Coxiella burnetii - MegaMicro

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Coxiella burnetii

Micro > Bacteriology > Intracellular bacteria > Anaplasmataceae
Coxiella burnetii

1.      Structure:
-          Small, gram negative-staining bacteria; pleiomorphic coccobacillus
2.      Pathobiology:
-          Obligate intracellular bacteria that replicates in macrophages and monocytes; Phase I is the wildtype antigenic form that is highly infectious because it has lipopolysaccharides, whereas Phase II is a lab-grown form that is attenuated and has a shorter LPS; two forms can exist in cells, large cell variant/vegetative and small cell variant/condensed (which result in a spore-like form when released during cell lysis)
-          resistant to heat, acidic/basic conditions, ultraviolet radiation, desiccation, extreme temperatures, and sunlight due to spore-like stage
3.      Epidemiology:
-          reservoirs include: domesticated cattle, sheep, and goats
-          transmission to humans via inhalation of aerosols or dusts with bacteria from infected animals
- high numbers of organisms in placenta of infected animals
-          rarely, ticks may transmit bacteria to humans
4.      Laboratory diagnosis:
-          antibody testing by indirect immunofluorescence; isolation of bacteria only available in high containment facilities
5.      Disease manifestations:
-          Q fever, characterized by fever and retro-orbital headache, diarrhea, facial pain, and speech impairment
-          endocarditis can occur with chronic disease (a cause of "culture negative endocarditis")
-          1% mortality rate from acute infections, although 5-50% rate in untreated chronic conditions
6.      Therapy:
-          Doxycycline for two weeks, then in combination with hydroxychloroquine
-          antibiotics may be used for anywhere from 18 months to multiple years for chronic infections
7.      Prevention:
-          vaccination of ruminants; human vaccine available in Australia‚Äč
Related concepts
  1. Q fever;
  2. ruminants;
  3. obligate intracellular bacteria

 
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