonmotile of alpha-proteobacteria group. Does not form spores.
• Grows in any high quality peptone-based media enriched with blood or serum. |
|
How does Brucellosis clinically present?
|
Tachycardia
Abdominal pain, enlargement of liver and spleen |
|
How is Brucellosis shed? What populations are susceptible?
|
• Chronic infection in farm animals
• Is shed in urine, milk, therefore infections are common in farmers, veterinarians, laboratory workers. B.canis has infected a few dog breeders. • Among animals, infection by conjunctival and genital mucosa, skin, respiratory, semen, contaminated abortion fluids, tissues. • B.abortus, is the most common species in the US! |
|
Are Brucella genomes highly conserved?
In what genes does the majority of the diversity between species lie? |
• The genomes of B.melitensis, B.suis and B.abortus have been sequenced
• 90% gene sequenced share 98-100% homology. Suggest that the genomes are very conserved • 33 different regions differ between B.abortus and others: 22 B.suis, 11 B.melitensis. The majority of the diversity is in pathogenicity islands; which are DNA acquired horizontally. |
|
What are the four routs of transmission of brucellosis to humans?
What are some risk factors in contracting it? What are the routes of transmission to animals? |
• Routes of Transmission to humans:
1- skin abrasions 2- ingestion of non-pasteurized products 3- aerosol 4- inoculated in the conjunctival sac • Person-to-person transmission rare • Rarely seen in HIV-1 infected patients • Risk factor: use of anti-acids, H2-receptor antagonist. • Routes of Transmission to animals: Oral Reproductive tract |
|
What is the pathogenesis of brucella?
|
• Brucella infects orally and localizes in the lymph nodes in the nasopharyngeal area. Then disseminates. The pregnant uterus is particularly susceptible to Brucella.
• Brucella localizes in the trophoblast of placenta, where it inhibitis secretion of chemokines and inflammatory cytokines • Infection spreads to fetus. Most have pneumonia • Mechanisms of abortion: 1- Interference with fetal circulation (vasculitis) 2- endotoxin 3- fetal stress |
|
What are the factors that increase the pathogenicity of brucella?
|
Type 4 secretion system is necessary for intracellular survival.
Establishment of the infection through the digestive tract requires Urease and bile salt hydrolase, and LPS (O antigen) - allows brucella to cross the barriers into the intestinal tract. |
|
Brucella is an intracellular bacteria. What type of cell does it live within?
How does it pull this off? |
Macrophages
1. does not trigger O 2 burst (doesn't let vacuole acidify) 2. P-L do not fuse 3. Prevent Apoptosis |
|
Where is it hypothesized that Brucella picked up its type IV secretion system?
|
A plant bacteria
|
|
What are the humoral and cell-mediated host immune responses to Brucella?
|
Humoral: IgM and IgG can be protective. antibodies offer partial protection. Even if an animal harbors a chronic infection of brucella, they won't keep having abortions.
Cellular: Effective immunity, CD4+ T cells, NK cells |
|
Is there a vaccine for Brucella abortus?
|
vax works for brucella abortus, but none are 100% effective.
Protect against abortion (<transmission) but not against infection Vaccination is not practiced for B.canis and B.suis |
|
How is Brucella diagnosed, treated and controlled?
|
• Staining and culture
• ELISA (blood, milk, semen) • PCR (differentiation from vaccine strains) • Treatment of cattle is not practical • Detection and slaughter • Control: Immunization at calf age, testing and removal |
|
How does Tularemia gram stain? Is it motile? What shape is it?
|
Francisella tularensis
Gram-negative, non motile, coccobacillus |
|
What are reservoirs for Francisella tularensis?
|
• Is believed to be maintained in the
environment (squirrels, rabbits, rats, etc) • Presence in water, associated with amoeba • Vectors: mosquitos Aedes, Culex, Anopheles or ticks, like Ixodes |
|
What makes F.tularensis LPS a pathogenic factor?
|
LPS has phase variation. The LPS phase variation is important. Disguises the bacteria from the host.
WT encapsulated bacteria are serum resistant |
|
Does Tularemia have a seasonality? What populations are more susceptible?
|
• Is more frequent from June to August (tick season), and December (hunting associated)
• Laboratory worker, farmer, veterinarian, sheep worker, hunter, cook are most affected |
|
How is Tularemia transmitted?
|
• Animal contact: skinning, eating
• Airborne transmission: contaminated water, dust or hay • Carnivorous animals carried it on claws or mouth (mechanism of domestic cat transmission) • Ticks predominates in the Rocky Mountains • Biting flies in California, Nevada, Utah • Mosquitoes in Sweden, Finland and Soviet Union • 13 species of ticks. The dog tick (Dermacentor variabilis) and the wood-tick (Dermacentor andersoni) |
|
What domestic animals are infected with tularemia?
What are the clinical signs? |
• Sheep, Horses, Pigs
• Dogs and Cats can be infected without symptoms • Transmission in outbreaks is frequently related to tick infestation or fly bite Clinical signs are not well documented. Apathy followed by fatal septicemia. |
|
Which bacteria has type IV pili, brucella or tularemia?
What is the function? |
Tularemia.
Brucella has type IV secretory system. • What is the function? Binding to mucosal surfaces? • Macrophage infection? |
|
How is tularemia diagnosed?
|
• Signs are non-specific. Suspect tularemia if tick infestation occurs in severely ill animals
• Wright’s or Giemsa • Serology (> 1:80), scrapings from ulcer, lymph node aspirate • Culture on blood agar with cysteine, 37C |
|
How do you control Tularemia?
|
• Ectoparasite control.
• Recognition of tularemia in the ecosystem • Sources of infection: water, contaminated carcasses, excreta of wildlife species • Prevention of hunting by cats and dogs |
|
Does tularemia infect domestic animals?
|
Although tularemia is mainly a disease of rodents, it occurs in domestic animals:
• Contact with infected food (dead rabbit) • Infected vectors: ticks, mosquitoes, deerflies. • Cats and sheep are the most frequently infected |
|
What are the subspecies of F. tularensis?
IMPORTANT ONE |
Three Sub-species:
1- F.tularensis ssp tularensis (type A) 2- F.tularensis ssp holartica (type B) 3- F.tularensis ssp mediasiatica |
|
Which hosts are susceptible to Tularemia infection?
IMPORTANT ONE |
broad host range (190 sp mammals, 23 of birds, 3 of amphibians, 88 of invertebrates)
|
|
When phagocytosed by macrophages, Francisella lives ( ) in a vacuole, ( ) in the cytoplasm?
IMPORTANT |
In the cytoplasm.
Escapes the phagosome!!! Unique |
|
Does Francisella has a pathogenicity island? Is it important for virulence?
IMPORTANT |
Yes
Pathogenicity island involved in virulence. Gene duplication, which suggests importance. |
|
Is nitric oxide important for host defense against Francisella? ( )Yes ( )No?
Is IFN-gamma? ( ) Yes ( ) No? IMPORTANT |
Yes to the Nitric Oxide. But I'm not sure how!
And...no to the IFN? This is what is says in the lecture: IFN-gamma, different results according to macrophage population |
|
How do one treats tularemia?
IMPORTANT |
Aminoglycosides
Fluoroquinolones Tetracycline have been used in animals |