Microbiological characterization in children with aggressive periodontitis

Subgingival 0.75% boric acid vs 1% povidone-iodine adjunctive to subgingival instrumentation in stage II and III periodontitis-A double-blind randomized clinical trial

PURPOSE

To compare the effects of subgingival irrigation with 0.75% boric acid (BA) and 1% povidone-iodine (PVP-I) as an adjunct to scaling and root planing (SRP) on clinical and microbiologic parameters in the management of patients with periodontitis after a 12-month follow-up.

METHODS

Sixty systemically healthy individuals diagnosed with periodontitis were included in this double-blind randomised clinical trial. The patients were randomly allocated to treatment groups: (1) SRP plus 0.75% BA and (2) SRP plus 1% PVP-I. Whole-mouth periodontals were clinically examined, and the counts of bacteria including Aggregatibacter actinomycetemcomitans (Aa), Fusobacterium nucleatum (Fn), Porphyromonas gingivalis (Pg), Treponema denticola (Td), Tannerella forsythia (Tf), Solobacterium moorei (Sm) and Streptococcus salivarius (Ss) were tested by real-time polymerase chain reaction (PCR).

RESULTS

All periodontal parameters and the counts of Aa, Fn, Pg, Td, Tf, Sm and Ss in both groups showed statistically significant reductions at T3, T6 and T12 compared to T0. Whole-mouth or moderate or severe PD and CAL improvements were significantly found in the 0.75% BA group compared to the 1% PVP-I group at T3, T6 and T12. The reduction in Aa or Fn and the reduction in Ss were significantly higher in the 0.75% BA group at T6 and T12 than in the 1% PVP-I group.

CONCLUSION

This study shows that subgingival irrigation with 0.75% BA may be an alternative to 1% PVP-I because it promotes greater PD reductions and CAL gain, particularly up to 12 months after treatment.

Anti-Porphyromonas gingivalis Antibody Levels in Patients With Stroke and Atrial Fibrillation: A Systematic Review and Meta-Analysis

OBJECTIVES

Atrial fibrillation (AF) and stroke are two highly related conditions, with periodontitis and periodontal pathogens, such as Porphyromonas gingivalis (Pg), appearing to be the most prominent common risk factors. In this study, we evaluated studies assessing Pg infection via serum/plasma anti-Pg antibodies in patients with AF and/or stroke.

MATERIAL AND METHODS

Online databases (PubMed, Scopus, Embase, and the Web of Science) were screened for studies showing the association between anti-Pg antibodies with stroke and/or AF. Relevant data were extracted, and a subsequent random-effects meta-analysis was performed to calculate the pooled odds ratio (OR) or standardized mean difference (SMD) and 95% confidence intervals (CIs) for Pg seropositivity or anti-Pg antibody levels in stroke patients compared to controls.

RESULTS

Sixteen studies were included in the systematic review. Based on the meta-analysis performed, there was no significant difference in Pg IgA and IgG levels between patients with stroke and controls (IgA: SMD 0.11, 95% CI -0.02 to 0.25, p = 0.1; IgG: SMD -0.12, 95% CI -1.24 to 0.99, p = 0.83). Similarly, no difference was observed between these groups in terms of Pg IgA and IgG seropositivity (IgA: OR 1.63, 95% CI 1.06-2.50, p = 0.026; IgG: OR 2.30, 95% CI 1.39-3.78, p < 0.001). Subsequently, we reviewed the results of six articles investigating serum or plasma IgG antibodies against Pg in patients with AF. Our results revealed a strict association between Pg infection and AF, with AF patients exhibiting either higher anti-Pg antibody levels or a higher prevalence of positive serum Pg antibodies.

CONCLUSIONS

Our study supports the clinical utility of Pg infection assessment in patients with periodontitis and those with AF and solicits more focused studies to corroborate its use in clinical settings to enhance overall outcomes, reduce the risk of complications like stroke, and help fine-tune personalized therapies.

A Rose by Any Other Name: The Long Intricate History of Localized Aggressive Periodontitis

This review addresses the recent World Workshop Consensus Conference (WWCC) decision to eliminate Localized Aggressive Periodontitis (LAgP) in young adults as a distinct form of periodontitis. A "Consensus" implies widespread, if not unanimous, agreement among participants. However, a significant number of attendees were opposed to the elimination of the LAgP classification. The substantial evidence supporting a unique diagnosis for LAgP includes the (1) incisor/molar pattern of disease, (2) young age of onset, (3) rapid progression of attachment and bone loss, (4) familial aggregation across multiple generations, and (5) defined consortium of microbiological risk factors including Aggregatibacter actinomycetemcomitans. Distinctive clinical signs and symptoms of LAgP are presented, and the microbial subgingival consortia that precede the onset of signs and symptoms are described. Using Bradford-Hill guidelines to assess causation, well-defined longitudinal studies support the unique microbial consortia, including A. actinomycetemcomitans as causative for LAgP. To determine the effects of the WWCC elimination of LAgP on research, we searched three publication databases and discovered a clear decrease in the number of new publications addressing LAgP since the new WWCC classification. The negative effects of the WWCC guidelines on both diagnosis and treatment success are presented. For example, due to the localized nature of LAgP, the practice of averaging mean pocket depth reduction or attachment gain across all teeth masks major changes in disease recovery at high-risk tooth sites. Reinstating LAgP as a distinct disease entity is proposed, and an alternative or additional way of measuring treatment success is recommended based on an assessment of the extension of the time to relapse of subgingival re-infection. The consequences of the translocation of oral microbes to distant anatomical sites due to ignoring relapse frequency are also discussed. Additional questions and future directions are also presented.

From Global to Nano: A Geographical Perspective of Aggregatibacter actinomycetemcomitans

The periodontal disease pathobiont Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) may exert a range of detrimental effects on periodontal diseases in general and, more specifically, with the initiation and progression of Localized Stage III Grade C periodontitis (molar-incisor pattern). In this review of the biogeography of this pathobiont, the full range of geographical scales for A. actinomycetemcomitans, from global origins and transmission to local geographical regions, to more locally exposed probands and families, to the individual host, down to the oral cavity, and finally, to spatial interactions with other commensals and pathobionts within the plaque biofilms at the micron/nanoscale, are reviewed. Using the newest technologies in genetics, imaging, in vitro cultures, and other research disciplines, investigators may be able to gain new insights to the role of this pathobiont in the unique initial destructive patterns of Localized Stage III Grade C periodontitis. These findings may incorporate the unique features of the microbiome that are influenced by variations in the geographic environment within the entire mouth. Additional insights into the geographic distribution of molar-incisor periodontal breakdown for Localized Stage III Grade C periodontitis may derive from the spatial interactions between A. actinomycetemcomitans and other pathobionts such as Porphyromonas gingivalis, Filifactor aclocis, and commensals such as Streptococcus gordonii. In addition, while the association of A. actinomycetemcomitans in systemic diseases is limited at the present time, future studies into possible periodontal disease-systemic disease links may also find A. actinomycetemcomitans and its geographical interactions with other microbiome members to provide important clues as to implications of pathobiological communications.

Grade C Molar-Incisor Pattern Periodontitis in Young Adults: What Have We Learned So Far?

Grade C molar-incisor pattern periodontitis (C-MIP) is a disease that affects specific teeth with an early onset and aggressive progression. It occurs in systemically healthy patients, mostly African descendants, at an early age, with familial involvement, minimal biofilm accumulation, and minor inflammation. Severe and rapidly progressive bone loss is observed around the first molars and incisors. This clinical condition has been usually diagnosed in children and young adults with permanent dentition under 30 years of age. However, this disease can also affect the primary dentition, which is not as frequently discussed in the literature. Radiographic records have shown that most patients diagnosed in the permanent dentition already presented disease signs in the primary dentition. A hyperresponsive immunological profile is observed in local (gingival crevicular fluid-GCF) and systemic environments. Siblings have also displayed a heightened inflammatory profile even without clinical signs of disease. A. actinomycetemcomitans has been classified as a key pathogen in C-MIP in both dentitions. Scaling and root planning associated with systemic antibiotics is the current gold standard to treat C-MIP, leading to GCF biomarker reduction, some systemic inflammatory response modulation and microbiome profile changes to a healthy-site profile. Further studies should focus on other possible disease-contributing risk factors.

Periodontal inflammatory and microbial profiles in healthy young African Americans and Caucasians

AIM

This study aimed to compare microbial and inflammatory profiles in periodontally/systemically healthy African American (AA) and Caucasian (C) individuals.

MATERIALS AND METHODS

Thirty-seven C and 46 AA aged from 5 to 25 years were evaluated regarding periodontal disease, caries, microbial subgingival profile via 16-s sequencing, as well as salivary and gingival crevicular fluid (GCF) inflammatory profile via multiplex assay.

RESULTS

Greater probing depth percentage was detected in AA (p = .0075), while a higher percentage of caries index (p = .0069) and decayed, missing, filled teeth (DMFT) index (p = .0089) was observed in C, after adjusting for number of teeth, sex and age. Salivary levels of IL-6, IL-8 and TNFα were higher for C, whereas GCF levels of eotaxin, IL-12p40, IL-12p70, IL-2 and MIP-1α were higher in AA (p < .05). Different microbial profiles were observed between the races (p = .02). AA presented higher abundance of periodontopathogens (such as Tanerella forsythia, Treponema denticola, Filifactor alocis, among others), and C presented more caries-associated bacteria (such as Streptococcus mutans and Prevotella species). Bacillaceae and Lactobacillus species were associated with higher DMFT index, whereas Fusobacterium and Tanerella species with periodontal disease parameters.

CONCLUSIONS

A different inflammatory and bacterial profile was observed between healthy AA and C, which may predispose these races to higher susceptibility to specific oral diseases.

Evaluation of microbiome in primary and permanent dentition in grade C periodontitis in young individuals

BACKGROUND

The aim of the present study was to evaluate the subgingival microbiome in patients with grade C molar-incisor pattern periodontitis (C-MIP) affecting the primary or permanent dentitions.

METHODS

DNA was isolated from subgingival biofilm samples from diseased and healthy sites from 45 C-MIP patients and subjected to phylogenetic microarray analysis. C-MIP sites were compared between children affected in the primary to those affected in the permanent dentitions. Within-subject differences between C-MIP-affected sites and dentition-matched healthy sites were also evaluated.

RESULTS

C-MIP sites of subjects affected in the primary dentition showed partially overlapping but distinct microbial communities from C-MIP permanent dentition sites (p < 0.05). Differences were due to increased levels in primary C-MIP sites of certain species of the genera Capnocytophaga and Leptotrichia, while C-MIP permanent dentition sites showed higher prevalence of Filifactor alocis. Aggregatibacter actinomycetemcomitans (Aa) was among species seen in high prevalence and levels in both primary and permanent C-MIP sites. Moreover, both permanent and primary C-MIP sites showed distinct microbial communities when compared to dentition-matched healthy sites in the same subject (p < 0.01).

CONCLUSIONS

Primary and permanent teeth with C-MIP showed a dysbiotic microbiome, with children affected in the primary dentition showing a distinct profile from those affected in the permanent dentition. However, Aa was enriched in both primary and permanent diseased sites, confirming that this microorganism is implicated in C-MIP in both dentitions.

Effect of 15 days -6° head-down bed rest on microbial communities of supragingival plaque in young men

Introduction

The microgravity environment astronauts experience during spaceflight can lead to an increased risk of oral diseases and possible changes in oral microecology. In this study, we aimed to assess changes in the microbial community of supragingival plaques to explore the effects of spaceflight microgravity environment on oral microecology.

Methods

Sixteen healthy male volunteers were recruited, and supragingival plaque samples were collected under -6° head-down bed rest (HDBR) at five-time points: day 1 before HDBR; days 5, 10, and 15 of HDBR; and day 6 of recovery. Bacterial genomic DNA was sequenced using gene sequencing technology with 16S ribosomal ribonucleic acid V3-V4 hypervariable region amplification and the obtained data were analyzed bioinformatically.

Results

Alpha diversity analysis showed a significant increase in species richness in supragingival plaque samples on day 15 of HDBR compared with that at pre-HDBR. Beta diversity analysis revealed that the community composition differed among the groups. Species distribution showed that, compared with those at pre-HDBR, the relative abundances of Corynebacterium and Aggregatibacter increased significantly during HDBR, while those of Veillonella, Streptococcus, and Lautropia decreased significantly. Moreover, compared with those at pre-HDBR, the relative abundance of Leptotrichia increased significantly on day 6 of recovery, whereas the relative abundances of Porphyromonas and Streptococcus decreased significantly. Network analysis showed that the interaction relationship between the dominant genera became simpler during HDBR, and the positive and negative correlations between them showed dynamic changes. Phylogenetic investigation of communities by reconstruction of unobserved states analysis showed that the amino acid metabolism function of plaque microorganisms was more enriched during HDBR.

Discussion

In summary, in a 15-day simulated microgravity environment, the diversity, species distribution, interaction relationship, and metabolic function of the supragingival plaque microbial community changed, which suggests that microgravity may affect the oral microecosystem by changing the balance of supragingival plaque microbial communities and further leading to the occurrence and development of oral diseases.

Comparison of the main pathogenic microorganisms of various common oral diseases in children and adults

The microorganisms in the human body gradually change and maintain a dynamic balance with the development of physiology and pathology. Oral microbiota is one of the most important microbiota in human body. It is not only closely related to the occurrence and development of oral diseases, but also plays an important role in the overall health. In childhood, the population of oral microorganisms is relatively small, but with the growth of age and tooth development, the species and quantity of oral microorganisms are gradually increasing. Different oral diseases also have their corresponding main microorganisms, and these dominant microorganisms change at different stages of the disease. In this review, we summarized and compared the main pathogenic microorganisms of several common oral diseases in children and adults. In addition, the possible association and difference between adults and children of the main pathogenic microorganisms in different stages of the same or different diseases are also discussed in order to provide research data for the development and diagnosis of common oral diseases in children and adults.

The homeostasis and therapeutic applications of innate and adaptive immune cells in periodontitis

OBJECTIVES

Periodontitis (PD) is one of the most common dental disorders. This chronic oral inflammation is caused by complicated interrelations between bacterial infections, dysregulated immune reactions, and environmental risk factors. A dysregulated immune response can lead to inflammatory bone resorption by allowing the recruitment of pro-inflammatory immune cells to the periodontal tissues.

SUBJECTS

The recruitment of innate and adaptive immune cells in PD initiates the acute and following chronic inflammatory processes. The inflamed tissues, on the other hand, can be restored if the anti-inflammatory lineages are predominantly established in the periodontal tissues. Therefore, we aimed to review the published literature to provide an overview of the existing knowledge about the role of immune cells in PD, as well as their possible therapeutic applications.

RESULTS

Experimental studies showed that drugs/systems that negatively regulate inflammatory cells in the body, as well as interventions aimed at increasing the number of anti-inflammatory cells such as Tregs and Bregs, can both help in the healing process of PD.

CONCLUSION

Targeting immune cells or their positive/negative manipulations has been demonstrated to be an effective therapeutic method. However, to use this sort of immunotherapy in humans, further pre-clinical investigations, as well as randomized clinical trials, are required.

Biomarkers for diagnosis of stage III, grade C with molar incisor pattern periodontitis in children and young adults: a systematic review and meta-analysis

AIM

To explore the existing salivary, gingival crevicular fluid (GCF), blood, and serum biomarkers associated with grade C molar-incisor pattern (C/MIP) periodontitis in systemically healthy children and young adults.

MATERIALS AND METHODS

Cross-sectional, case-control, and cohort studies on stage III grade C periodontitis or former equivalent diagnosis with analysis of molecular biomarkers in saliva, GCF, blood, or serum were retrieved from six databases and screened based on the eligibility criteria. The risk of bias in included studies was evaluated. Meta-analysis was planned for biomarkers assessed using the same detection methods and sample type in at least two papers.

RESULTS

Out of 5621 studies identified at initial screening, 28 papers were included in the qualitative analysis of which 2 were eligible for meta-analysis for IgG in serum samples. Eighty-seven biomarkers were assessed with the majority being higher in cases than in controls. Only the meta-analysis of total serum IgG with low heterogeneity value revealed a significant increase in its levels in C/MIPs compared to controls (standardised mean difference: 1.08; 95% CI: 0.76, 1.40).

CONCLUSION

There is a paucity of data on biomarkers associated with molar-incisor pattern periodontitis. Although serum IgG levels are raised, other more specific biomarkers in saliva, GCF, and blood/serum may be promising but require further investigation.

Characterization of the oral microbiome and gut microbiome of dental caries and extrinsic black stain in preschool children

Introduction

A lower prevalence of dental caries (hereafter termed “caries”) has been observed in children with dental extrinsic black stain (EBS).

Methods

We investigated the epidemiologic characterization of EBS and explored the possible role of the oral microbiome (OM) and gut microbiome (GM) in EBS formation and caries prevention. In an epidemiologic survey, 2,675 children aged 3–6 years were included. Thirty-eight of these children (7 children had both caries and EBS, 10 had EBS only, 11 had caries only, and 10 were healthy children) were recruited for 16S rRNA sequencing and collection of samples of supragingival plaque and feces. Collected plaque samples were divided into four groups: BCP (EBS+, caries+), BP (EBS+, caries−), CP (EBS−, caries+), and P (EBS−, caries−). Fecal samples were also divided into four groups: BCF (EBS+, caries+), BF (EBS+, caries−), CF (EBS−, caries+), and F (EBS−, caries−).

Results

EBS was observed in 12.10% of this population. Children with EBS had a significantly reduced prevalence of caries and a lower mean value of decayed–missing–filled teeth (dmft; p &lt; 0.01). According to analyses of dental plaque, the P group had the most complex microbiome. The BCP group exhibited greater operational taxonomic unit (OTU) richness but a reduced evenness compared with the BP group, and the CP group showed greater OTU richness than the BP group. At the genus level, higher abundance of Actinomyces and Cardiobacterium species was observed in the BCP group. Higher abundance of Lautropia and Pesudopropionibacteriumin species was observed in the BP group compared with P and CP groups, respectively (p &lt; 0.05). Veillonella species were significantly more common in P and CP groups than in BP groups, whereas Porphyromonas and Fusobacterium species were more common in the CP group (p &lt; 0.05). With regard to the GM, the CF group exhibited greater OTU diversity than the BF group. The GM in the BCF group exhibited the most complex relationships across all fecal groups. GM groups could be distinguished by various unique biomarkers, such as Escherichia and Shigella species in the BCF group, Agathobacter and Ruminococcus species in the CF group, Lactobacillus species in the BF group, and Roseburia species in the F group. Our results suggest that EBS is a possible protective factor against early-childhood caries. Dental plaque and the GM may be relevant to EBS in primary dentition.

Classification of salivary bacteriome in asymptomatic COVID-19 cases based on long-read nanopore sequencing

The coronavirus (COVID-19) global pandemic has impacted the health of almost everyone, including changes in their salivary microbiota. Since 2019, there has been an increase in the number of new COVID-19 cases in Thailand. Therefore, COVID-19 active case finding is important for early detection and epidemic control. Moreover, the dynamic changes of salivary bacteriome in asymptomatic COVID-19 cases are largely unknown. This research aimed to investigate and compare the salivary bacteriome and the co-infectious bacterial pathogens in the asymptomatic COVID-19 positive group to the negative group, based on novel nanopore sequencing. This cohort was a cross-sectional study including saliva samples collected from 82 asymptomatic participants (39 COVID-19 positive and 43 COVID-19 negative cases). All samples were sequenced for the full-length bacterial 16S rDNA. The alpha and beta diversity analyses were not significantly different between groups. The three major species in salivary bacteriome including Veillonella parvula, Streptococcus mitis, and Prevotella melaninogenica were observed in both groups. Interestingly, Lautropia mirabilis was a significantly enriched species in the saliva of the asymptomatic COVID-19-positive cases based on linear discriminant analysis effect size (LEfSe) analysis. The results suggested that L. mirabilis was a co-infectious agent in the asymptomatic COVID-19 group. However, the potential role of L. mirabilis should be validated in further experimental studies.

Can metagenomics unravel the impact of oral bacteriome in human diseases?

Oral microbial ecosystems are vital in maintaining the health of the oral cavity and the entire body. Oral microbiota is associated with the progression of oral diseases such as dental caries, periodontal diseases, head and neck cancer, and several systemic diseases such as cardiovascular disease, rheumatoid arthritis, adverse pregnancy outcomes, diabetes, lung infection, colorectal cancer, and pancreatic cancer. Buccal mucosa, tongue dorsum, hard palate, saliva, palatine tonsils, throat, keratinized gingiva, supra-gingival plaque, subgingival plaque, dentures, and lips are microbial habitats of the oral cavity. Porphyromonas gingivalis may have a role in the development of periodontal diseases, oral cancer, diabetes, and atherosclerotic disease. Fusobacterium nucleatum showed a higher abundance in periodontal diseases, oral and colon cancer, adverse pregnancy outcomes, diabetes, and rheumatoid arthritis. The higher abundance of Prevotella intermedia is typical in periodontal diseases, rheumatoid arthritis, and adverse pregnancy outcome. S. salivarius displayed higher abundance in both dental caries and OSCC. Oral bacteria may influence systemic diseases through inflammation by releasing pro inflammatory cytokines. Identification of oral bacteria using culture-dependent approaches and next-generation sequencing-based metagenomic approaches is believed to significantly identify the therapeutic targets and non-invasive diagnostic indicators in different human diseases. Oral bacteria in saliva could be exploited as a non-invasive diagnostic indicator for the early detection of oral and systemic disorders. Other therapeutic approaches such as the use of probiotics, green tea polyphenol, cold atmospheric plasma (CAP) therapy, antimicrobial photodynamic therapy, and antimicrobial peptides are used to inhibit the growth of biofilm formation by oral bacteria.

Immunotherapy with regulatory T and B cells in periodontitis

Periodontitis (PD), also known as gum disease, is a condition causing inflammatory bone resorption and tooth loss. Regulatory T cells (Tregs) and regulatory B cells (Bregs) are vital in controlling the immune response and hence play a role in infections and peripheral tolerance adjustment. These cells have immunosuppressive and tissue-repairing capabilities that are important for periodontal health; however, in inflammatory circumstances, Tregs may become unstable and dysfunctional, accelerating tissue deterioration. In recent years, Regulatory cell-mediated immunotherapy has been shown to be effective in many inflammatory diseases. Considering the roles of Tregs and Bregs in shaping immune responses, this study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the role of regulatory T and B cells, as well as their therapeutic applications in PD.

A comparative study on periodontitis and periodontitis-associated bacteria in Somali and non-Somali children and adolescents living in Trollhättan, Sweden

The reported prevalence of periodontitis in children and adolescents varies considerably between populations globally. This cross-sectional study compares clinical and microbiological findings on 83 Somali immigrants and 96 non-Somali children aged 10-17 years old living in Trollhättan, Sweden. The clinical examination included registration of bleeding on probing, plaque, and calculus on incisors and first molars. The distance between cemento-enamel junction and bone level was measured on bitewing radiographs. Pooled microbiological samples (1 μL) were taken from the mesial surface of 16, 11, 31, 36, and analyzed by culture and real-time polymerase chain reaction for seven periodontal associated bacterial species. The Somali participants had poorer oral hygiene and more bleeding, plaque, and calculus. Ten of the Somali but none of the non-Somali participants showed periodontal breakdown (radiographical bone loss > 3 mm), corresponding to a prevalence of 12% (95% CI: 5.9, 21.0%). The presence of A. actinomycetemcomitans was almost exclusively associated with Somali participants. Further, the JP2 clone was found in five Somalis (including two periodontitis cases) confirming the association of this clone with African populations. The Somali group showed significantly higher frequencies and numbers of Porphyromonas gingivalis and Treponema denticola, implying a mature and adult type of subgingival microbiota.

Polysaccharide-Based Micro- and Nanosized Drug Delivery Systems for Potential Application in the Pediatric Dentistry

The intensive development of micro- and nanotechnologies in recent years has offered a wide horizon of new possibilities for drug delivery in dentistry. The use of polymeric drug carriers turned out to be a very successful technique for formulating micro- and nanoparticles with controlled or targeted drug release in the oral cavity. Such innovative strategies have the potential to provide an improved therapeutic approach to prevention and treatment of various oral diseases not only for adults, but also in the pediatric dental practice. Due to their biocompatibility, biotolerance and biodegradability, naturally occurring polysaccharides like chitosan, alginate, pectin, dextran, starch, etc., are among the most preferred materials for preparation of micro- and nano-devices for drug delivery, offering simple particle-forming characteristics and easily tunable properties of the formulated structures. Their low immunogenicity and low toxicity provide an advantage over most synthetic polymers for the development of pediatric formulations. This review is focused on micro- and nanoscale polysaccharide biomaterials as dental drug carriers, with an emphasis on their potential application in pediatric dentistry.

Microbial characteristics across different tongue coating types in a healthy population

Background The physical appearance of tongue coatings is vital for traditional Chinese medicine (TCM) to diagnose health and disease status. The microbiota of different tongue coatings could also influence coating formation and be further associated with specific diseases. Previous studies have focused on bacteria from different tongue coatings in the context of specific diseases, but the normal variations in healthy individuals remain unknown.Aim: We examined the tongue microbiota by metagenomics in 94 healthy individuals classified into eight different tongue types.Results: The overall composition of the tongue coating microbiome is not drastically different among different coating types, similar to the findings of previous studies in healthy populations. Further analysis revealed microbiota characteristics of each coating type, and many of the key bacteria are reported to be implicated in diseases. Moreover, further inclusion of diabetic patients revealed disease-specific enrichment of Capnocytophaga, even though the same tongue coatings were studied.Conclusions: This work revealed the characteristic compositions of distinctive tongue coatings in a healthy population, which serves as a basis for understanding the tongue coating formation mechanism and provides a valuable reference to further investigate disease-specific tongue coating bacterial markers.

Comparative Microbial Profiles of Caries and Black Extrinsic Tooth Stain in Primary Dentition

Extrinsic black tooth stain (BS) is a common oral disease associated with lower caries experience in preschool children, although the microbiotic features contributing to the low risk of caries in this group remain elusive. In this study, we aimed at identifying the dominant bacteria in dental plaque to indicate the incidence of caries in the primary dentition. Subjects were divided into 3 groups based on the clinical examination: group CF, children without pigment who had no caries lesions or restorations (n = 18); group CS, children who were diagnosed with severe early childhood caries (n = 17); and group BS, children with pigment (black extrinsic stain) without caries or restorations (n = 15). The total microbial genomic DNA was extracted and subjected to bacterial 16S ribosomal RNA gene sequencing using an Illumina HiSeq platform. The differential dominant bacteria were determined using Wilcoxon rank-sum testing and linear discriminant analysis effect size (LEfSe). Co-occurrence network analysis was performed using sparse correlations for compositional data, calculation and functional features were predicted using PICRUSt. Interestingly, our results showed that the relative abundance of Pseudopropionibacterium, Actinomyces, Rothia, and Cardiobacterium was from high to low and that of Porphyromonas was low to high in the BS, CF, and CS groups, consistent with the clinical incidence of caries in the 3 groups. Moreover, an increased level of Selenomonas_3, Fusobacterium, and Leptotrichia was associated with high caries prevalence. We found that the interactions among genera in the BS and CS plaque communities are less complex than those in the CF communities at the taxon level. Functional features, including cofactor and vitamin metabolism, glycan biosynthesis and metabolism, and translation, significantly increased in caries plaque samples. These bacterial competition- and commensalism-induced changes in microbiota would result in a change of their symbiotic function, finally affecting the balance of oral microflora.

Anna Karenina and the subgingival microbiome associated with periodontitis

BACKGROUND

Although localized aggressive periodontitis (LAP), generalized aggressive periodontitis (GAP), and chronic periodontitis (CP) are microbially driven diseases, our inability to separate disease-specific associations from those common to all three forms of periodontitis has hampered biomarker discovery. Therefore, we aimed to map the genomic content of, and the biological pathways encoded by, the microbiomes associated with these clinical phenotypes. We also estimated the extent to which these biomes are governed by the Anna Karenina principle (AKP), which states that eubiotic communities are similar between individuals while disease-associated communities are highly individualized.

METHODS

We collected subgingival plaque from 25 periodontally healthy individuals and diseased sites of 59 subjects with stage 3 periodontitis and used shotgun metagenomics to characterize the aggregate of bacterial genes.

RESULTS

Beta-dispersion metrics demonstrated that AKP was most evident in CP, followed by GAP and LAP. We discovered broad dysbiotic signatures spanning the three phenotypes, with over-representation of pathways that facilitate life in an oxygen-poor, protein- and heme-rich, pro-oxidant environment and enhance capacity for attachment and biofilm formation. Phenotype-specific indicators were more readily evident in LAP microbiome than GAP or CP. Genes that enable acetate-scavenging lifestyle, utilization of alternative nutritional sources, oxidative and nitrosative stress responses, and siderophore production were unique to LAP. An attenuation of virulence-related functionalities and stress response from LAP to GAP to CP was apparent. We also discovered that clinical phenotypes of disease resolved variance in the microbiome with greater clarity than the newly established grading system. Importantly, we observed that one third of the metagenome of LAP is unique to this phenotype while GAP shares significant functional and taxonomic features with both LAP and CP, suggesting either attenuation of an aggressive disease or an early-onset chronic disease.

CONCLUSION

Within the limitations of a small sample size and a cross-sectional study design, the distinctive features of the microbiomes associated with LAP and CP strongly persuade us that these are discrete disease entities, while calling into question whether GAP is a separate disease, or an artifact induced by cross-sectional study designs. Further studies on phenotype-specific microbial genes are warranted to explicate their role in disease etiology. Video Abstract.

Effects of altitude on human oral microbes

Human oral microbes play a vital role maintaining host metabolic homeostasis. The Qinghai-Tibet Plateau is mainly characterized by a high altitude, dry, cold, and hypoxic environment. The oral microbiota is subject to selective pressure from the plateau environment, which affects oral health. Only a few studies have focused on the characteristics of oral microbiota in high-altitude humans. We collected saliva samples from 167 Tibetans at four altitudes (2800 to 4500 m) in Tibet to explore the relationship between the high altitude environment and oral microbiota. We conducted a two (high- and ultra-high-altitude) group analysis based on altitude, and adopted the 16S rRNA strategy for high-throughput sequencing. The results show that the alpha diversity of the oral microbiota decreased with altitude, whereas beta diversity increased with altitude. A LEfSe analysis revealed that the oral microbial biomarker of the high-altitude group (< 3650 m) was Streptococcus, and the biomarker of the ultra-high-altitude group (> 4000 m) was Prevotella. The relative abundance of Prevotella increased with altitude, whereas the relative abundance of Streptococcus decreased with altitude. A network analysis showed that the microbial network structure was more compact and complex, and the interaction between the bacterial genera was more intense in the high altitude group. Gene function prediction results showed that the amino acid and vitamin metabolic pathways were upregulated in the ultra-high-altitude group. These result show that altitude is an important factor affecting the diversity and community structure of the human oral microbiota.

Dysbiosis in the oral microbiomes of anti-CCP positive individuals at risk of developing rheumatoid arthritis

OBJECTIVES

An increased prevalence of periodontitis and perturbation of the oral microbiome has been identified in patients with rheumatoid arthritis (RA). The periodontal pathogen Porphyromonas gingivalis may cause local citrullination of proteins, potentially triggering anti-citrullinated protein antibody production. However, it is not known if oral dysbiosis precedes the onset of clinical arthritis. This study comprehensively characterised the oral microbiome in anti-cyclic citrullinated peptide (anti-CCP) positive at-risk individuals without clinical synovitis (CCP+at risk).

METHODS

Subgingival plaque was collected from periodontally healthy and diseased sites in 48 CCP+at risk, 26 early RA and 32 asymptomatic healthy control (HC) individuals. DNA libraries were sequenced on the Illumina HiSeq 3000 platform. Taxonomic profile and functional capability of the subgingival microbiome were compared between groups.

RESULTS

At periodontally healthy sites, CCP+at risk individuals had significantly lower microbial richness compared with HC and early RA groups (p=0.004 and 0.021). Microbial community alterations were found at phylum, genus and species levels. A large proportion of the community differed significantly in membership (523 species; 35.6%) and structure (575 species; 39.1%) comparing CCP+at risk and HC groups. Certain core species, including P. gingivalis, had higher relative abundance in the CCP+at risk group. Seventeen clusters of orthologous gene functional units were significantly over-represented in the CCP+at risk group compared with HC (adjusted p value <0.05).

CONCLUSION

Anti-CCP positive at-risk individuals have dysbiotic subgingival microbiomes and increased abundance of P. gingivalis compared with controls. This supports the hypothesis that the oral microbiome and specifically P. gingivalis are important in RA initiation.

Parents with periodontitis impact the subgingival colonization of their offspring

Early acquisition of a pathogenic microbiota and the presence of dysbiosis in childhood is associated with susceptibility to and the familial aggregation of periodontitis. This longitudinal interventional case-control study aimed to evaluate the impact of parental periodontal disease on the acquisition of oral pathogens in their offspring. Subgingival plaque and clinical periodontal metrics were collected from 18 parents with a history of generalized aggressive periodontitis and their children (6-12 years of age), and 18 periodontally healthy parents and their parents at baseline and following professional oral prophylaxis. 16S rRNA amplicon sequencing revealed that parents were the primary source of the child's microbiome, affecting their microbial acquisition and diversity. Children of periodontitis parents were preferentially colonized by Filifactor alocis, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Streptococcus parasanguinis, Fusobacterium nucleatum and several species belonging to the genus Selenomonas even in the absence of periodontitis, and these species controlled inter-bacterial interactions. These pathogens also emerged as robust discriminators of the microbial signatures of children of parents with periodontitis. Plaque control did not modulate this pathogenic pattern, attesting to the microbiome's resistance to change once it has been established. This study highlights the critical role played by parental disease in microbial colonization patterns in their offspring and the early acquisition of periodontitis-related species and underscores the need for greater surveillance and preventive measures in families of periodontitis patients.

Small, but smelly: the importance of Solobacterium moorei in halitosis and other human infections

Solobacterium moorei (S. moorei) has been described as Gram-positive, non spore forming, obligate anaerobic bacillus from human feces. The traditional culture and identification of these strains is very difficult (as the strains are often not cultivable or they grow only relatively slowly, in addition to producing only a very few positive biochemical reactions in commercially available identification kits); thus, reliable identification may only be carried out using methods, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and DNA sequencing. Regarding its pathogenic role, the relevance of S. moorei in halitosis (oral malodor) has a good standing, as it has been suggested by multiple studies, while the isolation of these bacteria from invasive infections is very rare; there are only a few reports available in the literature, regarding infections outside the oral cavity. Based on these reports, affected patients are predominantly characterized compromised immunity and are frequently associated with a dental focus of infection. The aim of our present review is to summarize the currently available knowledge on the pathogenic role of S. moorei in halitosis and other infections and to emphasize the relevance of this neglected anaerobic pathogen.

Grade C molar-incisor pattern periodontitis subgingival microbial profile before and after treatment

Aim: This study evaluated the influence of periodontal therapy on the microbiological profile of individuals with Grade C Molar-Incisor Pattern Periodontitis (C/MIP).

Methods: Fifty-three African-American participants between the ages of 5–25, diagnosed with C/MIP were included. Patients underwent full mouth mechanical debridement with systemic antibiotics (metronidazole 250 mg + amoxicillin 500 mg, tid, 7 days). Subgingival samples were collected from a diseased and a healthy site from each individual prior to treatment and at 3, 6, 12, 18 and 24 months after therapy from the same sites. Samples were subjected to a 16S rRNA gene based-microarray.

Results: Treatment was effective in reducing the main clinical parameters of disease. Aggregatibacter actinomycetemcomitans (A.a.) was the strongest species associated with diseased sites. Other species associated with diseased sites were Treponema lecithinolyticum and Tannerella forsythia. Species associated with healthy sites were Rothia dentocariosa/mucilaginosa, Eubacterium yurii, Parvimonas micra, Veillonella spp., Selenomonas spp., and Streptococcus spp. Overall, treatment was effective in strongly reducing A.a. and other key pathogens, as well as increasing health-associated species. These changes were maintained for at least 6 months.

Conclusions:Treatment reduced putative disease-associated species, particularly A.a., and shifted the microbial profile to more closely resemble a healthy-site profile. (Clinicaltrials.gov registration #NCT01330719).

Differences in the periodontal microbiome of successfully treated and persistent aggressive periodontitis

AIMS

The primary aim of this investigation was to analyse the periodontal microbiome in patients with aggressive periodontitis (AgP) following treatment.

METHODS

Sixty-six AgP patients were recalled on average 7 years after completion of active periodontal treatment and had subgingival plaque samples collected and processed for 16S rRNA gene sequencing analyses.

RESULTS

Of 66 participants, 52 showed persistent periodontal disease, while 13 participants were considered as "successfully treated AgP" (no probing pocket depths >4 mm) and 1 was fully edentulous. Genera associated with persistent generalized disease included Actinomyces, Alloprevotella, Capnocytophaga, Filifactor, Fretibacterium, Fusobacterium, Leptotrichia, Mogibacterium, Saccharibacteria [G-1], Selenomonas and Treponema. "Successfully treated" patients harboured higher proportions of Haemophilus, Rothia, and Lautropia and of Corynebacterium, Streptococcus and Peptidiphaga genera. Overall, patients with persistent generalized AgP (GAgP) revealed higher alpha diversity compared to persistent localized AgP (LAgP) and stable patients (p < .001). Beta diversity analyses revealed significant differences only between stable and persistent GAgP groups (p = .004).

CONCLUSION

Patients with persistent AgP showed a more dysbiotic subgingival biofilm than those who have been successfully treated. It remains to be established whether such differences were predisposing to disease activity or were a result of a dysbiotic change associated with disease recurrence in the presence of sub-standard supportive periodontal therapy or other patient-related factors.

Triclosan toothpaste as an adjunct therapy to plaque control in children from periodontitis families: a crossover clinical trial

OBJECTIVES

Studies have demonstrated that children from aggressive periodontitis (AgP) parents presented precocious alterations in their periodontal condition, and the use of chemical agents in association to plaque control could be useful to control these alterations. This study aimed to evaluate the effect of Triclosan toothpaste to modulate the clinical and subgingival condition in children from AgP parents.

METHODS

Fifteen children from AgP parents and 15 from periodontally healthy parents were included in this crossover placebo study. Children were randomly allocated into triclosan or placebo therapy, using selected toothpaste for 45 days. After 15 days of wash-out, groups were crossed, changing the used toothpaste. Clinical examination and saliva, crevicular gingival fluid (GCF), and subgingival biofilm collection were performed at baseline and 45 days of each phase. GCF cytokines' levels were analyzed by Luminex/MAGpix platform and subgingival and salivary periodontal pathogens' levels by qPCR.

RESULTS

At baseline, AgP group presented higher plaque index (PI), gingival index (GI), and bleeding on probing (BoP), higher Aggregatibacter actinomycetemcomitans (Aa) abundance in saliva and subgingival biofilm, and lower levels of INF-ɣ, IL-4, and IL-17 in GCF. Placebo therapy only reduced PI in both groups. Triclosan toothpaste reduced PI and GI in both groups. Triclosan promoted reduction of BoP and probing depth (PD), Aa salivary, and IL-1β levels in AgP group. In health group, triclosan reduced INF-ɣ and IL-4 concentration.

CONCLUSION

Triclosan toothpaste demonstrated to be more effective than placebo toothpaste to control the periodontal condition in children from AgP parents, by reducing the BoP, PD, salivary Aa, and IL-1β.

CLINICAL RELEVANCE

Triclosan toothpaste can improve oral conditions in higher-risk population for AgP.

TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov with the identifier NCT03642353.

Unique etiologic, demographic, and pathologic characteristics of localized aggressive periodontitis support classification as a distinct subcategory of periodontitis

BACKGROUND

Localized aggressive periodontitis (LAgP) occurs in 2% of African-American adolescents but only 0.15% of white adolescents. First molars and incisors are affected by rapid onset and progression.

METHODS

This nonsystematic critical review evaluated published data for LAgP and chronic periodontitis (CP), focusing on potential differences in epidemiology, microbiology, immunology, genetics, and response to therapy.

RESULTS

LAgP differs from CP by localization to incisors and first molars, early onset and rapid progression in adolescents and young adults, and a 10-fold higher prevalence in populations of African or Middle Eastern origin, often with strong familial aggregation. The bacterium Aggregatibacter actinomycetemcomitans and hyperresponsive neutrophils are frequently observed. Antibiotic and nonsurgical therapies are highly effective.

CONCLUSIONS

LAgP differs in many ways from the far more common CP that affects older adults. The substantial evidence of dissimilarities summarized in this review strongly supports the classification of LAgP as a distinct form of periodontitis.

PRACTICAL IMPLICATIONS

Classifying LAgP as a distinct subcategory of periodontitis will encourage future research and does not conflict with the newly proposed "staging and grading" system. The silent onset and rapid progression of LAgP make early diagnosis and frequent follow-up with patients essential for effective treatment.

Microbial differences between dental plaque and historic dental calculus are related to oral biofilm maturation stage

BACKGROUND

Dental calculus, calcified oral plaque biofilm, contains microbial and host biomolecules that can be used to study historic microbiome communities and host responses. Dental calculus does not typically accumulate as much today as historically, and clinical oral microbiome research studies focus primarily on living dental plaque biofilm. However, plaque and calculus reflect different conditions of the oral biofilm, and the differences in microbial characteristics between the sample types have not yet been systematically explored. Here, we compare the microbial profiles of modern dental plaque, modern dental calculus, and historic dental calculus to establish expected differences between these substrates.

RESULTS

Metagenomic data was generated from modern and historic calculus samples, and dental plaque metagenomic data was downloaded from the Human Microbiome Project. Microbial composition and functional profile were assessed. Metaproteomic data was obtained from a subset of historic calculus samples. Comparisons between microbial, protein, and metabolomic profiles revealed distinct taxonomic and metabolic functional profiles between plaque, modern calculus, and historic calculus, but not between calculus collected from healthy teeth and periodontal disease-affected teeth. Species co-exclusion was related to biofilm environment. Proteomic profiling revealed that healthy tooth samples contain low levels of bacterial virulence proteins and a robust innate immune response. Correlations between proteomic and metabolomic profiles suggest co-preservation of bacterial lipid membranes and membrane-associated proteins.

CONCLUSIONS

Overall, we find that there are systematic microbial differences between plaque and calculus related to biofilm physiology, and recognizing these differences is important for accurate data interpretation in studies comparing dental plaque and calculus.

Aggregatibacter actinomycetemcomitans (Aa) Under the Radar: Myths and Misunderstandings of Aa and Its Role in Aggressive Periodontitis

Aggregatibacter actinomycetemcomitans (Aa) is a low-abundance Gram-negative oral pathobiont that is highly associated with a silent but aggressive orphan disease that results in periodontitis and tooth loss in adolescents of African heritage. For the most part Aa conducts its business by utilizing strategies allowing it to conceal itself below the radar of the host mucosal immune defense system. A great deal of misinformation has been conveyed with respect to Aa biology in health and disease. The purpose of this review is to present misconceptions about Aa and the strategies that it uses to colonize, survive, and evade the host. In the process Aa manages to undermine host mucosal defenses and contribute to disease initiation. This review will present clinical observational, molecular, and interventional studies that illustrate genetic, phenotypic, and biogeographical tactics that have been recently clarified and demonstrate how Aa survives and suppresses host mucosal defenses to take part in disease pathogenesis. At one point in time Aa was considered to be the causative agent of Localized Aggressive Periodontitis. Currently, it is most accurate to look at Aa as a community activist and necessary partner of a pathogenic consortium that suppresses the initial host response so as to encourage overgrowth of its partners. The data for Aa's activist role stems from molecular genetic studies complemented by experimental animal investigations that demonstrate how Aa establishes a habitat (housing), nutritional sustenance in that habitat (food), and biogeographical mobilization and/or relocation from its initial habitat (transportation). In this manner Aa can transfer to a protected but vulnerable domain (pocket or sulcus) where its community activism is most useful. Aa's “strategy” includes obtaining housing, food, and transportation at no cost to its partners challenging the economic theory that “there ain't no such thing as a free lunch.” This “strategy” illustrates how co-evolution can promote Aa's survival, on one hand, and overgrowth of community members, on the other, which can result in local host dysbiosis and susceptibility to infection.

Periodontal Disease: A Risk Factor for Diabetes and Cardiovascular Disease

Periodontitis is a chronic inflammatory disease, initiated by the presence of a bacterial biofilm, called dental plaque, which affects both the periodontal ligaments and bone surrounding teeth. In the last decades, several lines of evidence have supported the existence of a relationship between periodontitis and systemic health. For instance, as periodontitis acts within the same chronic inflammatory model seen in cardiovascular disease (CVD), or other disorders, such as diabetes, several studies have suggested the existence of a bi-directional link between periodontal health and these pathologies. For instance, people with diabetes are more susceptible to infections and are more likely to suffer from periodontitis than people without this syndrome. Analogously, it is now evident that cardiac disorders are worsened by periodontitis, both experimentally and in humans. For all these reasons, it is very plausible that preventing periodontitis has an impact on the onset or progression of CVD and diabetes. On these grounds, in this review, we have provided an updated account on the current knowledge concerning periodontal disease and the adverse effects exerted on the cardiovascular system health and diabetes, informing readers on the most recent preclinical studies and epidemiological evidence.

Subgingival microbiome in Chinese patients with generalized aggressive periodontitis compared to healthy controls

OBJECTIVE

The aim of the study was to profile the subgingival microbiome of Chinese adults with generalized aggressive periodontitis (GAgP) using human oral microbe identification microarray (HOMIM), and to compare the results with matched periodontal healthy controls.

DESIGN

15 subjects with GAgP and 15 age- and gender- matched periodontal healthy controls were included. Subgingival plaque samples were collected from the deepest pockets of patients with GAgP and matched sites in controls and then analyzed by 16S rRNA-based microarrays. Student's paired t-test was used to compare clinical parameters and mean number of bacterial taxa detected between the two groups. Fisher's exact probability test and Wilcoxon Rank Sum were used to compare bacterial species between all samples. A multiple linear regression model was used for correlations among age, gender and bacterial with clinical parameters.

RESULTS

From a total sum of 379 strains tested, 171 bacterial strains were detected from subgingival plaques of the GAgP patients, more than the 157 strains detected in control group. Mean number of subgingival bacterial taxa detected in GAgP group was 68 (SD = 21.06) while in control group was 45 (SD = 21.60). 47 bacterial taxa were detected more frequently in GAgP group while 12 taxa were more prevalent in control group. The significantly more prevalent and abundant taxa of bacteria in GAgP group included Filifactor alocis, Desulfobulbus sp., Fretibacterium sp., Porphyromonas gingivalis, Tannerella forsythia, Porphyromon as endodontalis, Peptostreptococcaceae spp., Parvimonas micra, Eubacterium nodatum and Eubacterium saphenum. Meanwhile the more abundant taxa in control group were Streptococcus spp. and Pseudomonas aeruginosa.

CONCLUSIONS

There are more taxa of bacteria in subgingival plaques of Chinese patients with GAgP than in healthy controls. F. alocis, Desulfobulbus sp., Fretibacterium sp., P. gingivalis and T. forsythia are strongly associated with GAgP. High-throughout microbiological results may help dentists have a better understanding of subgingival microbiome of GAgP.

Comparison of the oral microbiome of patients with generalized aggressive periodontitis and periodontitis-free subjects

OBJECTIVE

The primary objectives of the study were to assess differences in complex subgingival bacterial composition between periodontitis-free persons and patients with generalized aggressive periodontitis (gAgP).

BACKGROUND

The composition of the oral microbiota plays an important role for both oral and systemic diseases. However, the complex nature of the oral microbiome and its homeostasis is still poorly understood.

MATERIAL AND METHODS

We compared the microbiome of 13 periodontitis-free persons to 13 patients with gAgP. The 16S rRNA genes were amplified, targeting the V3/V4 region using the MiSeq platform.

RESULTS

In total, 1713 different bacterial species were mapped according to the Greengenes database. Using the Shannon index, no significant differences in alpha diversity were found between the two study groups. In principal component and linear discriminant analyses, disease-specific differences in beta diversity of the microbiome composition were evaluated. Bacteroidetes, Spirochaetes, and Synergistetes were more abundant in gAgP whereas Proteobacteria, Firmicutes, and Actinobacteria were associated with a healthy periodontium. At the bacterial species level, we showed that Porphyromonas gingivalis is the strongest indicator of gAgP. Treponema denticola and Tanerella forsythia of the "red complex" as well as Filifactor alocis were among the ten best biomarkers for gAgP.

CONCLUSIONS

These results broaden our knowledge of disease-specific differences in the microbial community associated with generalized AgP. A more complex view of the composition of the oral microbiome describes the etiology of generalized AgP in more detail. These results could help to individually adapt periodontal therapy in these patients.

Biology of Oral Streptococci

Bacteria belonging to the genus Streptococcus are the first inhabitants of the oral cavity, which can be acquired right after birth and thus play an important role in the assembly of the oral microbiota. In this article, we discuss the different oral environments inhabited by streptococci and the species that occupy each niche. Special attention is given to the taxonomy of Streptococcus, because this genus is now divided into eight distinct groups, and oral species are found in six of them. Oral streptococci produce an arsenal of adhesive molecules that allow them to efficiently colonize different tissues in the mouth. Also, they have a remarkable ability to metabolize carbohydrates via fermentation, thereby generating acids as byproducts. Excessive acidification of the oral environment by aciduric species such as Streptococcus mutans is directly associated with the development of dental caries. However, less acid-tolerant species such as Streptococcus salivarius and Streptococcus gordonii produce large amounts of alkali, displaying an important role in the acid-base physiology of the oral cavity. Another important characteristic of certain oral streptococci is their ability to generate hydrogen peroxide that can inhibit the growth of S. mutans. Thus, oral streptococci can also be beneficial to the host by producing molecules that are inhibitory to pathogenic species. Lastly, commensal and pathogenic streptococci residing in the oral cavity can eventually gain access to the bloodstream and cause systemic infections such as infective endocarditis.

Consistent and reproducible long-term in vitro growth of health and disease-associated oral subgingival biofilms

BACKGROUND

Several in vitro oral biofilm growth systems can reliably construct oral microbiome communities in culture, yet their stability and reproducibility through time has not been well characterized. Long-term in vitro growth of natural biofilms would enable use of these biofilms in both in vitro and in vivo studies that require complex microbial communities with minimal variation over a period of time. Understanding biofilm community dynamics in continuous culture, and whether they maintain distinct signatures of health and disease, is necessary to determine the reliability and applicability of such models to broader studies. To this end, we performed next-generation sequencing on biofilms grown from healthy and disease-site subgingival plaque for 80 days to assess stability and reliability of continuous oral biofilm growth.

RESULTS

Biofilms were grown from subgingival plaque collected from periodontitis-affected sites and healthy individuals for ten eight-day long generations, using hydroxyapatite disks. The bacterial community in each generation was determined using Human Oral Microbe Identification by Next-Generation Sequencing (HOMINGS) technology, and analyzed in QIIME. Profiles were steady through the ten generations, as determined by species abundance and prevalence, Spearman's correlation coefficient, and Faith's phylogenetic distance, with slight variation predominantly in low abundance species. Community profiles were distinct between healthy and disease site-derived biofilms as demonstrated by weighted UniFrac distance throughout the ten generations. Differentially abundant species between healthy and disease site-derived biofilms were consistent throughout the generations.

CONCLUSIONS

Healthy and disease site-derived biofilms can reliably maintain consistent communities through ten generations of in vitro growth. These communities maintain signatures of health and disease and of individual donors despite culture in identical environments. This subgingival oral biofilm growth and perpetuation model may prove useful to studies involving oral infection or cell stimulation, or those measuring microbial interactions, which require the same biofilms over a period of time.

Saliva in the "Omics" era: A promising tool in paediatrics

In vulnerable populations, such as infants and children, saliva makes the perfect diagnostic medium because of its noninvasive collection, easy handling and storage of samples. Its unique biomarker profiles help tremendously in the diagnosis of many diseases and conditions. In fact, saliva genomics, proteomics, transcriptomics, metabolomics and microbiome-based discoveries have led to complementary and powerful diagnostic information. In children and neonates, saliva is the preferred medium not only for diagnosis of caries and aggressive periodontitis but also for a number of systemic conditions, metabolic diseases, cognitive functions, stress assessment and evaluation of immunological and inflammatory responses to vaccination. In this review, we provide an overview of current and future applications of saliva diagnostics to various diseases and conditions and highlight studies in paediatrics across the "omic" spectrum. Emerging frontiers in salivary diagnostics research that may significantly advance the field are also highlighted.

Oral Dysbiotic Communities and Their Implications in Systemic Diseases

The human body supports the growth of a wide array of microbial communities in various niches such as the oral cavity, gastro-intestinal and urogenital tracts, and on the surface of the skin. These host associated microbial communities include yet-un-cultivable bacteria and are influenced by various factors. Together, these communities of bacteria are referred to as the human microbiome. Human oral microbiome consists of both symbionts and pathobionts. Deviation from symbiosis among the bacterial community leads to “dysbiosis”, a state of community disturbance. Dysbiosis occurs due to many confounding factors that predispose a shift in the composition and relative abundance of microbial communities. Dysbiotic communities have been a major cause for many microbiome related systemic infections. Such dysbiosis is directed by certain important pathogens called the “keystone pathogens”, which can modulate community microbiome variations. One such persistent infection is oral infection, mainly periodontitis, where a wide array of causal organisms have been implied to systemic infections such as cardio vascular disease, diabetes mellitus, rheumatoid arthritis, and Alzheimer’s disease. The keystone pathogens co-occur with many yet-cultivable bacteria and their interactions lead to dysbiosis. This has been the focus of recent research. While immune evasion is one of the major modes that leads to dysbiosis, new processes and new virulence factors of bacteria have been shown to be involved in this important process that determines a disease or health state. This review focuses on such dysbiotic communities, their interactions, and their virulence factors that predispose the host to other systemic implications.

Characterizing oral microbial communities across dentition states and colonization niches

METHODS

The present study aimed to identify patterns and processes in acquisition of oral bacteria and to characterize the microbiota of different dentition states and habitats. Mucosal, salivary, supragingival, and subgingival biofilm samples were collected from orally and systemically healthy children and mother-child dyads in predentate, primary, mixed, and permanent dentitions. 16S rRNA gene sequences were compared to the Human Oral Microbiome Database (HOMD). Functional potential was inferred using PICRUSt.

RESULTS

Unweighted and weighted UniFrac distances were significantly smaller between each mother-predentate dyad than infant-unrelated female dyads. Predentate children shared a median of 85% of species-level operational taxonomic units (s-OTUs) and 100% of core s-OTUs with their mothers. Maternal smoking, but not gender, mode of delivery, feeding habits, or type of food discriminated between predentate microbial profiles. The primary dentition demonstrated expanded community membership, structure, and function when compared to the predentate stage, as well as significantly lower similarity between mother-child dyads. The primary dentition also included 85% of predentate core s-OTUs. Subsequent dentitions exhibited over 90% similarity to the primary dentition in phylogenetic and functional structure. Species from the predentate mucosa as well as new microbial assemblages were identified in the primary supragingival and subgingival microbiomes. All individuals shared 65% of species between supragingival and subgingival habitats; however, the salivary microbiome exhibited less than 35% similarity to either habitat.

CONCLUSIONS

Within the limitations of a cross-sectional study design, we identified two definitive stages in oral bacterial colonization: an early predentate imprinting and a second wave with the eruption of primary teeth. Bacterial acquisition in the oral microbiome is influenced by the maternal microbiome. Personalization begins with the eruption of primary teeth; however, this is limited to phylogeny; functionally, individuals exhibit few differences, suggesting that microbial assembly may follow a defined schematic that is driven by the functional requirements of the ecosystem. This early microbiome forms the foundation upon which newer communities develop as more colonization niches emerge, and expansion of biodiversity is attributable to both introduction of new species and increase in abundance of predentate organisms.

The subgingival microbiome in patients with established rheumatoid arthritis

OBJECTIVES

To profile and compare the subgingival microbiome of RA patients with OA controls.

METHODS

RA (n = 260) and OA (n = 296) patients underwent full-mouth examination and subgingival samples were collected. Bacterial DNA was profiled using 16 S rRNA Illumina sequencing. Following data filtering and normalization, hierarchical clustering analysis was used to group samples. Multivariable regression was used to examine associations of patient factors with membership in the two largest clusters. Differential abundance between RA and OA was examined using voom method and linear modelling with empirical Bayes moderation (Linear Models for Microarray Analysis, limma), accounting for the effects of periodontitis, race, marital status and smoking.

RESULTS

Alpha diversity indices were similar in RA and OA after accounting for periodontitis. After filtering, 286 taxa were available for analysis. Samples grouped into one of seven clusters with membership sizes of 324, 223, 3, 2, 2, 1 and 1 patients, respectively. RA-OA status was not associated with cluster membership. Factors associated with cluster 1 (vs 2) membership included periodontitis, smoking, marital status and Caucasian race. Accounting for periodontitis, 10 taxa (3.5% of those examined) were in lower abundance in RA than OA. There were no associations between lower abundance taxa or other select taxa examined with RA autoantibody concentrations.

CONCLUSION

Leveraging data from a large case-control study and accounting for multiple factors known to influence oral health status, results from this study failed to identify a subgingival microbial fingerprint that could reliably discriminate RA from OA patients.

Genetic polymorphisms and periodontal disease in populations of African descent: A review

Aggressive periodontitis is a rare but rapidly progressing form of periodontal disease that usually affects otherwise systemically healthy individuals, at a young age. It usually affects first molars and incisors, which are usually lost if treatment is not properly and early rendered. Although of low prevalence, it affects individuals of African descent at a higher prevalence, and usually multiple members within the same family. Several studies have been performed in the attempt to evaluate specific single nucleotide polymorphisms (SNPs) that could be associated with this disease. To the best of our knowledge, the present article provides the first review of the literature focusing on studies that evaluated SNPs in patients of African descent with aggressive periodontitis. Several SNPs have been evaluated in different genes according to their role in the pathogenesis of the disease, with positive and negative associations (such as IL1, FCGR3B, FPR1, LTF, CYBA, GLT6D1, TLR4) with both the localized and generalized forms of aggressive periodontitis. Given the complexity of periodontitis, the difficulty in gathering large cohorts diagnosed with this rare form of disease, and the fact that candidate gene studies may only determine part of the genetic risk of a disease, the search for specific SNPs associated with aggressive periodontitis seems to be a long one, most likely to result in the combination of multiple SNPs, in multiple genes.

Class III Histidine Kinases: a Recently Accessorized Kinase Domain in Putative Modulators of Type IV Pilus-Based Motility

Histidine kinases are key components of regulatory systems that enable bacteria to respond to environmental changes. Two major classes of histidine kinases are recognized on the basis of their modular design: classical (HKI) and chemotaxis specific (HKII). Recently, a new type of histidine kinase that appeared to have features of both HKIs and HKIIs was identified and termed HKIII; however, the details of HKIII's relationship to other two classes of histidine kinases, their function, and evolutionary history remain unknown. Here, we carried out genomic, phylogenetic, and protein sequence analyses that allowed us to reveal the unusual evolutionary history of this protein family, formalize its distinctive features, and propose its putative function. HKIIIs are characterized by the presence of sensory domains and the lack of a dimerization domain, which is typically present in all histidine kinases. In addition to a single-domain response regulator, HKIII signal transduction systems utilize CheX phosphatase and, in many instances, an unorthodox soluble chemoreceptor that are usual components of chemotaxis signal transduction systems. However, many HKIII genes are found in genomes completely lacking chemotaxis genes, thus decoupling their function from chemotaxis. By contrast, all HKIII-containing genomes also contain pilT, a marker gene for bacterial type IV pilus-based motility, whose regulation is proposed as a putative function for HKIII. These signal transduction systems have a narrow phyletic distribution but are present in many emerging and opportunistic pathogens, thus offering an attractive potential target for future antimicrobial drug design.IMPORTANCE Bacteria adapt to their environment and their hosts by detecting signals and regulating their cellular functions accordingly. Here, we describe a largely unexplored family of signal transduction histidine kinases, called HKIII, that have a unique modular design. While they are currently identified in a relatively short list of bacterial species, this list contains many emerging pathogens. We show that HKIIIs likely control bacterial motility across solid surfaces, which is a key virulence factor in many bacteria, including those causing severe infections. Full understanding of this putative function may help in designing effective drugs against pathogens that will not affect the majority of the beneficial human microbiome.

Non-Surgical Therapy Reduces Presence of JP2 Clone in Localized Aggressive Periodontitis

BACKGROUND

Previous studies have provided substantial evidence of the association of Aggregatibacter actinomycetemcomitans, and its highly leukotoxic JP2 genotype, with localized aggressive periodontitis (LAgP). The present study aims to evaluate presence of JP2 in individuals with LAgP after periodontal treatment.

METHODS

Sixty African-American patients with LAgP, aged 5 to 25 years, were examined. At baseline, probing depth (PD), clinical attachment level (CAL), bleeding on probing, and plaque index were measured, and subgingival plaque was collected from LAgP diseased and healthy sites for each participant. Patients received whole-mouth ultrasonic debridement, scaling and root planing, and a 7-day prescription of amoxicillin and metronidazole. Participants were reevaluated and resampled and received regular maintenance therapy at 3, 6, and 12 months after treatment. Polymerase chain reaction was used to detect presence of the JP2 genotype before and after treatment.

RESULTS

At baseline, the JP2 sequence was identified in 75% of LAgP diseased sites and in 56.67% of healthy sites. At 3, 6, and 12 months after treatment, the number of patients was 40, 31, and 31, respectively, and JP2 detection decreased to 17.5%, 6.45%, and 3.23%, respectively, in diseased sites (P <0.001) and to 2.5%, 3.23%, and 0%, respectively, in healthy sites (P <0.001). Clinical parameters of disease were also significantly reduced after therapy (P <0.001). Additionally, significant correlations were observed between JP2 presence and mean PD (P <0.002) and CAL (P <0.001), after therapy.

CONCLUSION

Periodontal therapy was successful in reducing clinical parameters of LAgP and subgingival presence of JP2 in diseased and healthy sites.

Potential Risk for Localized Aggressive Periodontitis in African American Preadolescent Children

PURPOSE

This study aimed to evaluate the potential risk for localized aggressive periodontitis (LAgP) in African American children by detection of the potential periodontal pathogen Aggregatibacter actinomycetemcomitans (Aa) using polymerase chain reaction (PCR) and microbiome analysis.

METHODS

Twenty-one pre-adolescents (age range equals 10.7 to 13.1 years old) were recruited, for this IRB-approved study. Oral examination included limited periodontal examination determining bleeding index (BOP) and periodontal probing (PD). An oral mucosa sample was used for analysis.

RESULTS

Nine of 21 children were Aa+ by PCR. The Aa+ group had a significantly higher proportion of teeth with BOP and PD greater than four mm than the Aa- group (P=0.014 and 0.006 for percent BOP and percent PD equal to or greater than four mm, respectively; Mann Whitney Test). No significant differences in microbe abundance or composition were found from comparison of Aa+ versus Aa- samples.

CONCLUSIONS

Detection of Aa from preadolescent African American children was associated with signs of periodontal inflammation. Although none of these children were diagnosed with LAgP, PCR targeting Aa could be a risk factor. Further study is indicated; however, the usefulness of PCR in dental practice setting to assess risk may be cost-effective for early diagnosis and prevention of LAgP.

Comprehensive analysis of microorganisms accompanying human archaeological remains

Metagenome analysis has become a common source of information about microbial communities that occupy a wide range of niches, including archaeological specimens. It has been shown that the vast majority of DNA extracted from ancient samples come from bacteria (presumably modern contaminants). However, characterization of microbial DNA accompanying human remains has never been done systematically for a wide range of different samples. We used metagenomic approaches to perform comparative analyses of microorganism communities present in 161 archaeological human remains. DNA samples were isolated from the teeth of human skeletons dated from 100 AD to 1200 AD. The skeletons were collected from 7 archaeological sites in Central Europe and stored under different conditions. The majority of identified microbes were ubiquitous environmental bacteria that most likely contaminated the host remains not long ago. We observed that the composition of microbial communities was sample-specific and not correlated with its temporal or geographical origin. Additionally, traces of bacteria and archaea typical for human oral/gut flora, as well as potential pathogens, were identified in two-thirds of the samples. The genetic material of human-related species, in contrast to the environmental species that accounted for the majority of identified bacteria, displayed DNA damage patterns comparable with endogenous human ancient DNA, which suggested that these microbes might have accompanied the individual before death. Our study showed that the microbiome observed in an individual sample is not reliant on the method or duration of sample storage. Moreover, shallow sequencing of DNA extracted from ancient specimens and subsequent bioinformatics analysis allowed both the identification of ancient microbial species, including potential pathogens, and their differentiation from contemporary species that colonized human remains more recently.