Human Oral Microbiome Database Research Articles

Insights into microorganisms, associated factors, and the oral microbiome in infective endocarditis patients.

Infective Endocarditis (IE) is a rare, life-threatening infection of the endocardium with multisystem effects. Culprit microorganisms derived from different niches circulate through the bloodstream and attach to the endocardium, particularly the heart valves. This study aimed to investigate culprit microorganisms among a cross-sectional cohort of IE patients, their associated factors, and to explore the potential relationship to the oral microbiome. In this observational study, we undertook a cross-sectional analysis of 392 medical records from patients diagnosed with IE. The primary outcome of this study was to analyse the association between the IE culprit microorganisms and the underlying anatomical types of IE (native valve (NVE), prosthetic valve (PVE), or cardiac device-related (CDE)). Secondary outcomes encompassed a comparative analysis of additional factors, including: the treatment approaches for IE, and the categorisation of blood cultures, extending to both genus and species levels. Additionally, we cross-referenced and compared the species-level identification of IE bacteraemia outcome measures with data from the expanded Human Oral Microbiome Database (eHOMD). A culprit microorganism was identified in 299 (76.28%) case participants. Staphylococcal infections were the most common (p < 0.001), responsible for 130 (33.16%) hospitalisations. There were 277 (70.66%) cases of NVE, 104 (26.53%) cases of PVE, and 11 (2.81%) cases of CDE. The majority of PVE occurred on prosthetic aortic valves (78/104, 75%), of which 72 (93.5%) were surgical aortic valve replacements (SAVR), 6 (7.8%) were transcatheter aortic valve implants, and one transcatheter pulmonary valve implant. Overall, underlying anatomy (p = 0.042) as well as the treatment approaches for IE (p < 0.001) were significantly associated with IE culprit microorganisms. Cross-reference between IE bacteraemia outcomes with the eHOMD was observed in 267/392 (68.11%) cases. This study demonstrated that IE patients with a history of stroke, smoking, intravenous drug use, or dialysis were more likely to be infected with Staphylococcus aureus. CDE case participants and patients who had previous SAVR were most associated with Staphylococcus epidermidis. IE patients aged 78+ were more likely to develop enterococci IE than other age groups. Oral microorganisms indicated by the eHOMD are significantly observed in the IE population. Further research, through enhanced dental and medical collaboration, is required to correlate the presence of oral microbiota as causative factor for IE.

Exploring the presence of oral bacteria in non-oral sites of patients with cardiovascular diseases using whole metagenomic data

Cardiovascular diseases (CVDs) encompass various conditions affecting the heart and its blood vessels and are often linked with oral microbes. Our data analysis aimed to identify oral bacteria from other non-oral sites (i.e., gut, arterial plaque and cultured blood) that could be linked with CVDs. Taxonomic profiling identified bacteria to the species level and compared with the Human Oral Microbiome Database (HOMD). The oral bacteria in the gut, cultured blood and arterial plaque samples were catalogued, with their average frequency calculated for each sample. Additionally, data were filtered by comparison with the Human Microbiome Project (HMP) database. We identified 17,243 microbial species, of which 410 were present in the HOMD database and further denominated as “oral”, and were found in at least one gut sample, but only 221 and 169 species were identified in the cultured blood and plaque samples, respectively. Of the 410 species, 153 were present solely in oral-associated environments after comparison with the HMP database, irrespective of their presence in other body sites. Our results suggest a potential connection between the presence of specific species of oral bacterial and occurrence of CVDs. Detecting these oral bacterial species in non-oral sites of patients with CVDs could help uncover the link between oral health and general health, including cardiovascular conditions via bacterial translocation.

Association of Root Biofilm Bacteriome with Root Caries Lesion Severity and Activity

Introduction: This research aimed to assess the association of root biofilm bacteriome with root caries lesion severity and activity in institutionalised Colombian elderlies and was conducted to gather data on the root caries bacteriome in this population. Methods: A bacteriome evaluation of biofilm samples from sound and carious root surfaces was performed. Root caries was categorised (ICDAS Root criteria) based on severity (sound surfaces, initial: non-cavitated, moderate/extensive combined: cavitated) and activity status (active and inactive). DNA was extracted and the V4 region of the 16S rRNA gene was sequenced; afterwards the classification of features was conducted employing amplicon sequence variants and taxonomic assignment via the Human Oral Microbiome Database (HOMD). Bacterial richness, diversity (Simpson’s and Shannon’s indices), and relative abundance estimation were assessed and compared based on root caries severity and activity status (including Sound surfaces). Results: A total of 130 biofilm samples were examined: sound (n = 45) and with root caries lesions (n = 85; by severity: initial: n = 41; moderate/extensive: n = 44; by activity: active: n = 60; inactive: n = 25). Species richness was significantly lower in biofilms from moderate/extensive and active groups compared to sound sites. There was a higher relative abundance of species like Lechtotricia wadei, Capnocytophaga granulosa, Cardiobacterium valvarum, Porphyromonas pasteri – in sound sites; Dialister invisus, Streptococcus mutans, Pseudoramibacter alactolyticus and Bacteroidetes (G-5) bacterium 511 – in moderate/extensive lesions, and Fusobacterium nucleatum subsp. animalis, Prevotella denticola, Lactobacillus fermentum, Saccharibacteria (TM7) (G-5)bacterium HMT 356 – in active lesions. Conclusion: Root caries bacteriome exhibited differences in species proportions between the compared groups. Specifically, cavitated caries lesions and active caries lesions showed higher relative abundance of acidogenic bacteria.

Difference in microbiome compositions of healthy peri-implant sulcus and peri-implantitis sulcus from the same patient

ObjectiveThe objective of this study is to compare the microbiome of healthy peri-implant sulcus (C) and peri-implantitis sulcus (U) from the same patient and analyze the difference in the microbiome composition. Materials and methodsDNA samples of subgingival biofilms from 10 C (control group) and 10 U (uncontrolled group) sites were sent to Microbiome Center in Korea Research Institute of Biomedical Science and analyzed using 16s rRNA gene amplification and sequencing (MiSeq, Illumina) and human oral microbiome database (HOMD). ResultsAt the phylum level, Firmicutes and Proteobacteria were more abundant in group C, while Firmicutes and Bacteroidetes were dominant in group U. At the genus level, the core peri-implant microbiome was Streptococcus in group C. On the other hand, the core peri-implant microbiome was Porphyromonas, especially P. gingivalis in group U. ConclusionIn this study, the microbiome composition of peri-implantitis sulcus was different from that of healthy peri-implant sulcus from the same patient. The peri-implantitis microbiome was pathogen-enriched and was similar to the microbiome associated with periodontitis.

Microbiological profile of peri-implantitis: Analyses of peri-implant microbiome.

To characterize the microbiome composition in peri-implant pocket of peri-implantitis and peri-implant sulcus controls using 16S rRNA gene sequencing. In this controlled clinical cross-sectional study, 23 subjects with control implants (n = 14) and diseased implants (peri-implantitis, n = 21) were included. The peri-implant pocket/sulcus was sampled and used to extract DNA and amplify the 16S rRNA gene using universal primers targeting the V3-V4 regions. The resulting 16S PCR amplicons were sequenced on Illumina MiSeq, and the sequences were processed using DADA2 and the Human Oral Microbiome Database (HOMD) as references. Alpha and Beta diversity, as well as core microbiome and differential abundance analyses, were performed using the MicrobiomeAnalyst workflow. There were no significant differences in microbial diversity between control implants and implants with peri-implantitis (Shannon p = 0.82). Overall bacterial community structure assessed through beta diversity analysis was also not significantly different between the two groups (p = 0.18). However, high levels of Gram-negative bacteria were detected in peri-implant pockets compared to the control sulcus. Abundant species in peri-implantitis were Capnocytophaga leadbetteri, Treponema maltophilum, Peptostreptococcus, Neisseria, P. gingivalis, and Porphyromonas endodontali, Lactococcus lactis and Filifactor alocis (p < 0.05). Gram-positive bacteria such as Streptococcus salivaris, Prevotella melaninogenica, L. wadei, and Actinomyces spp. serve were more abundant in peri-implant control sulcus. Peri-implant sulcus in control implants harbors predominantly Gram-positive bacteria, whereas pockets of implants with peri-implantitis harbor predominantly Gram-negative bacteria.

Comparative Analysis of Primers Used for 16S rRNA Gene Sequencing in Oral Microbiome Studies.

Recent advances in genomic technologies have enabled more in-depth study of the oral microbiome. In this study, we compared the amplicons generated by primers targeting different sites of the 16S rRNA gene found in the Human Oral Microbiome Database (HOMD). Six sets of primer targeting V1-V2, V1-V3, V3-V4, V4-V5, V5-V7 and V6-V8 regions of 16S rRNA were tested via in silico simulation. Primers targeting the V1-V2, V3-V4, and V4-V5 regions generated more than 90% of the original input sequences. Primers targeting the V1-V2 and V1-V3 regions exhibited a low number of mismatches and unclassified sequences at the taxonomic level, but there were notable discrepancies at the species level. Phylogenetic tree comparisons showed primers targeting the V1-V2 and V3-V4 regions showed performances similar to primers targeting the whole 16s RNA region in terms of separating total oral microbiomes and periodontopathogens. In an analysis of clinical oral samples, V1-V2 primers showed superior performance for identifying more taxa and had better resolution sensitivity for Streptococcus than V3-V4 primers. In conclusion, primers targeting the V1-V2 region of 16S rRNA showed the best performance for oral microbiome studies. In addition, the study demonstrates the need for careful PCR primer selections.

The salivary microbiota is altered in cervical dysplasia patients and influenced by conization

The salivary microbiota is altered in cervical dysplasia patients and influenced by conization

Suspension of oral hygiene practices highlights key bacterial shifts in saliva, tongue, and tooth plaque during gingival inflammation and resolution

Experimentally induced gingivitis is associated with inflammatory and microbiological changes in an otherwise healthy subject, demonstrating the impacts of discontinuing oral hygiene routines. Understanding the bacterial dynamics during the induction and resolution of gingival inflammation will aid in the development of bacterial prognostic tests and probiotics for severe oral disease. We profiled the bacterial community in 15 healthy subjects who suspended all oral-hygiene practices for three weeks. Saliva, tongue, subgingival, and supragingival plaque samples were collected over seven weeks and showed a return to community baseline after oral hygiene practices were resumed. Stronger temporal changes in subgingival and supragingival plaque suggest these sample types may be preferred over saliva or tongue plaque for future prognostics. Taxonomic groups spanning ten phyla demonstrated consistent abundance shifts, including a significant decrease in Streptococcus, Neisseria, and Actinomyces populations, and an increase in Prevotella, Fusobacterium, and Porphyromonas populations. With four distinct oral sites surveyed and results mapped to the Human Oral Microbiome Database reference set, this work provides a comprehensive taxonomic catalog of the bacterial shifts observed during the onset and resolution of gingival inflammation.

Short-term sugar stress induces compositional changes and loss of diversity of the supragingival microbiota

ABSTRACT Frequent intake of free sugars is a major risk factor for dental caries, but the immediate influence of sugar intake on the supragingival microbiota remains unknown. We aim to characterize the effect of 14 days of sugar rinsing on the supragingival microbiota. Forty orally and systemically healthy participants rinsed their mouth with a 10% sucrose solution, 6–8 times a day, for 14 days, followed by 14 days without sugar stress. Supragingival plaque samples were collected at baseline, and after 14, and 28 days. The supragingival microbiota was analyzed using 16S rDNA sequencing. Taxonomic classification was performed using the Human Oral Microbiome Database. After 14 days of sugar stress induced by the daily sugar rinses, a significant loss of α-diversity (p = 0.02) and a significant increase in the relative abundance of Actinomyces (6.5% to 9.6%, p = 0.006) and Corynebacterium (6.2% to 9.1%, p = 0.03) species were recorded. In addition, a significant decrease in Streptococcus (10.3% to 6.1%, p = 0.001) species was observed. Sugar-mediated changes returned to baseline conditions 14 days after the last sugar rinse. The present study shows that temporary sugar stress induces loss of diversity and compositional changes to the supragingival microbiota, which are reversible if oral care is maintained.

Microbiological profile of peri-implantitis: Analyses of microbiome within dental implants.

To characterize the microbiome composition within dental implants of peri-implantitis subjects and healthy controls using 16S rRNA gene sequencing. Twenty-three subjects with healthy (n=11 implants) and diseased (peri-implantitis, n=21) implants were included in this controlled clinical cross-sectional study. Samples were obtained from internal surfaces of dental implants using sterile paper points for microbiological analysis. DNA was extracted, and the16S rRNA gene was amplified using universal primers targeting the V3-V4 regions. The resulting 16S polymerize chain reaction amplicons were sequenced on Illumina MiSeq, and the sequences were processed using DADA2 and the Human Oral Microbiome Database (HOMD) as references. Alpha and Beta diversity, as well as core microbiome and differential abundance analyses were then performed using the MicrobiomeAnalyst workflow. A significant increase in microbial diversity was observed in the internal implant surface of healthy implants compared with the internal surfaces of peri-implantitis (Shannon p=0.02). Bacterial community structure was significantly different among groups (p=0.012). High levels of Gram-positive bacteria were detected inside implants with peri-implantitis compared to healthy implants, especially Enterococci. There is a shift in bacterial diversity inside implants with peri-implantitis from the healthy control. The microbial colonization within that space might contribute to the etiology of peri-implant disease.

The mediating roles of the oral microbiome in saliva and subgingival sites between e-cigarette smoking and gingival inflammation

BackgroundElectronic cigarettes (ECs) have been widely used by young individuals in the U.S. while being considered less harmful than conventional tobacco cigarettes. However, ECs have increasingly been regarded as a health risk, producing detrimental chemicals that may cause, combined with poor oral hygiene, substantial inflammation in gingival and subgingival sites. In this paper, we first report that EC smoking significantly increases the odds of gingival inflammation. Then, through mediation analysis, we seek to identify and explain the mechanism that underlies the relationship between EC smoking and gingival inflammation via the oral microbiome.MethodsWe collected saliva and subgingival samples from 75 EC users and 75 non-users between 18 and 34 years in age and profiled their microbial compositions via 16S rRNA amplicon sequencing. We conducted raw sequence data processing, denoising and taxonomic annotations using QIIME2 based on the expanded human oral microbiome database (eHOMD). We then created functional annotations (i.e., KEGG pathways) using PICRUSt2.ResultsWe found significant increases in α-diversity for EC users and disparities in β-diversity between EC users and non-users. We also found significant disparities between EC users and non-users in the relative abundance of 36 microbial taxa in the saliva site and 71 microbial taxa in the subgingival site. Finally, we found that 1 microbial taxon in the saliva site and 18 microbial taxa in the subgingival site significantly mediated the effects of EC smoking on gingival inflammation. The mediators on the genus level, for example, include Actinomyces, Rothia, Neisseria, and Enterococcus in the subgingival site. In addition, we report significant disparities between EC users and non-users in the relative abundance of 71 KEGG pathways in the subgingival site.ConclusionsThese findings reveal that continued EC use can further increase microbial dysbiosis that may lead to periodontal disease. Our findings also suggest that continued surveillance for the effect of ECs on the oral microbiome and its transmission to oral diseases is needed.

Comparison of Microbial Composition of Natural Teeth and Implants by 16S rRNA Gene Sequencing.

Exploring variations in the oral microbiome that predict the early stages of oral diseases could lead to more accurate diagnosis and therapy before the disease manifests clinically. This study compared the bacterial profile around prosthesis on natural teeth and implants in a healthy oral cavity. Fifteen participants with prosthesis on natural teeth and 15 participants with implants were recruited. All participants were periodontally healthy. Plaque samples were collected and then subjected to PCR amplification with 16S rRNA gene sequencing. Using the BlastN program, the sequenced data were compared to reference bacterial gene sequences in the Human Oral Microbiome Database. Finally, bacterial species in both groups' samples were identified, and a phylogenetic tree was created to compare the bacterial profile around prosthesis on natural teeth and implants. Microorganisms identified were Streptococcus, Fusobacterium, Corynebacterium, Micrococcus, Aeromonas, Leptotrichia, and Dechloromonas species; around implants were Streptococcus, Fusobacterium, Corynebacterium, Prevotella, Eikenella, Nisseria, Rothia, Aeromonas, Leptotrichia, and Actinomyces species. On comparing the bacterial profile around prosthesis on natural teeth and implants in periodontally healthy individuals, pathogenic bacterial species including Fusobacterium nucleatum, Prevotella intermedia, and Eikenella corrodens were identified around implants.

Microbiota of preterm infant develops over time along with the first teeth eruption.

The temporal growth of the infant microbiome in the early years of life influences short- and long-term infant health. The aim of this longitudinal study was to investigate bacterial dynamics in the microbiome of preterm infants during tooth eruption. Saliva samples from normally delivered (n = 24) and preterm infants (n = 31) were collected 30 days after birth and after the eruption of two primary mandibular incisors. Based on Illumina MiSeq Sequencing of the 16S rRNA gene, the dynamic microbial changes of newborns at two-time points were investigated. Meanwhile, the Human Oral Microbiome Database was adopted for assigning taxonomy. Using alpha and beta diversity analyses, different shift patterns of microbiome structures in preterm and healthy participants and bacterial diversity over time were observed. The relative abundance and shifts trend, along with the two lower primary central incisors eruption, of core oral flora varies in full-term and preterm groups, including Gemella spp., Rothia mucilaginosa, Veillonella atypica, etc. Several microorganisms colonize later in the oral microbiome development of premature babies, such as Gemella spp. In addition to teeth eruption, the growth of the saliva microbiome in preterm infants could be influenced by breastfeeding durations and birth weight. This study provided insights into how the oral microbiota changes during tooth eruption in preterm infants and how the colonization of the oral cavity with bacteria in preterm infants differs significantly from that in full-term infants.

Plaque Microbiome in Caries-Active and Caries-Free Teeth by Dentition.

Describe associations between dental caries and dental plaque microbiome, by dentition and family membership. This cross-sectional analysis included 584 participants in the Center for Oral Health Research in Appalachia Cohort 1 (COHRA1). We sequenced the 16S ribosomal RNA gene (V4 region) of frozen supragingival plaque, collected 10 y prior, from 185 caries-active (enamel and dentinal) and 565 caries-free (no lesions) teeth using the Illumina MiSeq platform. Sequences were filtered using the R DADA2 package and assigned taxonomy using the Human Oral Microbiome Database. Microbiomes of caries-active and caries-free teeth were most similar in primary dentition and least similar in permanent dentition, but caries-active teeth were significantly less diverse than caries-free teeth in all dentition types. Streptococcus mutans had greater relative abundance in caries-active than caries-free teeth in all dentition types (P < 0.01), as did Veillonella dispar in primary and mixed dentition (P < 0.01). Fusobacterium sp. HMT 203 had significantly higher relative abundance in caries-free than caries-active teeth in all dentition types (P < 0.01). In a linear mixed model adjusted for confounders, the relative abundance of S. mutans was significantly greater in plaque from caries-active than caries-free teeth (P < 0.001), and the relative abundance of Fusobacterium sp. HMT 203 was significantly lower in plaque from caries-active than caries-free teeth (P < 0.001). Adding an effect for family improved model fit for Fusobacterium sp. HMT 203 but notS. mutans. The diversity of supragingival plaque composition from caries-active and caries-free teeth changed with dentition, but S. mutans was positively and Fusobacterium sp. HMT 203 was negatively associated with caries regardless of dentition. There was a strong effect of family on the associations of Fusobacterium sp. HMT 203 with the caries-free state, but this was not true for S. mutans and the caries-active state. Patients' and dentists' concerns about transmission of bacteria within families causing caries should be tempered by the evidence that some shared bacteria may contribute to good oral health.

Differences in the subgingival microbiome according to stage of periodontitis: A comparison of two geographic regions

No microbiological criteria were included in the 2018 EFP-AAP classification of periodontal diseases that could be used to differentiate between stages and grades. Furthermore, differences in the subgingival microbiome depending on stage and grade have not been established. Sixty subgingival biofilm samples were collected in Spain (n = 30) and Colombia (n = 30) from three distinct patient categories: those with periodontal health/gingivitis (n = 20), those with stage I-II periodontitis (n = 20), and those with stage III-IV periodontitis (n = 20). Patients were evaluated by 16S rRNA gene amplification sequencing. Amplicon sequence variants were used to assign taxonomic categories compared to the Human Oral Microbiome Database (threshold ≥97% identity). Alpha diversity was established by Shannon and Simpson indices, and principal coordinate analysis, ANOSIM, and PERMANOVA of the UNIFRAC distances were performed using QIIME2. Although differences in the alpha diversity were observed between samples according to country, Filifactor alocis, Peptostreptococcaceae [XI][G-4] bacterium HMT 369, Fretibacterium fastidiosum, Lachnospiraceae [G-8] bacterium HMT 500, Peptostreptococcaceae [XI][G-5] [Eubacterium] saphenum, Peptostreptococcus stomatis, and Tannerella forsythia were associated with periodontitis sites in all stages. However, only F. alocis, Peptostreptococcaceae [XI][G-4] bacterium HMT 369, Peptostreptococcaceae [XI][G-9] [Eubacterium] brachy, Peptostreptococcaceae [XI][G-5] [Eubacterium] saphenum, and Desulfobulbus sp. HMT 041 were consistent in stage III-IV periodontitis in both countries. Porphyromonas gingivalis and Tannerella forsythia were differentially expressed in severe lesions in the countries studied. Although some non-cultivable microorganisms showed differential patterns between the different stages of periodontitis, they were not the same in the two countries evaluated. Further studies using larger samples with advanced next-generation techniques for high-throughput sequencing of phyla and non-cultivable bacteria within the subgingival microbiome could provide more insight into the differences between stages of periodontitis.

Oral ecological environment modifications by hard-cheese: from pH to microbiome: a prospective cohort study based on 16S rRNA metabarcoding approach

BackgroundThe oral ecosystem conditions dental health, and is known to be positively modified by oral hygiene which cannot always be performed between meals, especially outside home. It is therefore important to identify the practices to be adopted to influence the oral environment in an anticariogenic direction. Milk and cheese are considered functional foods and have a role on oral health. There are several mechanisms by which cheese exerts its beneficial effects on teeth. The aim of the present study was to examine whether short term consumption of hard cheese would affect the oral pH and microbial flora of healthy adults modifying ecological oral environment. The Next Generation Sequencing (NGS) approach was applied to study the effect of Italian Grana Padano (GP), as a prototype of typical hard cheese, on the oral microbiota composition. Finally, we explored Streptococcusmutans/sanguinis ratio as a marker of protective biofilm composition.MethodsNine oral-healthy adults were instructed to eat 25 gr of GP cheese for 5 consecutive days. Three time points were chosen for supragingival samples collection and pH measurement. 16S rRNA-gene sequences were obtained both from oral samples and GP cheese using the MiSeq platform and analyzed against the expanded Human Oral Microbiome Database (eHOMD). ProgPerm was used to perform statistical analyses to investigate strain differential representation after cheese consumption.ResultsTaxonomic analyses of the oral microbiota revealed that Firmicutes was the most abundant phylum, followed by Proteobacteria and Actinobacteria. GP cheese significantly modifies oral pH, causing a shift toward basic conditions which are kept for a few hours. The Streptococcus mutans/Streptococcus sanguinis ratio lowers in the last observed timepoint.ConclusionOur results reveal that a portion of GP cheese eaten after dinner provides important micronutrients (i.e. calcium, vitamins and some aminoacids such as arginine) and changes oral pH toward basic conditions, resulting in a light modification of the oral microbiome towards the reduction of the overall amount of acidophilic bacteria. Furthermore, the S.mutans/S. sanguinis ratio is reduced, contributing to obtain a more protecting environment towards caries establishment and evolution.

Site- and Time-Dependent Compositional Shifts in Oral Microbiota Communities.

ObjectivesThe oral microbiota plays a significant role in oral health. The present study aims to characterize variations in the oral microbiota relative to the collection site, the dynamics of biofilm accumulation, and inherent inter-individual differences.MethodsWhole stimulated saliva and tooth biofilm samples from the 16 defined tooth regions were collected after 1, 2, or 3 days without oral hygiene (accumulation time) in six healthy adults with no signs of active caries or periodontal disease. The routines and conditions before and between sample collections were carefully standardized. Genomic DNA was extracted, and the V3-V4 regions of the 16S rRNA gene were amplified by PCR and sequenced on an Illumina MiSeq platform. Sequences were quality controlled, amplicon sequence variants (ASVs) were clustered, and taxonomic allocation was performed against the expanded Human Oral Microbiome Database (eHOMD). Microbial community profiles were analyzed by multivariate modeling and a linear discriminant analysis (LDA) effect size (LEfSe) method.ResultsThe overall species profile in saliva and tooth biofilm differed between participants, as well as sample type, with a significantly higher diversity in tooth biofilm samples than saliva. On average, 45% of the detected species were shared between the two sample types. The microbiota profile changed from the most anterior to the most posterior tooth regions regardless of whether sampling was done after 1, 2, or 3 days without oral hygiene. Increasing accumulation time led to higher numbers of detected species in both the saliva and region-specific tooth biofilm niches.ConclusionThe present study confirms that the differences between individuals dominate over sample type and the time abstaining from oral hygiene for oral microbiota shaping. Therefore, a standardized accumulation time may be less important for some research questions aiming at separating individuals. Furthermore, the amount of DNA is sufficient if at least two teeth are sampled for microbiota characterization, which allows a site-specific characterization of, for example, caries or periodontitis.

Inside the Oral Microbiome: How Periodontitis May Increase the Risk for Alzheimers Disease

Abstract: The oral microbiome is the site of the second most abundant microbiota after the gastrointestinal tract. The expanded Human Oral Microbiome Database (eHOMD) that was last updated on November 22, 2017, contains the information of a number of bacterial species, scientists have struggled to categorize and understand every species due to their difficulty of laboratory study. While this much is known, the scientific community still has minimal knowledge of the entire oral microbiome and how it may relate to potential manifestations of various diseases. Periodontitis is one disease that is directly related to the oral microbiome. Periodontitis is the infection of the gums that is associated with poor dental hygiene. This oral malady has been hypothesized to be a potential precursor to neurological Alzheimer’s disease (AD.) Since AD is difficult to study until postmortem, there has been limited availability to study pathways where this may occur. The proposed method by which periodontitis, while primarily hypothesized, includes a shift in the microbiota of the oral cavity to a more pathogenic state. The shift to pathogenicity is mainly believed to be due to an increase in the bacterium Porphyromonas gingivalis. P. gingivalis produces protein plaques on the teeth that can travel through the bloodstream to the brain. The proposed mechanism is hypothesized to weaken the blood-brain barrier and allow for plaque aggregation on the brain seen in AD-infected brains. While more research is necessary to conclude the pathogenesis from periodontitis to Alzheimer’s disease definitively, strides are being made that may help give scientists, and healthcare workers begin preventative measures.

Prevotella illustrans sp. nov., derived from human oropharyngeal abscess puncture fluid.

An obligately anaerobic strain, designated as A2931T, was isolated from oropharyngeal abscess puncture fluid of a patient sampled during routine care at a hospital and further characterized both phenotypically, biochemically and genotypically. This Gram-negative rod-shaped bacterium was moderately saccharolytic and proteolytic. Phylogenetic analyses of full-length 16S rRNA gene and whole-genome sequences revealed it to be best placed in the genus Prevotella, but to be only comparatively distantly related to recognized species, with the closest relationship to Prevotella baroniae (average nucleotide identity and digital DNA-DNA hybridization values both well below the generally accepted thresholds). Strain A2931T had a genomic DNA G+C content of 47.7 mol%. Its most abundant cellular long-chain fatty acids were anteiso-C15 : 0, iso-C15 : 0 and C16 : 0. Taken together, this polyphasic data suggests strain A2931T to represent a novel species within the genus Prevotella, for which the name Prevotella illustrans sp. nov. is proposed. The type strain is A2931T (=DSM 108028T=CCOS 1232T=CCUG 72806T). Interestingly, we found strain A2931T to correspond to the oral taxon Prevotella HMT-820 in the Human Oral Microbiome Database, as supported by overall genome relatedness index analyses >99 %. Thus, our work not only closes one of the gaps of knowledge about hitherto unnamed species isolated from humans, but also will facilitate identification of this taxon both in the clinical microbiology context and in research alike.

Oral Microbiota Identifies Patients in Early Onset Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is the most common autoimmune inflammatory disease, and single periodontitis-associated bacteria have been suggested in disease manifestation. Here, the oral microbiota was characterized in relation to the early onset of RA (eRA) taking periodontal status into consideration. 16S rRNA gene amplicon sequencing of saliva bacterial DNA from 61 eRA patients without disease-modifying anti-rheumatic drugs and 59 matched controls was performed. Taxonomic classification at 98.5% was conducted against the Human Oral Microbiome Database, microbiota functions were predicted using PICRUSt, and periodontal status linked from the Swedish quality register for clinically assessed caries and periodontitis. The participants were classified into three distinct microbiota-based cluster groups with cluster allocation differences by eRA status. Independently of periodontal status, eRA patients had enriched levels of Prevotella pleuritidis, Treponema denticola, Porphyromonas endodontalis and Filifactor alocis species and in the Porphyromonas and Fusobacterium genera and functions linked to ornithine metabolism, glucosylceramidase, beta-lactamase resistance, biphenyl degradation, fatty acid metabolism and 17-beta-estradiol-17-dehydrogenase metabolism. The results support a deviating oral microbiota composition already in eRA patients compared with healthy controls and highlight a panel of oral bacteria that may be useful in eRA risk assessment in both periodontally healthy and diseased persons.