FRANCISELLA

Question 1

What is the principal species of Genus Francisella?

Answer 1

F. tularensis

Question 2

Give the species and biovars of Genus Francisella with the given data:

• Occurs in North America, Reservoir host is Cottontail Rabbit
• Highly virulent
• Highly infectious for mammals and humans
• LD50 in rabbits of fewer than 10 organisms

Answer 2

Francisella tularensis, biovar tularensis Type A

Question 3

Give the species and biovars of Genus Francisella with the given data:

• Occurs in Asia, Europe, North America
• Less virulent than type A
• Cause of epizootics in beavers, muskrats, and voles
• LD50 in rabbits more than 10 organisms

Answer 3

Francisella tularensis, biovar palaeartica type B

Question 4

Give the species and biovars of Genus Francisella with the given data:

• Recovered from water
• Not considered a significant pathogen

Answer 4

Francisella tularensis, biovar novicida type C

Question 5

Give the species and biovars of Genus Francisella with the given data:

• Associated with salty or brackish water
• Infrequent illness in humans: chronic granulomatous disease or myeloproliferative disorders

Answer 5

Francisella philomiragia (formerly: Yersinia philomiragia)

Question 6

Give the morphology and staining features of F. tularensis.

Answer 6

• Small
• Pleomorphic
• Non-motile
• Non-capsulated
• Gram negative
• Facultative Intracellular Parasite
• Oxidase negative

Question 7

F. tularensis requires _____ for isolation.

Answer 7

cysteine

Question 8

Tularemia is transmitted via ?

Answer 8

Insect vectors such as wood ticks, dog ticks, rabbit ticks, flear, deer flies, mites, mosquitoes, and lice

Question 9

Give the pathogenesis of F. tularensis.

Answer 9

• Organism lives for months at subfreezing temperatures and in frozen meat for years.
• Type A Biovar exhibits citrulline ureidase activity.
• Possess a thin, mainly lipid capsule (phagocyte resistant)
• Produce Phosphatase, unique acid for suppressing the destructive respiratory burst associated with phagocytes.
• Organism is highly toxic to macrophage, known to induce apoptosis in macrophage due to its Endotoxin
• Delayed Hypersensitivity may contribute to tissue damage
• Focal Granulomatous lesions in organs and lymph nodes,
• Bacteremia causes small abscessing granulomas in visceral organs
• Systemic disease is seen in animals near death or at necropsy
• Tularemia is rarely seen in dogs, Cats are infected by Ticks and eating infected rabbits

Question 10

What are immunization methods against F. tularensis?

Answer 10

1. Cell mediated
2. Recovery
3. Live attenuated Vaccine

Question 11

What are the diagnostic methods for F. tularensis?

Answer 11

• Grows well on cysteine-blood agar
• Plates are incubated for 3 weeks
• Minute-dew drops colonies
• Greenish discoloration (𝜶-hemolysis)
• Guinea Pig inoculation is sometimes used to overcome contaminants.
• Fluorescent Antibody Technique

Question 12

What are the treatment methods for F. tularensis?

Answer 12

• Streptomycin or Gentamicin given for 1-2 weeks
• Tetracycline and Chloramphenicol for 2 weeks