Environmental modulation of oral treponeme virulence in a murine model.
This investigation examined the effects of environmental alteration on the virulence of the oral treponemes Treponema denticola and Treponema pectinovorum. The environmental effects were assessed by using a model of localized inflammatory abscesses in mice. In vitro growth of T. denticola and T. pectinovorum as a function of modification of the cysteine concentration significantly enhanced abscess formation and size. In contrast, growth of T. denticola or T. pectinovorum under iron-limiting conditions (e.g., dipyridyl chelation) had no effect on abscess induction in comparison to that when the strains were grown under normal iron conditions. In vivo modulation of the microenvironment at the focus of infection with Cytodex beads demonstrated that increasing the local inflammation had no effect on lesion induction or size. In vivo studies involved the determination of the effects of increased systemic iron availability (e.g., iron dextran or phenylhydrazine) on the induction, kinetics, and size of lesions. T. denticola induced significantly larger lesions in mice with iron pretreatment and demonstrated systemic manifestations of the infectious challenge and an accompanying spreading lesion with phenylhydrazine pretreatment (e.g., increases in circulating free hemoglobin). In contrast, T. pectinovorum virulence was minimally affected by this in vivo treatment to increase iron availability. T. denticola virulence, as evaluated by lesion size, was increased additively by in vivo iron availability, and cysteine modified growth of the microorganism. Additionally, galactosamine sensitized mice to a lethal outcome following infection with both T. denticola and T. pectinovorum, suggesting an endotoxin-like activity in these treponemes. These findings demonstrated the ability to modify the virulence capacity of T. denticola and T. pectinovorum by environmental conditions which can be evaluated by using in vivo murine models. (+info)
Treponema lecithinolyticum sp. nov., a small saccharolytic spirochaete with phospholipase A and C activities associated with periodontal diseases.
Strong phospholipase A (PLA) and phospholipase C (PLC) activities as potential virulence factors are the outstanding characteristics of eight strains of small oral spirochaetes isolated from deep periodontal lesions. By qualitative dot-blot DNA-DNA hybridization and 16S rDNA sequence comparison, these spirochaetes form a distinct phylogenetic group, with Treponema maltophilum as its closest cultivable relative. Growth of these treponemes, cells of which contain two endoflagella, one at each pole, was autoinhibited by the PLA-mediated production of lysolecithin unless medium OMIZ-Pat was prepared without lecithin. N-Acetylglucosamine was essential and D-ribose was stimulatory for growth. All isolates were growth-inhibited when 1% foetal calf serum was added to the medium. Growth on agar plates supplemented with human erythrocytes produced haemolysis. In addition to PLA and PLC, the new isolates displayed strong activities of alkaline and acid phosphatases, beta-galactosidase, beta-glucuronidase, N-acetyl-beta-glucosaminidase and sialidase, intermediate activities of C4- and C8-esterases, naphthol phosphohydrolase and alpha-fucosidase and a distinctive 30 kDa antigen detectable on Western blots. This phenotypically and genotypically homogeneous group is proposed as a novel species, Treponema lecithinolyticum sp. nov., with isolate OMZ 684T designated as the type strain. A molecular epidemiological analysis using a T. lecithinolyticum-specific probe showed this organism to be associated with affected sites when compared with unaffected sites of periodontitis patients. This association was more pronounced in patients with rapidly progressive periodontitis than in those with adult periodontitis. (+info)
Inactivation of Treponema pallidum by silver sulfadiazine.
Silver sulfadiazine, an anti-infectious agent for the prevention and treatment of burn sepsis, has been found to possess antitreponemal activity against Treponema pallidum. At 28 C, complete inactivation of the organism was produced by exposure of the organism to a concentration of 50 mug of the drug per ml for 1 to 5 min, 12 to 25 mug/ml for 10 to 15 min, and 6.2 mug/ml for 30 min. At 37 C, the amounts of silver sulfadiazine required for inactivation were two- to fourfold less. (+info)
Detection of Treponema denticola in atherosclerotic lesions.
We examined 26 atherosclerotic lesions and 14 nondiseased aorta specimens to detect the periodontopathogenic part of the bacterial 16S rRNA locus by PCR. Treponema denticola sequence of the 16S rRNA locus was found in 6 out of 26 DNA samples (23.1%) from the formalin-fixed, paraffin-embeded atherosclerotic lesions obtained during surgery but not in any of the 14 nondiseased aorta samples from deceased persons. Utilizing immunofluorescence microscopy, we observed aggregated antigenic particles reacting with rabbit antiserum against T. denticola in thin sections of the PCR-positive samples, but we could not detect any reacting particles in the PCR-negative thin sections. (+info)
Treponema parvum sp. nov., a small, glucoronic or galacturonic acid-dependent oral spirochaete from lesions of human periodontitis and acute necrotizing ulcerative gingivitis.
Small oral spirochaetes with a strict dependence on either glucuronic acid (GluA) or galacturonic acid (GalA) were isolated from European patients with periodontitis and from Chinese patients with either gingivitis or acute necrotizing ulcerative gingivitis (ANUG). Thirteen such isolates were similar phenotypically to Treponema pectinovorum ATCC 33768T and this classification was confirmed by 16S rRNA sequencing. However, four isolates differed from T. pectinovorum by their small cell size, by a prominent beta-glucuronidase activity, by a distinct protein and antigen profile, by an inability to grow on pectin as sole source of carbohydrate and by a markedly enhanced growth rate when supplied with a second carbohydrate (L-arabinose, D-galactose, D-glucose, D-fructose, D-mannitol, D-mannose, pectin, D-ribose or D-xylose) in addition to the essential GluA/GalA. By 16S rRNA sequencing these four isolates clustered in the recently described phylotype 'Smibert-2'. T. pectinovorum (14 strains) and 'Smibert-2' (four isolates with beta-glucuronidase activity) could each be subdivided into two serotypes based on immunoblot reactivity with two mAbs. Representatives of the two groups, including T. pectinovorum ATCC 33768T, showed a 1:2:1-type periplasmic flagellar arrangement. 'Smibert-2' is described as a novel species, Treponema parvum sp. nov., with isolate OMZ 833T (= ATCC 700770T) proposed as the type strain and OMZ 842 (= ATCC 700773) as reference strain for a second serotype. (+info)
Biological characterization of lipopolysaccharide from Treponema pectinovorum.
This study investigated the endotoxic and biological properties of purified lipopolysaccharide (LPS) isolated from an oral spirochete, Treponema pectinovorum. Endotoxicity, measured by Limulus amoebocyte lysate kinetic assay, showed that the LPS contained 1.28 endotoxin units per microg of purified LPS, which was approximately 4,000 times less than Escherichia coli O55:B5 LPS. To determine in vivo endotoxicity, LPS responder mice were administered LPS following galactosamine (GalN) sensitization. The LPS induced neither endotoxic symptoms nor lethality for 96 h, suggesting negligible or very low endotoxicity. In contrast, infection with live T. pectinovorum induced 100% lethality within 12 h in GalN-sensitized LPS responder mice, indicating an endotoxin-like property of this treponeme. Heat-killed microorganisms exhibited no lethality in GalN-sensitized mice, suggesting that the endotoxicity was associated with heat-labile components. To determine cytokine and chemokine induction by LPS, human gingival fibroblasts were stimulated and secretion of interleukin 1beta (IL-1beta), granulocyte-macrophage colony-stimulating factor, gamma interferon, IL-6, IL-8, and monocyte chemoattractant protein 1 (MCP-1) was assessed. The purified LPS induced significant amounts of only IL-6, IL-8, and MCP-1, although they were substantially lower than levels after challenge with live T. pectinovorum. After injection of LPS or live or heat-killed T. pectinovorum, serum was collected from mice and analyzed for proinflammatory cytokines IL-1beta, tumor necrosis factor alpha (TNF-alpha), and IL-6. LPS induced only IL-6 consistently. Both live and heat-killed T. pectinovorum induced serum IL-6, which was higher than the level detected following LPS administration. Importantly, live bacteria elicited systemic TNF-alpha and IL-1beta levels similar to those induced by a lethal dose of live E. coli O111. The results indicated that T. pectinovorum LPS has very low or no endotoxicity, although it can elicit low levels of cytokines from host cells. In contrast to the LPS, live T. pectinovorum demonstrated in vivo toxicity, which was associated with serum IL-1beta, TNF-alpha, and IL-6, suggesting an endotoxin-like property of a heat-labile molecule(s) of the spirochete. (+info)
Isolation and characterisation of a novel spirochaete from severe virulent ovine foot rot.
A novel spirochaete was isolated from a case of severe virulent ovine foot rot (SVOFR) by immunomagnetic separation with beads coated with polyclonal anti-treponemal antisera and prolonged anaerobic broth culture. The as yet unnamed treponeme differs considerably from the only other spirochaete isolated from ovine foot rot as regards morphology, enzymic profile and 16S rDNA sequence. On the basis of 16S rDNA, it was most closely related to another unnamed spirochaete isolated from cases of bovine digital dermatitis in the USA, raising the possibility of cross-species transmission. Further information is required to establish this novel ovine spirochaete as the cause of SVOFR. (+info)
Role of Treponema denticola in periodontal diseases.
Among periodontal anaerobic pathogens, the oral spirochetes, and especially Treponema denticola, have been associated with periodontal diseases such as early-onset periodontitis, necrotizing ulcerative gingivitis, and acute pericoronitis. Basic research as well as clinical evidence suggest that the prevalence of T denticola, together with other proteolytic gram-negative bacteria in high numbers in periodontal pockets, may play an important role in the progression of periodontal disease. The accumulation of these bacteria and their products in the pocket may render the surface lining periodontal cells highly susceptible to lysis and damage. T. denticola has been shown to adhere to fibroblasts and epithelial cells, as well as to extracellular matrix components present in periodontal tissues, and to produce several deleterious factors that may contribute to the virulence of the bacteria. These bacterial components include outer-sheath-associated peptidases, chymotrypsin-like and trypsin-like proteinases, hemolytic and hemagglutinating activities, adhesins that bind to matrix proteins and cells, and an outer-sheath protein with pore-forming properties. The effects of T. denticola whole cells and their products on a variety of host mucosal and immunological cells has been studied extensively (Fig. 1). The clinical data regarding the presence of T. denticola in periodontal health and disease, together with the basic research results involving the role of T. denticola factors and products in relation to periodontal diseases, are reviewed and discussed in this article. (+info)