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Veterinary Bacteriology & Mycology > Coxiella burnetii > Flashcards

Coxiella burnetii Flashcards

1
Q

What does Coxiella burnetii cause?

A

Q (Query, Queensland) fever - occupational zoonotic disease categorized as a bioterrorism agent by the CDC

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2
Q

What are 4 reasons that Coxiella burnetii is recorded as a bioterrorism agent?

A
  1. causes disability, fever outbreaks, and epidemics of abortion in ruminants (huge economic loss)
  2. airborne transmission up to 20 km away
  3. highly infectious with low infective dose of 1-10 cells
  4. viable in the environment for years using a pseudo-spore-life life form (small cell variant)
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3
Q

What kind of bacteria is Coxiella burnetii? How does it differ from other of the same bacteria?

A

Gram-negative with an outer membrane composed of LPS and surface proteins and peptidoglycan

better stained with the Gimenez method

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4
Q

How does Coxiella burnetii differ from Chlamydia, Anaplasma, Ehrlichia, and Rickettsia?

A

not an ATP parasite on host cells
- cell envelop does not transport ATP across its membranes
- able to synthesize its own ATP

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5
Q

Why is Coxiella burnetii an obligate intracellular pathogen?

A

cannot synthesize its own amino acids, like cysteine and arginine and must steal it from the host cytoplasm

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6
Q

What are the 2 morphotypes of Coxiella brunetii?

A
  1. small cell variant (SCV) = extracellular
  2. large cell variant (LCV) = intracellular
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7
Q

What are the 4 major characteristics of the small cell variant of Coxiella burnetii?

A
  1. hardy form taken when it is in the environment, outside of the host cell, or when conditions are not favorable
  2. infectious and transmissible form
  3. electron-dense
  4. can remain in the environment for decades
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8
Q

What are the 3 major characteristics of the large cell variant of Coxiella burnetii?

A
  1. vegetative/replicative form
  2. activated when it enters the cytoplasm of the host cell
  3. metabolically active
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9
Q

What are the primary reservoirs of Coxiella burnetii? What species does it infect?

A

cattle, sheep, goats (ruminants!)

  • wildlife
  • marine mammals
  • domestic mammals
  • birds
  • reptiles
  • ticks
  • humans
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10
Q

Other than the environment, where can the small cell variant of Coxiella burnetii be found?

A

free living amoeba

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11
Q

What are the 4 entry routes of Coxiella burnetii? 5 exit routes?

A

ENTRY
1. inhalation**
2. ingestion
3. contact
4. ticks

EXIT = feces, abortion, urine, sexual activity, milk, ticks

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12
Q

Coxiella burnetii tranmission:

A
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13
Q

How are people, ruminants, dogs/cats, and ticks commonly infected with Coxiella burnetii?

A

PEOPLE: inhalation, direct/indirect contact with infected animals during parturition, ingestion of infected milk

RUMINANTS: reservoirs

DOGS/CATS: contact/ingestion of wildlife species

TICKS: harbor microorganism and maintain transmission to wildlife species, especially rodents, rabbits, and birds

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14
Q

What are the main 4 ways that Coxiella is transmitted transovarially?

A
  1. between wildlife
  2. between wildlife and domestic animals
  3. from wildlife to humans
  4. reservoir for maintenance in sylvatic environment
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15
Q

How is Coxiella burnetii able to survive in microbicidal cells, like monocytes and macrophages?

A
  • uses atypical LPS lacking sugars via genetic deletion to become avirulent (docile) by acquiring a rough surface and avoiding immune cells
  • enters cells in its non-replicative SCV form and resides in membrane-bound Coxiella-containing vacuoles and exponentially replicated
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16
Q

What is the function of Coxiella LPS?

A

protection for its optimal growth in phagocytes, non-phagocytic cells, and in cell-free culture media

17
Q

What is another name for the pili of Coxiella? What are 3 functions?

A

type 4 secretion system

  1. attachment
  2. injection of effector proteins into host cell
  3. promotes intracellular survival and replication
18
Q

How does Coxiella survive in vacuoles?

A

vacuole acidification by colliding with cell lysozyme using EEA1 and Rab5 (pH 5.4 to 4.5) —> allows for development and replication inside vacuole and protects it from damage from phagolysosome

19
Q

What are the 2 phases of the large cell variants of Coxiella?

A

VIRULENT PHASE I = LPS has intact O-antigen (smooth)

AVIRULENT PHASE II = LPS lost its O-antigen (rough)

20
Q

What are the 3 tropisms of Coxiella?

A
  1. MONOCYTES and MACROPHAGES of birds, mammals, and humans** - cells disseminate it into blood vessel endothelial cells
  2. ENDOTHELIAL CELLS of vital body parts of birds, mammals, and humans - localizes in lung, placenta, reproductive tract, liver, mammary glands, lymph nodes, heart, joints, bones, and brain
  3. MIDGUT and SALIVARY GLAND CELLS of ticks
21
Q

What are the 2 forms of clinical signs of Coxiella infection?

A
  1. ACUTE = fever + pneumonia, abortion and stillbirth, jaundice and granulomatous hepatitis, mastitis, lymphadenitis linked with lymphoma, vasculitis, rash/hemorrhage
  2. CHRONIC = endocarditis/heart failure (heart valves), osteoarthritis, brain

(60% are asymptomatic)

22
Q

What 6 specimens can be taken for Coxiella isolation?

A
  1. vaginal discharge
  2. abortion remains
  3. milk
  4. nasal discharge
  5. blood
  6. serum
23
Q

What is the gold standard of serological tests for Coxiella identification? What titers suggest primary Q fever infection?

A

indirect immunofluorescence assay
- ELISA can also be done

IgG > 200
IgM > 50

24
Q

What genes are targeted for PCR and sequencing for Coxiella identification?

A

16S-23S RNA, ompA, com1, superoxide dismutase gene, plasmids, mobile genetic repetitive insertion elements

25
Q

What are the 2 major methods of Coxiella culturing?

A
  1. on cell lines of chick fibroblasts
  2. broth or agar media using acidified citrate cysteine

(in a BSL3 containment laboratory)

26
Q

What is the sole example of an obligate intracellular bacterial pathogen for which specific axenic culture medium has been developed?

A

Coxiella burnetii

27
Q

What are 6 possible treatments of Coxiella burnetii infection? What is the safest option?

A
  1. Doxycycline
  2. Oxytetracycline
  3. Doxycycline + Hydroxychloroquine
  4. Chloramphenicol
  5. Erythromycin
  6. Fluoroquinolones

trimethoprim-sulfamethoxazole

28
Q

What are the 4 major ways to control/prevent Coxiella burnetii infection?

A
  1. whole-cell killed vaccine licensed in Australia and Europe used in cattle to lower the risk of spreading and in goats to reduce abortion/spreading
  2. tick control
  3. BSL 3 - PPE during isolation, N95 while performing Q fever positive autopsies/parturition
  4. clean the environment with quaternary ammonium detergent or household bleach to decontaminated surfaces from spore-like form

Veterinary Bacteriology & Mycology (47 decks)

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