Coxiella burnetii

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Coxiella burnetii is a tiny gram-negative coccobacillus, staining well according to Giemsa. C. burnetii is the only species of the genus Coxiella and is the causative agent of Q-fever. Due to its low infectious dose and good resistance to drying, Coxiella can be used as a biological weapon.

Morphology[edit | edit source]

  • highly pleiomorphic, small coccobacillus
  • the wall is formed similarly to G minus bacteria

Physiology[edit | edit source]

  • intracellular parasites, multiplying only in the phagolysosome of living cells
  • multiplies in cells, during the cycle large and small forms alternate and at the same time spore-like formations are formed, which, however, differ in their structure from spores of gram-positive bacteria (described by Czechoslovak authors)

Cultivation[edit | edit source]

  • multiplies at low pH phagolysosome of cells
  • grows on common media and yolk sac of chicken embryos
  • we prove it by special staining in infected cells

Laboratory diagnostics[edit | edit source]

  • isolation is very dangerous for laboratory workers, and therefore it is performed only in specialized workplaces (VÚ SAV Bratislava, rickettsia department)
  • usually, the diagnosis of Q-fever is performed serologically (immunofluorescence, binding Complement, PCR)

Antigens and toxicity[edit | edit source]

  • occurrence in a single antigenic type, but there are alternating two phases:

Pathogenesis[edit | edit source]

  • the infectious dose is very low, a single cell is enough
  • the first infected cell is mostly alveolar macrophages after its decay blood get Coxielly into many organs, and therefore the disease does not only occur in the lungs
  • antibodies against the first phase cause Coxiell to disappear from the bloodstream
  • cellular immunity is necessary for healing, it fails in a few percent of the infected and the infection then becomes chronic

Epidemiology[edit | edit source]

  • in nature, the source of the infection are various animals (cattle, goats, sheep, ticks), which excrete Coxielly milk, urine, faeces
  • the largest amount of Coxiell is found in placentas
  • transmission is most often carried out by inhalation of contaminated dust, less often when ingested or processed contaminated products, very rarely transmission by a tick is possible.

Disease[edit | edit source]

  • in about half of the cases, the infection is inapparent, therefore the number of registered diseases is not high
  • in other cases it causes an acute infection with an incubation period of 20 days, which is called Q-fever (query = question, because at first etiology was uncertain), it is a typical occupational zoonosis
  • Q fever is manifested as a disease similar to influenza, atypical pneumonia (without cough and no expectoration), very rarely as granulomatous hepatitis, splenomegaly
  • the chronic form is culture-negative endocarditis

Treatment[edit | edit source]

  • the acute form of Q fever is treated with doxycycline or macrolides
  • the chronic form must be treated for at least 18 months with a combination of doxycycline and hydrochloroquine (basifies the content of lysosomes)

Links[edit | edit source]

Related articles[edit | edit source]

External links[edit | edit source]

References[edit | edit source]

  • VOTAVA, Miroslav – BROUKAL, Zdeněk. Lékařská mikrobiologie pro zubní lékaře. 1. edition edition. 2007. ISBN 978-80-86850-03-0.
  • BEDNÁŘ, Marek – SOUČEK, Andrej – FRAŇKOVÁ, Věra. Lékařská mikrobiologie : Bakteriologie, virologie, parazitologie. 1. edition. 1999. ISBN 8023802976.