Spirochaete

Many organisms within the Spirochaetota phylum cause prevalent diseases. Pathogenic members of this phylum include the following: • Leptospira species, which causes leptospirosis • Borrelia burgdorferi, B. mayonii, B. bissettiae, B. garinii, B. afzelii, B. spielmanii, B. lusitaniae, which cause Lyme disease. • Borrelia recurrentis, which causes relapsing fever • Treponema pallidum subspecies which cause treponematoses such as syphilis and yaws. • Brachyspira pilosicoli and Brachyspira aalborgi, which cause intestinal spirochaetosis Salvarsan, the first partially organic synthetic antimicrobial drug in medical history, was effective against spirochaetes and primarily used to cure syphilis. Additionally, oral spirochaetes are known to play a significant role in the pathogenesis of human periodontal disease. ==Taxonomy and molecular signatures==

The class currently consists of 14 validly named genera across four orders and five families. The orders Brachyspirales, Brevinematales and Leptospirales each contain a single family, Brachyspiraceae, Brevinemataceae and Leptospiraceae, respectively. The Spirochaetales order harbours two families, Spirochaetaceae and Borreliaceae. Molecular markers in the form of conserved signature indels (CSIs) and CSPs have been found specific for each of the orders, with the exception of Brevinimetales, that provide a reliable means to demarcate these clades from one another within the diverse phylum. However, this study has been criticized, and other studies using different approaches do not support the proposed split. The new naming system for the Lyme and relapsing fever Borrelia has not been adopted by the scientific literature. Given that the CSI is exclusively shared by members within this phylum, it has been postulated that it may be related to the characteristic flagellar properties observed among Spirochaetota species. Historically, all families belonging to the Spirochaetota phylum were assigned to a single order, the Spirochaetales. However, the current taxonomic view is more connotative of accurate evolutionary relationships. The distribution of a CSI is indicative of shared ancestry within the clade for which it is specific. It thus functions as a synapomorphic characteristic, so that the distributions of different CSIs provide the means to identify different orders and families within the phylum and so justify the phylogenetic divisions. ==Phylogeny==

The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI). • Phylum Spirochaetota Garrity and Holt 2021 • Genus ?"Spirosymplokos" Guerrero et al. 1993 • Class Leptospiria Chuvochina et al. 2024 • Order Turneriellales Chuvochina et al. 2024 • Family Turneriellaceae Chuvochina et al. 2024 • Genus Turneriella Levett et al. 2005 • Order Leptospirales Gupta et al. 2014 • Family Leptonemataceae Chuvochina et al. 2024 • Genus Leptonema Hovind-Hougen 1983 • Family Leptospiraceae Hovind-Hougen 1979 • Genus Leptospira Noguchi 1917 • Class Brevinematia Chuvochina et al. 2024 • Order Brevinematales Gupta et al. 2014 • Family "Longinemataceae" Karnachuk et al. 2021 • Genus ?"Longinema" corrig. Karnachuk et al. 2021 • Family Brevinemataceae Paster 2012 • Genus Brevinema Defosse et al. 1995 • Family Thermospiraceae Ben Ali Gam et al. 2023 • Genus Thermospira Ben Ali Gam et al. 2023 • Class Brachyspiria Chuvochina et al. 2024 • Order Brachyspirales corrig. Gupta et al. 2014 • Family Brachyspiraceae Paster 2012 • Genus ?"Ca. Maribrachyspira" Matsuyama et al. 2017 • Genus Brachyspira Hovind-Hougen et al. 1982 non Foliella non Pfeiffer 1855 • Class Spirochaetia Paster 2020 • Order Spirochaetales Buchanan 1917 • Family "Pillotinaceae" Margulis & Hinkle 1992 • Genus ?Pillotina Hollande and Gharagozlou 1967 ex Bermudes et al. 1988 • Family Spirochaetaceae Swellengrebel 1907 ["Thiospirochaetaceae" Pallen, Rodriguez-R & Alikhan 2022] • Genus ?"Ca. Allospironema" Paster & Dewhirst 2000 • Genus ?"Canaleparolina" Wier, Ashen & Margulis 2000 • Genus ?Clevelandina Bermudes et al. 1988 • Genus ?Diplocalyx Gharagozlou 1968 ex Bermudes et al. 1988 non Richard 1850 non Presl 1845 • Genus ?Hollandina To et al. 1978 ex Bermudes et al. 1988 non Haynes 1956 • Genus ?"Mobilifilum" Margulis et al. 1990 • Genus ?Rarispira Podosokorskaya et al. 2025 • Genus ?"Spirophis" (Warming 1875) Lauterborn 1916 • Genus ?Spirochaeta Ehrenberg 1835 em. Pikuta et al. 2009 non Turczaninow 1851 • Genus "Ca. Haliotispira" Sharma et al. 2024 • Order "Exilispirales" Pallen, Rodriguez-R & Alikhan 2022 • Family "Exilispiraceae" Pallen, Rodriguez-R & Alikhan 2022 • Genus Exilispira Imachi et al. 2008 • Order Borreliales Chuvochina et al. 2024 • Family Borreliaceae Gupta et al. 2014 • Genus Borrelia Swellengrebel 1907 (relapsing fever Borrelia, reptile-associated Borrelia and Echidna-associated Borrelia) • Genus Borreliella Adeolu & Gupta 2015 (Lyme disease Borrelia) • Genus ?Cristispira Gross 1910 • Order "Entomospirales" Pallen, Rodriguez-R & Alikhan 2022 [WRBN01] • Family "Entomospiraceae" Pallen, Rodriguez-R & Alikhan 2022 • Genus Entomospira Grana-Miraglia et al. 2024 non Enderlein 1917 • Order "Salinispirales" Pallen, Rodriguez-R & Alikhan 2022 [DSM-27196] • Family "Thiospirochaetaceae" Pallen, Rodriguez-R & Alikhan 2022 [DSM-19205] • Genus Oceanispirochaeta Subhash & Lee 2017b • Genus "Ca. Thalassospirochaeta" Pragya et al. 2024 • Genus Thiospirochaeta Dubinina et al. 2020 • Family Alkalispirochaetceae Chuvochina et al. 2024 • Genus Alkalispirochaeta Sravanthi et al. 2016 • Family Salinispiraceae Chuvochina et al. 2024 • Genus Salinispira Ben Hania et al. 2015 • Order Winmispirales Podosokorskaya et al. 2025 [DSM-6578] • Family Winmispiraceae Podosokorskaya et al. 2025 • Genus Winmispira Podosokorskaya et al. 2025 • Order "Sediminispirochaetales" Pallen, Rodriguez-R & Alikhan 2022 • Family Sediminispirochaetaceae Chuvochina et al. 2024 • Genus Sediminispirochaeta Shivani et al. 2016 • Order "Marispirochaetales" Pallen, Rodriguez-R & Alikhan 2022 • Family Marispirochaetaceae Chuvochina et al. 2024 • Genus Marispirochaeta Shivani et al. 2017 • Order Sphaerochaetales Chuvochina et al. 2024 • Family Sphaerochaetaceae Hördt et al. 2020 • Genus Bullifex Wylensek et al. 2021 [incl. "Ca. Aphodenecus" Gilroy et al. 2021] • Genus "Ca. Ornithospirochaeta" Gilroy et al. 2021 • Genus Parasphaerochaeta Bidzhieva et al. 2020 • Genus ?"Ca. Physcosoma" Gilroy et al. 2022 • Genus ?Pleomorphochaeta Arroua et al. 2016 • Genus Sphaerochaeta Ritalahti et al. 2012 • Order Treponematales Chuvochina et al. 2024 • Family Rectinemataceae Brune et al. 2022 • Genus Rectinema Koelschbach et al. 2017 • Family Breznakiellaceae Brune et al. 2022 • Genus Breznakiella Song et al. 2022 • Genus Gracilinema Brune et al. 2022 • Genus ?Helmutkoenigia Brune et al. 2022 • Genus Leadbettera Brune et al. 2022 • Genus ?"Propulsinema" Fu et al. 2025 • Genus ?Zuelzera Brune et al. 2022 • Family Treponemataceae Robinson 1948 • Genus "Ca. Avitreponema" Gilroy et al. 2021 • Genus Brucepastera Song et al. 2023 • Genus "Ca. Gallitreponema" Gilroy et al. 2021 • Genus Teretinema Song et al. 2023 • Genus Treponema Schaudinn 1905 em. Abt et al. 2013 == See also ==