Taxonomy and virulence of oral spirochetes

Abstract

All oral spirochetes are classified in the genus Treponema. This genus is in the family Spirochaetaceae as in Bergey's manual of systematic bacteriology. Other generic members of the family include Spirochaeta, Cristispira and Borrelia. This conventional classification is in accord with phylogenetic analysis of the spirochetes based on 16S rRNA cataloguing. The oral spirochetes fall naturally within the grouping of Treponema. Only four species of Treponema have been cultivated and maintained reliably: Treponema denticola, Treponema pectinovorum, Treponema socranskii and Treponema vincentii. These species have valid names according to the rules of nomenclature except for Treponema vincentii, which only has had effective publication. The virulence factors of the oral spirochetes updated in this mini-review have been discussed within the following broad confines: adherence, cytotoxic effects, iron sequestration and locomotion. T. denticola has been shown to attach to human gingival fibroblasts, basement membrane proteins, as well as other substrates by specific attachment mechanisms. The binding of the spirochete to human gingival fibroblasts resulted in cytotoxicity and cell death due to enzymes and other proteins. Binding of the spirochete to erythrocytes was accompanied by agglutination and lysis. Hemolysis releases hemin, which is sequestered by an outer membrane sheath receptor protein of the spirochete. The ability to locomote through viscous environments enables spirochetes to migrate within gingival crevicular fluid and to penetrate sulcular epithelial linings and gingival connective tissue. The virulence factors of the oral spirochetes proven in vitro underscore the important role they play in the periodontal disease process. This role has been evaluated in vivo by use of a murine model.

Oral Treponemes and Their Outer Membrane Extracts Activate Human Gingival Epithelial Cells through Toll-Like Receptor 2

“…Among these bacteria, oral treponemes and gramnegative, anaerobic, motile, and helical rods are generally isolated from patients with periodontal diseases (15); in contrast, no or only a few treponemes are found in healthy people (31). These oral treponemes have been revealed to be closely associated with various types of periodontal diseases (10,13,42). Further, human immunodeficiency virus-positive people with gingivitis or adult periodontitis have been shown to have increased numbers of oral treponemes in subgingival plaque (41,45).…”

Upregulation of Intercellular Adhesion Molecule 1 and Proinflammatory Cytokines by the Major Surface Proteins of Treponema maltophilum and Treponema lecithinolyticum , the Phylogenetic Group IV Oral Spirochetes Associated with Periodontitis and Endodontic Infections

“…Oral spirochetes are known to be associated with acute necrotizing ulcerative gingivitis and periodontitis (5,27,44). These organisms include enormously diverse Treponema species (8,11), and 10 species have been cultivated so far (10,50,54).…”

Detection and Quantification of Oral Treponemes in Subgingival Plaque by Real-Time PCR

“…The oral flora found in patients with chronic periodontitis consists of a variety of oral bacterial species. Among these organisms, oral treponemes, which are gram-negative, anaerobic, motile, and helical rods, have been shown to be closely associated with various types of periodontal diseases such as gingivitis, acute necrotizing ulcerative gingivitis, and adult periodontitis (3,5,14,22). Human immunodeficiency virus-positive subjects with gingivitis and adult periodontitis also have elevated numbers of oral treponemes in their subgingival plaque (21,23).…”