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This article is about the bacterial phylum. For spiral-shaped bacteria in general, see spiral bacteria.
20100905 211652 Spirochetes.jpg
Spirochaetes.  Numbered ticks are 10 µm apart.  Gram-stained.
Treponema pallidum 01.png
Treponema pallidum spirochaetes.
Scientific classification
Domain: Bacteria
Phylum: "Spirochaetes"
Garrity & Holt 2001
Class: Spirochaetae
  • Spirochaetae Cavalier-Smith 2002
  • Spirochaetaeota Oren et al. 2015
Cross section of a spirochaete cell

Spirochaetes English pronunciation: /ˈspʌɪrə(ʊ)kiːt/[1] (also spelled spirochetes) belong to a phylum of distinctive diderm (double-membrane) bacteria, most of which have long, helically coiled (corkscrew-shaped or spiraled, hence the name) cells.[2] Spirochaetes are chemoheterotrophic in nature, with lengths between 3 and 500 µm and diameters around 0.09 to at least 3 µm.[3]

Spirochaetes are distinguished from other bacterial phyla by the location of their flagella, sometimes called axial filaments, which run lengthwise between the bacterial inner membrane and outer membrane in periplasmic space. These cause a twisting motion which allows the spirochaete to move about. When reproducing, a spirochaete will undergo asexual transverse binary fission.

Most spirochaetes are free-living and anaerobic, but there are numerous exceptions.

Spirochetes may cause dementia and may be involved in the pathogenesis of Alzheimer's disease.[4]


The spirochaetes are divided into three families (Brachyspiraceae, Leptospiraceae, and Spirochaetaceae), all placed within a single order (Spirochaetales). Disease-causing members of this phylum include the following:

Cavalier-Smith has postulated that the Spirochaetes belong in a larger clade called Gracilicutes.[8]

Spirochaetes are gram-negative bacteria.


The phylogeny is based on 16S rRNA-based LTP release 123 by 'The All-Species Living Tree' Project.[9]


Turneriella parva (Hovind-Hougen et al. 1982) Levett et al. 2005

Leptonema illini Hovind-Hougen 1983

Leptospira Noguchi 1917 emend. Faine and Stallman 1982



Brevinema andersonii Defosse et al. 1995


Brachyspira Hovind-Hougen et al. 1982


Exilispira thermophila Imachi et al. 2008


Spirochaeta Ehrenberg 1835 emend. Pikuta et al. 2009

Treponema Schaudinn 1905 emend Abt et al. 2013

Spirochaeta clade 2

Spirochaeta aurantia (ex Vinzent 1926) Canale-Parola 1980


Borreliella Adeolu & Gupta 2015 (Lyme disease Borrelia)

Borrelia Swellengrebel 1907 emend. Adeolu & Gupta 2014 (relapsing fever Borrelia)


The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[10] and National Center for Biotechnology Information (NCBI).[11]

♦ Type strain lost or not available
♪ Prokaryotes where no pure (axenic) cultures are isolated or available, i. e. not cultivated or can not be sustained in culture for more than a few serial passages
♠ Strains found at the National Center for Biotechnology Information (NCBI) but not listed in the List of Prokaryotic names with Standing in Nomenclature (LSPN)


Salvarsan, the first partially organic synthetic antimicrobial drug in medical history, was effective against spirochaetes only and was primarily used to cure syphilis.

See also[edit]


  1. ^ spirochaete - Oxford Dictionaries
  2. ^ Ryan KJ; Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. ISBN 0-8385-8529-9. 
  3. ^ Margulis, L.; Ashen, J. B.; Solé, M.; Guerrero, R. (1993-08-01). "Composite, large spirochetes from microbial mats: spirochete structure review" (PDF). Proceedings of the National Academy of Sciences. 90 (15): 6966–6970. doi:10.1073/pnas.90.15.6966. ISSN 0027-8424. PMC 47056free to read. PMID 8346204. 
  4. ^ Miklossy, Judith (2011-08-04). "Alzheimer's disease - a neurospirochetosis. Analysis of the evidence following Koch's and Hill's criteria". Journal of Neuroinflammation. 8: 90. doi:10.1186/1742-2094-8-90. ISSN 1742-2094. PMC 3171359free to read. PMID 21816039. 
  5. ^ McBride A, Athanazio D, Reis M, Ko A (2005). "Leptospirosis". Current Opinion in Infectious Diseases. 18 (5): 376–86. doi:10.1097/01.qco.0000178824.05715.2c. PMID 16148523. 
  6. ^ Schwan T (1996). "Ticks and Borrelia: model systems for investigating pathogen-arthropod interactions". Infect Agents Dis. 5 (3): 167–81. PMID 8805079. 
  7. ^ Amat Villegas I, Borobio Aguilar E, Beloqui Perez R, de Llano Varela P, Oquiñena Legaz S, Martínez-Peñuela Virseda JM (January 2004). "[Colonic spirochetes: an infrequent cause of adult diarrhea]". Gastroenterol Hepatol (in Spanish). 27 (1): 21–3. PMID 14718105. 
  8. ^ Cavalier-Smith, T. (2006). "Rooting the tree of life by transition analyses". Biology Direct. 1 (19): 19. doi:10.1186/1745-6150-1-19. PMC 1586193free to read. PMID 16834776. 
  9. ^ 'The All-Species Living Tree' Project."16S rRNA-based LTP release 123 (full tree)" (PDF). Silva Comprehensive Ribosomal RNA Database. Retrieved 2013-03-20. 
  10. ^ J.P. Euzéby. "Spirochaetes". List of Prokaryotic names with Standing in Nomenclature (LPSN). Retrieved 2013-03-20. 
  11. ^ Sayers; et al. "Spirochaetes". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 2013-03-20. 

External links[edit]