Persistent presence of Bacteroides forsythus as a risk factor for attachment loss in a population with low prevalence and severity of adult periodontitis

Subgingival host-microbiome metatranscriptomic changes following scaling and root planing in grade II/III periodontitis

AIM

To assess the effects of scaling and root planing (SRP) on the dynamics of gene expression by the host and the microbiome in subgingival plaque samples.

MATERIALS AND METHODS

Fourteen periodontitis patients were closely monitored in the absence of periodontal treatment for 12 months. During this period, comprehensive periodontal examination and subgingival biofilm sample collection were performed bi-monthly. After 12 months, clinical attachment level (CAL) data were compiled and analysed using linear mixed models (LMM) fitted to longitudinal CAL measurements for each tooth site. LMM classified the sites as stable (S), progressing (P), or fluctuating (F). After the 12-month visit, subjects received SRP, and at 15 months they received comprehensive examination and supportive periodontal therapy. Those procedures were repeated at the 18-month visit, when patients were also sampled. Each patient contributed with one S, one P, and one F site collected at the 12- and 18-month visits. Samples were analysed using Dual RNA-Sequencing to capture host and bacterial transcriptomes simultaneously.

RESULTS

Microbiome and host response behaviour were specific to the site's progression classification (i.e., S, P, or F). Microbial profiles of pre- and post-treatment samples exhibited specific microbiome changes, with progressing sites showing the most significant changes. Among them, Porphyromonas gingivalis was reduced after treatment, while Fusobacterium nucleatum showed an increase in proportion. Transcriptome analysis of the host response showed that interleukin (IL)-17, TNF signalling pathways, and neutrophil extracellular trap formation were the primary immune response activities impacted by periodontal treatment.

CONCLUSIONS

SRP resulted in a significant "rewiring" of host and microbial activities in the progressing sites, while restructuring of the microbiome was minor in stable and fluctuating sites.

Subgingival microbiome is associated with alveolar bone loss measured 5 years later in postmenopausal women

BACKGROUND

The aim of this study was to quantify the association between subgingival microbiota and periodontal disease progression in older women, for which limited published data exist.

METHODS

A total of 1016 postmenopausal women, aged 53 to 81 years, completed baseline (1997 to 2001) and 5-year (2002 to 2006) dental exams that included probing depth, clinical attachment level, gingival bleeding, and radiographic alveolar crestal height (ACH). Baseline microbiota were measured in subgingival plaque using 16S rRNA sequencing. Associations between 52 microbiota we previously found statistically significantly associated with clinical periodontal disease at baseline, were examined with disease progression. The traditional Socransky microbiota complexes also were evaluated. Side-by-side radiograph comparisons were used to define progression as ≥2 teeth with ≥1 mm ACH loss or ≥1 new tooth loss to periodontitis. The association between baseline centered log(2) ratio transformed microbial relative abundances and 5-year periodontal disease progression was measured with generalized linear models.

RESULTS

Of 36 microbiota we previously showed were elevated in moderate/severe disease at baseline, 24 had statistically significantly higher baseline mean relative abundance in progressing compared with non-progressing women (P < .05, all); which included all Socransky red bacteria (P. gingivalis, T. forsythia, T. denticola). Of 16 microbiota elevated in none/mild disease at baseline, five had statistically significantly lower baseline abundance in non-progressing compared with progressing women (P < 0.05, all), including one Socransky yellow bacteria (S. oralis). When adjusted for baseline age, socioeconomic status, and self-rated general health status, odds ratios for 5-year progression ranged from 1.18 to 1.51 (per 1-standard deviation increment in relative abundance) for microbiota statistically significantly (P < 0.05) positively associated with progression, and from 0.77 to 0.82 for those statistically significantly (P < 0.05) inversely associated with progression. These associations were similar when stratified on baseline levels of pocket depth, gingival bleeding, ACH, and smoking status.

CONCLUSIONS

These prospective results affirm clearly that subgingival microbiota are measurably elevated several years prior to progression of alveolar bone loss, and include antecedent elevations in previously undocumented taxa additional to known Socransky pathogenic complexes.

Localization and density of Porphyromonas gingivalis and Tannerella forsythia in gingival and subgingival granulation tissues affected by chronic or aggressive periodontitis

Porphyromonas gingivalis and Tannerella forsythia have been thought to be associated with periodontitis; however comprehensive histopathological localization of bacteria in affected human periodontal tissues is not well documented. In the present study, we examined formalin-fixed paraffin-embedded gingival and subgingival granulation tissues from 71 patients with chronic periodontitis and 11 patients with aggressive periodontitis, using immunohistochemistry with novel monoclonal antibodies specific to P. gingivalis or T. forsythia, together with quantitative real-time polymerase chain reaction for each bacterial DNA. Immunohistochemisty revealed both bacterial species extracellularly, as aggregates or within bacterial plaque, and intracellularly in stromal inflammatory cells, squamous epithelium, and capillary endothelium of granulation tissue. Combined analysis with the results from polymerase chain reaction suggested that localization and density of T. forsythia is closely associated with those of P. gingivalis, and that bacterial density is a factor responsible for the cell-invasiveness and tissue-invasiveness of these periodontal bacteria. Detection of these bacteria in the capillary endothelium in some samples suggested possible bacterial translocation into the systemic circulation from inflamed gingival and subgingival granulation tissues. Immunohistochemistry with the novel antibodies showed high specificity and sensitivity, and can be used to locate these periodontal bacteria in routinely-used formalin-fixed paraffin-embedded human tissue sections from systemic locations.

Comparative evaluation of two subgingival irrigating solutions in the management of periodontal disease: A clinicomicrobial study

Context

Local administration of antimicrobial agents offer a "site-specific" approach to the periodontal therapy and it has several benefits.

Aim

The present study was aimed to assess the clinical and microbial changes by subgingival irrigation using different subgingival irrigants in periodontitis patients and also to assess the mechanical effect of different local irrigation devices; if any.

Settings and Design

Split-mouth design was employed on ten individuals.

Materials and Methods

The study sample consisted of 10 individuals in whom full-mouth scaling and root planing was performed and subgingival irrigation therapy was instituted for an experimental period of 30 days. The clinical as well as microbiological parameters were evaluated.

Statistical Analysis Used

To calculate baseline data with day thirty data, paired t-test was used. Intergroup comparison was carried out using one-way ANOVA. Multiple comparisons among groups were carried out using post hoc Tamhane's T2 test.

Results

Among the different subgingival irrigants used, 0.2% chlorhexidine gluconate is most effective followed by ozonated water, whereas saline was found to be ineffective when compared to the other two subgingival irrigants. Subgingival irrigation using pulsated device may not have any additive effect in alteration of the subgingival microflora.

Conclusion

Within the limits and scope of the study, it can be safely concluded that 0.2% chlorhexidine may be used as an adjunct to mechanical therapy for achieving a significant reduction in inflammatory periodontal changes and also reduction in periodontopathogenic microflora.

Introduction to Clinical Microbiology for the General Dentist

Clinical oral microbiology may help dental professionals identify infecting pathogenic species and evaluate their in vitro antimicrobial susceptibility. Saliva, dental plaque biofilms, mucosal smears, abscess aspirates, and soft tissue biopsies are sources of microorganisms for laboratory testing. Microbial-based treatment end points may help clinicians better identify patients in need of additional or altered dental therapies before the onset of clinical treatment failure, and help improve patient oral health outcomes. Microbiological testing appears particularly helpful in periodontal disease treatment planning. Further research and technological advances are likely to increase the availability and clinical utility of microbiological analysis in modern dental practice.

Point-of-care detection of Tannerella forsythia using an antigen-antibody assisted dielectrophoretic impedance measurement method

The importance of periodontal treatment planning based on diagnosis with clinical detection of periodontal pathogens has been well recognized. However, reliable detection and quantification methods that can be conveniently used at chair-side have yet to be developed. This study aimed to evaluate the clinical use of a novel apparatus which uses an antigen-antibody reaction assisted dielectrophoretic impedance measurement (AA-DEPIM) for the detection of a prominent periodontal pathogen, Tannerella forsythia. A total of 15 patients with a clinical diagnosis of chronic periodontitis, three periodontally healthy volunteers and two with gingivitis were subjected to clinical and microbiological examinations. Saliva samples were analyzed for the presence of T. forsythia using AA-DEPIM, PCR-Invader and real-time PCR methods. The measurement values for total bacteria and T. forsythia using the prototype AA-DEPIM apparatus were significantly greater in periodontitis group than those in healthy/gingivitis group. Using the AA-DEPIM apparatus with tentative cut-off values, T. forsythia was detected for 14 (12 with periodontitis and 2 either healthy or with gingivitis) out of 20 individuals. The measurement for the detection of T. forsythia by the AA-DEPIM method showed a significant positive correlation with the detection by PCR-Invader (r = 0.541, p = 0.01) and the real-time PCR method (r = 0.834, p = 0.01). When the PCR-Invader method was used as a reference, the sensitivity and specificity of the AA-DEPIM method were 76.5% and 100%, respectively. The results suggested that the AA-DEPIM method has potential to be used for clinically evaluating salivary presence of T. forsythia at chair-side.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN-CTR) UMIN000012181.

Crevicular fluid biomarkers and periodontal disease progression

AIM

Assess the ability of a panel of gingival crevicular fluid (GCF) biomarkers as predictors of periodontal disease progression (PDP).

MATERIALS AND METHODS

In this study, 100 individuals participated in a 12-month longitudinal investigation and were categorized into four groups according to their periodontal status. GCF, clinical parameters and saliva were collected bi-monthly. Subgingival plaque and serum were collected bi-annually. For 6 months, no periodontal treatment was provided. At 6 months, patients received periodontal therapy and continued participation from 6 to 12 months. GCF samples were analysed by ELISA for MMP-8, MMP-9, Osteoprotegerin, C-reactive Protein and IL-1β. Differences in median levels of GCF biomarkers were compared between stable and progressing participants using Wilcoxon Rank Sum test (p = 0.05). Clustering algorithm was used to evaluate the ability of oral biomarkers to classify patients as either stable or progressing.

RESULTS

Eighty-three individuals completed the 6-month monitoring phase. With the exception of GCF C-reactive protein, all biomarkers were significantly higher in the PDP group compared to stable patients. Clustering analysis showed highest sensitivity levels when biofilm pathogens and GCF biomarkers were combined with clinical measures, 74% (95% CI = 61, 86).

CONCLUSIONS

Signature of GCF fluid-derived biomarkers combined with pathogens and clinical measures provides a sensitive measure for discrimination of PDP (ClinicalTrials.gov NCT00277745).

Specific infections as the etiology of destructive periodontal disease: a systematic review

Destructive periodontal disease has been primarily defined and investigated as an infectious disease. The aim of this study was to systematically search for cohort studies where microbiological diagnoses were performed before the onset of destructive periodontal disease and where statistically significant associations were identified. A search was executed in PubMed. The results showed that three studies published after 2005 supported the infection hypothesis for one putative periodontal pathogen: Aggregatibacter actinomycetemcomitans. These three studies were conducted in predominantly non-Caucasian pediatric populations living in geographic areas with an elevated child-mortality rate. These studies did not obtain physical or laboratory markers of health, making it possible that A. actinomycetemcomitans was not a cause but a marker for poor environmental or systemic health. No cohort studies were identified supporting the infection hypothesis in adults, Caucasians or in a population residing in areas with child-mortality rates reflective of healthy population goals. While the possibility cannot be excluded that A. actinomycetemcomitans has an etiological role in certain specific pediatric populations, there are no cohort studies supporting an infectious etiology of destructive periodontal disease in adults.

Salivary biomarkers for predicting the progression of chronic periodontitis

OBJECTIVE

Predicting the progression of periodontitis would allow for targeted supportive periodontal therapy. The purpose of this study was to determine the usefulness of salivary biomarkers for predicting the progression of periodontitis.

DESIGN

Eighty-five chronic periodontitis patients were enrolled in an 18-month longitudinal study. Amongst them, 57 experienced progression of periodontitis, indicated at the end of the 18 months by at least one site with >3mm loss of attachment compared with baseline. We determined the levels of aspartate aminotransferase, alanine aminotransferase (ALT), lactate dehydrogenase, alkaline phosphatase and free haemoglobin as biomarkers, as well as the counts of Porphyromonas gingivalis, Prevotella intermedia and Tannerella forsythia, which represented the periodontal bacteria, in the stimulated saliva. The Mann-Whitney U test was used to compare patients with and without progression. After categorising the diagnostic values, the chi-square test was applied.

RESULTS

Counts and ratios (ratio to total bacteria) of P. gingivalis and P. intermedia were found to be significant predictors of the progression of periodontitis. To increase prediction accuracy, combination analyses were performed. The combination of ALT level and the P. gingivalis ratio showed the highest likelihood (p<0.001, sensitivity 0.40, specificity 0.96, likelihood 11.30).

CONCLUSION

Our findings suggest that salivary ALT level and the P. gingivalis ratio may be potential indicators for the progression of periodontitis. Such a salivary test could be a useful diagnostic tool for predicting periodontal disease progression.

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.

The OxyR homologue in Tannerella forsythia regulates expression of oxidative stress responses and biofilm formation

Tannerella forsythia is an anaerobic periodontal pathogen that encounters constant oxidative stress in the human oral cavity due to exposure to air and reactive oxidative species from coexisting dental plaque bacteria as well as leukocytes. In this study, we sought to characterize a T. forsythia ORF with close similarity to bacterial oxidative stress response sensor protein OxyR. To analyse the role of this OxyR homologue, a gene deletion mutant was constructed and characterized. Aerotolerance, survival after hydrogen peroxide challenge and transcription levels of known bacterial antioxidant genes were then determined. Since an association between oxidative stress and biofilm formation has been observed in bacterial systems, we also investigated the role of the OxyR protein in biofilm development by T. forsythia. Our results showed that aerotolerance, sensitivity to peroxide challenge and the expression of oxidative stress response genes were significantly reduced in the mutant as compared with the wild-type strain. Moreover, the results of biofilm analyses showed that, as compared with the wild-type strain, the oxyR mutant showed significantly less autoaggregation and a reduced ability to form mixed biofilms with Fusobacterium nucleatum. In conclusion, a gene annotated in the T. forsythia genome as an oxyR homologue was characterized. Our studies showed that the oxyR homologue in T. forsythia constitutively activates antioxidant genes involved in resistance to peroxides as well as oxygen stress (aerotolerance). In addition, the oxyR deletion attenuates biofilm formation in T. forsythia.

Bacterial markers of periodontal diseases and their practical significance in dentistry

The incidence and prevalence of Actinobacillus actinomycetemcomitans, Porphyronmonas gingivalis, and Tannerella forsythensis in specimens of subgingival dental deposit were evaluated in 495 residents of St. Petersburg aged 6-82 years. The microorganisms were detected by gene-specific PCR of 16S rDNA. In accordance with age-specific increase in the incidence of gingival diseases, the percentage of samples containing T. forsythensis and P. gingivalis was significantly higher in adult and elderly patients in comparison with adolescents. The presence of T. forsythensis significantly correlated with the presence of gingivitis and dental deposit. In addition, the incidence of T. forsythensis was significantly higher in tobacco smokers. These results attest to a relationship between T. forsythensis infection and more frequent periodontal diseases associated with aging and tobacco smoking.

Comparative analysis of putative periodontopathic bacteria by multiplex polymerase chain reaction

BACKGROUND AND OBJECTIVE

The polymerase chain reaction (PCR) has been applied for the rapid and specific detection of periodontopathic bacteria in subgingival plaque and is potentially of clinical benefit in the diagnosis and treatment of periodontitis subjects. However, several technical points need to be modified before the conventional PCR detection system can be used by clinicians.

MATERIAL AND METHODS

To develop a PCR-based technique more applicable for clinical use than conventional PCR, we established a multiplex PCR for five putative periodontopathic (Treponema denticola, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella intermedia and Tannerella forsythia) and two nonperiodontopathic (Streptococcus sanguinis and Streptococcus salivarius) species of bacteria using whole-plaque suspension as templates, and detected bacteria in subgingival plaque taken from 85 subjects at the supportive periodontal therapy stage after active periodontal treatments.

RESULTS

Among putative periodontopathic bacteria, the detection frequency of T. denticola and P. gingivalis was elevated in parallel with higher probing pocket depth and clinical attachment loss, and had 4.2-14.1 times increasing odds of the clinical parameters tested. Detection of any of the five species of putative periodontopathic bacteria markedly increased the odds ratio of a higher probing pocket depth, clinical attachment loss and bleeding on probing.

CONCLUSION

The multiplex PCR system developed in this study enabled the detection of all the bacteria under investigation in one reaction tube in a less time- and labor-intensive manner than conventional PCR. These results support the potential clinical use of multiplex PCR for detecting periodontopathic bacteria and for evaluating therapeutic strategies and predicting the prognosis for each subject.

Toll-like receptor 2-mediated interleukin-8 expression in gingival epithelial cells by the Tannerella forsythia leucine-rich repeat protein BspA

Tannerella forsythia is a gram-negative anaerobe strongly associated with chronic human periodontitis. This bacterium expresses a cell surface-associated and secreted protein, designated BspA, which has been recognized as an important virulence factor. The BspA protein belongs to the leucine-rich repeat (LRR) and bacterial immunoglobulin-like protein families. BspA is, moreover, a multifunctional protein which interacts with a variety of host cells, including monocytes which appear to respond to BspA through Toll-like receptor (TLR) signaling. Since gingival epithelium forms a barrier against periodontal pathogens, this study was undertaken to determine if gingival epithelial cells respond to BspA challenge and if TLRs play any role in BspA recognition. This study was also directed towards identifying the BspA domains responsible for cellular activation. We provide direct evidence for BspA binding to TLR2 and demonstrate that the release of the chemokine interleukin-8 from human gingival epithelial cells by BspA is TLR2 dependent. Furthermore, the LRR domain of BspA is involved in activation of TLR2, while TLR1 serves as a signaling partner. Thus, our findings suggest that BspA is an important modulator of host innate immune responses through activation of TLR2 in cooperation with TLR1.

Mucosal HIV-binding antibody and neutralizing activity in high-risk HIV-uninfected female participants in a trial of HIV-vaccine efficacy

BACKGROUND

This study investigated gp120-binding antibody and neutralizing activity, at the gingival- and cervical-mucosal levels, in response to a bivalent gp120 candidate vaccine.

METHODS

Women who met the study's inclusion criteria for documented high-risk behaviors participated in a nested substudy of the multicenter phase 3 trial of human immunodeficiency virus (HIV)-vaccine efficacy, VAX004. Gingival, cervicovaginal lavage, and plasma specimens were collected at 6-month intervals for 3 years. Binding-antibody and neutralizing-activity assays quantified the presence of anti-HIV activity in mucosal specimens.

RESULTS

Vaccine recipients were more likely than placebo recipients to have IgG binding antibodies in all 3 compartments tested and to have only IgA binding antibody in plasma (P<.0001). The relationship between vaccine and cervicovaginal IgG achieved significance (odds ratio [OR], 6.6 [P=.01]) but was weakened by the presence of cervicovaginal leukocytes. There was no relationship between immunization and the presence of neutralizing activity, in either bivariate or multivariate modeling (OR, 6.0 [P=.29]).

CONCLUSIONS

Vaccination is associated with the presence of both gp120-binding IgG in all compartments and plasma IgA but not with neutralizing activity. There is a role for the measurement of mucosal immunity in response to candidate vaccines and, in particular, for a determination of HIV-specific neutralizing antibodies.

Clinical characteristics and microbiota of progressing slight chronic periodontitis in adults

AIM

This study sought clinical and microbial risk indicators for progressing slight periodontitis.

MATERIAL AND METHODS

One hundred and seventeen periodontally healthy or slight periodontitis adults (20-40 years) were monitored clinically at 6-month intervals followed by supragingival cleaning. Inter-proximal sites with >1.5 mm increase in clinical attachment over 18 months were considered disease active. Subgingival plaque was analysed by 78 16S rDNA and 38 whole-genomic DNA probes and by PCR to Porphyromonas gingivalis and Tannerella forsythia. Characteristics were compared between active and inactive subjects.

RESULTS

Twenty-two subjects showed disease activity principally at molars. Mean baseline gingival and plaque indices, bleeding on probing, probing depth and clinical attachment level (CAL) were higher in active subjects. DNA probes detected species and not-yet-cultivated phylotypes from chronic periodontitis, although few species were associated with active subjects. By PCR P. gingivalis (p=0.007) and T. forsythia (p=0.075) were detected more frequently during monitoring in active subjects. Stepwise logistic analysis associated baseline levels of gingival index, clinical attachment and bleeding with subsequent clinical attachment loss.

CONCLUSIONS

Gingivitis and CAL were significantly associated with progressing slight periodontitis in 20--40-year-old adults. Species associated with moderate and advanced chronic periodontitis were detected in slight periodontitis.

Bacterial Species in Subgingival Plaque and Oral Bone Loss in Postmenopausal Women

BACKGROUND

Oral bacteria are widely recognized in the etiology of periodontal disease. We investigated the prevalence of subgingival bacterial infection with eight species, tested associations between infection and oral bone loss, and assessed potential confounding factors and effect modifiers of those associations in a large community-based cohort of postmenopausal women.

METHODS

A cross-sectional study of oral health and osteoporosis in 1,256 postmenopausal women recruited from the Buffalo, New York Women's Health Initiative Observational Study was conducted. Standardized dental radiographs were used to measure alveolar crestal height (ACH). Subgingival plaque samples were taken, and the presence of eight bacterial species was assessed by indirect immunofluorescent microscopy in each participant.

RESULTS

The most prevalent infection was Streptococcus sanguis (59.5%), followed by Prevotella intermedia (43.4%), Tannerella forsythensis (37.9%), Capnocytophaga sp. (36.9%), Eubacterium saburreum (32.7%), Campylobacter rectus (17.4%), Porphyromonas gingivalis (15.1%), and Fusobacterium nucleatum (14.2%). Infections with P. gingivalis, T. forsythensis, P. intermedia, and C. rectus were associated with an increased likelihood of having oral bone loss as measured by ACH, even after adjustment for age, smoking, and income. The body mass index (BMI) was a modifier of this association. Overweight women with T. forsythensis infection were more likely to have oral bone loss (OR = 3.37; 95% confidence interval [CI]: 2.08 to 5.46) than normal weight (OR = 1.27; 95% CI: 0.82 to 1.98) or obese (OR = 1.26, 95% CI: 0.72 to 2.20) women with T. forsythensis infection.

CONCLUSIONS

The prevalence of specific bacterial infections was determined for a large group of postmenopausal women. Those with infection were more likely to have oral bone loss. Further studies should investigate potential modifying effects of BMI and/or inflammatory factors.

Role of a Tannerella forsythia exopolysaccharide synthesis operon in biofilm development

Tannerella forsythia is a Gram-negative oral anaerobe implicated in the development of periodontitis, a chronic inflammatory disease induced by bacterial infections which leads to tooth loss if untreated. Since biofilms formed by periodontal bacteria are considered important in disease progression and pose difficulties in treatment, we sought to investigate the underlying mechanisms of T. forsythia biofilm formation. This was carried out by screening random insertion mutants of T. forsythia for alterations in biofilm development. This approach lead to the identification of an operon involved in exopolysaccharide (EPS) synthesis. An isogenic mutant of one of the genes, wecC, contained within the operon was constructed. The isogenic wecC mutant showed increased ability to form biofilms as compared to the parent strain. The wecC mutant also formed aggregated microcolonies and showed increased cell-surface associated hydrophobicity as compared to the parent strain. Moreover, biochemical characterization of the wecC mutant indicated that glycosylation of surface glycoproteins was reduced. Therefore, our results suggest that the wecC operon is associated with glycosylation of surface-glycoprotein expression and likely plays an inhibitory role in T. forsythia biofilm formation.

Association of Eubacterium nodatum and Treponema denticola with human periodontitis lesions

BACKGROUND

The purpose of the present investigation was to compare the levels, proportions and percentage of sites colonized by 40 bacterial species in subgingival plaque samples from periodontally healthy subjects and patients with chronic periodontitis to seek possible pathogens other than the consensus pathogens Porphyromonas gingivalis and Tannerella forsythia.

METHOD

Subgingival plaque samples were taken from the mesial aspect of each tooth in 635 subjects with chronic periodontitis and 189 periodontally healthy subjects. The samples were individually analyzed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization (total samples = 21,832). Mean counts, % DNA probe counts and percentage of sites colonized at >10(5) were determined for each species in each subject and then averaged in each clinical group. Significance of difference between groups was determined using the Mann-Whitney test. Association between combinations of species and periodontal status was examined by stepwise logistic regression analysis. Analyses were repeated using a subset of subjects from both clinical groups who had proportions of P. gingivalis plus T. forsythia less than the median (4.42%) found in periodontally healthy subjects. All analyses were adjusted for multiple comparisons.

RESULTS

For the 824 subjects the consensus pathogens P. gingivalis and T. forsythia as well as Eubacterium nodatum and Treponema denticola had significantly higher mean counts, proportions and percentage of sites colonized in samples from subjects with periodontitis than from periodontally healthy subjects. There were significantly more Capnocytophaga gingivalis, Streptococcus gordonii and Veillonella parvula in periodontally healthy subjects. E. nodatum, T. denticola, Streptococcus oralis, Streptococcus intermedius, Fusobacterium nucleatum ssp. vincentii all had higher counts and proportions in diseased than healthy subjects who had low proportions of P. gingivalis and T. forsythia. Logistic regression analysis indicated that the same species groups were associated with disease status after adjusting for the proportions of the other species.

CONCLUSIONS

This investigation confirmed the strong association of P. gingivalis and T. forsythia with chronic periodontitis and emphasized a strong association of E. nodatum and T. denticola with periodontitis whether in the presence or absence of high levels of the consensus pathogens. Other species, including S. oralis, Eikenella corrodens, S. intermedius and F. nucleatum ssp. vincentii, were associated with disease when P. gingivalis and T. forsythia were present in low proportions.

Porphyromonas gingivalis vesicles enhance attachment, and the leucine-rich repeat BspA protein is required for invasion of epithelial cells by "Tannerella forsythia"

The human oral cavity harbors more than 500 species of bacteria. Periodontitis, a bacterially induced inflammatory disease that leads to tooth loss, is believed to result from infection by a select group of gram-negative periodontopathogens that includes Porphyromonas gingivalis, Treponema denticola, and "Tannerella forsythia" (opinion on name change from Tannerella forsythensis pending; formerly Bacteroides forsythus). Epithelial cell invasion by periodontopathogens is considered to be an important virulence mechanism for evasion of the host defense responses. Further, the epithelial cells with invading bacteria also serve as reservoirs important in recurrent infections. The present study was therefore undertaken to address the epithelial cell adherence and invasion properties of T. forsythia and the role of the cell surface-associated protein BspA in these processes. Further, we were interested in determining if P. gingivalis, one of the pathogens frequently found associated in disease, or its outer membrane vesicles (OMVs) could modulate the epithelial cell adherence and invasion abilities of T. forsythia. Here we show that epithelial cell attachment and invasion by T. forsythia are dependent on the BspA protein. In addition, P. gingivalis or its OMVs enhance the attachment and invasion of T. forsythia to epithelial cells. Thus, interactions between these two bacteria may play important roles in virulence by promoting host cell attachment and invasion.

Subgingival and tongue microbiota during early periodontitis

Periodontal infections have a microbial etiology. Association of species with early disease would be useful in determining which microbes initiate periodontitis. We hypothesized that the microbiota of subgingival and tongue samples would differ between early periodontitis and health. A cross-sectional evaluation of 141 healthy and early periodontitis adults was performed with the use of oligonucleotide probes and PCR. Most species differed in associations with sample sites; most subgingival species were associated with subgingival samples. Few species were detected more frequently in early periodontitis by DNA probes. Porphyromonas gingivalis and Tannerella forsythia (Tannerella forsythensis) were associated with early periodontitis by direct PCR. In conclusion, the microbiota of tongue samples was less sensitive than that of subgingival samples in detecting periodontal species, and there was overlap in species detected in health and early periodontitis. Detection of periodontal pathogens in early periodontitis suggests an etiology similar to that of more advanced disease.

prtHinTannerella forsythensisIs Not Associated With Periodontitis

BACKGROUND

It has been suggested that prtH in Tannerella forsythensis encodes for a cystein proteinase that is associated with its pathogenic potential and can discriminate between periodontal health and disease. The aim of this investigation was to further establish this potentially important observation.

METHODS

A group of 33 consecutive adult patients with periodontitis (mean age: 47.6 +/- 10.1 years) harboring T. forsythensis was selected to investigate the presence of prtH by polymerase chain reaction (PCR). The T. forsythensis strains were isolated by anaerobic culture techniques. To investigate the association of this gene with periodontitis, a group of 14 age-matched subjects (mean age: 56.4 +/- 6.9 years) without any signs of periodontal disease (probing depths <3 mm and no radiographic attachment loss) was tested for comparison. Pure isolates and crude subgingival plaque samples were used as a template for the PCR.

RESULTS

In the group of 33 T. forsythensis-positive patients, we found two T. forsythensis isolates to be prtH negative. Despite repeated analyses, testing of the whole subgingival plaque samples revealed only 17 of 33 samples to be prtH positive. The T. forsythensis isolates from the 14 periodontally healthy subjects were all prtH positive. The odds ratio of the presence of prtH in T. forsythensis in periodontitis patients versus healthy controls is 1.06 (P >0.05).

CONCLUSIONS

On the basis of our data, we conclude that the presence of prtH in T. forsythensis is not discriminative for patients with T. forsythensis-associated periodontitis compared to healthy carriers of T. forsythensis. In addition, the use of whole subgingival plaque samples to test for the prevalence of prtH in bacteria appeared unreliable. Culture of the microorganism is an important condition to receive a sufficient amount of template DNA to detect the specific locus of the genome.

Identification and characterization of the genes encoding a unique surface (S-) layer of Tannerella forsythia

A newly emerged periodontopathic pathogen Tannerella forsythia (formerly Bacteroides forsythus), a Gram-negative, filament-shaped, strict anaerobic, non-pigmented oral bacterium, possesses a surface (S-) layer. In our previous studies, the S-layer has been isolated, and shown to mediate hemagglutination, adhesion/invasion of epithelial cell, and murine subcutaneous abscess formation. In the present study, biochemical and molecular genetic characterization of the S-layer are reported. Amino acid sequencing and mass spectrometry indicated that the S-layer is composed of two different proteins, termed 200 and 210 kDa proteins. It was also shown that these proteins are glycosylated. The genes encoding the core proteins of these glycoproteins, designated as tfsA and tfsB, have been identified in silico, cloned, and their sequences have been determined. The tfsA (3.5 kb) and tfsB (4.1 kb) genes are located in tandem, and encode for 135 and 152 kDa proteins, respectively. An apparent discrepancy in molecular weights, 135 vs. 200 kDa and 152 vs. 210 kDa, is accounted for carbohydrate residues attached to the core proteins. Amino acid sequence comparison exhibited a 24% similarity between the 200 and 210 kDa proteins. Further sequence analyses showed that TfsA and TfsB possess putative signal peptide sequences with cleavage sites at alanine residues, and transmembrane domains on the C-terminal region. Northern blot and RT-PCR analyses confirmed an operon structure of tfsAB, suggesting co-regulation of these genes in producing the S-layer. Putative promoter sequences and transcription termination sequences for this operon have also been identified. Comparison with database indicates that the S-layer of T. forsythia has a unique structure exhibiting no homology to other known S-layers of prokaryotic organisms. The present study shows that the T. forsythia S-layer is very unique, since it appears to be composed of two large glycoproteins, and it does not reveal any homology to other known S-layer proteins or glycoproteins of prokaryotic organisms.

Contact-dependent regulation of a Tannerella forsythia virulence factor, BspA, in biofilms

Tannerella forsythia is one of the periodontal organisms implicated in the development of periodontal diseases. The surface associated and secreted protein, BspA (encoded by the bspA gene), of this bacterium is an important virulence factor. The present study was carried out to examine the regulation of the bspA gene during biofilm growth and contact stimuli encountered in interbacterial interactions. The expression levels of the bspA transcript were determined by real-time RT-PCR approach. The levels of bspA transcript were found to be significantly reduced as a result of contact stimulus and in biofilm cells relative to planktonic cells. The results of our study suggest that the likely downregulation of the BspA protein in biofilms and following contact may have implications in pathogenesis as a plausible mechanism of evasion of host immune responses.

Disease progression: identification of high-risk groups and individuals for periodontitis

AIMS

While the role of bacteria in the initiation of periodontitis is primary, a range of host-related factors influence the onset, clinical presentation and rate of progression of disease. The objectives of this review are (1) to present evidence for individual predictive factors associated with a patient's susceptibility to progression of periodontitis and (2) to describe the use of prognostic models aimed at identifying high-risk groups and individuals in a clinical setting.

METHODS

Relevant publications in the English language were identified after Medline and PubMed database searches. Because of a paucity of longitudinal studies investigating factors including clinical, demographic, environmental, behavioural, psychosocial, genetic, systemic and microbiologic parameters to identify individuals at risk for disease progression, some association studies were also included in this review.

FINDINGS AND CONCLUSIONS

Cigarette smoking is a strong predictor of progressive periodontitis, the effect of which is dose related. High levels of specific bacteria have been predictive of progressive periodontitis in some studies but not all. Diabetics with poor glycaemic control have an increased risk for progression of periodontitis. The evidence for the effect of a number of putative factors including interleukin-1 genotype, osteoporosis and psychosocial factors is inconclusive and requires further investigation in prospective longitudinal studies. Specific and sensitive diagnostic tests for the identification of individuals susceptible to disease progression are not yet a reality. While factors assessed independently may not be valuable in predicting risk of future attachment loss, the combination of factors in a multifactorial model may be useful in identifying individuals at risk for disease progression. A number of multifactorial models for risk assessment, at a subject level have been developed but require validation in prospective longitudinal studies.

Synergy between Tannerella forsythia and Fusobacterium nucleatum in biofilm formation

During dental plaque formation, the interaction of different organisms is important in the development of complex communities. Fusobacterium nucleatum is considered a 'bridge-organism' that facilitates colonization of other bacteria by coaggregation-mediated mechanisms and possibly by making the environment conducive for oxygen intolerant anaerobes. These studies were carried out to determine whether coaggregation between F. nucleatum and Tannerella forsythia is important in the formation of mixed species biofilms. Further, the role of BspA protein, a surface adhesin of T. forsythia, in coaggregation and biofilm formation was investigated. The results showed the development of synergistic mixed biofilms of F. nucleatum and T. forsythia when these bacteria were cocultured. The BspA protein was not involved in biofilm formation. Though BspA plays a role in coaggregation with F. nucleatum, presumably other adhesins are also involved. The synergistic biofilm formation between the two species was dependent on cell-cell contact and soluble components of the bacteria were not required. This study demonstrates that there is a positive synergy between F. nucleatum and T. forsythia in the development of mixed biofilms and that the cell-cell interaction is essential for this phenomenon.

Culture-independent identification of periodontitis-associated Porphyromonas and Tannerella populations by targeted molecular analysis

Periodontitis is the commonest bacterial disease of humans and is the major cause of adult tooth loss. About half of the oral microflora is unculturable; and 16S rRNA PCR, cloning, and sequencing techniques have demonstrated the high level of species richness of the oral microflora. In the present study, a PCR primer set specific for the genera Porphyromonas and Tannerella was designed and used to analyze the bacterial populations in subgingival plaque samples from inflamed shallow and deep sites in subjects with periodontitis and shallow sites in age- and sex-matched controls. A total of 308 clones were sequenced and found to belong to one of six Porphyromonas or Tannerella species or phylotypes, one of which, Porphyromonas P3, was novel. Tannerella forsythensis was found in significantly higher proportions in patients than in controls. Porphyromonas catoniae and Tannerella phylotype BU063 appeared to be associated with shallow sites. Targeted culture-independent molecular ecology studies have a valuable role to play in the identification of bacterial targets for further investigations of the pathogenesis of bacterial infections.

Methods of detection of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythensis in periodontal microbiology, with special emphasis on advanced molecular techniques: a review

BACKGROUND

Certain specific bacterial species from the subgingival biofilm have demonstrated aetiological relevance in the initiation and progression of periodontitis. Among all the bacteria studied, three have shown the highest association with destructive periodontal diseases: Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Tannerella forsythensis (Tf). Therefore, the relevance of having accurate microbiological diagnostic techniques for their identification and quantification is clearly justified.

AIM

To evaluate critically all scientific information on the currently available microbial diagnostic techniques aimed for the identification and quantification of Aa, Pg and Tf.

SUMMARY

Bacterial culturing has been the reference diagnostic technique for many years and, in fact, most of our current knowledge on periodontal microbiology derives from cultural data. However, the advent of new microbial diagnostics, mostly based on immune and molecular technologies, has not only highlighted some of the shortcomings of cultural techniques but has also allowed their introduction as easy and available adjunct diagnostic tools to be used in clinical research and practice. These technologies, mostly polymerase chain reaction (PCR), represent a field of continuous development; however, we still lack the ideal diagnostic to study the subgingival microflora. Qualitative PCR is still hampered by the limited information provided. Quantitative PCR is still in development; however, the promising early results reported are still hampered by the high cost and the equipment necessary for the processing.

CONCLUSION

Quantitative PCR technology may have a major role in the near future as an adjunctive diagnostic tool in both epidemiological and clinical studies in periodontology. However, culture techniques still hold some inherent capabilities, which makes this diagnostic tool the current reference standard in periodontal microbiology.

Human salivary function in relation to the prevalence of Tannerella forsythensis and other periodontal pathogens in early supragingival biofilm

OBJECTIVE

Previously, we screened 149 subjects and established four groups high or low for salivary killing of oral bacteria, and for aggregation and live and dead adherence of oral bacteria (as a combined factor). Caries scores were significantly lower in both High Aggregation-Adherence groups. Subsequently, we found that supragingival total biofilm DNA, total streptococci and two major streptococcal rRNA variants also were significantly lower in the High Aggregation-Adherence groups. In this study, we looked at the effects of those differences in salivary function on three periodontal pathogens.

DESIGN

Quantitative PCR was used to determine levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythensis (formerly Bacteroides forsythus) in stored DNA extracts of overnight supragingival biofilm collected from buccal upper central incisors (UC), lingual lower central incisors (LC) and buccal upper and lower first molars (BM) and lingual upper and lower first molars (LM) of subjects in the four groups.

RESULTS

A. actinomycetemcomitans and P. gingivalis were almost completely absent from these samples. T. forsythensis was found in 11 of 35 persons at the buccal molar site. Only two of those subjects were in the High Aggregation-Adherence groups, and that difference was statistically significant. The mean quantity of T. forsythensis also was significantly lower in the High Aggregation-Adherence groups.

CONCLUSIONS

The difference between the Low and High Aggregation-Adherence groups might reflect direct interactions of salivary proteins with T. forsythensis. Alternatively, the higher levels of total biofilm and total streptococci seen in the Low Aggregation-Adherence groups might create a favourable environment for early secondary colonization of T. forsythensis.

Persistent colonization with Tannerella forsythensis and loss of attachment in adolescents

Colonization with Tannerella forsythensis may characterize the conversion of periodontally healthy sites into diseased sites. This three-year study describes the prevalence of T. forsythensis and its relationship to clinical loss of attachment (LOA) in a group of adolescents considered at risk of developing early chronic periodontitis. Adolescents with (LOA+) and without (LOA-) loss of attachment were examined at baseline and 1.5 and 3 yrs subsequently. On each occasion, attachment loss was measured on selected teeth, and the presence of T. forsythensis in their subgingival plaque samples was determined by PCR. T. forsythensis prevalence in LOA+ subjects at baseline (64%) increased to 82% and 86% on subsequent examinations. In contrast, prevalence of T. forsythensis in LOA- subjects was always significantly lower (25%, 36%, and 32%, respectively). The odds of loss of attachment were 8.16 times greater in subjects infected with T. forsythensis at each examination. These results suggest that T. forsythensis is strongly associated with loss of attachment in this adolescent population.

The surface (S-) layer is a virulence factor of Bacteroides forsythus

Bacteroides forsythus has emerged as a crucial periodontal pathogen with possible implications for systemic disease. The aim of this study was to isolate the S-layer from B. forsythus and examine its virulence potential as a part of efforts to characterize virulence factors of B. forsythus. The role of the S-layer in the haemagglutinating and adherent/invasive activities was evaluated. It was observed that the S-layer alone was able to mediate haemagglutination. In adherent and invasive studies, transmission electron microscopy clearly revealed that B. forsythus cells were able to attach to and invade KB cells, showing the formation of a microvillus-like extension around adherent and intracellular bacteria. The quantitative analysis showed that five different B. forsythus strains exhibited attachment (1.9-2.3 %) and invasion (0.4-0.7 %) capabilities. It was also observed through antibody inhibition assays that adherent/invasive activities of B. forsythus are mediated by the S-layer. Furthermore, an in vivo immunization study adopting a murine abscess model was used to prove that the S-layer is involved in the infectious process of abscess formation. While mice immunized with purified S-layer and B. forsythus whole cells did not develop any abscesses when challenged with viable B. forsythus cells, unimmunized mice developed abscesses. Collectively, the data obtained from these studies indicate that the S-layer of B. forsythus is a virulence factor.

Prevalence of periodontopathic bacteria in aggressive periodontitis patients in a Japanese population

BACKGROUND

Actinobacillus actinomycetemcomitans is considered a major etiologic agent of aggressive periodontitis. Other periodontopathic bacteria such as Porphyromonas gingivalis are also suspected of participating in aggressive periodontitis, although the evidence is controversial. The aim of the present study was to investigate the prevalence of periodontopathic bacteria and to clarify the microbiological features of aggressive periodontitis in Japanese patients.

METHODS

Subgingival plaque was collected from 50 aggressive periodontitis (AgP) patients (localized 10, generalized 40). Samples from 35 generalized chronic periodontitis (CP) patients and 18 healthy subjects were examined as controls. Plaque samples were examined using culture and polymerase chain reaction (PCR) method.

RESULTS

The prevalence of A. actinomycetemcomitans was relatively low in the localized (20%) and generalized (17.5%) AgP patients, with no significant difference observed in detection frequencies between AgP and the control groups (CP 8.6%, healthy 0%). On the other hand, Tannerella forsythensis (formerly Bacteroides forsythus), Campylobacter rectus, P. gingivalis, and Treponema denticola were frequently detected in localized as well as generalized aggressive periodontitis patients. The prevalence and proportion of P. gingivalis correlated with severity of clinical attachment loss in both localized and generalized aggressive periodontitis.

CONCLUSIONS

T. forsythensis, C. rectus, P. gingivalis, and T. denticola were the predominant periodontopathic bacteria of aggressive periodontitis patients in Japan. Although A. actinomycetem- comitans was also detected in AgP patients, the prevalence of this bacterium was much lower than that of P. gingivalis.

Specific Antibiotics in the Treatment of Periodontitis – A Proposed Strategy

BACKGROUND

The purpose of the present study was to propose a strategy for the selection of antibiotics that specifically target complexes of periodontal pathogens present in patients with periodontitis.

METHODS

Seven hundred seventy-four (774) patients with various forms of periodontitis were included in the study. Subgingival plaque samples were taken from the deepest periodontal pockets in each quadrant using a sterile curet, and pooled. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Eikenella corrodens, Tannerella forsythensis, Prevotella intermedia, and Prevotella nigrescens were identified by polymerase chain reaction, and the prevalence of combinations of these pathogens was determined. To each pathogen complex (PC), i.e., combination of pathogens, those antibiotics were assigned that were most specific according to the published minimum inhibitory concentration (MIC90) values and the gingival crevicular fluid (GCF) concentrations achievable in vivo. Antibiotic GCF concentrations had to be at least 10 times the MIC90 values, and the narrowest spectrum was selected with respect to the assessed periodontal pathogens.

RESULTS

Nine major PCs (each > or = 3% of all patients) were found in 73.4% of all patients, whereas 38 minor PCs (each < 3% of all patients) were distributed in 26.6% of all patients. Ten different antibiotic regimens were found to be specific for the total of 46 PCs; i.e., metronidazole and amoxicillin in 11 PCs (55.0% of all patients), metronidazole and amoxicillin/clavulanic acid or metronidazole and ciprofloxacin in 13 PCs (18.9%), amoxicillin in 4 PCs (8.3%), doxycycline in 2 PCs (6.1%), metronidazole in 8 PCs (4.1%), amoxicillin/clavulanic acid in 3 PCs (2.9%), clindamycin in 2 PCs (1.5%), ciprofloxacin in 2 PCs (0.4%), and tetracycline in 1 PC (0.3%).

CONCLUSION

The results of the study indicate that there are at least 46 different combinations of the assessed periodontal pathogens in subjects with periodontitis, and at least 10 different antibiotic regimens might be required to specifically target the various pathogen complexes.

Microbial Identification in the Management of Periodontal Diseases. A Systematic Review

BACKGROUND

Our understanding of the complexity of the oral microbiota continues to improve as new technologies, such as the analysis of 16S rRNA bacterial genes, are utilized. Despite the difficult of cataloguing all microorganisms and determining their pathogenic potential, some species, mostly members of the resident oral microbiota, have been identified as likely periodontal pathogens. However, for microbial diagnosis to be of value, it needs to affect disease diagnosis and/or treatment planning as well as result in superior treatment outcomes and/or provide an economic benefit to the patient.

RATIONALE

The purposes of this systematic review were to determine if microbial identification influences periodontal patient management and whether treatment outcomes are better compared to patients whose treatment plans are developed without this information.

FOCUSED QUESTION

In patients with periodontal diseases, does microbial identification influence patient management compared to treatment prescribed without this information?

SEARCH PROTOCOL

The MEDLINE database was searched for clinical studies in English from 1991 through 2002 by 2 investigators. Hand searches were performed on the Journal of Clinical Periodontology, Journal of Periodontology, Journal of Periodontal Research, Oral Microbiology and Immunology, and Periodontology 2000. In addition, directors of diagnostic laboratories were contacted about unpublished data.

SELECTION CRITERIA

INCLUSION CRITERIA

Articles in which bacterial identification influenced patient treatment were preferred as were those reporting longitudinal data demonstrating a direct relationship between the presence or absence of certain bacteria and subsequent alterations in clinical variables. Because of the limited number of studies, all articles, including case reports, were considered.

EXCLUSION CRITERIA

Review articles without original data were excluded, although references were examined for possible inclusion. Articles reporting data showing associations between certain microorganisms and disease or health that did not affect treatment were excluded. Clinical trials testing antibacterial agents for their ability to enhance mechanical debridement were not included since bacterial identification had little effect on drug selection or experimental group assignment. Articles dealing with implants rather than natural teeth were omitted. DATA ANALYSIS AND COLLECTION: The heterogeneity of the published data precludes any meaningful pooling of data or meta-analysis. The pertinent literature, including relevant variables of plaque, gingivitis, and bleeding on probing scores; probing depth; clinical attachment level; number of lost teeth; and microbial changes; and patient-centered outcomes including decrease in morbidity, reduced need for surgery, and duration and cost of treatment are summarized.

MAIN RESULTS

1. There was a lack of articles with a high evidence rating; most pertinent articles were either case reports or case series without controls. 2. Because reports were heterogeneous regarding study design, patient selection, and data collection, meta-analysis was not feasible and results are summarized in tabular format. 3. This report is based on a total of 24 studies, representing a total patient population of approximately 835. 4. Thirteen studies reported on microbiological identification as an aid in treatment planning. 5. Eleven studies reported a differential clinical response depending on the detection or lack of detection of specific organisms.

REVIEWERS' CONCLUSIONS

1. The published material suggests that microbiological monitoring may be useful in management of selected patients who do not respond to standard therapy. 2. Some practitioners consider microbial identification a valuable adjunct to managing patients with certain forms of periodontitis, although there is a lack of strong evidence to this effect. 3. Additional research is needed to address this issue.

Progression of destructive periodontal diseases in three urban minority populations: role of clinical and demographic factors

BACKGROUND, AIMS

Differences in prevalence, severity and risk factors for destructive periodontal diseases have been reported for ethnic/racial groups. However, it is not certain whether this disparity is due to ethnicity/race or factors associated with ethnicity/race. Therefore, the present study addressed whether the rates of disease progression and clinical and demographic factors associated with disease progression varied among three ethnic/racial groups.

METHODS

The study population consisted of 53 Asian-, 69 African- and 62 Hispanic-Americans. Clinical measurements included probing depth, attachment level, gingival erythema, bleeding upon probing, suppuration and plaque. Disease progression was defined as a > 2 mm loss of attachment 2 months post baseline. The demographic variables examined included occupational status, report of a private dentist, years resident in the United States and smoking history.

RESULTS

The rate of attachment loss for the entire population was 0.04 mm or 0.24 mm/year. No significant differences were found among the three ethnic/racial groups. Variables associated with subsequent attachment loss for the entire population were age, male gender, mean whole-mouth plaque, erythema, bleeding upon probing, suppuration, attachment loss and probing depth, and belonging to the "unskilled" occupational group. No differences in risk profiles were found among the 3 ethnic/racial groups. Using stepwise logistic regression analysis, a model was developed to relate the clinical and demographic variables examined with subsequent attachment loss. The model indicated that prior attachment loss, gingival erythema, suppuration, being a current smoker and belonging to the "unskilled" occupational group conferred high risk of > 1 site of attachment loss of > 2 mm.

CONCLUSIONS

The results of this study suggest that variables associated with ethnicity/race, such as occupational status, are largely responsible for the observed disparity in destructive periodontal disease progression in these populations.

Endpoint quantitative PCR assays for Bacteroides forsythus, Porphyromonas gingivalis, and Actinobacillus actinomycetemcomitans

BACKGROUND

Conventional polymerase chain reaction (PCR) assays for periodontal pathogens are so sensitive that they detect infections of no clinical significance. Quantitative PCR (qPCR) may provide a solution to this problem. However, most qPCR systems require expensive real-time thermal cyclers.

OBJECTIVE

Our goal was to develop qPCR assays which would allow endpoint quantification.

MATERIALS AND METHODS

16S rRNA primers for Bacteroides forsythus, Porphyromonas gingivalis, and Actinobacillus actinomycetemcomitans were adapted to the Amplifluor qPCR system, which incorporates fluorescein into the PCR product so that endpoint fluorescence is proportional to the original amount of template. DNA dilutions representing known numbers of cells were used as standard curves. Pooled subgingival plaques from the four deepest pockets of 21 severe adult periodontitis patients were assayed. Buccal molar supragingival plaque from 35 dental students provided healthy controls. Endpoint fluorescence was measured with a microplate reader.

RESULTS

Optimized standard curves were linear in log-log or semilog fits over a range of 100-10(6) cells. Countable B. forsythus was present in all patients, with counts (as logs) from 2.4 to 7.3 (mean = 5.0), and 11 controls with counts from 2.1 to 4.5 (mean = 3.0). P. gingivalis was present in 11 patients and no controls, with counts from 2.2 to 4.7 (mean = 3.2). A. actinomycetemcomitans was present in two patients, with counts of 1.5 and 3.5.

CONCLUSIONS

Amplifluor qPCR assays discriminated between plaque samples differing by one log or more, allowing major infections to be distinguished from minor ones. This approach allows high-throughput qPCR of plaque samples, using equipment available to many laboratories.

Distribution of Bacteroides forsythus genotypes in a Japanese periodontitis population

Bacteroides forsythus is an important pathogen in periodontal diseases and has been associated with advanced and refractory periodontitis. The difficulties associated with culturing this species have meant that the distribution and pathogenic mechanisms of B. forsythus remain unclear. In this study, the arbitrarily primed polymerase chain reaction (AP-PCR) method was used to investigate the genotype distribution of B. forsythus in a Japanese periodontitis population, as well as the relationship between AP-PCR genotypes and periodontal status. B. forsythus reference strain, ATCC 43037T and 137 clinical bacterial isolates from 64 subjects were separated into 11 distinct AP-PCR genotypes using a single randomly-sequenced primer, 5'-CCGGCGGCG-3' (A-05). The majority (80.9%) of B. forsythus strains examined belonged to AP-PCR genotypes I, II, III and IV (accounting for 39.7%, 20.6%, 10.3% and 10.3%, respectively). Types I and III primarily consisted of isolates from chronic periodontitis subjects (80.8% and 85.7%, respectively), while Types II and IV consisted mainly of isolates from aggressive periodontitis subjects (85.7% and 100%, respectively). Except for three subjects who harbored two different B. forsythus genotypes in the oral cavity, all subjects only infected with one genotype intraindividually. These results demonstrate that the AP-PCR method is useful for genotypic analysis of B. forsythus. This species showed a genetic diversity among the investigated population. A clonal nature of B. forsythus infection is suggested. Furthermore, different AP-PCR genotypes of B. forsythus appear to be associated with different types of periodontitis.

Humoral immune responses to S-layer-like proteins of Bacteroides forsythus

Bacteroides forsythus is one of the important periodontopathic bacteria, and this microorganism is known to have an S-layer outside the outer membrane. The S-layer-like antigens were recently isolated from B. forsythus, and they were found to be 270- and 230-kDa proteins in the envelope fraction. In this study, these proteins were confirmed to be specific to B. forsythus by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and they were clearly recognized by sera from patients with adult and early-onset periodontitis in Western immmunoblot analysis. We compared the immunoglobulin G (IgG) responses against the purified S-layer-like antigen by enzyme-linked immunosorbent assay. IgG responses against this antigen were low in healthy control subjects, but they were significantly higher in subjects with adult and early-onset periodontitis. Together with the fact that the IgG responses against the crude extract of B. forsythus did not rise significantly in patients with periodontitis, S-layer-like proteins are considered to be specific antigens of B. forsythus and may play an important role in the progression of periodontitis.

Porphyromonas gingivalis, Bacteroides forsythus and other putative periodontal pathogens in subjects with and without periodontal destruction

BACKGROUND AND AIMS

Bacteria play an essential role in the pathogenesis of destructive periodontal disease. It has been suggested that not all bacteria associated with periodontitis may be normal inhabitants of a periodontally healthy dentition. In particular, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans have been isolated infrequently from subjects without periodontitis. The aim of the present study was to compare prevalence and proportions of a number of periodontal bacteria in periodontitis patients and control subjects.

MATERIAL AND METHODS

In all, 116 consecutive subjects diagnosed with moderate to severe periodontitis (mean age 42.4) and 94 subjects without radiographic evidence of alveolar bone loss (mean age 40.4) were recruited for the study. The gingival condition in the control group varied between gingival health and various degrees of gingivitis. In patients, the deepest pocket in each quadrant was selected for microbiological sampling. In control subjects all mesial and distal sites of all first molars were selected for sampling. All paper points from a patient were pooled and processed for anaerobic cultivation within 6 h after sampling. Clinical variables of sampled sites included bleeding index, probing pocket depth and clinical attachment level.

RESULTS

A. actinomycetemcomitans, P. gingivalis, Prevotella intermedia, Bacteroides forsythus, Fusobacterium nucleatum and Peptostreptococcus micros were significantly more often prevalent in patients than in controls. The highest odds ratios were found for P. gingivalis and B. forsythus (12.3 and 10.4 resp.). Other odds ratios varied from 3.1 to 7.7 for A. actinomycetemcomitans and P. micros, respectively. Absolute numbers of target bacteria were all higher in patients, but only the mean percentage of B. forsythus was significantly higher in patients in comparison to controls (P < 0.001).

CONCLUSIONS

A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus, F. nucleatum and P. micros are all significant markers for destructive periodontal disease in adult subjects. Based on calculated odds ratios, B. forsythus and P. gingivalis are the strongest bacterial markers for this disease and are infrequently cultured from subjects without periodontal bone loss.