Potential diagnostic value of sampling oral mucosal surfaces for Actinobacillus actinomycetemcomitans in young adults

Salivary CCL20 Level as a Biomarker for Oral Squamous Cell Carcinoma

BACKGROUND/AIM

This study investigated the utility of C-C motif chemokine ligand 20 (CCL20) expression in saliva as a biomarker for oral squamous cell carcinoma (OSCC) and also examined the associated microbiome.

MATERIALS AND METHODS

The study group included patients with OSCC or oral potentially malignant disorder (OPMD), and healthy volunteers (HVs). microarray and qRT-PCR were used to compare salivary CCL20 expression levels among groups. Data on CCL20 levels in oral cancer tissues and normal tissues were retrieved from a public database and examined. Furthermore, next-generation sequencing was used to investigate the salivary microbiome.

RESULTS

A significant increase in the expression level of CCL20 was observed in both OSCC tissues and saliva from patients with oral cancer. Fusobacterium was identified as the predominant bacteria in OSCC and correlated with CCL20 expression level. OSCC screening based on salivary CCL20 expression enabled successful differentiation between patients with OSCC and HVs.

CONCLUSION

CCL20 expression may be a useful biomarker for OSCC.

Comparison of Subgingival and Buccal Mucosa Microbiome in Chronic and Aggressive Periodontitis: A Pilot Study

Periodontal microorganisms not only colonize subgingival pockets, but also are detected on various mucous membranes in patients with periodontitis. The object of this pilot study was, using the next-generation sequencing of 16S RNA gene, to characterize the microbiota in two oral habitats (buccal mucosas and subgingival pockets) in patients with different forms of periodontitis. Thirty-two buccal swab samples and 113 subgingival samples were obtained from eleven subjects with chronic periodontitis (ChP), twelve subjects with aggressive periodontitis (AgP), and nine periodontally healthy individuals (HP). Using Miseq Sequencing of 16S rRNA gene, we found that the subgingival and buccal mucosa microbiome of ChP and AgP patients both differed from HP. Meanwhile, Veillonella, Treponema, Filifactor, Fretibacterium, Peptostreptococcaceae_[XI][G-6], Peptostreptococcaceae_[XI][G-5], Bacteroidetes_[G-5], Bacteroidetes_[G-3], Peptostreptococcaceae_[XI][G-4], Peptostreptococcaceae_[XI][G-2] significantly increased both in buccal and subgingival plaque samples in periodontitis subjects (ChP and AgP) compared with HP. Moreover, the results based on the Unweighted UniFrac distance showed that buccal and subgingival plaque samples from the same individuals show higher community divergence than same habitats from different subject samples. This study demonstrated that the microbiome of buccal mucosa can be influenced by periodontitis. However, subgingival and buccal mucosa microbiome seem to be characterized by species-specific colonization patterns. This pilot study provides a glimpse at the changes of subgingival and buccal mucosa associated with periodontitis from a holistic view. Further studies should be taken to illuminate the interplay between these detected changes and periodontitis development.

A Case-Control Study to Determine the Prognostic Features of Salivary Epithelial Cells in Periodontitis

Periodontitis-a biofilm-induced immunoinflammatory pathology-often progresses gradually, exhibiting periodic bursts and resolution. Exfoliating oral epithelial cells act as reservoirs for key periodontal pathogens, facilitating reinfection or infection of new sites. Since saliva is a rich source of oral epithelial cells, we hypothesized that the microbial and functional profile of salivary epithelial cells (SECs) will reflect the in situ host response and disease severity. We used a case-control study design. Unstimulated whole saliva was collected from 20 chronic periodontitis patients and 20 healthy controls in accordance with the institutional review board. The isolated SECs were assessed for viability by trypan blue exclusion. Gram-stained SECs were analyzed by ImageJ, and Gram stain index (GSI) per SEC was calculated. Equal numbers of SECs from each sample were exposed to 2 periodontal pathogens- Porphyromonas gingivalis and Fusobacterium nucleatum-in biofilm or planktonic formulations at varying proportions. Cytokines in culture supernatants were assessed by ELISA (enzyme-linked immunosorbent assay). Additionally, soluble Toll-like receptor 2 (sTLR-2)-a pattern recognition receptor capable of binding microbial ligands associated with periodontitis-was measured in clarified saliva by ELISA. An increased number of SECs, a higher GSI/SEC, and a lower sTLR-2 were observed in periodontitis saliva as compared with healthy saliva. SECs from periodontitis saliva secreted higher amounts of interleukin 8 in response to P. gingivalis, and the presence of F. nucleatum dampened the response. Nonsurgical periodontal treatment improved clinical parameters, reduced the number of SECs, decreased GSI/SEC, and increased sTLR-2 in clarified saliva. In conclusion, our data suggest that SECs can provide a phenotypically distinct individualized resource for assessing epithelial response to pathogens in the course of periodontal disease. Furthermore, correlation between the sTLR-2 and GSI/SEC suggests that the expression profile of epithelial and soluble Toll-like receptor could provide an indirect measure of periodontal disease-associated dysbiosis. Knowledge Transfer Statement: The results of this study can be used for prognostic evaluation of chronic periodontitis in response to therapy and provide an opportunity for early identification of poor responders. A chip-based simple test incorporating the identified salivary epithelial cell characteristics can be developed and validated for future clinical applications, especially for monitoring patients with increased susceptibility for refractory and/or recurrent periodontitis.

Role of salivary epithelial toll-like receptors 2 and 4 in modulating innate immune responses in chronic periodontitis

BACKGROUND AND OBJECTIVE

Chronic periodontitis is initiated by sequential colonization with a broad array of bacteria and is perpetuated by an immune-inflammatory response to the changing biofilm. Host recognition of microbes is largely mediated by toll-like receptors (TLRs), which interact with conserved pathogen-associated molecular patterns. Based on ligand recognition, TLR-2 and TLR-4 interact with most periodontal pathogens. Extracrevicular bacterial reservoirs, such as the oral epithelial cells, contribute to the persistence of periodontitis. Human saliva is a rich source of oral epithelial cells that express functional TLRs. In this study we investigated the role of salivary epithelial cell (SEC) TLR-2 and TLR-4 in patients with generalized chronic periodontitis.

MATERIAL AND METHODS

Unstimulated whole saliva (UWS) was collected from patients with generalized chronic periodontitis and from healthy individuals after obtaining informed consent. Epithelial cells isolated from each UWS sample were assessed for TLR-2, TLR-4, peptidoglycan recognition protein (PGRP)-3 and PGRP-4 by quantitative real-time PCR. In addition, the SECs were stimulated in vitro with microbial products for up to 24 h. The culture supernatant was assessed for cytokines by ELISA.

RESULTS

Stimulation with TLR-2- or TLR-4-specific ligands induced cytokine secretion with differential kinetics and up-regulated TLR2 and TLR4 mRNAs, respectively, in cultures of SECs from patients with periodontitis. In addition, the SECs from patients with periodontitis exhibited reduced PGRP3 and PGRP4 mRNAs, the TLR-responsive genes with antibacterial properties.

CONCLUSION

SECs derived from the UWS of patients with chronic periodontitis are phenotypically distinct and could represent potential resources for assessing the epithelial responses to periodontal pathogens in the course of disease progression and persistence.

Aggregatibacter actinomycetemcomitans as an early colonizer of oral tissues: epithelium as a reservoir?

This study examined in vivo and in vitro colonization by Aggregatibacter actinomycetemcomitans, an organism highly associated with aggressive periodontitis. Thirteen volunteers (5 were A. actinomycetemcomitans positive for buccal epithelial cells [BECs] and teeth, 5 were A. actinomycetemcomitans positive for teeth only, and 3 were A. actinomycetemcomitans-negative controls) had two mandibular stents fabricated. Each stent contained 3 removable hydroxyapatite (HA) tooth surrogates. One HA square was removed from a stent at 5 time points over 7 h to assess the transfer of A. actinomycetemcomitans from teeth or BECs to HA. Streptococcus, Actinomyces, A. actinomycetemcomitans, and total anaerobic counts were evaluated on each square over time. In vitro experiments evaluated binding, desorption, transfer, and reattachment of A. actinomycetemcomitans wild-type and mutant strains to BECs and saliva-coated HA (SHA). Streptococcus and Actinomyces formed 80% of the cultivable flora on HA in all subjects. Transfer of A. actinomycetemcomitans to HA was not seen in subjects with A. actinomycetemcomitans on teeth only. All 5 subjects with A. actinomycetemcomitans on BECs showed transfer of A. actinomycetemcomitans to HA. In vitro, A. actinomycetemcomitans desorbed from BECs and transferred to SHA. A. actinomycetemcomitans binding to SHA was irreversible and did not transfer to BECs. The adhesin Aae showed specificity for BECs. Fimbrial mutants showed the greatest reduction in binding to SHA. A. actinomycetemcomitans migrated from BECs to HA in vivo and to SHA in vitro; however, A. actinomycetemcomitans movement from teeth and SHA to BECs did not occur. In vivo, A. actinomycetemcomitans colonized HA within 6 h and thus can be considered an early colonizer. BECs are a likely reservoir for A. actinomycetemcomitans tooth colonization.

Mapping the epithelial-cell-binding domain of the Aggregatibacter actinomycetemcomitans autotransporter adhesin Aae

The Gram-negative periodontopathogen Aggregatibacter actinomycetemcomitans (Aa) binds selectively to buccal epithelial cells (BECs) of human and Old World primates by means of the outer-membrane autotransporter protein Aae. We speculated that the exposed N-terminal portion of the passenger domain of Aae would mediate binding to BECs. By using a series of plasmids that express full-length or truncated Aae proteins in Escherichia coli, we found that the BEC-binding domain of Aae was located in the N-terminal surface-exposed region of the protein, specifically in the region spanning amino acids 201–284 just upstream of the repeat region within the passenger domain. Peptides corresponding to amino acids 201–221, 222–238 and 201–240 were synthesized and tested for their ability to reduce Aae-mediated binding to BECs based on results obtained with truncated Aae proteins expressed in E. coli. BEC-binding of E. coli expressing Aae was reduced by as much as 50 % by pre-treatment of BECs with a 40-mer peptide (201–240; P40). Aae was also shown to mediate binding to cultured human epithelial keratinocytes (TW2.6), OBA9 and TERT, and endothelial (HUVEC) cells. Pre-treatment of epithelial cells with P40 resulted in a dose-dependent reduction in binding and reduced the binding of both full-length and truncated Aae proteins expressed in E. coli, as well as Aae expressed in Aa. Fluorescently labelled P40 peptides reacted in a dose-dependent manner with BEC receptors. We propose that these proof-of-principle experiments demonstrate that peptides can be designed to interfere with Aa binding mediated by host-cell receptors specific for Aae adhesins.

Presence of Aggregatibacter actinomycetemcomitans in young individuals: a 16-year clinical and microbiological follow-up study

AIM

To look for clinical signs of periodontal disease in young adults who exhibited radiographic bone loss and detectable numbers of Aggregatibacter actinomycetemcomitans in their primary dentition.

MATERIAL AND METHODS

Periodontal status and radiographic bone loss were examined in each of the subjects 16 years after the baseline observations. Techniques for anaerobic and selective culture, and checkerboard, were used to detect periodontitis-associated bacterial species. The isolated A. actinomycetemcomitans strains were characterized by polymerase chain reaction.

RESULTS

Signs of localized attachment loss were found in three out of the 13 examined subjects. A. actinomycetemcomitans was recovered from six of these subjects and two of these samples were from sites with deepened probing depths and attachment loss. Among the isolated A. actinomycetemcomitans strains, serotypes a-c and e, but not d or f, were found. None of the isolated strains belonged to the highly leucotoxic JP2 clone, and one strain lacked genes for the cytolethal distending toxin.

CONCLUSIONS

This study indicates that the presence of A. actinomycetemcomitans and early bone loss in the primary dentition does not necessarily predispose the individual to periodontal attachment loss in the permanent dentition.

[Not Available]

Human saliva can be separated by centrifugation into cell pellet and cell-free supernatant, which are called cellular phase and liquid phase in this study. While it is well documented that the cellular phase of saliva contains hundreds of oral bacteria species, little is known whether the liquid phase of saliva contains any information related to oral microbiota. In this study, we analyzed the bacterial nucleic acid contents of the liquid phase of saliva. Using primers universal to most eubacterial 16S rDNA, we detected large amounts of bacterial 16S rRNA and rDNA in the cell-free phase of saliva. Random sequencing analysis of forty PCR amplicons from the cell-free phase of saliva led to 15 operational taxonomic unit (OTU) groups. Furthermore, using denaturing gradient gel electrophoresis (DGGE), we compared 16S rRNA/rDNA profiles derived from liquid phases and cellular phases of saliva samples, and found positive correlations (Pearson Correlation=0.822, P<0.001) between these sample groups. These findings indicate that the liquid phase of saliva contains numerous bacterial 16S rRNA/rDNA molecules that have correlations with bacteria existing in the cellular phase.

Aggregatibacter actinomycetemcomitans and its relationship to initiation of localized aggressive periodontitis: longitudinal cohort study of initially healthy adolescents

Aggregatibacter actinomycetemcomitans is frequently associated with localized aggressive periodontitis (LAP); however, longitudinal cohort studies relating A. actinomycetemcomitans to initiation of LAP have not been reported. A periodontal assessment was performed on 1,075 primarily African-American and Hispanic schoolchildren, ages 11 to 17 years. Samples were taken from each child for A. actinomycetemcomitans. A cohort of 96 students was established that included a test group of 38 A. actinomycetemcomitans-positive students (36 periodontally healthy and 2 with periodontal pockets) and 58 healthy A. actinomycetemcomitans-negative controls. All clinical and microbiological procedures were repeated at 6-month intervals. Bitewing radiographs were taken annually for definitive diagnosis of LAP. At the initial examination, clinical probing attachment measurements indicated that 1.2% of students had LAP, while 13.7% carried A. actinomycetemcomitans, including 16.7% of African-American and 11% of Hispanic students (P = 0.001, chi-square test). A. actinomycetemcomitans serotypes a, b, and c were equally distributed among African-Americans; Hispanic students harbored predominantly serotype c (P = 0.05, chi-square test). In the longitudinal phase, survival analysis was performed to determine whether A. actinomycetemcomitans-positive as compared to A. actinomycetemcomitans-negative students remained healthy ("survived") or progressed to disease with attachment loss of >2 mm or bone loss (failed to "survive"). Students without A. actinomycetemcomitans at baseline had a significantly greater chance to remain healthy (survive) compared to the A. actinomycetemcomitans-positive test group (P = 0.0001). Eight of 38 A. actinomycetemcomitans-positive and none of 58 A. actinomycetemcomitans-negative students showed bone loss (P = 0.01). A. actinomycetemcomitans serotype did not appear to influence survival. These findings suggest that detection of A. actinomycetemcomitans in periodontally healthy children can serve as a risk marker for initiation of LAP.

The rationale for the daily use of an antimicrobial mouthrinse

BACKGROUND

This article reviews the rationale for incorporating effective antimicrobial mouthrinses into a daily oral hygiene regimen along with mechanical plaque control methods.

TYPES OF STUDIES REVIEWED

The author reviewed studies demonstrating the essential etiologic role of a pathogenic dental plaque biofilm in the development of gingivitis, as well as studies indicating that most people fail to maintain a level of mechanical plaque control sufficient to prevent disease. In addition, he did a brief review of studies of oral microbial ecology that identified the oral mucosal tissues as a reservoir of bacteria that colonize tooth surfaces, and he summarized six-month clinical studies of marketed antimicrobial mouthrinse ingredients and products.

CONCLUSIONS

There is a twofold rationale for daily use of antimicrobial mouthrinses: first, given the inadequacy of mechanical plaque control by the majority of people, as a component added to oral hygiene regimens for the control and prevention of periodontal diseases; second, as a method of delivering antimicrobial agents to mucosal sites throughout the mouth that harbor pathogenic bacteria capable of recolonizing supragingival and subgingival tooth surfaces, thereby providing a complementary mechanism of plaque control. The efficacy of several mouthrinse ingredients and products is supported by published six-month clinical trials.

CLINICAL IMPLICATIONS

The daily use of an effective antiplaque/antigingivitis antimicrobial mouthrinse is well-supported by a scientific rationale and can be a valuable component of oral hygiene regimens.

Population-based study of salivary carriage of periodontal pathogens in adults

Large, general population-based data on carriage rates of periodontal pathogens hardly exist in the current literature. The objectives of the present study were to examine the salivary detection of Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans, Campylobacter rectus, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Treponema denticola in a representative sample of the adult population living in southern Finland and to clarify which determinants are associated with the presence of these pathogens in saliva. 16S rRNA-based PCR methods with species-specific primers were employed to determine the presence of the six target bacteria in stimulated saliva samples, which were available from 1,294 subjects aged > or =30 years. The age group, gender, level of education, marital status, smoking history, number of teeth, and number of teeth with deepened pockets were included in the statistical analysis. In general, the carriage of periodontal pathogens was common, since at least one of the examined pathogens was found in 88.2% of the subjects. In descending order, the total detection rates were 56.9%, 38.2%, 35.4%, 31.3%, 20.0%, and 13.9% for T. forsythensis, T. denticola, P. gingivalis, C. rectus, A. actinomycetemcomitans, and P. intermedia, respectively. Age per se was strongly associated with the carriage of P. gingivalis (P = 0.000), and the level of education with that of T. denticola (P = 0.000). There was an association between the number of teeth with deepened pockets and carriage of P. gingivalis (P = 0.000), P. intermedia (P = 0.000), T. denticola (P = 0.000), and A. actinomycetemcomitans (P = 0.004). The data suggest that distinct species have a different carriage profile, depending on variables such as age, educational level, and periodontal status.

Comparison of subgingival bacterial sampling with oral lavage for detection and quantification of periodontal pathogens by real-time polymerase chain reaction

BACKGROUND

Saliva has been studied for the presence of subgingival pathogens in periodontitis patients. With the anaerobic culture technique, the discrepancy between salivary recovery and subgingival presence has been significant, which makes this approach not suitable for practical use in the microbial diagnosis of periodontitis patients. The real-time polymerase chain reaction (PCR) technique represents a very sensitive technique to detect and quantify bacterial pathogens. The aim of the study was to compare the presence and numbers of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia, and Micromonas micros in subgingival plaque and mouthwash samples by the anaerobic culture and real-time PCR techniques.

METHODS

Pooled subgingival plaque samples and 10-ml mouthwash samples were collected from 21 adult patients with periodontitis and analyzed by quantitative anaerobic culture and real-time PCR for A. actinomycetemcomitans, P. gingivalis, T. forsythensis, P. intermedia, and M. micros.

RESULTS

The detection frequency of A. actinomycetemcomitans, P. gingivalis, and T. forsythensis in subgingival plaque was identical by culture and real-time PCR and was higher for P. intermedia and M. micros by real-time PCR. The highest detection frequencies for the target bacteria were found in mouthwash samples by real-time PCR. The additional value of the real-time PCR to detect target bacteria was 38% for P. gingivalis, 73% for T. forsythensis, 77% for P. intermedia, and 71% for M. micros. The sensitivity to detect target species in mouthwash by real-time PCR was 100% for all test species except for P. intermedia (93.8%).

CONCLUSIONS

Rapid detection and quantification of periodontal pathogens in mouthwash samples are possible by real-time PCR. The procedure is significantly less time-consuming than subgingival sampling with paper points. This approach to detect major periodontal pathogens in mouthwash samples may simplify microbial diagnosis in periodontitis patients and may be used to monitor periodontal treatment.

Sampling strategy for intraoral detection of periodontal pathogens before and following periodontal therapy

BACKGROUND

The aim of this study was to identify a sampling strategy with high probability for detecting oral colonization by Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Eikenella corrodens, Tannerella forsythensis, Prevotella intermedia, Prevotella nigrescens, and Treponema denticola before and following mechanical periodontal therapy.

METHODS

Samples were taken from the following intraoral sites in 35 patients with untreated chronic periodontitis before and 1.5, 3, and 6 months after non-surgical periodontal therapy: supra- and subgingival plaque from the deepest pockets in each sextant; pooled supra- and subgingival plaque from another six randomly selected, less affected teeth; mucosal swab samples from the tongue, tonsils, throat, and buccal mucosa; and stimulated and unstimulated saliva. Microbial species were identified by polymerase chain reaction (PCR).

RESULTS

Of the sampling of all assessed sites, the highest probability for simultaneously detecting the tested pathogens was found in respect to the combination of supra- and subgingival plaque samples taken from the most affected tooth in each sextant in untreated patients (probability: 83% to 95% for the assessed bacteria). These results were consistently observed throughout the study period.

CONCLUSIONS

For determining the intraoral carrier state of patients with periodontitis, a combined sample of supra- and subgingival plaque taken from the deepest periodontal pocket in each sextant may yield the most reliable result. This sampling strategy may be used in routine microbial testing and clinical research.

The salivary microbiota as a diagnostic indicator of oral cancer: a descriptive, non-randomized study of cancer-free and oral squamous cell carcinoma subjects

Background

The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls.

Methods

Unstimulated saliva samples were collected from 229 OSCC-free and 45 OSCC subjects and evaluated for their content of 40 common oral bacteria using checkerboard DNA-DNA hybridization. DNA counts per ml saliva were determined for each species, averaged across subjects in the 2 subject groups, and significance of differences between groups determined using the Mann-Whitney test and adjusted for multiple comparisons. Diagnostic sensitivity and specificity in detection of OSCC by levels of salivary organisms were computed and comparisons made separately between a non-matched group of 45 OSCC subjects and 229 controls and a group of 45 OSCC subjects and 45 controls matched by age, gender and smoking history.

Results

Counts of 3 of the 40 species tested, Capnocytophaga gingivalis, Prevotella melaninogenica and Streptococcus mitis, were elevated in the saliva of individuals with OSCC (p < 0.001). When tested as diagnostic markers the 3 species were found to predict 80% of cancer cases (sensitivity) while excluding 83% of controls (specificity) in the non-matched group. Diagnostic sensitivity and specificity in the matched group were 80% and 82% respectively.

Conclusion

High salivary counts of C. gingivalis, P. melaninogenica and S. mitis may be diagnostic indicators of OSCC.

The Actinobacillus actinomycetemcomitans autotransporter adhesin Aae exhibits specificity for buccal epithelial cells from humans and old world primates

Cells of the gram-negative periodontopathogen Actinobacillus actinomycetemcomitans express a surface-exposed, outer membrane autotransporter protein, designated Aae, which has been implicated in epithelial cell binding. We constructed a mutant strain of A. actinomycetemcomitans that contained a transposon insertion in the Aae structural gene (aae) and tested the mutant to determine its ability to bind to buccal epithelial cells (BECs) isolated from healthy volunteers. Significantly fewer mutant cells than wild-type cells bound to BECs. A broad-host-range plasmid that contained an intact aae gene driven by a heterologous tac promoter restored the ability of the mutant strain to bind to BECs at wild-type levels. This plasmid also conferred upon Escherichia coli the ability to express the Aae protein on its surface and to bind to human BECs. Aae-expressing E. coli also bound to BECs isolated from six Old World primates but not to BECs isolated from four New World primates or nine other nonprimate mammals, as well as to human gingival epithelial cells but not to human pharyngeal, palatal, tongue, bronchial, or cervical epithelial cells. Our findings indicate that Aae mediates binding of A. actinomycetemcomitans to BECs from humans and Old World primates and that this process may contribute to the host range specificity and tissue tropism exhibited by this bacterium.

Effects of periodontitis and smoking on the microbiota of oral mucous membranes and saliva in systemically healthy subjects

BACKGROUND/AIM

To examine the differences in the proportions of 40 bacterial species in samples from eight oral soft-tissue surfaces and saliva in systemically healthy adult subjects with and without periodontitis and in smokers and nonsmokers.

METHODS

Saliva and microbial samples were taken from eight oral soft-tissue surfaces in 229 systemically healthy subjects stratified by periodontal and smoking status. Subjects included 84 periodontally healthy and 145 periodontitis individuals. Of these, there were 182 nonsmokers and 47 smokers. Soft-tissue samples were taken using a "buccal brush" and saliva was taken by expectoration. All samples were individually evaluated for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The percentage of total DNA probe count was determined for each species at each sample location and averaged across subjects. The significance of differences among the proportions of the 40 test species at different sample locations was sought in these populations using the Kruskall-Wallis test and adjusted for multiple comparisons.

RESULTS

When stratified for periodontal status or smoking status, microbial profiles at most sites did not differ significantly. Generally, periodontal pathogens were found at higher levels on the soft tissues of periodontitis subjects than in periodontally healthy subjects, and at higher levels in smokers than nonsmokers. Few significant differences were found, although trends in the populations were noted.

CONCLUSIONS

Small differences in the proportions of bacterial species were observed on soft tissues and in saliva comparing periodontally healthy and periodontitis subjects. Somewhat greater differences between smokers and nonsmokers were found; however, these were not statistically significant.

Clinical Responses to Mechanical Periodontal Treatment in Chinese Chronic Periodontitis Patients with and withoutActinobacillus actinomycetemcomitans

BACKGROUND

The purpose of this study was to compare 12-month clinical responses to mechanical periodontal treatment in Chinese chronic periodontitis patients at sites with and without Actinobacillus actinomycetemcomitans at baseline, and to investigate the ability of mechanical periodontal treatment to eliminate A. actinomycetemcomitans.

METHODS

Nineteen patients and a total of 76 selected sites with a mean probing depth (PD) of > or = 7 mm were studied. Whole mouth presence or absence of supragingival plaque (PI%), bleeding on probing (BOP%), probing depth (PD), and probing attachment level (PAL) were recorded at six sites per tooth at baseline and after 3, 9, and 12 months. Baseline subgingival plaque samples were taken from the deepest PD site in each quadrant using sterile paper points and were cultured on TSBV plates for 5 days in a 5% CO2-air incubator. All sites received mechanical periodontal treatment, which included oral hygiene instructions and supragingival and subgingival instrumentation with or without surgical access, with maintenance care being provided once every 3 months thereafter.

RESULTS

At baseline, A. actinomycetemcomitans was isolated in 13 of the 19 subjects (68%) and in 29 out of the 76 sampled sites (38%). At the end of 12 months, in three of the initially A. actinomycetemcomitans-positive subjects, A. actinomycetemcomitans was not detected in the sampled sites, while one subject, in whom A. actinomycetemcomitans was not initially found at the sampled sites was A. actinomycetemcomitans-positive at 12 months. Multi-level variance component models showed there was no statistically significant difference in all clinical parameters between A. actinomycetemcomitans-positive and -negative subjects (P > 0.05). In the sampled sites of the initially A. actinomycetemcomitans-positive subjects, the mean PD was reduced from 7.6 +/- 1.6 mm to 3.2 +/- 1.8 mm, the mean PAL gain was 1.4 +/- 2.0 mm, and the mean recession was 3.0 +/- 2.3 mm. The corresponding figures in the sampled sites of the initially A. actinomycetemcomitans-negative subjects were 7.5 +/- 1.6 mm to 2.7 +/- 1.0 mm, 2.3 +/- 2.6 mm and 2.4 +/- 2.2 mm for mean PD changes, PAL gain, and mean recession, respectively.

CONCLUSIONS

Favorable clinical responses to mechanical periodontal therapy may occur in Chinese chronic periodontitis patients at sites infected with A. actinomycetemcomitans. The mere detection of subgignival A. actinomycetemcomitans does not necessarily imply poorer treatment outcomes in the control of chronic periodontitis.

Distribution of selected bacterial species on intraoral surfaces

BACKGROUND/AIM

To examine the proportions of 40 bacterial species in samples from 8 oral soft tissue surfaces and saliva in systemically healthy adult subjects and to compare these microbiotas with those of supra- and subgingival plaque.

METHODS

Microbial samples were taken from 8 oral soft tissue surfaces of 225 systemically healthy subjects using a "buccal brush". Saliva was taken by expectoration. Forty-four of these subjects provided additional supra- and subgingival plaque samples. Samples were individually evaluated for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The percentage of total DNA probe count was determined for each species, at each sample location and averaged across subjects. The significance of differences among the proportions of the 40 test species at different sample locations was sought in the 225 and 44 subjects separately using the Quade test and adjusted for multiple comparisons. Cluster analysis was performed using the proportions of the 40 species at the different sample locations using the minimum similarity coefficient and an average unweighted linkage sort. The proportions of each species were averaged across subjects in the resulting cluster groups and the significance of differences was tested using the t-test and ANOVA.

RESULTS

Microbial profiles differed markedly among sample locations in the 225 subjects, with 34 of 40 species differing significantly. Proportions of Veillonella parvula and Prevotella melaninogenica were higher in saliva and on the lateral and dorsal surfaces of the tongue, while Streptococcus mitis and S. oralis were in significantly lower proportions in saliva and on the tongue dorsum. Cluster analysis resulted in the formation of 2 clusters with >85% similarity. Cluster 1 comprised saliva, lateral and dorsal tongue surfaces, while Cluster 2 comprised the remaining soft tissue locations. V. parvula, P. melaninogenica, Eikenella corrodens, Neisseria mucosa, Actinomyces odontolyticus, Fusobacterium periodonticum, F. nucleatum ss vincentii and Porphyromonas gingivalis were in significantly higher proportions in Cluster 1 and S. mitis, S. oralis and S. noxia were significantly higher in Cluster 2. These findings were confirmed using data from the 44 subjects providing plaque samples. The microbial profiles of supra- and subgingival plaque differed from the other sample locations, particularly in the increased proportions of the Actinomyces species. Species of different genera exhibited different proportions on the various intraoral surfaces, but even within the genus Streptococcus, there were differences in colonization patterns. S. oralis, S. mitis and S. constellatus colonized the soft tissues and saliva in higher proportions than the samples from the teeth, while the other 4 streptococcal species examined colonized the dental surfaces in proportions comparable to the soft tissue locations and saliva.

CONCLUSIONS

Proportions of bacterial species differed markedly on different intraoral surfaces. The microbiota of saliva was most similar to that of the dorsal and lateral surfaces of the tongue. The microbiotas of the soft tissues resembled each other more than the microbiotas that colonized the teeth both above and below the gingival margin.

Tight-adherence genes of Actinobacillus actinomycetemcomitans are required for virulence in a rat model

Actinobacillus actinomycetemcomitans is a Gram-negative coccobacillus that has been associated with localized aggressive periodontitis and infections of the heart, brain, and urinary tract. Wild-type clinical isolates have the remarkable ability to adhere tenaciously and nonspecifically to solid surfaces such as glass, plastic, and hydroxyapatite. Adherence by A. actinomycetemcomitans is mediated by the tight-adherence (tad) gene locus, which consists of 14 genes (flp-1-flp-2-tadV-rcpCAB-tadZABCDEFG). All but 2 of the genes have been shown to be required for the secretion and assembly of long, bundled Flp1 fibrils. To test whether the tad locus is required for colonization and disease, we developed a rat model for periodontal disease. To mimic the natural route of infection, Sprague-Dawley rats were inoculated orally by adding bacteria directly to their food for 8 days. After inoculation with wild-type or mutant strains defective in adherence (flp-1 and tadA), the rats were assessed for colonization of the oral cavity and pathogenesis. Wild-type A. actinomycetemcomitans was able to colonize and persist for at least 12 weeks in the oral cavity, elicit a humoral immune response, and cause significant bone loss in rats. In contrast, rats fed flp-1 or tadA mutant strains showed no bone loss and their immune responses were indistinguishable from those of the uninoculated controls. These results demonstrate the critical importance of the tad locus in the colonization and pathogenesis of A. actinomycetemcomitans.

Effects of Streptococcus crista and human saliva on the viability of Fusobacterium nucleatum ATCC 10953

Associations with facultative species might help planktonic oral anaerobes survive when they traverse saliva. This study investigated whether co-aggregation with Streptococcus crista ATCC 51110 enhanced the viability of Fusobacterium nucleatum ATCC 10953. Two tubes each of co-aggregates and Fus. nucleatum ATCC 10953 alone were prepared. One of each set was resuspended in buffer, and the other in clarified saliva from each of 20 donors. After 1 h, cells were stained for viability. The median percentage of viable Fus. nucleatum ATCC 10953 in buffer with Strep. crista (86%) was significantly higher (p=0.04) than in buffer alone (77%). A similar trend was observed for saliva with Strep. crista (81%) and saliva alone (74%), although that difference was not significant (p=0.41). The median percentage of Fus. nucleatum co-aggregated in buffer (44%) was significantly reduced after incubation in saliva (16%) (p<0.0002). No such change was seen when saliva was replaced with purified salivary proline-rich glycoprotein, which can bind both species. For co-aggregate suspensions, there was no difference in the viability of fusobacteria that were or were not in direct contact with Strep. crista. In both cases, viability was significantly reduced in saliva relative to buffer. Strep. crista may enhance the viability of planktonic Fus. nucleatum ATCC 10953, but it is not yet clear whether that requires co-aggregation. Transmission of fusobacteria through saliva could depend on the interplay between protective factors, such as the presence of streptococci, and antimicrobial factors, which kill cells or disassociate co-aggregates.

Microbial ecology of Actinobacillus actinomycetemcomitans, Eikenella corrodens and Capnocytophaga spp. in adult periodontitis

Information on intraoral distribution of putative periodontal pathogens might be essential for controlling different forms of periodontal disease. Colonization may be either promoted or impeded by other bacteria competing in the subgingival ecosystem. In recent investigations microbial associations between dental organisms have been determined in a multitude of subgingival plaque samples within multiple patients and described by odds ratios, in most circumstances without taking into account the correlated structure of the observations within a single individual. The present investigation had 3 major objectives: (i) to describe the intraoral distribution of some facultatively anaerobic, Gram-negative rods, i.e. Actinobacillus actinomycetemcomitans, Eikenella corrodens-like organisms and Capnocytophaga spp., in a multitude of subgingival and extracrevicular samples of 10 adult subjects with A. actinomycetemcomitans-associated periodontitis; (ii) to analyse possible inconsistencies of microbial associations between these periodontal organisms; and (iii) to determine factors increasing the likelihood of isolating these bacteria in a given subgingival site by employing Generalized Estimation Equation (GEE) methods. Clinical examinations were carried out at 6 sites of every tooth present. In each subject, 13 extracrevicular (2 cheek mucosa, 3 tongue, 4 gingival, 2 tonsillar samples, 1 palatinal, 1 saliva sample) and between 22 and 44 subgingival samples from deepest sites of every tooth present (n = 296) were selectively cultivated for A. actinomycetemcomitans, E. corrodens and Capnocytophaga spp. In extracrevicular material, A. actinomycetemcomitans, Capnocytophaga spp. and E. corrodens were isolated in 9, 10 and 6 patients, and from 65, 82 and 15% samples, respectively. The organisms were recovered from 51, 62 and 27% subgingival plaque samples, respectively. Heterogeneity tests did not reveal significant inconsistencies of microbial associations between bacteria in subgingival plaque. Mantel-Haenszel's odds ratios ranged between 2.0 for A. actinomycetemcomitans and Capnocytophaga spp. and 18.7 for Capnocytophaga spp. and E. corrodens. An exchangeable working dependence structure was employed in the GEE approach. The odds of isolating A. actinomycetemcomitans was increased by factor 3.7 in 4-6 mm deep pockets, and 9.5 in > or = 7 mm deep pockets. The odds of presence of E. corrodens was increased by factor 10.8 in the case of presence of Capnocytophaga spp. and 2.1 in the case of presence of A. actinomycetemcomitans. Capnocytophaga spp. were associated with bleeding on probing and molar sites. Presence of E. corrodens was associated with clinical attachment loss but not periodontal probing depth. Results of the present study indicated an association of A. actinomycetemcomitans with periodontal pathology. Whereas this organism and Capnocytophagae were widely distributed in extracrevicular ecosystems of the mouth, E. corrodens only occasionally appeared in saliva or on mucous membranes of the oral cavity. In general, GEE methods seem to allow to determine factors associated with the presence of periodontal organisms in a multivariate approach and considering the correlated structure of the data.