Safety, Feasibility, and Advantages of Oral Microbiota Transplantation: The First Clinical Case

The pilot clinical study presented demonstrates the possibility, safety, and effectiveness of oral microbiota transplantation from a healthy donor to a patient with neuroblastoma to prevent chemotherapy-induced oral mucositis. A 6-month-old patient with a diagnosis of retroperitoneal neuroblastoma was treated according to the NB 2004 protocol. Due to the development of severe oral mucositis, it was decided to perform oral microbiota transplantation. During the next 3 chemotherapy cycles and conditioning regimen before autologous hematopoietic cell transplantation (auto-HCT), the patient was repeatedly injected per os with donor saliva from her healthy mother. Oral microbiota transplantation was shown to effectively prevent the development of oral mucositis after chemotherapy, and only grade 1 oral mucositis developed after auto-HCT. In all loci of the oral cavity, there was a decreased abundance of bacteria from the Staphylococcaceae, Micrococcaceae, and Xanthomonadaceae families. Conversely, there was an increase in the relative abundance of Streptococcaceae and certain other bacterial taxa. In conclusion, the transplantation of maternal saliva in this patient prevented severe mucositis and was accompanied by a compositional change of the patient's oral microbiota. No adverse events due to the transplantation of maternal saliva were noted.

Biochemical and Microbiological Aspects of the Oral Cavity of Children and Young People with Neurological Impairment and Oropharyngeal Dysphagia

The components and the salivary flow have a direct influence on the composition of the oral microbiota of children and young people with oropharyngeal dysphagia, and studies have already demonstrated the excessive accumulation of supragingival dental calculus in individuals with enteral nutrition. This study aimed to compare the oral hygiene, biochemical, and microbiological aspects of the oral cavity of children and young people with neurological impairment and oropharyngeal dysphagia. Forty children and young people with neurological impairment and oropharyngeal dysphagia were enrolled and divided into two groups: group I, encompassing 20 participants fed via gastrostomy; and group II, encompassing 20 participants fed via the oral route. Oral hygiene and salivary pH and flow were assessed, and a polymerase chain reaction was performed to evaluate the messenger RNA expressions of Porphyromonas gingivalis, Tanerella forsythia, and Treponema denticola. In groups I and II, the mean Oral Hygiene Index-Simplified scores were 4 and 2, respectively, showing a significant difference; the mean Calculus Index scores were 2 and 0, respectively, showing a significant difference; and the mean pH was 7.5 and 6.0, respectively, showing a significant difference. Bacterial analysis indicated no association between the two groups. It can be concluded that children and young people who use gastrostomy had a poorer oral hygiene, greater dental calculus deposition, and higher salivary pH. The saliva of patients in both groups contained Porphyromonas gingivalis, Tanerella forsythia, and Treponema denticola.

The influence of nasal and oropharyngeal mucosal dysbiosis on the condition of the middle ear in children with congenital cleft palate

Disturbance of the microbiocenosis of the nasal cavity and oropharynx in children with congenital cleft palate presents serious therapeutic difficulties. Pathobionts colonizing the upper respiratory tract and chronic adenoiditis pose a threat of acute purulent otitis media and chronic otitis media with effusion. The authors studied nasal and oropharyngeal mucosal dysbiosis in patients before elective uranoplasty and the effect of dysbiotic manifestations on the condition of the middle ear in the postoperative period. The results of microbiological examination of 80 swabs from the nasal cavity and oropharynx in patients with congenital cleft palate were analyzed. Among the culture-positive results in patients in clinical and laboratory remission of ENT-infections dysbiosis of 2–3 degrees prevails, the presence of bacterial-bacterial and bacterial-fungal associations is often noted, the predominance of gram-negative microflora is noted. There was an increase in the frequency of perforations of the tympanic membrane in the presence of bacterial and fungal associations, the appearance of retraction pockets in the presence of gram-negative microflora, the relationship between grade 3 dysbiosis and the appearance of purulent otitis media after uranoplasty were revealed.

Conclusion. Disturbance of microbiocenosis in patients with congenital cleft palate before uranoplasty requires the inclusion of a microbiological study in the preoperative preparation schedule and a personalized approach to perioperative antibiotic prophylaxis. 

Oral Commensal Streptococci: Gatekeepers of the Oral Cavity

Oral commensal streptococci are primary colonizers of the oral cavity. These streptococci produce many adhesins, metabolites, and antimicrobials that modulate microbial succession and diversity within the oral cavity. Often, oral commensal streptococci antagonize cariogenic and periodontal pathogens such as Streptococcus mutans and Porphyromonas gingivalis, respectively. Mechanisms of antagonism are varied and range from the generation of hydrogen peroxide, competitive metabolite scavenging, the generation of reactive nitrogen intermediates, and bacteriocin production. Furthermore, several oral commensal streptococci have been shown to alter the host immune response at steady state and in response to oral pathogens. Collectively, these features highlight the remarkable ability of oral commensal streptococci to regulate the structure and function of the oral microbiome. In this review, we discuss mechanisms used by oral commensal streptococci to interact with diverse oral pathogens, both physically and through the production of antimicrobials. Finally, we conclude by exploring the critical roles of oral commensal streptococci in modulating the host immune response and maintaining health and homeostasis.

Antimicrobial Effect of Isotretinoin Therapy on Periodontal Pathogens: A Case-Control Study

Isotretinoin (INN), a drug used to treat severe acne, has anti-inflammatory and antibacterial properties. INN may affect periodontal pathogenic bacteria, so we aimed to study the effect of INN on intraoral microbial profiles of periodontal disease and healthy periodontium. Our case-control study divided 180 subjects into six groups according to periodontal health status and INN usage as follows: healthy periodontium receiving INN (HINN; n = 30); those with generalized plaque-induced gingivitis receiving INN (GINN; n = 30); and those with stage I generalized periodontitis receiving INN (PINN; n = 30). Subjects not taking INN, were categorized in the same manner: those with a healthy periodontium (HC; n = 30); those with generalized plaque-induced gingivitis (GC; n = 30); and those with generalized periodontitis stage I (PC; n = 30). Plaque samples were collected to determine the prevalence of four periodontal pathogens (Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Fusobacterium nucleatum) in each study group using real-time polymerase chain reaction. Data were analyzed using IBM SPSS software, and multiple regression analysis was performed for each parameter tested in each group at a significance level of 0.05. All INN groups showed significantly lower levels of P. gingivalis, T. forsythia, and T. denticola and higher levels of F. nucleatum (p < 0.001). INN had an observable antimicrobial effect on the periodontal pathogen count in patients with plaque-induced gingivitis and chronic periodontitis. INN may have a potential additive antimicrobial value in the treatment of periodontal disease.

Titanium Dioxide Nanoparticles Induce Inhibitory Effects against Planktonic Cells and Biofilms of Human Oral Cavity Isolates of Rothia mucilaginosa, Georgenia sp. and Staphylococcus saprophyticus

Multi-drug resistant (MDR) bacterial cells embedded in biofilm matrices can lead to the development of chronic cariogenesis. Here, we isolated and identified three Gram-positive MDR oral cocci, (1) SJM-04, (2) SJM-38, and (3) SJM-65, and characterized them morphologically, biochemically, and by 16S rRNA gene-based phylogenetic analysis as Georgenia sp., Staphylococcus saprophyticus, and Rothia mucilaginosa, respectively. These three oral isolates exhibited antibiotic-resistance against nalidixic acid, tetracycline, cefuroxime, methicillin, and ceftazidime. Furthermore, these Gram positive MDR oral cocci showed significant (p < 0.05) variations in their biofilm forming ability under different physicochemical conditions, that is, at temperatures of 28, 30, and 42 °C, pH of 6.4, 7.4, and 8.4, and NaCl concentrations from 200 to 1000 µg/mL. Exposure of oral isolates to TiO2NPs (14.7 nm) significantly (p < 0.05) reduced planktonic cell viability and biofilm formation in a concentration-dependent manner, which was confirmed by observing biofilm architecture by scanning electron microscopy (SEM) and optical microscopy. Overall, these results have important implications for the use of tetragonal anatase phase TiO2NPs (size range 5-25 nm, crystalline size 13.7 nm, and spherical shape) as an oral antibiofilm agent against Gram positive cocci infections. We suggest that TiO2NPs pave the way for further applications in oral mouthwash formulations and antibiofilm dental coatings.

Periodontitis associates with species-specific gene expression of the oral microbiota

The purpose of the present investigation was to characterize species-specific bacterial activity of the oral microbiota in periodontitis. We tested the hypotheses that chronic inflammation, i.e., periodontitis, associates with bacterial gene expression of the oral microbiota. Oral microbial samples were collected from three oral sites—subgingival plaque, tongue, and saliva from patients with periodontitis and healthy controls. Paired metagenomics and metatranscriptomics were used to perform concomitant characterization of taxonomic composition and to determine species-specific bacterial activity as expressed by the ratio of specific messenger RNA reads to their corresponding genomic DNA reads. Here, we show the association of periodontitis with bacterial gene expression of the oral microbiota. While oral site was the main determinant of taxonomic composition as well as bacterial gene expression, periodontitis was significantly associated with a reduction of carbohydrate metabolism of the oral microbiota at three oral sites (subgingival plaque, tongue, and saliva). Data from the present study revealed the association of periodontitis with bacterial gene expression of the oral microbiota. Conditions of periodontitis was associated with bacterial activity of local subgingival plaque, but also on tongue and the salivary microbiota. Collectively, data suggest that periodontitis associates with impaired carbohydrate metabolism of the oral microbiota. Future longitudinal and interventional studies are warranted to evaluate the potential pathogenic role of impaired bacterial carbohydrate metabolism not only in periodontitis but also in other diseases with low-grade inflammation, such as type 2 diabetes mellitus.

Cariogenic and oral health taxa in the oral cavity among children and adults: A scoping review

OBJECTIVE

To review published oral microbiome studies and create a comprehensive list of bacterial species found in saliva and dental plaque among healthy children and adults associated with presence of carious lesions and caries-free state (oral health).

DESIGN

This review followed PRISMA-ScR guidelines. We searched published studies querying PUBMED and EMBASE using the following keywords: (plaque OR saliva) AND caries AND (next generation sequencing OR checkerboard OR 16s rRNA or qPCR). Studies were limited to human studies published in English between January 1, 2010 and June 24, 2020 that included > 10 caries-active and > 10 caries-free participants, and assessed the entire bacterial community.

RESULTS

Our search strategy identified 298 articles. After exclusion criteria, 22 articles remained; we considered 2 studies that examined saliva and plaque as separate studies, for a total of 24 studies. Species associated with caries or oral health varied widely among studies reviewed, with notable differences by age and biologic sample type. No bacterial species was associated with caries in all studies. Streptococcus mutans was found more frequently among those with caries (14/24 (58.3 %)) and Fusobacterium periodonticum was found more frequently among those that were caries-free (5/24 (20.8 %)).

CONCLUSION

No bacterial species was associated with caries or oral health across all studies supporting multiple pathways to cariogenesis. However, the variation may be due to sampling at different time points during caries development, varying methods of specimen sampling, storage, sequencing or analysis or differences in host factors such as age.

Microbial Screening Reveals Oral Site-Specific Locations of the Periodontal Pathogen Selenomonas noxia

INTRODUCTION

Selenomonas noxia (SN) is an important periodontal pathogen, associated with gingivitis and periodontitis. Many studies have found associations between SN and indicators of poor health outcomes, such as smoking, low socioeconomic status and obesity. However, less is known about the prevalence of this organism and more specifically about other oral site-specific locations that may harbor this organism.

METHODS

Using an existing patient repository (n = 47) of DNA isolated from saliva and other oral sites (n = 235), including the dorsum of the tongue, lower lingual incisor, upper buccal molar and gingival crevicular fluid (GCF), molecular screening for SN was performed. Screening results were analyzed for associations between demographic variables (age, sex, race/ethnicity) and clinical information (body mass index or BMI, presence of orthodontic brackets, primary/mixed/permanent dentition).

RESULTS

qPCR screening revealed a total of n = 62/235 sites or 26.3% harboring SN with saliva and GCF (either alone or in combination with one or more sites) most often observed (Saliva, n = 23/27 or 85.18%, GCF, n = 14/27 or 51%). Analysis of site-specific data revealed most positive results were found among saliva and GCF alone or in combination, with fewer positive results observed among the tongue (33.3%), lower lingual incisor (29.6%), and upper buccal molar (25.9%). No significant associations were found between demographic or clinical variables and presence of SN at any site.

CONCLUSIONS

These results may be among the first to describe site-specific locations of S. noxia among various additional oral biofilm sites. These data may represent a significant advancement in our understanding of the sites and locations that harbor this organism, which may be important for our understanding of the prevalence and distribution of these organisms among patients of different ages undergoing different types of oral treatments, such as orthodontic treatment or therapy.

Acquisition and establishment of the oral microbiota

Acquisition and establishment of the oral microbiota occur in a dynamic process over various stages and involve close and continuous interactions with the host and its environment. In the present review, we discuss the stages of this process in chronological order. We start with the prenatal period and address the following questions: ‘Is the fetus exposed to maternal microbiota during pregnancy?’ and ‘If so, what is the potential role of this exposure?’ We comment on recent reports of finding bacterial DNA in placenta during pregnancies, and provide current views on the potential functions of prenatal microbial encounters. Next, we discuss the physiological adaptations that take place in the newborn during the birth process and the effect of this phase of life on the acquisition of the oral microbiota. Is it really just exposure to maternal vaginal microbes that results in the difference between vaginally and Cesarian section‐born infants? Then, we review the postnatal phase, in which we focus on transmission of microbes, the intraoral niche specificity, the effects of the host behavior and environment, as well as the role of genetic background of the host on shaping the oral microbial ecosystem. We discuss the changes in oral microbiota during the transition from deciduous to permanent dentition and during puberty. We also address the finite knowledge on colonization of the oral cavity by microbes other than the bacterial component. Finally, we identify the main outstanding questions that limit our understanding of the acquisition and establishment of a healthy microbiome at an individual level.

Optimizing the quality of clinical studies on oral microbiome: A practical guide for planning, performing, and reporting

With this review, we aim to increase the quality standards for clinical studies with microbiome as an output parameter. We critically address the existing body of evidence for good quality practices in oral microbiome studies based on 16S rRNA gene amplicon sequencing. First, we discuss the usefulness of microbiome profile analyses. Is a microbiome study actually the best approach for answering the research question? This is followed by addressing the criteria for the most appropriate study design, sample size, and the necessary data (study metadata) that should be collected. Next, we evaluate the available evidence for best practices in sample collection, transport, storage, and DNA isolation. Finally, an overview of possible sequencing options (eg, 16S rRNA gene hypervariable regions, sequencing platforms), processing and data interpretation approaches, as well as requirements for meaningful data storage, sharing, and reporting are provided.

Comparison of subgingival and gingival margin plaque microbiota from dogs with healthy gingiva and early periodontal disease

The purpose of the investigation was to determine whether canine gingival margin (GM) plaque is a reliable surrogate for subgingival (SG) plaque from a microbial community (microbiota) perspective. SG and GM plaque samples were collected from 381 dogs visiting pet hospitals in the USA, China and Thailand. Dogs with clinically healthy gingivae through to early periodontitis were included in the study. The samples were subject to next generation Illumina sequence analysis to allow microbiota comparisons to be made between the two plaque sources. Overall, the SG and GM samples indicated commonality via the majority community that were shared between them; health associations led to the identification of some significant taxa-specific differences. GM microbiota exhibited lower variability and diversity and were shown to reflect a sub-population of those associated with SG plaque. Both plaque niches, however, demonstrated similar changes in microbial signatures with health and early periodontal disease and did not indicate divergent trends. The key, most abundant microbiota of GM plaque strongly reflect those observed with SG plaque across health and early periodontitis. Microbiota in plaque from above the gum line may therefore be employed as a biomarker of oral health. This opens up the potential to use plaque, sampled from conscious dogs, to define oral health status and improve the diagnosis, treatments and interventions for periodontal disease.

Construction of a Mutant in Prevotella melaninogenica Using the Conjugation Transfer Method with Escherichia coli

Prevotella melaninogenica is a bacterium that is resident in the oral cavity and upper respiratory tract and is associated with periodontal disease and aspiration pneumonia. Prevotella mutants are difficult to produce and only few reports have been reported. We examined several methods and many strains and succeeded in producing mutants in Prevotella melaninogenica GAI 07411. In this chapter, we will describe how to create a mutation of a target gene by carrying out conjugation transfer using Escherichia coli S17-1 as a donor and introducing a plasmid into P. melaninogenica.

Clinical outcomes for congenital heart disease patients presenting with infective endocarditis

INTRODUCTION

Infective endocarditis (IE) is a life-threatening adverse event for patients with congenital heart disease (CHD). Its incidence has changed little over time despite progress in techniques for diagnosis and treatment, and guidelines for prophylaxis.

AREAS COVERED

The review sought for key-words: 'congenital heart disease,' 'infective endocarditis,' 'microbial diagnosis,' 'imaging diagnosis,' 'surgical techniques,' 'prognosis,' 'prophylaxis.' Objectives were to investigate epidemiology, novel techniques for imaging and microbial diagnosis, therapeutic management and prognosis, and guidelines for prophylaxis in patients with CHD. The incidence of IE is increasing in adults with CHD. Morbidity caused by a broad clinical spectrum of cardiac and extracardiac episode-related complications is high. Surgical management is increasingly required in the early phase of the disease. Despite new techniques for diagnosis and microbiological therapy, mortality rate is still up to 10-20%.

EXPERT OPINION

IE has increased in the growing cohort of adults with complex heart disease, living with residual cardiac lesions and prosthetic materials. Diagnosis is challenging for complex heart defects. Pet-scan technique can provide beneficial information to locate intracardiac lesions and embolic foci. Identification of the microbiological agents is improving. Innovative surgical techniques aim to avoid prosthetic material. Guidelines for prophylaxis currently emphasize oral and skin daily hygiene.

New Paradigms of Pilus Assembly Mechanisms in Gram-Positive Actinobacteria

Adhesive pili in Gram-positive bacteria represent a variety of extracellular multiprotein polymers that mediate bacterial colonization of specific host tissues and associated pathogenesis. Pili are assembled in two distinct but coupled steps, an orderly crosslinking of pilin monomers and subsequent anchoring of the polymer to peptidoglycan, catalyzed by two transpeptidase enzymes - the pilus-specific sortase and the housekeeping sortase. Here, we review this biphasic assembly mechanism based on studies of two prototypical models, the heterotrimeric pili in Corynebacterium diphtheriae and the heterodimeric pili in Actinomyces oris, highlighting some newly emerged basic paradigms. The disparate mechanisms of protein ligation mediated by the pilus-specific sortase and the spatial positioning of adhesive pili on the cell surface modulated by the housekeeping sortase are among the notable highlights.

Effect of feeding a daily oral care chew on the composition of plaque microbiota in dogs

The objective of this study was to investigate the influence of daily feeding of an oral care chew on the composition of canine supragingival plaque microbiota. Twelve beagle dogs were recruited to the randomized cross-over study. The dogs were fed one of two dietary regimes, both consisting of a commercially available wet and dry diet mix, either with or without daily supplementation with an oral care chew. After each 28-day test phase, supragingival plaque samples were collected and processed via Illumina sequencing to determine the microbiota composition. A comparative analysis of bacterial species associated with health and periodontal disease, identified from prior clinical studies, revealed differences between the dietary regimes. Consumption of the daily oral care chew, resulted in a significant increase in proportion of 6 health associated taxa but only 3 disease associated taxa compared to no chew. In contrast, 8 disease and 1 health associated taxa showed increased proportions for no chew versus the oral care chew. Daily feeding of the oral care chew tested in this study has therefore been shown to increase the proportion of health associated bacteria, over bacteria associated with periodontal disease, in supragingival plaque compared to no chew. By influencing plaque microbiota towards a bias for health associated bacteria, feeding of the oral care chew provides a means to reduce the prevalence of bacterial species shown to be associated with periodontal disease in dogs.

Roles of TroA and TroR in Metalloregulated Growth and Gene Expression in Treponema denticola

The availability of divalent metal cations required as cofactors for microbial metabolism is severely limited in the host environment. Bacteria have evolved highly regulated uptake systems to maintain essential metal homeostasis to meet cellular demands while preventing toxicity. The Tro operon (troABCDR), present in all sequenced Treponema spp., is a member of a highly conserved family of ATP-binding cassette transporters involved in metal cation uptake whose expression is controlled by TroR, a DtxR-like cation-responsive regulatory protein. Transcription of troA responds to divalent manganese and iron (T. denticola) or manganese and zinc (T. pallidum), and metal-dependent TroR binding to the troA promoter represses troA transcription. We report here the construction and complementation of defined T. denticola ΔtroR and ΔtroA strains to characterize (i) the role of TroA in metal-dependent T. denticola growth and (ii) the role of TroR in T. denticola gene expression. We show that TroA expression is required for T. denticola growth under iron- and manganese-limited conditions. Furthermore, TroR is required for the transcriptional regulation of troA in response to iron or manganese, and deletion of troR results in significant differential expression of more than 800 T. denticola genes in addition to troA These results suggest that (i) TroA-mediated cation uptake is important in metal homeostasis in vitro and may be important for Treponema survival in the host environment and (ii) the absence of TroR results in significant dysregulation of nearly one-third of the T. denticola genome. These effects may be direct (as with troA) or indirect due to dysregulation of metal homeostasis.IMPORTANCE Treponema denticola is one of numerous host-associated spirochetes, a group including commensals, pathobionts, and at least one frank pathogen. While most T. denticola research concerns its role in periodontitis, its relative tractability for growth and genetic manipulation make it a useful model for studying Treponema physiology, metabolism, and host-microbe interactions. Metal micronutrient acquisition and homeostasis are highly regulated both in microbial cells and by host innate defense mechanisms that severely limit metal cation bioavailability. Here, we characterized the T. denticola troABCDR operon, the role of TroA-mediated iron and manganese uptake in growth, and the effects of TroR on global gene expression. This study contributes to our understanding of the mechanisms involved in cellular metal homeostasis required for survival in the host environment.

Early and accurate detection of bacterial isolates from dental plaque in subjects with primary, mixed, and permanent dentition by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry technique

Background:

Bacterial colonization of dentition in different age groups can impact prognosis in different dental diseases. Latest diagnostic technique such as matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF) is increasingly being used for accurate identification of bacteria. This study was undertaken to evaluate the MALDI-TOF MS technique to identify bacterial pathogens from dental plaques in subjects with primary, mixed, and permanent dentition.

Materials and Methods:

The study included 150 subjects of different age groups and were divided into three groups - Group A: Subjects with primary dentition (n = 50), Group B: Subjects with mixed dentition (n = 50), and Group C: Subjects with permanent dentition (n = 50). Subgingival dental plaque samples were collected from buccal and lingual surfaces of premolar and molar teeth. Clinical parameters such as gingival index were recorded. Samples were cultured in routine aerobic and anaerobic medium. Bacterial growths were assessed by semiquantitative methods. Bacterial isolates were confirmed by MALDI-TOF MS technique.

Results:

MALDI-TOF MS detected all the culture-grown bacteria. In primary dentition group, purple and yellow complex bacteria predominated. Streptococcus spp. was the predominant bacteria (51%) followed by Escherichia coli (19%) and Veillonella spp. (19%). In mixed dentition and permanent group also, Streptococcus spp. was predominant (46%) followed by Veillonella spp. (24%) and E. coli(19%). However, in both groups, orange complex bacteria (bridge complex) such as Prevotella nigrescens and red complex bacteria (Porphyromonas gingivalis, 3%) were seen. For majority of bacteria, the load increased with age.

Conclusions:

The bacterial isolates showed a distinct age-specific colonization. The use of advanced technique such as MALDI-TOF MS is helpful in the detection of periodontal pathogens, and the effective oral health programs can be implemented to minimize the risk of periodontal diseases.

The canine oral microbiome: variation in bacterial populations across different niches

BACKGROUND

Microbiota from different niches within the canine oral cavity were profiled and compared. Supragingival plaque and stimulated saliva, were collected alongside samples from the buccal and tongue dorsum mucosa, from 14 Labrador retrievers at three timepoints within a 1 month timeframe. The V3-V4 region of the 16S rRNA gene was sequenced via Illumina MiSeq.

RESULTS

Supragingival plaque microbiota had the highest bacterial diversity and the largest number of significant differences in individual taxa when compared to the other oral niches. Stimulated saliva exhibited the highest variability in microbial composition between dogs, yet the lowest bacterial diversity amongst all the niches. Overall, the bacteria of the buccal and tongue dorsum mucosa were most similar.

CONCLUSIONS

The bacterial community profiles indicated three discrete oral niches: soft tissue surfaces (buccal and tongue dorsum mucosa), hard tissue surface (supragingival plaque) and saliva. The ability to distinguish the niches by their microbiota signature offers the potential for microbial biomarkers to be identified in each unique niche for diagnostic use.

Patterns of Oral Microbiota Diversity in Adults and Children: A Crowdsourced Population Study

Oral microbiome dysbiosis has been associated with various local and systemic human diseases such as dental caries, periodontal disease, obesity, and cardiovascular disease. Bacterial composition may be affected by age, oral health, diet, and geography, although information about the natural variation found in the general public is still lacking. In this study, citizen-scientists used a crowdsourcing model to obtain oral bacterial composition data from guests at the Denver Museum of Nature & Science to determine if previously suspected oral microbiome associations with an individual's demographics, lifestyle, and/or genetics are robust and generalizable enough to be detected within a general population. Consistent with past research, we found bacterial composition to be more diverse in youth microbiomes when compared to adults. Adult oral microbiomes were predominantly impacted by oral health habits, while youth microbiomes were impacted by biological sex and weight status. The oral pathogen Treponema was detected more commonly in adults without recent dentist visits and in obese youth. Additionally, oral microbiomes from participants of the same family were more similar to each other than to oral microbiomes from non-related individuals. These results suggest that previously reported oral microbiome associations are observable in a human population containing the natural variation commonly found in the general public. Furthermore, these results support the use of crowdsourced data as a valid methodology to obtain community-based microbiome data.

Maturation of the Oral Microbiome in Caries-Free Toddlers: A Longitudinal Study

Understanding the development of the oral microbiota in healthy children is of great importance to oral and general health. However, limited data exist on a healthy maturation of the oral microbial ecosystem in children. Moreover, the data are biased by mislabeling “caries-free” populations. Therefore, we aimed to characterize the healthy salivary and dental plaque microbiome in young children. Caries-free (ICDAS [International Caries Detection and Assessment System] score 0) children (n = 119) and their primary caregivers were followed from 1 until 4 y of child age. Salivary and dental plaque samples were collected from the children at 3 time points (T1, ~1 y old; T2, ~2.5 y old; and T3, ~4 y old). Only saliva samples were collected from the caregivers. Bacterial V4 16S ribosomal DNA amplicons were sequenced using Illumina MiSeq. The reads were denoised and mapped to the zero-radius operational taxonomic units (zOTUs). Taxonomy was assigned using HOMD. The microbial profiles of children showed significant differences (P = 0.0001) over time. Various taxa increased, including Fusobacterium, Actinomyces, and Corynebacterium, while others showed significant decreases (e.g., Alloprevotella and Capnocytophaga) in their relative abundances over time. Microbial diversity and child-caregiver similarity increased most between 1 and 2.5 y of age while still not reaching the complexity of the caregivers at 4 y of age. The microbiome at 1 y of age differed the most from those at later time points. A single zOTU (Streptococcus) was present in all samples (n = 925) of the study. A large variation in the proportion of shared zOTUs was observed within an individual child over time (2% to 42% of zOTUs in saliva; 2.5% to 38% in dental plaque). These findings indicate that the oral ecosystem of caries-free toddlers is highly heterogeneous and dynamic with substantial changes in microbial composition over time and only few taxa persisting across the 3 y of the study. The salivary microbiome of 4-y-old children is still distinct from that of their caregivers.

Oral microbiome diversity in chimpanzees from Gombe National Park

Historic calcified dental plaque (dental calculus) can provide a unique perspective into the health status of past human populations but currently no studies have focused on the oral microbial ecosystem of other primates, including our closest relatives, within the hominids. Here we use ancient DNA extraction methods, shotgun library preparation, and next generation Illumina sequencing to examine oral microbiota from 19 dental calculus samples recovered from wild chimpanzees (Pan troglodytes schweinfurthii) who died in Gombe National Park, Tanzania. The resulting sequences were trimmed for quality, analyzed using MALT, MEGAN, and alignment scripts, and integrated with previously published dental calculus microbiome data. We report significant differences in oral microbiome phyla between chimpanzees and anatomically modern humans (AMH), with chimpanzees possessing a greater abundance of Bacteroidetes and Fusobacteria, and AMH showing higher Firmicutes and Proteobacteria. Our results suggest that by using an enterotype clustering method, results cluster largely based on host species. These clusters are driven by Porphyromonas and Fusobacterium genera in chimpanzees and Haemophilus and Streptococcus in AMH. Additionally, we compare a nearly complete Porphyromonas gingivalis genome to previously published genomes recovered from human gingiva to gain perspective on evolutionary relationships across host species. Finally, using shotgun sequence data we assessed indicators of diet from DNA in calculus and suggest exercising caution when making assertions related to host lifestyle. These results showcase core differences between host species and stress the importance of continued sequencing of nonhuman primate microbiomes in order to fully understand the complexity of their oral ecologies.

Metaproteomics analysis of microbial diversity of human saliva and tongue dorsum in young healthy individuals

Background: The human oral microbiome influences initiation or progression of diseases like caries or periodontitis. Metaproteomics approaches enable the simultaneous investigation of microbial and host proteins and their interactions to improve understanding of oral diseases.

Objective: In this study, we provide a detailed metaproteomics perspective of the composition of salivary and tongue microbial communities of young healthy subjects.

Design: Stimulated saliva and tongue samples were collected from 24 healthy volunteers, subjected to shotgun nLC-MS/MS and analyzed by the Trans-Proteomic Pipeline and the Prophane tool.

Results: 3,969 bacterial and 1,857 human proteins could be identified from saliva and tongue, respectively. In total, 1,971 bacterial metaproteins and 1,154 human proteins were shared in both sample types. Twice the amount of bacterial metaproteins were uniquely identified for the tongue dorsum compared to saliva. Overall, 107 bacterial genera of seven phyla formed the microbiome. Comparative analysis identified significant functional differences between the microbial biofilm on the tongue and the microbiome of saliva.

Conclusion: Even if the microbial communities of saliva and tongue dorsum showed a strong similarity based on identified protein functions and deduced bacterial composition, certain specific characteristics were observed. Both microbiomes exhibit a great diversity with seven genera being most abundant.

Analysis of the effect of smoking on the buccal microbiome using next-generation sequencing technology

PURPOSE

This study aimed to investigate the effect of smoking on the buccal microbiome and to analyse the descriptive ability of each of the seven hypervariable regions in their 16S rRNA genes.

METHODOLOGY

Microbiome compositions of 40 buccal swab samples collected from smokers (n =20) and non-smokers (n =20) were determined using 16S rRNA sequencing. Seven different 16S rRNA hypervariable regions (V2, V3, V4, V6-7, V8 and V9) in each sample were amplified using the Ion Torrent 16S Metagenomics kit and were sequenced on the Ion S5 instrument.

RESULTS

Seven hypervariable regions in the 16S rRNA gene were successfully sequenced for all samples tested. The data obtained with the V2 region was found to be informative but the consensus data generated according to a number of operational taxonomic unit reads gathered from all seven hypervariable regions gave the most accurate result. At the phylum level, no statistically significant difference was found between smokers and non-smokers whereas relative abundances of Veillonella atypica, Streptococcus australis, Prevotella melaninogenica, Prevotella salivae and Rothia mucilaginosa showed significant increases in the smoker group (P-adj=0.05). Alpha diversity results did not show a significant difference between the two groups; however, beta diversity analysis indicated that samples of smoker and non-smoker groups had a tendency to be clustered within themselves.

CONCLUSION

The results of the current study indicate that smoking is a factor influencing buccal microbiome composition. In addition, sequencing of all seven hypervariable regions yielded more accurate results than those with any of the single variable regions.

The oral microbiota - a mechanistic role for systemic diseases

Human oral microbiota is the ecological community of commensal, symbiotic, and pathogenic microorganisms found in the oral cavity. Oral microbiota generally exists in the form of a biofilm and plays a crucial role in maintaining oral homeostasis, protecting the oral cavity and preventing disease development. Human oral microbiota has recently become a new focus research for promoting the progress of disease diagnosis, assisting disease treatment, and developing personalised medicines. In this review, the scientific evidence supporting the association that endogenous and exogenous factors (diet, smoking, drinking, socioeconomic status, antibiotics use and pregnancy) modulate oral microbiota. It provides insights into the mechanistic role in which oral microbiota may influence systemic diseases, and summarises the challenges of clinical diagnosis and treatment based on the microbial community information. It provides information for noninvasive diagnosis and helps develop a new paradigm of personalised medicine. All these benefit human health in the post-metagenomics era.

Microbial species associated with dental caries found in saliva and in situ after use of self-ligating and conventional brackets

Objectives

Enamel demineralization is among the main topics of interest in the orthodontic field. Self-ligating brackets have been regarded as advantageous in this aspect. The aim of this study was to evaluate the break homeostasis in the oral environment and the levels of microorganisms associated with dental caries among the different types of brackets.

Material and Methods

Twenty patients received two self-ligating brackets: In-Ovation^®R, SmartClip^TM, and one conventional Gemini^TM. Saliva was collected before bonding (S0), 30 (S1) and 60 (S2) days after bonding. One sample of each bracket was removed at 30 and 60 days for the in situ analysis. Checkerboard DNA-DNA Hybridization was employed to evaluate the levels of microbial species as-sociated with dental caries. Data were evaluated by nonparametric Friedman and Wilcoxon tests at 5% significance level.

Results

The salivary levels of L. casei (p=0.033), S. sobrinus (p=0.011), and S. sanguinis (p=0.004) increased in S1. The in situ analyses showed alteration in S. mutans (p=0.047), whose highest levels were observed to the In-Ovation^®R.

Conclusions

The orthodontic appliances break the salivary homeostasis of microorganisms involved in dental caries. The contamination pattern was different between self-ligating and conventional brackets. The In-Ovation^®R presented worse performance considering the levels of cariogenic bacterial species.

In Sickness and in Health-What Does the Oral Microbiome Mean to Us? An Ecological Perspective

The oral microbiome is natural and has a symbiotic relationship with the host by delivering important benefits. In oral health, a dynamic balance is reached between the host, the environment, and the microbiome. However, the frequent intake of sugar and/or reductions in saliva flow results in extended periods of low pH in the biofilm, which disrupts this symbiotic relationship. Such conditions inhibit the growth of beneficial species and drive the selection of bacteria with an acid-producing/acid-tolerating phenotype, thereby increasing the risk of caries (dysbiosis). A more detailed understanding of the interdependencies and interactions that exist among the resident microbiota in dental biofilms, and an increased awareness of the relationship between the host and the oral microbiome, is providing new insights and fresh opportunities to promote symbiosis and prevent dysbiosis. These include modifying the oral microbiome (e.g., with prebiotics and probiotics), manipulating the oral environment to selectively favor the growth of beneficial species, and moderating the growth and metabolism of the biofilm to reduce the likelihood of dysbiosis. Evidence is provided to suggest that the regular provision of interventions that deliver small but relevant benefits, consistently over a prolonged period, can support the maintenance of a symbiotic oral microbiome.

Involvement of PorK, a component of the type IX secretion system, in Prevotella melaninogenica pathogenicity

Prevotella melaninogenica is a gram-negative anaerobic commensal bacterium that resides in the human oral cavity and is isolated as a pathogen of suppurative diseases both inside and outside the mouth. However, little is known about the pathogenic factors of P. melaninogenica. The periodontal pathogens Porphyromonas gingivalis and Tanerella forsythia secrete virulence factors such as protease and bacterial cell surface proteins via a type IX secretion system (T9SS) that are involved in pathogenicity. P. melaninogenica also possesses all known orthologs of T9SS. In this study, a P. melaninogenica GAI 07411 mutant deficient in the orthologue of the T9SS-encoding gene, porK, was constructed. Hemagglutination and biofilm formation were decreased in the porK mutant. Furthermore, following growth on skim milk-containing medium, the diameters of the halos surrounding the porK mutant were smaller than those of the wild-type strain, suggesting a decrease in secretion of proteases outside the bacterium. To investigate this in detail, culture supernatants of wild-type and porK mutant strains were purified and compared by two-dimensional electrophoresis. In the mutant strain, fewer spots were detected, indicating fewer secreted proteins. In infection experiments, the mortality rate of mice inoculated with the porK mutant strain was significantly lower than in the wild-type strain. These results suggest that P. melaninogenica secretes potent virulence factors via the T9SS that contribute to its pathogenic ability.

Real-time PCR quantification of 9 periodontal pathogens in saliva samples from periodontally healthy Korean young adults

Purpose

Few studies have examined periodontal pathogens from saliva samples in periodontally healthy young adults. The purposes of this study were to determine the prevalence of periodontopathic bacteria and to quantify periodontal pathogens in saliva samples using real-time polymerase chain reaction (PCR) assays in periodontally healthy Korean young adults under 35 years of age.

Methods

Nine major periodontal pathogens were analyzed by real-time PCR in saliva from 94 periodontally healthy young adults. Quantification of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Peptostreptococcus anaerobius, and Eikenella corrodens was performed by DNA copy number measurement.

Results

F. nucleatum and E. corrodens were detected in all subjects; the numbers of positive samples were 87 (92.6%), 91 (96.8%), and 90 (95.7%) for P. gingivalis, P. anaerobius, and C. rectus, respectively. Other pathogens were also detected in periodontally healthy subjects. Analysis of DNA copy numbers revealed that the most abundant periodontal pathogen was F. nucleatum, which was significantly more prevalent than all other bacteria (P<0.001), followed by P. anaerobius, P. gingivalis, E. corrodens, C. rectus, and T. denticola. There was no significant difference in the prevalence of each bacterium between men and women. The DNA copy number of total bacteria was significantly higher in men than in women.

Conclusions

Major periodontal pathogens were prevalent in the saliva of periodontally healthy Korean young adults. Therefore, we suggest that the development of periodontal disease should not be overlooked in periodontally healthy young people, as it can arise due to periodontal pathogen imbalance and host susceptibility.

Actinomyces and Alimentary Tract Diseases: A Review of Its Biological Functions and Pathology

Actinomyces are nonmotile, filamentous, Gram-positive bacteria that cause actinomycosis in immunodeficiency patients. Although the prognosis of actinomycosis is good, the diagnosis of actinomycosis is quite difficult. Recent studies on actinomycosis have shown that Actinomyces play an important role in various biological and clinical processes, such as the formation of dental plaque and the degradation of organics in the gastrointestinal tract. Here, the distribution of Actinomyces in the digestive tract, and different biological effects of actinomycosis, and its clinical association with inflammatory diseases are discussed. Furthermore, an overview of the most commonly used treatment methods and drugs used to treat Actinomyces infected alimentary canal diseases is presented.

Oral Biofilm Sampling for Microbiome Analysis in Healthy Children

Oral biofilm and its molecular analysis provide a basis for investigating various dental research and clinical questions. Knowledge of biofilm composition leads to a better understanding of cariogenic and periopathogenic mechanisms. Microbial changes taking place in the oral cavity during childhood are of interest for several reasons. The evolution of the child oral microbiota and shifts in its composition need to be analyzed further to understand and possibly prevent the onset of disease. At the same time, advanced knowledge of the natural composition of oral biofilm is needed. Early stages of caries-free permanent dentition with healthy gums provide a widely unaffected subgingival habitat that can serve as an in situ baseline for studying features of oral health and disease. Analysis of children's oral biofilm during different stages in life is thus an important theme in the field. Modern molecular analysis methods can provide comprehensive information about the bacterial diversity of such biofilms. To enable microbiota data comparison, it is important to standardize each step in the procedure for molecular data generation. This procedure spans from clinical sampling, Next Generation Sequencing (NGS), bioinformatic data processing, to taxonomic interpretation. One of the most critical factors here is biofilm sampling. Sampling in children is even more challenging in particular due to limited space in subgingival areas. We thus focus on the use of paper points for subgingival sampling. This article provides a detailed protocol for oral biofilm sampling of the subgingival sulcus, the mucosa, and saliva in children.

In silico search of inhibitors of Streptococcus mutans for the control of dental plaque

Biofilm is an extremely complex microbial community arranged in a matrix of polysaccharides and attached to a substrate. Its development is crucial in the pathophysiology of oral infections like dental caries, as well as in periodontal, pulp, and periapical diseases. Streptococcus mutans is one of the most effective microorganisms in lactic acid production of the dental biofilm. Identifying essential Streptococcus mutans proteins using bioinformatics methods helps to search for alternative therapies. To this end, the bacterial genomes of several Streptococcus mutans strains and representative strains of other cariogenic and non-cariogenic bacteria were analysed by identifying pathogenicity islands and alignments with other bacteria, and by detecting the exclusive genes of cariogenic species in comparison to the non-pathogenic ones. This study used tools for orthology prediction such as BLAST and OrthoMCL, as well as the server IslandViewer for the detection of pathogenicity islands. In addition, the potential interactome of Streptococcus mutans was rebuilt by comparing it to interologues of other species phylogenetically close to or associated with cariogenicity. This protocol yielded a final list of 20 proteins related to potentially virulent factors that can be used as therapeutic targets in future analyses. The EIIA and EIIC enzymatic subunits of the phosphotransferase system (PTS) were prioritized, as well as the pyruvate kinase enzyme, which are directly involved in the metabolism of carbohydrates and in obtaining the necessary energy for the microorganism's survival. These results will guide a subsequent experimental trial to develop new, safe, and effective molecules in the treatment of dental caries.

Potassium is a key signal in host-microbiome dysbiosis in periodontitis

Dysbiosis, or the imbalance in the structural and/or functional properties of the microbiome, is at the origin of important infectious inflammatory diseases such as inflammatory bowel disease (IBD) and periodontal disease. Periodontitis is a polymicrobial inflammatory disease that affects a large proportion of the world's population and has been associated with a wide variety of systemic health conditions, such as diabetes, cardiovascular and respiratory diseases. Dysbiosis has been identified as a key element in the development of the disease. However, the precise mechanisms and environmental signals that lead to the initiation of dysbiosis in the human microbiome are largely unknown. In a series of previous in vivo studies using metatranscriptomic analysis of periodontitis and its progression we identified several functional signatures that were highly associated with the disease. Among them, potassium ion transport appeared to be key in the process of pathogenesis. To confirm its importance we performed a series of in vitro experiments, in which we demonstrated that potassium levels a increased the virulence of the oral community as a whole and at the same time altering the immune response of gingival epithelium, increasing the production of TNF-α and reducing the expression of IL-6 and the antimicrobial peptide human β-defensin 3 (hBD-3). These results indicate that levels of potassium in the periodontal pocket could be an important element in of dysbiosis in the oral microbiome. They are a starting point for the identification of key environmental signals that modify the behavior of the oral microbiome from a symbiotic community to a dysbiotic one.

Homeostasis of the human microbiome plays a key role in maintaining the healthy status of the human body. Changes in composition and function of the human microbiome (dysbiosis) are at the origin of important infectious inflammatory diseases such as inflammatory bowel disease (IBD) and periodontal disease. However, the environmental elements that trigger the development of dysbiotic diseases are largely unknown. In previous studies, using community-wide transcriptome analysis, we identified ion potassium transport as one of the most important functions in the pathogenesis of periodontitis and its progression. Here, we confirm with a series of in vitro experiments that potassium can act as an important signal in the dysbiotic process inducing pathogenesis in the oral microbiome and altering the host response in front of the microbial challenge that could lead to microbial immune subversion. Our study provides new insights into the important role that ion potassium plays a signal in oral dysbiosis during periodontitis.

Sampling Modification Effects in the Subgingival Microbiome Profile of Healthy Children

Background: Oral microbiota are considered major players in the development of periodontal diseases. Thorough knowledge of intact subgingival microbiomes is required to elucidate microbial shifts from health to disease.

Aims: This comparative study investigated the subgingival microbiome of healthy children, possible inter- and intra-individual effects of modified sampling, and basic comparability of subgingival microprints.

Methods: In five 10-year-old children, biofilm was collected from the upper first premolars and first molars using sterilized, UV-treated paper-points inserted into the subgingival sulcus at eight sites. After supragingival cleaning using an electric toothbrush and water, sampling was performed, firstly, excluding (Mode A) and, secondly, including (Mode B) cleansing with sterile cotton pellets. DNA was extracted from the pooled samples, and primers targeting 16S rRNA hypervariable regions V5 and V6 were used for 454-pyrosequencing. Wilcoxon signed rank test and t-test were applied to compare sampling modes. Principal coordinate analysis (PCoA) and average agglomerative hierarchical clustering were calculated with unweighted UniFrac distance matrices. Sample grouping was tested with permutational MANOVA (Adonis).

Results: Data filtering and quality control yielded 67,218 sequences with an average sequence length of 243bp (SD 6.52; range 231–255). Actinobacteria (2.8–24.6%), Bacteroidetes (9.2–25.1%), Proteobacteria (4.9–50.6%), Firmicutes (16.5–57.4%), and Fusobacteria (2.2–17.1%) were the five major phyla found in all samples. Differences in microbial abundances between sampling modes were not evident. High sampling numbers are needed to achieve significance for rare bacterial phyla. Samples taken from one individual using different sampling modes were more similar to each other than to other individuals' samples. PCoA and hierarchical clustering showed a grouping of the paired samples. Permutational MANOVA did not reveal sample grouping by sampling modes (p = 0.914 by R² = 0.09).

Conclusion: A slight modification of sampling mode has minor effects corresponding to a natural variability in the microbiome profiles of healthy children. The inter-individual variability in subgingival microprints is greater than intra-individual differences. Statistical analyses of microbial populations should consider this baseline variability and move beyond mere quantification with input from visual analytics. Comparative results are difficult to summarize as methods for studying huge datasets are still evolving. Advanced approaches are needed for sample size calculations in clinical settings.

Detection of selected periodontal bacteria in preschool children affected by early childhood caries

The aim of this study was to compare the detection frequency of periodontal bacteria in dental plaque in children with early childhood caries (ECC) with and without gingival inflammation. A convenience sample of 25 preschool children (mean age 3.61 years, SD 1.42) was recruited. Dental plaque was taken from periodontal areas with and without visible signs of inflammation and processed using the StomaGene® (Protean s.r.o. Czech Republic) and ParoCheck® 20 (Greiner Bio-one GmbH, Germany) detection kits. The two sample t tests between percents for differences between inflammatory and healthy sites and kappa statistics for the agreement of both systems were used. At the inflammatory sites, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans were significantly more frequently detected by StomaGene® while Fusobacterium nucleatum, A. actinomycetemcomitans, Tanarella forsythia and Prevotella intermedia were significantly more frequently identified by ParoCheck® test. The agreement between the two detection systems was substantial for A. actinomycetemcomitans and F. nucleatum in the samples collected from inflamed sites and only for F. nucleatum from clinically healthy sites. Therefore, we recommend that the same system should be used when the same patient is examined repeatedly.

Bacterial Diversity and Community Structure of Supragingival Plaques in Adults with Dental Health or Caries Revealed by 16S Pyrosequencing

Dental caries has a polymicrobial etiology within the complex oral microbial ecosystem. However, the overall diversity and structure of supragingival plaque microbiota in adult dental health and caries are not well understood. Here, 160 supragingival plaque samples from patients with dental health and different severities of dental caries were collected for bacterial genomic DNA extraction, pyrosequencing by amplification of the 16S rDNA V1–V3 hypervariable regions, and bioinformatic analysis. High-quality sequences (2,261,700) clustered into 10,365 operational taxonomic units (OTUs; 97% identity), representing 453 independent species belonging to 122 genera, 66 families, 34 orders, 21 classes, and 12 phyla. All groups shared 7522 OTUs, indicating the presence of a core plaque microbiome. α diversity analysis showed that the microbial diversity in healthy plaques exceeded that of dental caries, with the diversity decreasing gradually with the severity of caries. The dominant phyla of plaque microbiota included Bacteroidetes, Actinobacteria, Proteobacteria, Firmicutes, Fusobacteria, and TM7. The dominant genera included Capnocytophaga, Prevotella, Actinomyces, Corynebacterium, Neisseria, Streptococcus, Rothia, and Leptotrichia. β diversity analysis showed that the plaque microbial community structure was similar in all groups. Using LEfSe analysis, 25 differentially abundant taxa were identified as potential biomarkers. Key genera (27) that potentially contributed to the differential distributions of plaque microbiota between groups were identified by PLS-DA analysis. Finally, co-occurrence network analysis and function predictions were performed. Treatment strategies directed toward modulating microbial interactions and their functional output should be further developed.

Supragingival Microbial Profiles of Permanent and Deciduous Teeth in Children with Mixed Dentition

Objectives

The present study was designed to investigate the microbial profiles of teeth in different locations in mixed-dentition-stage children, and to compare the microbiomes of permanent and deciduous teeth in the same healthy oral cavity.

Methods

Supragingival plaque samples of teeth in various locations—the first permanent molars, deciduous molars, deciduous canines and incisors and permanent incisors—were collected from 20 healthy mixed-dentition-stage children with 10–12 permanent teeth erupted. Plaque DNA was extracted, and the V3–V4 hypervariable region of the bacterial 16S rRNA gene was amplified and subjected to sequencing.

Results

On average, 18,051 high-quality sequences per sample were generated. Permanent tooth sites tended to host more diverse bacterial communities than those of deciduous tooth sites. A total of 12 phyla, 21 classes, 38 orders, 66 families, 74 genera were detected ultimately. Five predominant phyla (Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria and Actinobacteria) were highly variable among sites. Of 26 genera with a mean relative abundance of >0.1%, 16 showed significant differences in relative abundance among the groups. More than 20% of the total operational taxonomical units were detected only in permanent or deciduous teeth. The variation in the microbial community composition was due mainly to permanent teeth being enriched in Actinomyces and deciduous teeth in Treponema. The core microbiome of supragingival plaque in mixed dentition comprised 19 genera with complex correlationships.

Conclusion

Our results suggest differences in microbial diversity and composition between permanent and deciduous teeth sites in mixed dentition. Moreover, the core microbiome of these sites was determined. These findings enhance our understanding of the development of the native oral microbiota with age.

Microbiology of aggressive periodontitis

For decades, Aggregatibacter actinomycetemcomitans has been considered the most likely etiologic agent in aggressive periodontitis. Implementation of DNA-based microbiologic methodologies has considerably improved our understanding of the composition of subgingival biofilms, and advanced open-ended molecular techniques even allow for genome mapping of the whole bacterial spectrum in a sample and characterization of both the cultivable and not-yet-cultivable microbiota associated with periodontal health and disease. Currently, A. actinomycetemcomitans is regarded as a minor component of the resident oral microbiota and as an opportunistic pathogen in some individuals. Its specific JP2 clone, however, shows properties of a true exogenous pathogen and has an important role in the development of aggressive periodontitis in certain populations. Still, limited data exist on the impact of other microbes specifically in aggressive periodontitis. Despite a wide heterogeneity of bacteria, especially in subgingival samples collected from patients, bacteria of the red complex in particular, and those of the orange complex, are considered as potential pathogens in generalized aggressive periodontitis. These types of bacterial findings closely resemble those found for chronic periodontitis, representing a mixed polymicrobial infection without a clear association with any specific microorganism. In aggressive periodontitis, the role of novel and not-yet-cultivable bacteria has not yet been elucidated. There are geographic and ethnic differences in the carriage of periodontitis-associated microorganisms, and they need to be taken into account when comparing study reports on periodontal microbiology in different study populations. In the present review, we provide an overview on the colonization of potential periodontal pathogens in childhood and adolescence, and on specific microorganisms that have been suspected for their role in the initiation and progression of aggressive forms of periodontal disease.

Towards microbiome transplant as a therapy for periodontitis: an exploratory study of periodontitis microbial signature contrasted by oral health, caries and edentulism

BACKGROUND

Conventional periodontal therapy aims at controlling supra- and subgingival biofilms. Although periodontal therapy was shown to improve periodontal health, it does not completely arrest the disease. Almost all subjects compliant with periodontal maintenance continue to experience progressive clinical attachment loss and a fraction of them loses teeth. An oral microbial transplant may be a new alternative for treating periodontitis (inspired by fecal transplant). First, it must be established that microbiomes of oral health and periodontitis are distinct. In that case, the health-associated microbiome could be introduced into the oral cavity of periodontitis patients. This relates to the goals of our study: (i) to assess if microbial communities of the entire oral cavity of subjects with periodontitis were different from or oral health contrasted by microbiotas of caries and edentulism patients; (ii) to test in vitro if safe concentration of sodium hypochlorite could be used for initial eradication of the original oral microbiota followed by a safe neutralization of the hypochlorite prior transplantation.

METHODS

Sixteen systemically healthy white adults with clinical signs of one of the following oral conditions were enrolled: periodontitis, established caries, edentulism, and oral health. Oral biofilm samples were collected from sub- and supra-gingival sites, and oral mucosae. DNA was extracted and 16S rRNA genes were amplified. Amplicons from the same patient were pooled, sequenced and quantified. Volunteer's oral plaque was treated with saline, 16 mM NaOCl and NaOCl neutralized by ascorbate buffer followed by plating on blood agar.

RESULTS

Ordination plots of rRNA gene abundances revealed distinct groupings for the oral microbiomes of subjects with periodontitis, edentulism, or oral health. The oral microbiome in subjects with periodontitis showed the greatest diversity harboring 29 bacterial species at significantly higher abundance compared to subjects with the other assessed conditions. Healthy subjects had significantly higher abundance in 10 microbial species compared to the other conditions. NaOCl showed strong antimicrobial properties; nontoxic ascorbate was capable of neutralizing the hypochlorite.

CONCLUSIONS

Distinct oral microbial signatures were found in subjects with periodontitis, edentulism, or oral health. This finding opens up a potential for a new therapy, whereby a health-related entire oral microbial community would be transplanted to the diseased patient.