Comparison of three dispersion procedures for quantitative recovery of cultivable species of subgingival spirochetes

Spirochetes in Periodontal Disease in the Dog: A Review

The importance and the role of spirochetes in periodontal disease is controversial since the means to study these particular bacteria are limited. Because of specific requirements for growth, spirochetes are difficult to culture. Spirochetes could have profound effects on the perpetuation of periodontal disease. A review of the literature related to spirochetes is described.

The Role of Treponema denticola Motility in Synergistic Biofilm Formation With Porphyromonas gingivalis

Chronic periodontitis has a polymicrobial biofilm etiology and interactions between key oral bacterial species, such as Porphyromonas gingivalis and Treponema denticola contribute to disease progression. P. gingivalis and T. denticola are co-localized in subgingival plaque and have been previously shown to exhibit strong synergy in growth, biofilm formation and virulence in an animal model of disease. The motility of T. denticola, although not considered as a classic virulence factor, may be involved in synergistic biofilm development between P. gingivalis and T. denticola. We determined the role of T. denticola motility in polymicrobial biofilm development using an optimized transformation protocol to produce two T. denticola mutants targeting the motility machinery. These deletion mutants were non-motile and lacked the gene encoding the flagellar hook protein of the periplasmic flagella (ΔflgE) or a component of the stator motor that drives the flagella (ΔmotB). The specificity of these gene deletions was determined by whole genome sequencing. Quantitative proteomic analyses of mutant strains revealed that the specific inactivation of the motility-associated gene, motB, had effects beyond motility. There were 64 and 326 proteins that changed in abundance in the ΔflgE and ΔmotB mutants, respectively. In the ΔflgE mutant, motility-associated proteins showed the most significant change in abundance confirming the phenotype change for the mutant was related to motility. However, the inactivation of motB as well as stopping motility also upregulated cellular stress responses in the mutant indicating pleiotropic effects of the mutation. T. denticola wild-type and P. gingivalis displayed synergistic biofilm development with a 2-fold higher biomass of the dual-species biofilms than the sum of the monospecies biofilms. Inactivation of T. denticola flgE and motB reduced this synergy. A 5-fold reduction in dual-species biofilm biomass was found with the motility-specific ΔflgE mutant suggesting that T. denticola periplasmic flagella are essential in synergistic biofilm formation with P. gingivalis.

Conservation and revised annotation of the Treponema denticola prcB-prcA-prtP locus encoding the dentilisin (CTLP) protease complex

Interstrain differences in antigenic surface proteins may reflect immunological pressure or differences in receptor specificity of the antigen. Treponema denticola exhibits considerable interstrain variability in its major surface protein (Msp), but no studies have addressed this issue in dentilisin (CTLP), a surface protease complex that has a significant role in T. denticola-host interactions in periodontal disease. Furthermore, the genome annotation of the prcB-prcA-prtP operon encoding dentilisin contains apparent errors and lacks a deduced PrtP amino acid sequence. To address these issues we analysed the protease operon from diverse T. denticola strains, as well as clones of the ATCC 35405 Type strain from which the genome sequence and original GenBank prtP sequence were derived. 6xHis-tagging of the PrtP C-terminus in ATCC 35405 demonstrated absence of the 'authentic frameshift' in PrtP reported in the genome databases. We propose that T. denticola genome annotations be updated to reflect this new information. PrcB and the PrtP N-terminal region that includes the catalytic domain were highly conserved in common laboratory strains and clinical isolates of T. denticola. Dentilisin proteolytic activity varied considerably between strains. Antibodies against PrcB, PrcA and PrtP from the type strain recognized these proteins in most T. denticola strains. PrtP varied up to 20% over the C-terminal 270 residues between strains. The PrtP C-terminal eight-residues (DWFYVEYP) was present in all strains, with two strains containing an additional Y-residue preceding the stop codon. Such conserved PrtP domains may be required for interactions with PrcA and PrcB, or for substrate interactions.

Synergistic virulence of Porphyromonas gingivalis and Treponema denticola in a murine periodontitis model

Chronic periodontitis is characterized by the destruction of the tissues supporting the teeth and has been associated with the presence of a subgingival polymicrobial biofilm containing Porphyromonas gingivalis and Treponema denticola. We have investigated the potential synergistic virulence of P. gingivalis and T. denticola using a murine experimental model of periodontitis. An inoculation regime of four intra-oral doses of 1 × 10(10) P. gingivalis cells induced significant periodontal bone loss compared with loss in sham-inoculated mice, whereas doses of 1 × 10(9) cells or lower did not induce bone loss. Inoculation with T. denticola with up to eight doses of 1 × 10(10) cells failed to induce bone loss in this model. However, four doses of a co-inoculum of a 1 : 1 ratio of P. gingivalis and T. denticola at 5 × 10(8) or 1 × 10(9) total bacterial cells induced the same level of bone loss as four doses of 1 × 10(10) P. gingivalis cells. Co-inoculation induced strong P. gingivalis-specific T-cell proliferative and interferon-γ-dominant cytokine responses, and induced a strong T. denticola-specific interferon-γ dominant cytokine response. Only at the higher co-inoculum dose of 1 × 10(10) total cells was a T. denticola-specific T-cell proliferative response observed. These data show that P. gingivalis and T. denticola act synergistically to stimulate the host immune response and to induce alveolar bone loss in a murine experimental periodontitis model.

An efficient method for enumerating oral spirochetes using flow cytometry

Spirochetes, such as Treponema denticola, are thin walled, helical, motile bacteria. They are notoriously difficult to enumerate due to their thinness and the difficulties associated with culturing them. Here we have developed a modified oral bacterial growth medium (OBGM) that significantly improves the cultivation of T. denticola compared with a previously published growth medium. Three methods for the enumeration of T. denticola, semi-solid growth medium colony-forming unit (CFU) counts, DNA analysis and flow cytometry, are described and compared. Enumeration of T. denticola using the semi-solid agar method resulted in a positive linear relationship with absorbance of the culture (R(2)=0.9423). However, the semi-solid agar method was found to consistently underestimate (by 50 fold) the T. denticola cell density compared to previously published data. DNA analysis of T. denticola cultures reliably and consistently resulted in a positive linear relationship with absorbance (R(2)=0.9360), giving a calculated cell density of 6.9 x 10(8)cells/mL at an absorbance of 0.2 at 650 nm. Flow cytometry was also found to result in a positive linear relationship with absorbance (R(2)=0.9874), giving a calculated cell density of 6.6 x 10(8)cells/mL at an absorbance of 0.2 at 650 nm. In comparing all of these enumeration methods, the flow cytometry method was found to have distinct advantages, as it is accurate, rapid, and could distinguish between live and dead bacteria. Thus flow cytometry is a recommended means for the rapid and reliable enumeration of viable spirochetes from culture.

Laboratory maintenance of Treponema denticola

This unit describes the methods, media, and equipment necessary for routine laboratory culture and handling of the anaerobic oral spirochete Treponema denticola. Topics discussed include nutrient requirements, recommended media formulations, and expected growth kinetics, as well as methods and equipment necessary to maintain anaerobic conditions. An additional protocol on isolation of T. denticola from clinical samples is included.

Effects of whole cell sonicates of Treponema lecithinolyticum on osteoclast differentiation

BACKGROUND

Alveolar bone destruction is a characteristic feature of periodontal diseases and multinucleated osteoclast cells derived from hemopoietic cells are responsible for bone resorption. Treponema lecithinolyticum is a novel oral spirochete isolated from the periodontal lesions.

METHODS

The effect of whole cell sonicates on the osteoclast differentiation was examined in a co-culture system of hemopoietic mouse bone marrow cells and calvaria derived-osteoblastic cells to clarify the role of T. lecithinolyticum in the alveolar bone destruction associated with periodontal diseases. The differentiated osteoclasts were confirmed by tartrate-resistant acid phosphatase (TRAP) staining.

RESULTS

Sonicates of this bacterium stimulated the osteoclast formation in the co-culture system in a dose-dependent manner. The sonicates-induced osteoclast formation was partially inhibited by the heat treatment of sonicates. Indomethacin, which is a prostaglandin inhibitor, decreased the osteoclast formation induced by the bacterial sonicates.

CONCLUSIONS

These findings suggest that T. lecithinolyticum induces osteoclast differentiation by a prostaglandin E2-dependent mechanism and that heat-labile components may be involved in this process.

Methods for the spiral Salmonella mutagenicity assay including specialized applications

An automated approach to bacterial mutagenicity testing - the spiral Salmonella assay - was developed to simplify testing and to reduce the labor and materials required to generate dose-responsive mutagenicity information. This document provides the reader with an overview of the spiral assay and a discussion of its application for examining the mutagenic potential of pure compounds, complex environmental mixtures, and interactive effects. Guidelines for performing a routine spiral assay are presented, and alternative test methods intended to overcome a variety of technical difficulties (such as restricted sample availability, sample viscosity or volatility, etc.) are recommended. Methods for the computerized analysis of data and the interpretation of results are discussed.

Molecular epidemiology of oral treponemes associated with periodontal disease

Periodontitis, a disease responsible for tooth loss worldwide, is characterized by chronic inflammation of the periodontium, eventually leading to destruction of periodontal ligaments and supporting alveolar bone. Spirochetes, identified by dark-field microscopy as being the most predominant bacteria in advanced lesions, are thought to play a causative role. Various spirochetal morphotypes were observed, but most of these morphotypes are as yet uncultivable. To assess the role of these organisms we designed oligonucleotide probes for the identification of both cultivable and so far uncultivable spirochetes in periodontitis patients. Subgingival plaque specimens taken from diseased sites (n = 200) and healthy control sites (n = 44) from 53 patients with rapidly progressive periodontitis (RPP) were submitted to direct in situ hybridization or dot blot hybridization after prior amplification with eubacterial primers. Spirochetes were found in all patients, but their distributions varied considerably. Parallel use of oligonucleotide probes specific for cultivable or so far uncultivable treponemes suggested the presence of novel yet unknown organisms at a high frequency. These uncultivable treponemes were visualized by fluorescence in situ hybridization, and their morphologies, sizes, and numbers could be estimated. All RPP patients included in this study harbored oral treponemes that represent either novel species, e.g., Treponema maltophilum, or uncultivable phylotypes. Therefore, it is necessary to include these organisms in etiologic considerations and to strengthen efforts to cultivate these as yet uncultivable treponemes.

"Checkerboard" versus culture: a comparison between two methods for identification of subgingival microbiota

The present study compared the "checkerboard" DNA-DNA hybridization methodology with culture techniques for the analysis of the composition of the subgingival microbiota. 70 subjects, presenting with a variety of periodontal conditions, contributed with a total of 283 subgingival plaque samples analyzed with respect to the following species: Porphyromonas gingivalis, Prevotella intermedia/Prevotella nigrescens, Fusobacterium nucleatum, Campylobacter rectus, Eikenella corrodens, Bacteroides forsythus, Actinobacillus actinomycetemcomitans, Streptococcus sanguis and Streptococcus mutans. Species identification and quantification was performed by (i) the checkerboard method, using whole genomic, digoxigenin labeled DNA probes; and (ii) culture, including non-selective and selective media in combination with routine biochemical testing using commercial test panels. We found that the checkerboard technology resulted in higher prevalence figures for half of the species tested when compared to culture data. If the latter were used as the reference, checkerboard detection sensitivities ranged from 0.17 to 0.86, specificities from 0.17 to 1.0, and diagnostic accuracies from 0.51 to 0.81, depending on bacterial species. The use of the checkerboard data as the reference resulted in detection sensitivities for the culture procedures between 0.24 and 1.0 and specificities between 0.21 and 0.87. The checkerboard methodology resulted in statistically significant higher bacterial counts for the majority of the species. It was further observed that, for most species, the higher the total number colony-forming units in the sample, the higher the discrepancy between the results obtained by the two techniques.

Nutritional analysis and an enriched medium for fermentative treponemes isolated from subgingival plaque

In order to cultivate fermentative treponemes isolated on Medium 10 with the plate-in-bottle method from subgingival plaque, we developed the enriched Medium 10. Enriched Medium 10 broth consisted mainly of Trypticase peptone (2 g/L), yeast extract (10 g/l), glucose (5 g/l) and volatile fatty acids mixture (3.1 ml/l). The growth curves in enriched Medium 10 broth showed that clinical isolates of Treponema socranskii reached the early stationary phase on the 3rd-5th day, and the doubling times averaged 22.2h. By using enriched Medium 10, the nutritional analysis of oral treponemes was examined for each compound of the volatile fatty acid and various sera. Clinical isolates were found to require iso-butyric acid, 2-methylbutyric acids and/or iso-caproic acid independently for their growth. However, the growth of these fermentative treponemes was inhibited by addition of various sera to this medium.

Characterization of oral treponemes isolated from human periodontal pockets

A total of 90 clinical strains of oral treponemes was isolated from subgingival plaque in patients with periodontal disease. They were characterized by biochemical means as well as cell enzyme, protein analysis using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and DNA dot blot hybridization. Sixty strains were isolated on Medium 10 (M10), which was fundamentally serum-free. The remainder were isolated on serum-containing media. Isolates were divided into 6 groups according to their biochemical characteristics. Three of the 6 groups were asaccharolytic, and 2 of these 3 groups were Treponema denticola and "Treponema vincentii". The other 3 groups were saccharolytic and further divided into 9 subgroups. The analysis of cell enzyme, cell protein and dot blot hybridization with the DNA probe of Treponema socranskii indicated that all the saccharolytic groups were T. socranskii or closely related species. This study indicated that the newly characterized saccharolytic oral treponemes could be identified using M10 from the human periodontal pocket.

Enumeration of viable oral spirochetes from periodontal pockets

We recently developed a successful method for quantifying oral anaerobic spirochetes in pure culture by a viable count. New oral spirochete medium was used with low temperature-gelling agarose in polystyrene tissue-culture flasks. We have extended the use of this method to determine the viable count of spirochetes from periodontal pockets. Sixteen subgingival plaque samples were obtained by insertion of sterile paper points into deep periodontal pockets. The points were placed into reduced transport medium at chairside, vortexed in the microbiology laboratory and aliquots of the medium inoculated into molten new oral spirochete-agarose medium (37 degrees C) containing rifampin (20 micrograms/ml) in a flask. Subsequent dilutions were made from this initial flask to other flasks containing selective medium in sequence. All flasks were incubated anaerobically. Most other subgingival bacteria were selectively inhibited by rifampin. Spirochete colonies were typically spherical and were either dense or cottony. Their identities were checked by darkfield examination. Counts of colony-forming units of cultivable spirochetes ranged from 12.5% to 28.2% of the total cultivable anaerobic flora by the method described.

The antimicrobial activity of essential oils and essential oil components towards oral bacteria

A method for reproducibly determining minimal inhibitory concentrations and minimal bactericidal concentrations of plant extracts towards fastidiously and facultatively anaerobic oral bacteria, predicated upon measurements of optical densities in microtitre plate wells, was devised. The antimicrobial properties of some botanical oils were surveyed; of these, Australian tea tree oil, peppermint oil, and sage oil proved to be the most potent essential oils, whereas thymol and eugenol were potent essential oil components.

Proteolytic and oxidoreductase activity of Treponema denticola ATCC 35405 grown in an aerobic and anaerobic gaseous environment

The cells of a human oral spirochete, Treponema denticola ATCC 35405, and of seven clinical isolates of this organism obtained from the subgingival dental plaque of periodontitis patients were studied for their ability to grow in an aerobic and an anaerobic environment, and for their profile of peptidohydrolase and oxidoreductase enzymes. The growth yield of aerobically grown cultures was either comparable to or higher than that of anaerobically grown ones regardless of whether prereduced broth, freshly prepared broth or oxidized broth was used. However, elimination of certain supplements from the growth media resulted in poor growth regardless of the nature of the gaseous environment. The microscopic morphology and motility of the cells were not affected by differences in the gaseous atmosphere. Quantitative studies on several peptidohydrolase activities suggest that anaerobically grown cells displayed higher specific activity especially toward N alpha-L-prolyl-2-naphthylamine, indicating that increased synthesis of proline iminopeptidase enzymes (or enzyme) of the cells was associated with anaerobic growth conditions. The formation of enzymes hydrolysing N alpha-benzoyl-DL-arginyl-2-naphthylamine (and the corresponding p-nitroaniline) was not affected to the same extent. Growth experiments suggest that T. denticola ATCC 35405 is a facultatively anaerobic spirochete instead of an obligate anaerobe as reported in previous literature. The quantitative enzyme studies suggest that the gaseous growth atmosphere of the cells can exert a selective effect on the activity levels of certain peptidolytic enzymes of this organism. Such effects were not observed when the whole cells were studied by means of qualitative or semi-quantitative enzyme tests. The activities of catalase, peroxidase and superoxide dismutase of the cells were low and variable. Because of this, it was not possible to relate these oxidoreductase activities to the composition of the gaseous atmosphere.

A successful method for quantifying viable oral anaerobic spirochetes

Spirochetes are markedly prevalent in periodontal disease but are not included as predominant cultivable organisms because of the inability to quantify them by viable count. A successful method was developed for enumerating viable oral spirochetes as colony-forming units (CFU) in an agarose-based medium. Treponema denticola, Treponema vincentii and Treponema socranskii in log-phase growth in new oral spirochete (NOS) broth were used for evaluation of the method. Critical components of the method include enzyme-free low temperature-gelling (37 degrees C) agarose in NOS medium in small tissue-culture flasks into which the spirochetes were seeded and diluted. The flasks were anaerobically incubated in a glove-box. Reliable, consistent and reproducible viable counts of pure spirochete cultures were obtained. The injurious effects of spirochete temperature-sensitivity were averted by using molten agarose at 37 degrees C. Distinctive colony morphologies of spirochete species could be compared from pure cultures. Addition of rifampin into the medium showed no decrease in spirochete CFU count. The method as described allows for selection of mutants and detection of biochemical activity and is potentially useful for enumeration of spirochetes from periodontal pockets as members of the predominant cultivable flora.

Comparison of the benzoyl-DL-arginine-naphthylamide (BANA) test, DNA probes, and immunological reagents for ability to detect anaerobic periodontal infections due to Porphyromonas gingivalis, Treponema denticola, and Bacteroides forsythus

Most forms of periodontal disease are associated with the presence or overgrowth of anaerobic species that could include Treponema denticola, Porphyromonas gingivalis, and Bacteroides forsythus among others. These three organisms are among the few cultivable plaque species that can hydrolyze the synthetic trypsin substrate benzoyl-DL-arginine-naphthylamide (BANA). In turn, BANA hydrolysis by the plaque can be associated with periodontal morbidity and with the presence of these three BANA-positive organisms in the plaque. In this investigation, the results of the BANA test, which simultaneously detects one or more of these organisms, were compared with the detection of these organisms by (i) highly specific antibodies to P. gingivalis, T. denticola, and B. forsythus; (ii) whole genomic DNA probes to P. gingivalis and T. denticola; and (iii) culturing or microscopic procedures. The BANA test, the DNA probes, and an enzyme-linked immunosorbent assay or an indirect immunofluorescence assay procedure exhibited high sensitivities, i.e., 90 ot 96%, and high accuracies, i.e., 83 to 92%, in their ability to detect combinations of these organisms in over 200 subgingival plaque samples taken from the most periodontally diseased sites in 67 patients. This indicated that if P. gingivalis, T. denticola, and B. forsythus are appropriate marker organisms for an anaerobic periodontal infection, then the three detection methods are equally accurate in their ability to diagnose this infection. The same statement could not be made for the culturing approach, where accuracies of 50 to 62% were observed.

Comparison of various detection methods for periodontopathic bacteria: can culture be considered the primary reference standard?

The development of diagnostic tests for a periodontal infection raises the issue as to what the appropriate reference standard, or "gold standard," should be for the evaluation of a new test. The present research was initiated to compare the ability of several detection methods, i.e., a serial dilution anaerobic culture and/or microscopic procedure, a DNA probe procedure, and immunological reagents using both an enzyme-linked immunosorbent assay and an indirect immunofluorescence assay to detect Treponema denticola, Porphyromonas gingivalis, Bacteroides forsythus, and Actinobacillus actinomycetemcomitans in subgingival plaque samples taken from 204 periodontally diseased tooth sites. The prevalence of the four monitored species varied as a function of both the species and the detection method. Spirochetes were present in 99% of the plaques, whereas A. actinomycetemcomitans was detected at the lowest frequency. The culture method yielded the lowest prevalence values for the three cultivable species. This raised the question as to which results, those obtained by culture or those obtained by the DNA probes and the immunological reagents, were the most reliable. This issue was addressed by looking at the prevalence profile of the monitored organisms, as determined by all the detection methods. If the species was detected by three or four of the detection methods, then it was considered present, whereas if it was absent by three or four of the detection methods, then it was considered absent. This approach showed the DNA probes and immunological reagents to be significantly superior (P less than 0.05) to the culture approach for the detection of P. gingivalis, A. actinomycetemcomitans, and B. forsythus and to be comparable to the microscopic approach in the detection of T. denticola.

Detection of two anaerobic periodontopathogens in children by means of the BANA and ELISA assays

The mouths of young children become colonized by a variety of bacteria, but there have been only a few studies that have sought the presence of periodontopathic species in this population. Almost all of these studies used culturing techniques rather than the newer detection methodologies for various periodontopathogens. Studies in adults have shown that Treponema denticola and Porphyromonas (Bacteroides) gingivalis can be detected in dental plaque by use of the BANA and ELISA diagnostic tests. In the present study, plaque samples from four subgingival sites in each of 157 children (aged from two to 18 years) were tested for BANA hydrolysis with a BANA reagent card, and for T. denticola and P. gingivalis with an ELISA assay. Anaerobic periodontopathogens hydrolyzing the BANA substrate were found to be present in at least one of four plaque samples in 88 children (56%). T. denticola and/or P. gingivalis were detected by ELISA in at least one plaque sample in each of 135 children (86%). This study shows that children are widely colonized by these micro-organisms. A higher proportion of Black children than Caucasian children was colonized by these BANA-positive organisms. Also, children having a parent with a documented history of periodontal disease were more likely to be BANA-positive than were children of parents with unknown periodontal status.

Benzoyl-arginine naphthylamide (BANA) hydrolysis by Treponema denticola and/or Bacteroides gingivalis in periodontal plaques

Treponema denticola and Bacteroides gingivalis are among the few recognized species found in periodontal pockets that can hydrolyze the synthetic peptide N-benzoyl-DL-arginine-2-naphthylamide (BANA). We determined the presence of these periodontal pathogens in BANA-positive and -negative plaque samples through the use of indirect immunofluorescent antibody techniques. Eighteen of 27 diseased sites gave BANA-positive reactions, and 9 gave BANA-negative reactions. T. denticola was present in 16 of 18 BANA-positive reactions, whereas B. gingivalis was detected in 9 of the 18 BANA-positive reactions. T. denticola was present in 1 and B. gingivalis in 2 of the 9 BANA-negative reactions. Neither organism was detected in the 19 healthy sites that were negative for BANA. All measured differences between BANA-positive and BANA-negative plaques obtained in the same individuals were statistically significant. The accuracy of the BANA test, compared with clinical parameters such as bleeding upon probing and increased probing depth, was about 80%. The accuracy of the test in detecting the presence of T. denticola was 93%, for B. gingivalis, 76% and for T. denticola and/or B. gingivalis, 96%. This study indicated that BANA-positive plaques were associated with the presence of T. denticola and/or B. gingivalis, that T. denticola was found at a greater frequency and levels in BANA-positive plaques than B. gingivalis, and that the presence of these organisms was associated with clinical disease.

Cross-reactivity of nonspecific treponemal antibody in serologic tests for Lyme disease

Serum samples obtained from 59 persons who had acute necrotizing ulcerative gingivitis, periodontitis, syphilis, or Lyme disease were tested against Treponema phagedenis biotype Reiter, Treponema denticola, Treponema vincentii, and Treponema scoliodontum by indirect fluorescent-antibody staining methods. Although there were positive reactions for sera representing each of these study groups and for 20 (13%) of 156 samples collected from the general population (premarital screening for syphilis), titration endpoints were relatively low (less than or equal to 1:256). Serum samples from 18 persons who had gingivitis or periodontitis but no history of Lyme borreliosis were tested by enzyme-linked immunosorbent assay for antibodies to Borrelia burgdorferi. Of these, five (28%) had immunoglobulin M antibody and four (22%) contained immunoglobulin G antibodies to this spirochete. Adsorption with either sorbent commercially prepared from T. phagedenis biotype Reiter or with washed, whole cells of T. phagedenis biotype Reiter reduced cross-reactivity in the enzyme-linked immunosorbent assay for Lyme borreliosis.

Improved detection of oral spirochetes with an anaerobic culture method

A method for routine culturing of oral spirochetes was studied in periodontitis patients and subjects with healthy gingivae. Subgingival plaque bacteria, including oral spirochetes were cultured anaerobically using the steel wool jar method, the glove-box procedure and the plate-in-bottle method. They were also observed directly with a phase-contrast microscope. The number of colonies of recovered spirochetes was significantly higher with the plate-in-bottle method when Medium 10 (M10) or M10 supplemented with 10% rumen fluid was used. In almost all cases, spirochetes were detected with this culture method. The ratios of spirochetes from patient samples, cultured by the plate-in-bottle method, and of other microorganisms, cultured in Eggerth-Gagnon (EG) medium by the steel wool jar method, were almost identical of those observed by phase-contrast microscopy. These results indicate that it can be just as possible to culture certain oral spirochetes as other anaerobic bacteria.

The role of spirochetes in periodontal disease

The spirochetal accumulation in subgingival plaque appears to be a function of the clinical severity of periodontal disease. It is not known how many different spirochetal species colonize the plaque, but based upon size alone, there are small, intermediate-sized, and large spirochetes. Four species of small spirochetes are cultivable, and of these, T. denticola has been shown to possess proteolytic and keratinolytic enzymes as well as factors or mechanisms which suppress lymphocyte blastogenesis and inhibit fibroblast and polymorphonuclear leukocyte (PMNL) function. All of these attributes could contribute to periodontal tissue insult. Yet independent of these potential virulence mechanisms, the overgrowth of spirochetes can be clinically useful if simply interpreted as indicating the result of tissue damage. In this case, the spirochetes would be indicators of disease and could be easily monitored by microscopic examination of plaque, or possibly by the measurement of benzoyl-DL-arginine-2-naphthylamide (BANA) hydrolytic activity in the plaque.

Enzyme profiles of oral spirochetes in RapID-ANA system

Enzyme profiles of oral Treponema species were determined by using RapID-ANA (Innovative Diagnostic System, Atlanta, Ga.), a 4-h test system which detects 18 enzymatic reactions, including aminopeptidases and glycosidases. Seventy-two clinical isolates of Treponema denticola, four reference strains of T. denticola (ATCC 35404, ATCC 35405, ATCC 35520, and ATCC 33521), one strain of T. vincentii (ATCC 35580), and two strains of T. socranskii subspecies (T. socranskii subsp. buccale ATCC 35534 and T. socranskii subsp. socranskii ATCC 35536) were used in this study. All T. denticola strains produced indole and a variety of aminopeptidases and glycosidases. These organisms could be differentiated into two groups on the basis of tetrazolium reductase and serine, phenylalanine, and glycine aminopeptidase activities. T. vincentii produced N-acetylglucosaminidase and arginine aminopeptidase, which facilitated the differentiation of this organism from T. socranskii subspecies and the T. denticola group. T. socranskii subspecies gave positive reactions for alkaline phosphatase only. These findings suggest that the RapID-ANA system is useful for enzymatic characterization and differentiation of oral spirochetes.