Rickettsia prowazekii: Difference between revisions

From Citizendium
Jump to navigation Jump to search
imported>Howard C. Berkowitz
(New page: '''''Rickettsia prowazekii''''' is the pathogen of epidemic typhus. Its epidemic potential caused it to be listed as a human threat in the [[Select Agent Pr...)
 
imported>Meg Taylor
m (spelling: clasically -> classically)
(2 intermediate revisions by one other user not shown)
Line 1: Line 1:
'''''Rickettsia prowazekii''''' is the [[pathogen]] of [[typhus#epidemic typhus|epidemic typhus]].  Its epidemic potential caused it to be listed as a human threat in the [[Select Agent Program]].
{{subpages}}
'''''Rickettsia prowazekii''''' is the [[pathogen]] of [[typhus#epidemic typhus|epidemic typhus]].  Its epidemic potential caused it to be listed as a human threat in the [[Select Agent Program]], and in [[CDC Bioterrorism Agents-Disease list]] Category B.
 
The organism appears to have a fundamental niche in the development of the cells of higher organisms. The functional profiles of its genes show similarities to those of mitochondrial genes: no genes required for anaerobic [[glycolysis]] are found in either ''R. prowazekii'' or mitochondrial genomes, but a complete set of genes encoding components of the [[tricarboxylic acid cycle]] and the respiratory-chain complex is found in ''R. prowazekii''. <blockquote>In effect, ATP production in Rickettsia  is the same as that in mitochondria....Phylogenetic analyses indicate that ''R. prowazekii'' is more closely related to [[mitochondria]] than is any other microbe studied so far. <ref name=Andersson>{{citation
| journal = Nature
| volume = 396
| pages =133-140
| date = 12 November 1998
| doi=10.1038/24094
| title = The genome sequence of ''Rickettsia prowazekii'' and the origin of mitochondria
| author =Andersson SGE ''et al.''
| url =http://www.nature.com/nature/journal/v396/n6707/full/396133a0.html}}</ref></blockquote>


==Life cycle==
==Life cycle==
Line 15: Line 26:


==Antibiotic sensitivity==
==Antibiotic sensitivity==
The organism has clasically been sensitive to [[doxycycline]] and [[chloramphenicol]]
The organism has classically been sensitive to [[doxycycline]] and [[chloramphenicol]]
==References==
{{reflist}}

Revision as of 04:52, 6 February 2010

This article is developing and not approved.
Main Article
Discussion
Related Articles  [?]
Bibliography  [?]
External Links  [?]
Citable Version  [?]
 
This editable Main Article is under development and subject to a disclaimer.

Rickettsia prowazekii is the pathogen of epidemic typhus. Its epidemic potential caused it to be listed as a human threat in the Select Agent Program, and in CDC Bioterrorism Agents-Disease list Category B.

The organism appears to have a fundamental niche in the development of the cells of higher organisms. The functional profiles of its genes show similarities to those of mitochondrial genes: no genes required for anaerobic glycolysis are found in either R. prowazekii or mitochondrial genomes, but a complete set of genes encoding components of the tricarboxylic acid cycle and the respiratory-chain complex is found in R. prowazekii.

In effect, ATP production in Rickettsia is the same as that in mitochondria....Phylogenetic analyses indicate that R. prowazekii is more closely related to mitochondria than is any other microbe studied so far. [1]

Life cycle

The organism's reservoir is the alimentary tract of lice. When a louse carrying R. prowazekii bites a human to drain blood for its own nutrition, the louse defecates as it eats. Since the bite causes itching, the human victim scratches the site, crushes the louse, and drives the excrement into the skin. There is no direct transmission into human blood by an untouched louse.

If the louse does survive the human encounter, it is still doomed, although it acquired R. prowazekii from its bite. Of the arthropod vectors of the various forms of typhus, the louse is the only one that is doomed by the pathogen. [2] The relationship between the louse and R. prowazekii is, in their small world, rather reminiscent of Greek tragedy; the outcome differing only to the extent by which the louse enjoyed, in its lousy way, its meals.

Laboratory characteristics

Like all Rickettsiae, it is a small pleomorphic organism that can assume various shapes, such as a coccus or bacillus. It is cultured and stained only with difficulty, so the diagnosis is principally clinical, and confirmed by various immunologic mechanisms.

Antibiotic sensitivity

The organism has classically been sensitive to doxycycline and chloramphenicol

References

  1. Andersson SGE et al. (12 November 1998), "The genome sequence of Rickettsia prowazekii and the origin of mitochondria", Nature 396: 133-140, DOI:10.1038/24094
  2. Okulicz JF et al. (May 12, 2006), "Typhus", eMedicine