Treponema pallidum
From Wikipedia, the free encyclopedia
| Treponema pallidum | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 |
||||||||||||||
| Scientific classification | ||||||||||||||
|
||||||||||||||
| Binomial name | ||||||||||||||
| Treponema pallidum Schaudinn & Hoffmann, 1905 |
Treponema pallidum is a Gram-negative spirochaete bacterium.
Contents |
[edit] Subspecies
There are at least four known subspecies:
- T. pallidum pallidum, which causes syphilis[1]
- T. pallidum pertenue, which causes yaws
- T. pallidum endemicum, which causes bejel
- T. pallidum carateum, which causes pinta
There is some variation as to which are considered subspecies, and which are species. For example, one source enumerates only three subspecies.[2]
The cause of pinta is sometimes described as "Treponema carateum", rather than a subspecies of Treponema pallidum, even when the subspecies convention is used for the other agents.[3]
[edit] Laboratory identification
This bacterium is too thin to be visualized with a standard Gram stain so two techniques to visualize it with a light microscope are dark field microscopy and immunofluorescence.
Treponema pallidum is also detected by serology, including nontreponemal (VDRL, Rapid plasma reagin (RPR) and treponemal antibody tests (FTA-ABS, Treponema pallidum immobilization reaction (TPI) and Syphilis TPHA test). [4]
[edit] Clinical significance
T. pallidum pallidum is a motile spirochaete that is generally acquired by close sexual contact, entering the host via breaches in squamous or columnar epithelium. The organism can also be transmitted to a fetus by transplacental passage during the later stages of pregnancy, giving rise to congenital syphilis. The helical structure of T. pallidum pallidum allows it to move in a corkscrew motion through a viscous medium such as mucus. It gains access to host's blood and lymph systems through tissue and mucous membranes.
The subspecies causing yaws, pinta, and bejel are morphologically and serologically indistinguishable from T. pallidum pallidum (syphilis); however, their transmission is not venereal in nature and the course of each disease is significantly different.
[edit] Genome
In the July 17, 1998 issue of the journal Science, a group of biologists reported how they sequenced the genome of T. pallidum.[5] The recent sequencing of the genomes of several spirochetes permits a thorough analysis of the similarities and differences within this bacterial phylum. Treponema pallidum subsp. pallidum has one of the smallest bacterial genomes at 1.14 million base pairs (Mb) and has limited metabolic capabilities, reflecting its adaptation through genome reduction to the rich environment of mammalian tissue.
[edit] Vaccine
There is no vaccine for syphilis. The outer membrane of T. pallidum has too few surface proteins for an antibody to be effective. Efforts to develop a safe and effective syphilis vaccine have been hindered by uncertainty about the relative importance of humoral and cellular mechanisms to protective immunity[citation needed] and the fact that T. pallidum outer membrane proteins have not been unambiguously identified.[6]
[edit] References
- ^ Kolman CJ, Centurion-Lara A, Lukehart SA, Owsley DW, Tuross N (December 1999). "Identification of Treponema pallidum subspecies pallidum in a 200-year-old skeletal specimen". J. Infect. Dis. 180 (6): 2060–3. doi:. PMID 10558971. http://www.journals.uchicago.edu/cgi-bin/resolve?JID990539.
- ^ Centurion-Lara A, Molini BJ, Godornes C, et al (September 2006). "Molecular differentiation of Treponema pallidum subspecies". J. Clin. Microbiol. 44 (9): 3377–80. doi:. PMID 16954278. PMC: 1594706. http://jcm.asm.org/cgi/pmidlookup?view=long&pmid=16954278.
- ^ Antal GM, Lukehart SA, Meheus AZ (January 2002). "The endemic treponematoses". Microbes Infect. 4 (1): 83–94. PMID 11825779. http://linkinghub.elsevier.com/retrieve/pii/S1286457901015131.
- ^ Fisher, Bruce; Harvey, Richard P.; Champe, Pamela C.. Lippincott's Illustrated Reviews: Microbiology (Lippincott's Illustrated Reviews Series). Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-8215-5.
- ^ Fraser CM, Norris SJ, Weinstock GM, et al (July 1998). "Complete genome sequence of Treponema pallidum, the syphilis spirochete". Science (journal) 281 (5375): 375–88. PMID 9665876. http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=9665876.
- ^ Tomson FL, Conley PG, Norgard MV, Hagman KE (September 2007). "Assessment of cell-surface exposure and vaccinogenic potentials of Treponema pallidum candidate outer membrane proteins". Microbes Infect. 9 (11): 1267–75. doi:. PMID 17890130. PMC: 2112743. http://linkinghub.elsevier.com/retrieve/pii/S1286-4579(07)00200-6.
[edit] External links
- Bak, Matthew. "Treponema pallidum: The Etiologic Agent of Syphilis." 7 February 2006
- "Syphilis- CDC Fact Sheet." Centers for Disease Control and Prevention. May. 2004. Centers for Disease Control and Prevention. 7 February 2006
|
||||||||||||||||||||||||||||
