The predominant cultivable microbiota of crevicular epithelial cells

Clinical Efficacy of Scaling and Root Planing With Placental Extract Gel Under Magnification in Chronic Periodontitis Patients: A Split-Mouth Study

Background Chronic localized periodontitis is a prevalent and persistent inflammatory condition in which there is the gradual degradation of the gingiva, periodontal ligament fibers, and alveolar bone loss. The objectives of periodontal therapy encompass not solely the elimination of local factors from the periodontal pocket but also the eradication of the dysbiotic microbial milieu to restore periodontal health. The present study aimed to compare the efficacy of scaling and root planing (SRP) with and without the placement of placental extract gel in the therapeutic management of chronic localized periodontitis under magnification. Materials and methods The present investigation encompassed 40 sites in 20 systemically healthy patients with chronic localized periodontitis. The allocation of the sites was done randomly, resulting in two distinct groups: group I (test site) and group II (control site). Group I was subjected to SRP, followed by the placement of placental extract gel, while group II solely received SRP. Clinical evaluations of pocket probing depth, plaque index, relative attachment level (RAL), gingival index (GI), and bleeding on probing (BoP) were performed at each site at baseline, six weeks, and three months. Results Placental extract gel as an accompaniment to SRP showed significant improvement in clinical parameters like pocket probing depth, RAL, GI, and BoP. Conclusion Placental extract gel may significantly act as a local drug delivery agent in the treatment of localized periodontal pockets.

Who is in the driver's seat? Parvimonas micra: An understudied pathobiont at the crossroads of dysbiotic disease and cancer

Recent advances in our understanding of microbiome composition at sites of inflammatory dysbiosis have triggered a substantial interest in a variety of historically understudied bacteria, especially among fastidious obligate anaerobes. A plethora of new evidence suggests that these microbes play outsized roles in establishing synergistic polymicrobial infections at many different sites in the human body. Parvimonas micra is a prime example of such an organism. Despite being almost completely uncharacterized at the genetic level, it is one of the few species commonly detected in abundance at multiple mucosal sites experiencing either chronic or acute inflammatory diseases, and more recently, it has been proposed as a discriminating biomarker for multiple types of malignancies. In the absence of disease, P. micra is commonly found in low abundance, typically residing within the oral cavity and gastrointestinal tract. P. micra exhibits the typical features of an inflammophilic organism, meaning its growth actually benefits from active inflammation and inflammatory tissue destruction. In this mini-review, we will describe our current understanding of this underappreciated but ubiquitous pathobiont, specifically focusing upon the role of P. micra in polymicrobial inflammatory dysbiosis and cancer as well as the key emerging questions regarding its pathobiology. Through this timely work, we highlight Parvimonas micra as a significant driver of disease and discuss its unique position at the crossroads of dysbiosis and cancer.

Infection Route of Parvimonas micra: A Case Report and Systematic Review

Parvimonas micra (P. micra), a bacterium that colonizes the gastrointestinal tract, is often isolated from periodontitis and abscesses as part of a complex bacterial infection. However, reports of monobacterium infections due to P. micra are limited. Here, we report a case of monobacterial bacteremia caused by P. micra with the aim of identifying the source of the invasion and clarifying the clinical features. A 54-year-old patient presented with bacteremia due to P. micra and with an oral invasion that we suspected resulted from prior dental treatment. Using PubMed and Google Scholar databases, we undertook a systematic review of monobacteremia caused by P. micra. We identified 26 patients (mean age, 70.15 years) in our systematic review. P. micra bacteremia and its associated phenotypes were most frequently identified in spinal discitis, followed by epidural and lumbar abscesses, and infective endocarditis. The major risk factors were malignancy, diabetes mellitus, and post-arthroplasty. When P. micra is detected in blood cultures, evaluation and intervention for oral contamination may be indicated.

Assessment of antibacterial effect of hydrogen water on plaque from patients with chronic periodontitis

Background:

Periodontitis is an inflammatory disease causing destruction of tissues surrounding the teeth. The primary etiological factor for periodontitis is plaque. An inference could be drawn that an overall reduction in microorganisms halts disease progression. It is desirable to have natural agents with minimal side effects to reduce the microbial load.

Aim:

The aim of the study is to assess the effect of hydrogen water on microbial count in plaque obtained from chronic periodontitis patients and to determine the antibacterial activity of hydrogen water at various time intervals.

Materials and Methods:

A total of twenty chronic periodontitis patients were included after obtaining approval from the institutional ethical committee. Written informed consent was obtained from all the twenty participants. Plaque samples were collected and exposed to hydrogen water at baseline, 1 min, 2 min 30 s, and 5 min. Samples were then cultured on blood agar and incubated in aerobic and anaerobic conditions. The colony forming units and total bacterial count were recorded after 24–48 h.

Statistical Analysis:

Intragroup pair-wise comparison was done using Wilcoxon sign-ranked test.

Results:

Hydrogen water showed antibacterial activity against aerobic and anaerobic organisms associated with chronic periodontitis. There was a statistically significant difference in the number of colony forming units from baseline to 1 and 2.5 min for the aerobic culture and also for baseline to 1, 2.5, and 5 min for the anaerobic culture.

Conclusion:

The data of the present study indicate that hydrogen water has an antibacterial effect on microorganisms associated with chronic periodontitis.

Host surface ectonucleotidase-CD73 and the opportunistic pathogen, Porphyromonas gingivalis, cross-modulation underlies a new homeostatic mechanism for chronic bacterial survival in human epithelial cells

Cell surface nucleotide-metabolizing enzyme, ectonucleotidase-CD73, has emerged as a central component of the cellular homeostatic-machinery that counterbalances the danger-molecule (extracellular-ATP)-driven proinflammatory response in immune cells. While the importance of CD73 in microbial host fitness and symbiosis is gradually being unraveled, there remains a significant gap in knowledge of CD73 and its putative role in epithelial cells. Here, we depict a novel host-pathogen adaptation mechanism where CD73 takes a center role in the intracellular persistence of Porphyromonas gingivalis, a major colonizer of oral mucosa, using human primary gingival epithelial cell (GEC) system. Temporal analyses revealed, upon invasion into the GECs, P. gingivalis can significantly elevate the host-surface CD73 activity and expression. The enhanced and active CD73 significantly increases P. gingivalis intracellular growth in the presence of substrate-AMP and simultaneously acts as a negative regulator of reactive oxygen species (ROS) generation upon eATP treatment. The inhibition of CD73 by siRNA or by a specific inhibitor markedly increases ROS production. Moreover, CD73 and P. gingivalis cross-signaling significantly modulates pro-inflammatory interleukin-6 (IL-6) in the GECs. Conversely, exogenous treatment of the infected GECs with IL-6 suppresses the intracellular bacteria via amplified ROS generation. However, the decreased bacterial levels can be restored by overexpressing functionally active CD73. Together, these findings illuminate how the local extracellular-purine-metabolism, in which CD73 serves as a core molecular switch, can alter intracellular microbial colonization resistance. Further, host-adaptive pathogens such as P. gingivalis can target host ectonucleotidases to disarm specific innate defenses for successful intracellular persistence in mucosal epithelia.

Antibiotic Resistance of Human Periodontal Pathogen Parvimonas micra Over 10 Years

Changes were evaluated over 10 years in the in vitro resistance of human periodontopathic strains of Parvimonas micra to four antibiotics. Subgingival biofilms culture positive for P. micra from 300 United States adults with severe periodontitis in 2006, and from a similar group of 300 patients in 2016, were plated onto anaerobically incubated enriched Brucella blood agar alone, or supplemented with either doxycycline (4 mg/L), clindamycin (4 mg/L), amoxicillin (8 mg/L), or metronidazole (16 mg/L). P. micra growth on antibiotic-supplemented media indicated in vitro resistance to the evaluated antibiotic concentration. P. micra resistance was significantly more frequent among patients in 2016, as compared to 2006, for doxycycline (11.3% vs. 0.3% patients; 37.7-fold increase), and clindamycin (47.3% vs. 2.0% patients; 23.7-fold increase) (both p < 0.001), whereas resistance to amoxicillin (2.3% vs. 1.0% patients) and metronidazole (0% vs. 0.3% patients) remained low and statistically unchanged between the two patient groups (p-values > 0.05). No P. micra isolates in 2006 or 2016 were jointly resistant in vitro to both amoxicillin and metronidazole. The alarming increases in subgingival P. micra resistance to doxycycline and clindamycin raise serious questions about the empiric use of these antibiotics, either locally or systemically, in the treatment of United States periodontitis patients harboring subgingival P. micra.

Streptococcus gordonii programs epithelial cells to resist ZEB2 induction by Porphyromonas gingivalis

The polymicrobial microbiome of the oral cavity is a direct precursor of periodontal diseases, and changes in microhabitat or shifts in microbial composition may also be linked to oral squamous cell carcinoma. Dysbiotic oral epithelial responses provoked by individual organisms, and which underlie these diseases, are widely studied. However, organisms may influence community partner species through manipulation of epithelial cell responses, an aspect of the host microbiome interaction that is poorly understood. We report here that Porphyromonas gingivalis, a keystone periodontal pathogen, can up-regulate expression of ZEB2, a transcription factor which controls epithelial-mesenchymal transition and inflammatory responses. ZEB2 regulation by P. gingivalis was mediated through pathways involving β-catenin and FOXO1. Among the community partners of P. gingivalis, Streptococcus gordonii was capable of antagonizing ZEB2 expression. Mechanistically, S. gordonii suppressed FOXO1 by activating the TAK1-NLK negative regulatory pathway, even in the presence of P. gingivalis Collectively, these results establish S. gordonii as homeostatic commensal, capable of mitigating the activity of a more pathogenic organism through modulation of host signaling.

Establishment of a counter-selectable markerless mutagenesis system in Veillonella atypica

Using an alternative sigma factor ecf3 as target, we successfully established the first markerless mutagenesis system in the Veillonella genus. This system will be a valuable tool for mutagenesis of multiple genes for gene function analysis as well as for gene regulation studies in Veillonella.

Hyaluronic Acid as an adjunct to scaling and root planing in chronic periodontitis. A randomized clinical trail

AIM

AIM of the present study was to evaluate the adjunctive effect of local application of hyaluronon gel following scaling and root planing (SRP) in chronic periodontitis patients.

MATERIALS AND METHODS

In this randomized split mouth study 33 subjects with chronic periodontitis were evaluated after full mouth SRP. In the test sites hyaluronon gel was applied immediately after SRP and one week post therapy, the control sites were treated with SRP alone. Bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) were recorded at baseline, 4 wk and 12 wk.

RESULTS

Significant reduction in BOP scores was observed in both the groups at 12weeks (p<0.001). The hyaluronon group showed a greater reduction in BOP (p<0.001). In the hyaluronon group the mean PPD at baseline was 6.33±0.09 which reduced to 2.49±0.51 at 12 weeks which was statistically significant (p<0.001). In the control group the mean PPD at baseline was 6.09±1.26 which reduced to 4.36±1.29 at 12 weeks which was statistically significant (p<0.001). The CAL measurements showed a significant difference between the groups (p<0.001) at 12 wk post therapy.

CONCLUSION

Hyaluronic Acid (HA) has a beneficial effect on periodontal health in patients with chronic Periodontitis. HA appears to be a suitable candidate as an adjunct to SRP in chronic periodontitis patients.

Gram-positive anaerobic cocci--commensals and opportunistic pathogens

Among the Gram-positive anaerobic bacteria associated with clinical infections, the Gram-positive anaerobic cocci (GPAC) are the most prominent and account for approximately 25-30% of all isolated anaerobic bacteria from clinical specimens. Still, routine culture and identification of these slowly growing anaerobes to the species level has been limited in the diagnostic laboratory, mainly due to the requirement of prolonged incubation times and time-consuming phenotypic identification. In addition, GPAC are mostly isolated from polymicrobial infections with known pathogens and therefore their relevance has often been overlooked. However, through improvements in diagnostic and in particular molecular techniques, the isolation and identification of individual genera and species of GPAC associated with specific infections have been enhanced. Furthermore, the taxonomy of GPAC has undergone considerable changes over the years, mainly due to the development of molecular identification methods. Existing species have been renamed and novel species have been added, resulting in changes of the nomenclature. As the abundance and significance of GPAC in clinical infections grow, knowledge of virulence factors and antibiotic resistance patterns of different species becomes more important. The present review describes recent advances of GPAC and what is known of the biology and pathogenic effects of Anaerococcus, Finegoldia, Parvimonas, Peptoniphilus and Peptostreptococcus, the most important GPAC genera isolated from human infections.

Hemin nutritional stress inhibits bacterial invasion of radicular dentine by two endodontic anaerobes

AIM

To determine if anaerobic bacteria routinely found in infected dentine and root canals require the presence of heme in the environment in order for them to invade dentinal tubules.

METHODOLOGY

Noncarious, unrestored human teeth with single root canals were prepared for invasion experiments and soaked in either TSB-M supplemented with hemin (5 microg mL(-1)) (n = 12 roots), TSB-M media (n = 12 roots) or TSB-M media followed by hemin soak (n = 12 roots) for 2 days, then inoculated with either Prevotella intermedia ATCC 25611 or Peptostreptococcus micros ATCC 33270 and incubated anaerobically for 14 days. Roots were prepared for light microscopy, stained with Brown and Brenn or antisera raised to the bacteria, and invasion within tubules assessed using a tubule invasion index (TI). Data were analysed using Student's t-test and Mann-Whitney U-test.

RESULTS

Prevotella intermedia (TI = 0.7 +/- 0.04) and P. micros (TI = 0.96 +/- 0.08) showed low invasion when grown in the presence of hemin with cells generally restricted to the superficial 20 microm of the tubules, whilst neither bacteria invaded tubules (TI = 0) when hemin was absent from the growth media (P < 0.01).

CONCLUSIONS

Hemin was required in the growth medium for P. intermedia and P. micros to invade dentinal tubules.

Identification of oral bacteria associated with crevicular epithelial cells from chronic periodontitis lesions

Bacterial invasion of host epithelial cells plays an important role in the pathogenesis of periodontal diseases; however, the interactions between subgingival species and the gingival crevice cells are not fully understood. This study determined the prevalence of a group of oral bacterial species on or in epithelial cells derived from periodontal pockets and the gingival crevice of subjects with periodontitis. Samples of epithelial cells were obtained from 120 sites with periodontal pockets > or =4 mm and 92 periodontally healthy sites from 49 patients (mean age 46.3+/-1.4 years; 43% males) with chronic periodontitis. Bacteria in or on epithelial cells were separated from unattached bacteria by Percoll density-gradient centrifugation. The presence and levels of 33 oral species were determined in epithelial cell samples by whole genomic DNA probes and the checkerboard method. The most frequently detected species were Porphyromonas gingivalis (42%), Treponema denticola (38%), Prevotella intermedia (37%), Streptococcus intermedius (36%), Campylobacter rectus (35%), Streptococcus sanguinis (35%) and Streptococcus oralis (34%). Species of Actinomyces were found in low prevalence and levels. The data indicated that there were more micro-organisms on or in epithelial cells obtained from periodontal pockets than from healthy sulci; however, no significant differences regarding the percentage and level of any specific species were found between these sites. Veillonella parvula, S. oralis, Streptococcus gordonii and Streptococcus mitis tended to be more prevalent in sites without disease. These findings demonstrated that a wide range of oral species may be detected on or in crevicular epithelial cells from sites with periodontitis and from periodontally healthy sulci.

Effects of zinc and copper on adhesion and hemagglutination of Prevotella intermedia and Prevotella nigrescens

This study investigated the mechanism of protein attachment to the surface of the putative periodontal pathogens Prevotella intermedia and Prevotella nigrescens in artificial gingival crevicular fluid, and ways to increase protein attachment to the bacterial cells. The effects of cations on protein attachment, bacterial adhesion, and hemagglutination were examined, and cation-binding components on both bacterial species were identified. The presence of cations, especially zinc, copper and cerium, increased attachment of human serum proteins to both bacterial species. In contrast, the presence of hydrophobic inhibitors or sugars had little effect. Protein attachment was reduced by heat treatment of the bacterial cells. Pretreatment of bacteria with human serum proteins inhibited adhesion of both species to buccal epithelial cells and hemagglutination. These effects were enhanced by the presence of zinc and copper during pretreatment. Using a chelating column, specific zinc- and copper-binding proteins were identified on the surfaces of both bacterial species.

Identification of candidate periodontal pathogens and beneficial species by quantitative 16S clonal analysis

Most studies of the bacterial etiology of periodontitis have used either culture-based or targeted DNA approaches, and so it is likely that pathogens remain undiscovered. The purpose of this study was to use culture-independent, quantitative analysis of biofilms associated with chronic periodontitis and periodontal health to identify pathogens and beneficial species. Samples from subjects with periodontitis and controls were analyzed using ribosomal 16S cloning and sequencing. Several genera, many of them uncultivated, were associated with periodontitis, the most numerous of which were gram positive, including Peptostreptococcus and Filifactor. The genera Megasphaera and Desulfobulbus were elevated in periodontitis, and the levels of several species or phylotypes of Campylobacter, Selenomonas, Deferribacteres, Dialister, Catonella, Tannerella, Streptococcus, Atopobium, Eubacterium, and Treponema were elevated in disease. Streptococcus and Veillonella spp. were found in high numbers in all samples and accounted for a significantly greater fraction of the microbial community in healthy subjects than in those with periodontitis. The microbial profile of periodontal health also included the less-abundant genera Campylobacter, Abiotrophia, Gemella, Capnocytophaga, and Neisseria. These newly identified candidates outnumbered Porphyromonas gingivalis and other species previously implicated as periodontopathogens, and it is not clear if newly identified and more numerous species may play a more important role in pathogenesis. Finally, more differences were found in the bacterial profile between subjects with periodontitis and healthy subjects than between deep and shallow sites within the same subject. This suggests that chronic periodontitis is the result of a global perturbation of the oral bacterial ecology rather than a disease-site specific microbial shift.

Synergistic biofilm formation byTreponema denticolaandPorphyromonas gingivalis

Biofilm formation is an important step in the etiology of periodontal diseases. In this study, in vitro biofilm formation by Treponema denticola and Porphyromonas gingivalis 381 displayed synergistic effects. Confocal microscopy demonstrated that P. gingivalis attaches to the substratum first as a primary colonizer followed by coaggregation with T. denticola to form a mixed biofilm. The T. denticola flagella mutant as well as the cytoplasmic filament mutant were shown to be essential for biofilm formation as well as coaggregation with P. gingivalis. The major fimbriae and Arg-gingipain B of P. gingivalis also play important roles in biofilm formation with T. denticola.

Etiology and pathogenesis of periodontal diseases

The two most prevalent and most investigated periodontal diseases are dental plaque-induced gingivitis and chronic periodontitis. The last 10 to 15 years have seen the emergence of several important new findings and concepts regarding the etiopathogenesis of periodontal diseases. These findings include the recognition of dental bacterial plaque as a biofilm, identification and characterization of genetic defects that predispose individuals to periodontitis, host-defense mechanisms implicated in periodontal tissue destruction, and the interaction of risk factors with host defenses and bacterial plaque. This article reviews current aspects of the etiology and pathogenesis of periodontal diseases.

Micromonas (Peptostreptococcus) micros: unusual case of prosthetic joint infection associated with dental procedures

Micromonas (Peptostreptococcus) micros is frequently associated with periodontal disease as well as respiratory, gastrointestinal and female genitourinary tract infections, but only rarely has been reported as a pathogenic agent of prosthetic joint infections. Here we describe a case of a 63-year-old woman with prosthetic joint infection of total hip arthroplasty caused by the anaerobic species Micromonas micros, associated with tooth extraction. Samples obtained intraoperatively and from the oral cavity were positive for the presence of M. micros by culture and by real-time PCR. This case report indicates that infections of prosthetic joints can be associated with dental procedures and that sensitive molecular techniques are necessary for their routine diagnostic.

Adhesion of Porphyromonas gingivalis to cultured pocket epithelium: mono- and multi-layered

Adhesion of bacteria to epithelial cells might be influenced by the degree of cell differentiation, as observed in the multi-layering process of epithelial cells. In the present study, the adhesion of a large group of clinical Porphyromonas gingivalis strains (n=11) to in vitro cultured mono- and multi-layers of epithelial cells was examined and compared. The tissue samples originated from 6 patients with chronic adult periodontitis. Porphyromonas gingivalis bacteria adhered more to mono-layers as opposed to the more differentiated multi-layers. Differences between the clinical P. gingivalis strains, however, became obvious only on multi-layers. These partially differentiated cells may also better represent the individual subject variations. Mono-layer cultures, which are simpler to obtain, seem to be less precise. The importance of cell differentiation on bacterial adhesion needs more attention.

Adhesion of Porphyromonas gingivalis strains to cultured epithelial cells from patients with a history of chronic adult periodontitis or from patients less susceptible to periodontitis

BACKGROUND

The present study aimed to explain the interindividual variation in periodontitis susceptibility by differences in the initial adhesion rate of Porphyromonas gingivalis to the pocket epithelium of these individuals, and/or by inter-P. gingivalis strain differences in association capacity (adhesion and internalization).

METHODS

Adhesion assays were performed on epithelial monolayers (cultured in vitro from pocket epithelium belonging to patients who were less or more susceptible to chronic adult periodontitis) using 11 genetically different clinical strains of P. gingivalis.

RESULTS

Both the disease category (less susceptible versus susceptible) and the interstrain variation were found to have a significant effect (both P <0.05) on the initial bacterial association. The chronic adult periodontitis group showed significantly more association of P. gingivalis when compared to less susceptible patients (4.2 x 10(6) versus 3.5 x 10(6)). Also, the interstrain variation was significant, with strains Pg 4 and 5 representing the least and best associating bacteria (1.8 x 10(6) colony forming units for Pg 4, 9 x 10(6) for Pg 5).

CONCLUSIONS

These results indicate that periodontitis susceptibility is influenced by both the interindividual differences in pocket epithelium (allowing more adhesion of P. gingivalis) or by the strain type by which the patient is infected (intra-species differences in adhesion capacity).

Oral Chlamydia trachomatis in patients with established periodontitis

Periodontitis is considered a consequence of a pathogenic microbial infection at the periodontal site and host susceptibility factors. Periodontal research supports the association of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Bacteroides forsythus, and periodontitis; however, causality has not been demonstrated. In pursuit of the etiology of periodontitis, we hypothesized that the intracellular bacteria Chlamydia trachomatis may play a role. As a first step, a cross-sectional study of dental school clinic patients with established periodontitis were assessed for the presence of C. trachomatis in the oral cavity, and in particular from the lining epithelium of periodontal sites. C. trachomatis was detected using a direct fluorescent monoclonal antibody (DFA) in oral specimens from 7% (6/87) of the patients. Four patients tested positive in specimens from the lining epithelium of diseased periodontal sites, one patient tested positive in healthy periodontal sites, and one patient tested positive in the general mucosal specimen. In conclusion, this study provides preliminary evidence of C. trachomatis in the periodontal sites. Planned studies include the use of a more precise periodontal epithelial cell collection device, the newer nucleic acid amplification techniques to detect C. trachomatis, and additional populations to determine the association of C. trachomatis and periodontitis.

Prevotella intermedia stimulates expansion of Vbeta-specific CD4(+) T cells

Recent evidence suggests that certain periodontal pathogens preferentially stimulate T cells expressing specific variable regions on the beta chain (Vbeta) of the T-cell receptor, which may indicate the presence of a superantigen. Superantigens are microbial proteins that activate large numbers of CD4(+) T cells in a Vbeta-specific manner. The purpose of this study was to determine whether Prevotella intermedia, a putative periodontal pathogen, activates populations of specific Vbeta on CD4(+) T cells. Among the bacterial strains tested, P. intermedia strain 17, a clinical isolate, induced the strongest proliferative response in peripheral blood mononuclear cells. Antibodies raised against whole cells of this organism blocked the proliferative activity. P. intermedia-induced proliferation was T-cell specific and required the presence of antigen-presenting cells. Flow cytometric analysis showed that CD4(+) T-cell subsets expressing Vbeta8, Vbeta12, and Vbeta17 expanded in response to P. intermedia strain 17. The ability of P. intermedia to stimulate CD4(+)-T-cell proliferation was further supported by the production profiles of key T-cell cytokines, gamma interferon and interleukin-2. The data collectively suggest that certain strains of P. intermedia can activate Vbeta-specific T cells in a manner similar to that of other known microbial superantigens.

Peptostreptococcus micros smooth and rough genotypes in periodontitis and gingivitis

BACKGROUND

Two genotypes can be distinguished within the species Peptostreptococcus micros: a smooth (Sm) and a rough (Rg) type. To date no systematic study has been performed on the prevalence and proportion of both types in untreated periodontitis patients and subjects without destructive periodontal disease. Therefore, the present study was performed to investigate: 1) the relative importance of the Sm and the Rg genotype of P micros in periodontitis and gingivitis; 2) the correlation between smoking and the 2 genotypes of P micros; and 3) the systemic antibody response against the 2 genotypes in relation to the periodontal condition and smoking.

METHODS

A total of 104 untreated periodontitis patients and 41 individuals with gingivitis underwent clinical examination and microbiological sampling. Pocket samples were cultured anaerobically on blood agar plates to determine the prevalence and proportion of the Sm and Rg types of P micros. Serum antibody titers against both types of P micros were determined in all subjects by enzyme-linked immunosorbent assay (ELISA) using whole bacterial cells as antigen. Additionally, in a representative group of subjects, the antigen specificity of the serum antibodies was assessed by immunoblotting experiments.

RESULTS

The prevalence of the Sm genotype was higher in subjects with periodontitis (94%) compared to subjects with gingivitis (59%), whereas the prevalence of the Rg type was not significantly different (38% versus 29%). Similar analyses were performed for subgroups of smokers and non-smokers; within the periodontitis group, the prevalence of the Sm type was not different between smokers and non-smokers (96% and 92%, respectively), whereas the prevalence of the Rg type was higher in smokers (48%) compared to non-smokers (19%). No difference in prevalence of both types was observed between smokers and non-smokers within the gingivitis group. The titers and specificity of P micros-specific immunoglobulins in periodontitis patients were not different from those in gingivitis subjects, nor were they related to smoking status or culture-positivity.

CONCLUSIONS

The results of this study suggest that both the Sm and the Rg genotypes of P micros are part of the normal oral microbiota. However, the elevated prevalence of the Sm genotype in periodontitis and the elevated prevalence of the Rg type in periodontitis patients who smoke implies that both types can behave as opportunistic pathogens in destructive periodontal disease.

Peptostreptococcus micros coaggregates with Fusobacterium nucleatum and non-encapsulated Porphyromonas gingivalis

Coaggregation is one of the potential colonization strategies of oral microorganisms, often involving fimbrial structures in the interactions. In this study, the coaggregation characteristics of the rough and smooth genotypes of the periodontal pathogen Peptostreptococcus micros were compared to investigate the role of the fibril-like structures of the rough genotype in coaggregation. Of the 11 oral species tested, only Fusobacterium nucleatum strains and non-encapsulated Porphyromonas gingivalis strains coaggregated with P. micros. No differences in coaggregation between the smooth type (Sm), the rough type (Rg) and the smooth variant of the Rg type (Rg(Sm)) of P. micros were observed. Heat-stable, periodate-sensitive structures on P. micros appeared to interact with heat- and protease-sensitive structures on F. nucleatum and P. gingivalis. These data indicate that these unimodal coaggregations are not mediated by the proteinaceous fibril-like structures of the Rg genotype, but by carbohydrates present on both genotypes of P. micros.

Cloning of fibA, encoding an immunogenic subunit of the fibril-like surface structure of Peptostreptococcus micros

Although we are currently unaware of its biological function, the fibril-like surface structure is a prominent characteristic of the rough (Rg) genotype of the gram-positive periodontal pathogen Peptostreptococcus micros. The smooth (Sm) type of this species as well as the smooth variant of the Rg type (RgSm) lack these structures on their surface. A fibril-specific serum, as determined by immunogold electron microscopy, was obtained through adsorption of a rabbit anti-Rg type serum with excess bacteria of the RgSm type. This serum recognized a 42-kDa protein, which was subjected to N-terminal sequencing. Both clones of a lambdaTriplEx expression library that were selected by immunoscreening with the fibril-specific serum contained an open reading frame, designated fibA, encoding a 393-amino-acid protein (FibA). The 15-residue N-terminal amino acid sequence of the 42-kDa antigen was present at positions 39 to 53 in FibA; from this we conclude that the mature FibA protein contains 355 amino acids, resulting in a predicted molecular mass of 41,368 Da. The putative 38-residue signal sequence of FibA strongly resembles other gram-positive secretion signal sequences. The C termini of FibA and two open reading frames directly upstream and downstream of fibA exhibited significant sequence homology to the C termini of a group of secreted and surface-located proteins of other gram-positive cocci that are all presumably involved in anchoring of the protein to carbohydrate structures. We conclude that FibA is a secreted and surface-located protein and as such is part of the fibril-like structures.

Adherence of Peptostreptococcus micros morphotypes to epithelial cells in vitro

Peptostreptococcus micros, which is associated with oral and non-oral mixed anaerobic infections, occurs in three colony morphotypes, the smooth type, the rough type and the smooth variant of the rough type. These types differ in surface structures; the rough type expresses large fibrillar surface appendages, which are absent on the surface of both the smooth and the smooth variant of the rough type. To determine the role of these surface structures in adherence we characterized the adherence of the three morphotypes of P. micros to epithelial cells in vitro. Although all three types adhered well to epithelial cells, adhering numbers of the rough type were significantly lower than those of the smooth and the smooth variant of the rough type. Protease treatment increased the adherence of the rough type of the level of the two other types. The adherence of all three types was reduced more than 85% by treatment with 10 mM sodium periodate. Furthermore, the adherence was pH independent and could not be blocked by incubation with antisera to the bacteria. In addition, we determined the capacity to invade epithelial cells by P. micros. In an acridine orange assay such invasion could not be detected. Our results suggest that the adherence of P. micros to epithelial cells is mediated by periodate-sensitive extracellular polysaccharides and that the protruding fibril-like protein surface structures of the rough type have an obstructive effect on the adherence.

The binding and utilization of hemoglobin by Prevotella intermedia

Prevotella intermedia, a putative periodontopathic microorganism, requires iron for growth. Hemoglobin can be a major source of iron for bacterial growth in vivo since it is present in the crevicular fluid collected from periodontitis sites. Experiments studying the growth of P. intermedia in iron-depleted Todd-Hewitt broth supplemented with human hemoglobin showed that the bacteria were able to utilize human hemoglobin as a source of iron. The uptake of iron from hemoglobin by P. intermedia appears to be initiated by the binding of hemoglobin to the bacteria as shown by direct binding studies using 125I-labeled human hemoglobin. Scatchard analysis of saturation binding data revealed that 125I-labeled human hemoglobin had a dissociation constant (Kd) of 2.53 x 10(-8) M for the receptor on P. intermedia. Binding of labeled hemoglobin to P. intermedia was competitively inhibited by unlabeled human hemoglobin showing that the binding was specific. The ability of bovine hemoglobin, but not hemin or non-hemoglobin heme-containing compounds, to inhibit binding competitively suggested that the globin moiety of the hemoglobin molecule is recognized by the hemoglobin binding receptors.

Identification of bacterial species on or in crevicular epithelial cells from healthy and periodontally diseased patients using DNA-DNA hybridization

The purpose of this investigation was to identify bacterial species present on or in crevicular epithelial cells in healthy and diseased sites using DNA probes. In order to achieve this aim, further improvements were made in the separation of unattached bacteria from those adherent to epithelial cells isolated from the human gingival crevice or periodontal pocket. Then the DNA probes were used to determine the prevalence of detectable DNA from 15 microbial species on or in crevicular epithelial cells. One sample was taken from a single subgingival site in each of 51 individuals ranging in age from 19 to 45 years. Samples were taken from 27 sites of clinically healthy subjects and 24 samples were taken from subjects having periodontally diseased sites. DNA-DNA hybridization indicated that a majority of epithelial cells from healthy sites (63%) were in contact with or harbored Streptococcus oralis. On the other hand, species such as Bacteroides forsythus, Prevotella intermedia, Capnocytophaga ochracea and Campylobacter rectus were more frequently detected in elevated numbers in periodontally diseased sites. Cluster analysis of the microbial profiles generally aggregated subjects with and without periodontitis into separate cluster groups. The cluster patterns suggest the possibility that microbial complexes will be, in part, determined by the receptors available on the epithelial cells.

Hemin-induced modifications of the antigenicity and hemin-binding capacity of Porphyromonas gingivalis lipopolysaccharide

Previous studies have shown that the physical, biochemical, and antigenic properties of the bacterial outer membrane are profoundly influenced by the growth environment. In the present study, the effects of growth in hemin-replete (H+) and hemin-depleted (H-) media on the lipopolysaccharide (LPS) of the oral pathogen Porphyromonas gingivalis were investigated. Our studies show that LPS from P. gingivalis cultured in H+ media (H+LPS) expressed additional low-molecular-mass antigens, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) analysis. Particularly evident was a 26-kDa antigen (26 LPSC) that was lost from the LPS upon transfer of P. gingivalis into H- media. The loss of the 26 LPSC was accompanied by a marked reduction in the hemin-binding capacity of the LPS. The 26 LPSC was refractory to Coomassie blue staining and proteinase K digestion. H+LPS from strain W50/BE1, a nonpigmented pleiotropic strain, lacked the 26 LPSC and did not bind hemin. Polyclonal antiserum raised to whole-cell antigens of P. gingivalis A7436, W83, and HG405 grown in H+ media, but not in H- media, recognized the 26 LPSC in the purified H+LPS from any of the three strains. The immunoreactivities of sera from humans with (n = 24) or without (n = 25) periodontitis to the 26 LPSC and other H+LPS determinants were analyzed by Western blot. Overall, 75% of adult periodontitis patient sera reacted with multiple bands in the H+LPS stepladder, particularly in the range of 14 to 27 kDa. In contrast, only 20% of control sera reacted faintly with H+LPS bands in the range 27 to 34 kDa. The 26 LPSC was recognized by over 40% of sera from adult patients with periodontitis and none of the healthy control sera. Taken together, these results suggest that the antigenicity and hemin-binding properties of P. gingivalis LPS can be modified by growth in H+ media.

Treatment of subjects with refractory periodontal disease

The aim of the present study was to evaluate the effect of non-surgical periodontal therapy with the adjunct of a selected antibiotic in subjects diagnosed with refractory periodontal disease. 21 subjects were selected for the study; all had a history of periodontal surgery, tetracycline therapy, and regular maintenance by a periodontist. When disease activity was detected, a bacterial sample was taken and a whole plaque susceptibility test was performed. Before the outcome of the susceptibility test the subjects were assigned to either antibiotic or placebo therapy. All subjects received scaling and rootplaning prior to antibiotic or placebo therapy. Based on the susceptibility test, subjects in the antibiotic group were treated either with Augmentin or clindamycin. The results demonstrated that in subjects with refractory periodontal disease there was no significant difference (N.S.) in the proportion of sites losing attachment before and after treatment (11.3% and 12.4%, respectively) over a 2-year post therapy observation period. However, the proportion of sites showing gain of attachment increased from 0.9% before therapy to 5.1% (p = 0.029) following selective antibiotic therapy when combined with scaling and rootplaning. The remainder of sites showed no change between pre- and post-therapy monitoring periods. The progression of attachment loss in the active sites could not be completely stopped over the entire 2-year period. After 12-15 months following therapy, there was a tendency towards new loss of attachment and an increase of pocket depth. However, all 4 subjects treated with placebo drug demonstrated continuous deterioration and had to be retreated. Although the proportion of sites losing attachment decreased from 5.1% to 2.3% (N.S.), the proportion of sites gaining attachment also decreased from 2.0% to 1.0% (N.S.). The results suggest that scaling and rootplaning together with selected antibiotic therapy repeated every 12-15 months may be beneficial for these subjects although it may not completely stop progressive attachment loss.

Campylobacter rectus in human periodontitis

Campylobacter rectus (formerly Wolinella recta) in periodontitis lesions was studied relative to age and sex distribution, relationship to disease-active periodontitis, response to periodontal debridement and in vitro antimicrobial susceptibility. Subgingival C. rectus was collected with paper points, transported in VMGA III and plated onto nonselective enriched brucella blood agar and Hammond's selective medium for C. rectus, both incubated anaerobically. C. rectus was recovered from 80% of 1654 periodontitis patients. Although the organism showed similar age and sex occurrence, its proportional recovery in culture-positive adults was inversely related to increasing age (r = 0.999, P < 0.001). The organism was positively associated (summary odds ratio = 2.95) with disease activity in a 24-month longitudinal study of 93 adult periodontitis patients on maintenance therapy. C. rectus decreased from 8.2% to 0.7% following local periodontal debridement of 20 culture-positive adult periodontitis patients. The organism exhibited high in vitro susceptibility to therapeutic levels of tetracycline hydrochloride, metronidazole, penicillin G and ciprofloxacin. These findings further delineate the epidemiology and potential pathogenic role of C. rectus in human periodontitis.

Effects of antibiotic treatment on clinical conditions and bacterial growth with guided tissue regeneration

Mucogingival flaps were reflected over pairs of mandibular molar teeth with Class II furcation invasions. The dimensions of the furcations were measured. The teeth were debrided and an expanded polytetrafluoroethylene (e-PTFE) membrane was placed and retained over one furcation of each pair (test site) for 4 weeks. The second site served as a control. Eight patients (group 1) with 12 e-PTFE sites received no antibiotic. Seven patients (group 2) with 12 e-PTFE sites were administered amoxicillin/clavulanate potassium for 10 days. Paper-points were used to collect bacterial samples and clinical indices were recorded at baseline and weekly for 4 weeks. Paper-point samples and the e-PTFE collected at week 4 were sonicated and analyzed by DNA probes for seven putative pathogens. At baseline no parameter showed statistical differences between groups or sites. At week 1 significantly greater levels of Prevotella intermedia type I (P < 0.05) and Fusobacterium nucleatum (P < 0.01) were found in group 1. At week 4, paper-point samples from test sites (P < 0.05) and e-PTFE materials (P < 0.001) showed significantly higher presence of Bacteroides forsythus in group 1. No significant microbial changes were found for control sites over time or between groups. The total bacterial load at test sites over time increased similarly for patients administered or not administered the antibiotic. Clinical signs of inflammation were significantly greater in group 1 and associated with the presence of B. forsythus (P < 0.01).

Coaggregation of Prevotella intermedia with oral Actinomyces species

Five strains of Prevotella intermedia were examined for their ability to coaggregate with various gram-positive and gram-negative species of oral bacteria. Two of the P. intermedia strains coaggregated with selected Actinomyces species, P. intermedia 27 with Actinomyces viscosus T14V and Actinomyces naeslundii ATCC 12104, PK606, PK984, and PK947, and P. intermedia 113 with Actinomyces odontolyticus WVU 1546 and Actinomyces israelii WVU 838. Exposure of both Prevotella strains but not the Actinomyces strains to heat, trypsin, or proteinase K abolished most coaggregations. All pairs were disaggregated by the addition of sodium dodecyl sulfate, but only those coaggregations involving P. intermedia 113 were reversed by the addition of 2.0 M urea. P. intermedia 27 was sensitive to periodate oxidation, whereas the partner strains were stable to this treatment. Most coaggregations occurred in the presence of saliva; however, reactions involving P. intermedia 27 were not as strong as those of buffer-suspended cells. Treatment of both P. intermedia 113 coaggregations pairs with proteinase K and the results obtained from suspensions of these pairs in saliva suggest that different surface molecules of this P. intermedia strain may mediate each of these coaggregations. These data suggest that all of these coaggregations involve either a protein or glycoprotein on the Prevotella strain, which may interact with carbohydrates or carbohydrate-containing molecules on the surface of the Actinomyces strain.

Interaction of Porphyromonas gingivalis with gingival epithelial cells maintained in culture

Interactions between Porphyromonas gingivalis and gingival epithelial cells were investigated. Gingival epithelial cells were cultured from surgically removed gingival tissue. Electron microscopy demonstrated adherence of P. gingivalis to the cell membranes and microvilli followed by internalization of the bacteria into the epithelial cell cytoplasm. Saliva from healthy and periodontally diseased patients inhibited P. gingivalis association with the epithelial cells. Attachment to and penetration of gingival epithelial cells by P. gingivalis may be important virulence factors in periodontal disease. Salivary molecules may play a role in modulating these interactions.

The age-dependence of bacterial presence on oral epithelial surfaces in vivo

Epithelial cells obtained by gentle scraping with a brush tip from the gingival margin of d 11 or 51, adjacent labial mucosa and buccal mucosa of children, adolescents and adults were stained with acridine orange and examined under a fluorescence microscope. The amount of bacteria appearing on the epithelial cells was assessed and the form of the adhered bacteria was evaluated. An age-related descending trend (negative Pearson's r in all sites) could be seen in the number of colonized cells (> 50 bacteria present) in gingival, labial and buccal areas. Adolescents and adults had significantly fewer epithelial cells with colonization of bacteria in the labial and buccal areas compared with children under 6 years. Only cocciformed bacteria were seen associated with the epithelial cells. By studying bacterial adhesion according to methods outlined in the present study, it should be possible to more closely investigate the bacteria-host relationships as they appear in nature.

Suppressive effect of soluble factor(s) derived from Prevotella loescheii ATCC 15930 on proliferation of human lymphocytes

Soluble sonic extracts of Prevotella loescheii caused a dose-dependent inhibition of human peripheral blood lymphocyte proliferation by mitogen and of the proliferation of a leukemic cell line, BALL-1, when assessed by DNA synthesis (3H-thymidine incorporation). RNA (3H-uridine incorporation) and protein (3H-leucine incorporation) synthesis were similarly altered after exposure to the extract. There was no effect on cell viability as measured by either trypan blue exclusion or extracellular release of the cytoplasmic enzyme lactate dehydrogenase. Preliminary characterization indicates the suppressive factor(s) derived from P. loescheii to be a protein since it is heat-labile and trypsin-sensitive. The factor eluted in a peak on a high-pressure liquid chromatography gel filtration corresponding to a molecular weight of approximately 32,000. Since black-pigmented anaerobic rods have been implicated in the pathogenesis of periodontal disease, the data suggest that P. loescheii contributes to the disease process by suppressing lymphocyte function.

Porphyromonas gingivalis virulence in mice: induction of immunity to bacterial components

Selected cell envelope components of Porphyromonas gingivalis were tested in a BALB/c mouse model in an attempt to elucidate further the outer membrane components of this putative oral pathogen that might be considered as virulence factors in host tissue destruction. Lipopolysaccharide (LPS), outer membrane, and outer membrane vesicles of P. gingivalis W50, ATCC 53977, and ATCC 33277 were selected to examine an immunological approach for interference with progressing tissue destruction. Mice were actively immunized with heat-killed (H-K) or Formalin-killed (F-K) whole cells or with the outer membrane fraction, LPS, or outer membrane vesicles of the invasive strain P. gingivalis W50. The induction of invasive spreading lesions with tissue destruction and lethality were compared among different immunization groups in normal, dexamethasone-treated (dexamethasone alters neutrophil function at the inflammatory site), and galactosamine-sensitized (galactosamine sensitization increases endotoxin sensitivity) mice after challenge infection with the homologous strain (W50) and heterologous strains (ATCC 53977 and ATCC 33277). Enzyme-linked immunosorbent assay analyses revealed significantly elevated immunoglobulin G and M antibody responses after immunization with H-K or F-K cells or the outer membrane fraction compared with those of nonimmunized mice. The killed whole-cell vaccines provided significantly greater protection against challenge infection in normal mice (decreased lesion size and death) than did either the outer membrane fraction or LPS immunization. The lesion development observed in dexamethasone-pretreated mice was significantly enhanced compared with that of normal mice after challenge with P. gingivalis. Immunization with P. gingivalis W50 provided less protection against heterologous challenge infection with P. gingivalis ATCC 53977; however, some species-specific antigens were recognized and induced protective immunity. Only viable P. gingivalis induced a spreading lesion in normal, dexamethasone-treated, or galactosamine-sensitized mice; F-K or H-K bacteria did not induce lesions. The F-K and outer membrane vesicle immunization offered greater protection from lesion induction than did the H-K immunogen after challenge infection simultaneous with galactosamine sensitization. The H-K cell challenge with galactosamine sensitization produced 100% mortality without lesion induction, suggesting that LPS or LPS-associated outer membrane molecules were functioning like endotoxin. Likewise, P. gingivalis W50 LPS (1 micrograms per animal) administered intravenously produced 80% mortality in galactosamine-sensitized mice. In contrast to the effects of immunization on lesion development, immunization with H-K or F-K cells or LPS provided no protection against intravenous challenge with LPS; 100% of the mice died from acute endotoxin toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)

Peptostreptococcus micros in human periodontitis

Peptostreptococcus micros is a recognized pathogen in medical infections, and its association with progressive periodontitis was examined in this study. P. micros was isolated from paper-point subgingival samples on anaerobic enriched blood agar plates and identified on the basis of cellular and colonial morphology and selected biochemical tests. In a cross-sectional study involving 907 people with advanced adult periodontitis, 127 with early-onset periodontitis, and 12 with localized juvenile periodontitis, P. micros in these patient groups occurred with a prevalence of 58-63%. In culture-positive patients, P. micros averaged 12-15% of total viable counts. P. micros demonstrated similar occurrence and proportional recovery in all age groups. In a longitudinal study of 91 adult periodontitis patients on maintenance therapy, P. micros demonstrated a significantly higher prevalence in disease-active than in disease-inactive patients (47% vs 14%). Mechanical subgingival debridement and 0.12% chlorhexidine pocket irrigation was unable to eradicate subgingival P. micros from 18 of 22 adult periodontitis patients. In vitro antimicrobial susceptibility testing showed P. micros to be sensitive to therapeutic levels of penicillin, clindamycin and metronidazole. Our findings indicate that P. micros is a potential pathogen in adult periodontitis. The methods for its eradication from subgingival sites remain to be determined.

Using antimicrobial agents to manage periodontal diseases

Periodontal diseases are bacterial infections and anti-microbials have been shown to be useful in their treatment and prevention. State-of-the-art treatment of refractory forms of destructive periodontal disease presently includes adjunctive use of systemic antibiotics directed to eliminating or suppressing pathogenic subgingival bacteria. Also, local application of antimicrobials by subgingival deposition or their use as irrigants during periodontal therapy are soon likely to be major components of anti-infective management of periodontal diseases. A new approach to anti-infective periodontal therapy combines ultrasonic surgical debridement with antimicrobial irrigation.

Clinical, microbiological and immunological characteristics of subjects with "refractory" periodontal disease

The aim of the present study was to analyze the relationship between attachment loss and clinical, microbiological, and immunological parameters in a group of 21 human subjects exhibiting poor response to previous periodontal therapy. All had been treated with periodontal surgery, tetracycline, and subsequent maintenance recalls to periodontists who, upon detection of disease progression, referred the subjects to our clinic. In our clinic, each subject received oral hygiene instruction and a thorough subgingival scaling and root planing utilizing as many appointments as necessary. Clinical indices, including gingival index, bleeding on probing, suppuration, plaque index, pocket depth, and duplicate measurements of attachment level from an acrylic stent, were collected at monthly intervals. Probing measurements were performed using the Florida Probe. When significant attachment loss (0.8-1.2 mm) was detected in at least 1 site, a bacterial sample was taken from that site and from a comparably deep, but non-progressing, control site. Microbial samples were enumerated by darkfield microscopy, on selective and non-selective media, and by predominant cultivable technique. Blood samples were also collected to determine antibody levels against potential pathogens. There was no difference in the amount of plaque present in sites gaining or losing attachment, but losing sites exhibited more bleeding and suppuration. 20 of the 21 subjects were tested; of these, 17 exhibited elevated serum antibody against one or more of the following microorganisms: Actinobacillus actinomycetemcomitans, Bacteroides, gingivalis, and Eikenella corrodens. However, few, if any, of the "classical" pathogens were detected in the plaque samples obtained at the time progressive disease was diagnosed. The only exception was Streptococcus intermedius, which occurred in slightly higher numbers in active sites.

The effect of clindamycin on the microbiota associated with refractory periodontitis

The purpose of this investigation was to determine the effect of clindamycin hydrochloride, as an adjunct to scaling, on the microbiota associated with refractory periodontitis and to elucidate the probable causative bacteria associated with the disease. Microbial samples were collected from a subset of 9 patients with severe adult periodontitis who had not responded to conventional treatment modalities including the use of tetracycline and other antibiotics. Microbial samples were collected from a relatively deep site determined to be actively losing attachment and a comparably deep, but quiescent, control site in each patient prior to clindamycin therapy. Samples continued to be collected from the same sites for up to 1 year post-therapy. The microbial flora of each sample were enumerated by darkfield microscopy and predominant cultivable methods. Prior to clindamycin therapy, both active and control sites consisted on average of approximately 50% spirochetes and motile rods and 40% Gram-negative anaerobic rods. Bacteroides intermedius and Porphyromonas gingivalis (formerly B. gingivalis) were elevated in the active, as compared to control, sites and accounted for approximately 20% of the cultured microbiota in the former. Following treatment with clindamycin, the Gram-negative components of the microbiota were either eliminated or severely suppressed. At 1 year post-therapy, spirochetes and motile rods together accounted for about 15% of the microscopic flora. Total Gram-negative anaerobic rods accounted for approximately 20%, and B. intermedius and P. gingivalis combined accounted for less than 2% of the cultured microbiota from historical active sites.(ABSTRACT TRUNCATED AT 250 WORDS)

The formation of hydrogen sulfide and methyl mercaptan by oral bacteria

The capacity to form volatile sulfur compounds was tested in bacteria isolated from subgingival microbiotas and in a representative number of reference strains. A majority of the 75 tested oral bacterial species and 7 unnamed bacterial taxa formed significant amounts of hydrogen sulfide from L-cysteine. The most active bacteria were found in the genera Peptostreptococcus, Eubacterium, Selenomonas, Centipeda, Bacteroides and Fusobacterium. Methyl mercaptan from L-methionine was formed by some members of the genera Fusobacterium, Bacteroides, Porphyromonas and Eubacterium. When incubated in serum for 7 d, the most potent producers of hydrogen sulfide were Treponema denticola and the black-pigmented species, Bacteroides intermedius, Bacteroides loescheii, Porphyromonas endodontalis and Porphyromonas gingivalis. P. endodontalis and P. gingivalis also produced significant amounts of methyl mercaptan in serum. No other volatile sulfur compound was detected in serum or in the presence of L-cysteine and L-methionine. These findings significantly increase the list of oral bacteria known to produce volatile sulfur compounds.