Genomic Diversity among Strains and Closely Related Species.

The aim of this study was to investigate and clarify the ambiguous taxonomy of and its closely related species using state-of-the-art high-throughput sequencing techniques, and, furthermore, to determine whether sub-clusters identified within and in a previous study by multi locus sequence typing (MLST) using concatenation of seven housekeeping genes should either be classified as subspecies or distinct species. The strains in this study were broadly classified under group as genospecies I and genospecies II. Based on MLST data analysis, these were further classified as and .

Role of microbial biofilms in the maintenance of oral health and in the development of dental caries and periodontal diseases. Consensus report of group 1 of the Joint EFP/ORCA workshop on the boundaries between caries and periodontal disease.

Background And Aims: The scope of this working group was to review (1) ecological interactions at the dental biofilm in health and disease, (2) the role of microbial communities in the pathogenesis of periodontitis and caries, and (3) the innate host response in caries and periodontal diseases.

Results And Conclusions: A health-associated biofilm includes genera such as Neisseria, Streptococcus, Actinomyces, Veillonella and Granulicatella. Microorganisms associated with both caries and periodontal diseases are metabolically highly specialized and organized as multispecies microbial biofilms.

Isolation of Propionibacterium acnes among the microbiota of primary endodontic infections with and without intraoral communication.

Objectives: The presence of opportunistic pathogens such as Propionibacterium acnes (P. acnes) may contribute to the endodontic pathology. The presence of P.

Acidogenicity of dual-species biofilms of bifidobacteria and Streptococcus mutans.

Objective: The aim of this study was to evaluate the acidogenicity of dual-species biofilms of bifidobacteria and Streptococcus mutans.

Materials And Methods: The following strains were tested: Bifidobacterium dentium DSM20436, Parascardovia denticolens DSM10105, and Scardovia inopinata DSM10107. Streptococcus mutans UA159 and Lactobacillus acidophilus ATCC4356 were used as control.

Bifidobacteria inhibit the growth of Porphyromonas gingivalis but not of Streptococcus mutans in an in vitro biofilm model.

There is growing interest in the use of probiotic bifidobacteria for enhancement of the therapy, and in the prevention, of oral microbial diseases. However, the results of clinical studies assessing the effects of bifidobacteria on the oral microbiota are controversial, and the mechanisms of actions of probiotics in the oral cavity remain largely unknown. In addition, very little is known about the role of commensal bifidobacteria in oral health.

Influence of saliva on the oral microbiota.

Saliva plays a major role in determining the composition and activity of the oral microbiota, via a variety of mechanisms. Molecules, mainly from saliva, form a conditioning film on oral surfaces, thus providing receptors for bacterial attachment. The attached cells use saliva components, such as glycoproteins, as their main source of nutrients for growth.

Transcriptomic analysis of three Veillonella spp. present in carious dentine and in the saliva of caries-free individuals.

Veillonella spp. are predominant bacteria found in all oral biofilms. In this study, a metatranscriptomic approach was used to investigate the gene expression levels of three oral Veillonella spp.

Identification of the 'Streptococcus anginosus group' by matrix-assisted laser desorption ionization--time-of-flight mass spectrometry.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) provides rapid, accurate and cost-effective identification of a range of bacteria and is rapidly changing the face of routine diagnostic microbiology. However, certain groups of bacteria, for example streptococci (in particular viridans or non-haemolytic streptococci), are less reliably identified by this method. We studied the performance of MALDI-TOF MS for identification of the 'Streptococcus anginosus group' (SAG) to species level.

The effectiveness of enzymic irrigation in removing a nutrient-stressed endodontic multispecies biofilm.

Aim: To establish a nutrient-stressed multispecies model biofilm and investigate the dynamics of biofilm killing and disruption by 1% trypsin and 1% proteinase K with or without ultrasonic activation.

Methodology: Nutrient-stressed biofilms (Propionibacterium acnes, Staphylococcus epidermidis, Actinomyces radicidentis, Streptococcus mitis and Enterococcus faecalis OMGS 3202) were grown on hydroxyapatite discs and in prepared root canals of single-rooted teeth in modified fluid universal medium. The treatment groups included trypsin, proteinase K, 0.

Oral health patterns of independently living dentate older people: a cross-sectional survey of dental attendees in south-east London.

Background: The oral health needs of older adults present increasing challenges to dental services.

Objectives: To examine the clinical oral health status of dentate older people living in the community and attending dental services.

Methods: One hundred and eighty-six dentate adults, aged ≥60 years, underwent clinical examination (DMFS, Plaque and Gingival Indexes), salivary analysis and completed a questionnaire.

Evolutionary and population genomics of the cavity causing bacteria Streptococcus mutans.

Streptococcus mutans is widely recognized as one of the key etiological agents of human dental caries. Despite its role in this important disease, our present knowledge of gene content variability across the species and its relationship to adaptation is minimal. Estimates of its demographic history are not available.

Dental caries from a molecular microbiological perspective.

Dental caries results from an imbalance of the metabolic activity in the dental biofilm. The microbial communities of teeth have traditionally been studied by standard cultural approaches. More recently, cloning and sequencing of the 16S rRNA gene have been used to characterize the microbial composition of the oral biofilm, but the methodological limitations of this approach have now been recognized.

Multidisciplinary research agenda for novel antimicrobial agents for caries prevention and treatment.

Antimicrobial methods to augment fluoride-mediated caries inhibition are necessary. Several methods are described here, but none was considered likely to be as effective as fluoride usage. None had been tested in effective models to demonstrate their ability to act either additively or synergistically with fluoride-containing toothpastes.

The potential benefits of sugar-free chewing gum on the oral health and quality of life of older people living in the community: a randomized controlled trial.

Objectives: To determine the effects of prescribing sugar-free chewing gum on the oral health and quality of life of dentate older people living in the community and attending for routine dental care.

Methods: A randomized controlled trial was conducted on 186 older people who were not regular chewers of gum, (aged 60 years and over with ≥ 6 teeth) recruited from primary care clinics. Participants were randomly allocated to a gum-chewing group (chewing xylitol-containing gum twice a day for 15 min; n = 95) or a control group (no gum; n = 91).

Fluoride-supplemented milk inhibits acid tolerance in root caries biofilms.

In this study we investigated the effect of fluoride on plaque acid tolerance. The test group consumed 200 ml of milk supplemented with 5 mg F/l as NaF once a day, the milk control group drank 200 ml of unsupplemented milk, and the no-milk control group did not consume milk in this manner. Plaque samples were taken at baseline and after 15 months.

Salivary levels of Bifidobacteria in caries-free and caries-active children.

Background: Salivary levels of Bifidobacteria have been shown to be significantly correlated with caries experience in adults but not as yet in children.

Hypothesis: Salivary levels of Bifidobacteria are positively associated with caries experience in children.

Aim: To compare the salivary concentrations of Bifidobacteria of caries-free and caries-active children.

Clonal structure of Streptococcus sanguinis strains isolated from endocarditis cases and the oral cavity.

A collection of Streptococcus sanguinis strains from patients with endocarditis (n = 21) and from the oral cavity (n = 34) was subjected to a multi-locus sequence typing analysis using seven housekeeping genes, carbamoyl-phosphate synthetase (carB), Co/Zn/Cd efflux system component (czcD), d-alanyl-d-alanine ligase (ddl), DNA polymerase III (dnaX), glucose-6-phosphate dehydrogenase (gdh), DNA-directed RNA polymerase, beta subunit (rpoB) and superoxide dismutase (sodA). The scheme was expanded by the inclusion of two the putative virulence genes, bacitracin-resistance protein (bacA) and saliva-binding protein (ssaB), to increase strain discrimination. Extensive intra-species recombination was apparent in all genes but inter-species recombination was also apparent with strains apparently harbouring gdh and ddl from unidentified sources and one isolate harboured a sodA allele apparently derived from Streptococcus oralis.

Application of MLST and pilus gene sequence comparisons to investigate the population structures of Actinomyces naeslundii and Actinomyces oris.

Actinomyces naeslundii and Actinomyces oris are members of the oral biofilm. Their identification using 16S rRNA sequencing is problematic and better achieved by comparison of metG partial sequences. A.

Genetic diversity of Lactobacillus paracasei isolated from in situ human oral biofilms.

Aim: To determine the genetic diversity and possible origin of Lactobacillus paracasei found in the oral biofilm.

Methods And Results: Lactobacilli were isolated from a biofilm model, formed in situ prior to and during a period of exposure to 20% sucrose solution (28 days), using Rogosa Agar. The lactobacillus colonies were randomly selected (n = 222) and subcultured.

Resistance to acidic environments of caries-associated bacteria: Bifidobacterium dentium and Bifidobacterium longum.

Oral Bifidobacteriaceae, Bifidobacterium dentium and Bifidobacterium longum, are known to be isolated together with mutans streptococci and lactobacilli from caries lesions, suggesting that these Bifidobacteriaceae are caries associated and acid resistant. This study aimed to investigate effects of acidification on B. dentium and B.

Propionibacterium acnes and Staphylococcus epidermidis isolated from refractory endodontic lesions are opportunistic pathogens.

The predominant cultivable microbiota from 20 refractory endodontic lesions (9 with abscesses and 11 without abscesses) were determined, and Propionibacterium acnes and Staphylococcus epidermidis were among the most predominant organisms. The number of species identified from lesions with abscesses (14.1 ± 2.

Non-oral bifidobacteria and the aciduric microbiota of the denture plaque biofilm.

The microbiota of the denture plaque biofilm colonizing the fitting surface of dentures in edentulous subjects with healthy palates (n = 20) and in edentulous subjects with denture stomatitis (n = 20) was studied. The numbers of bacteria colonizing the dentures of healthy subjects was significantly less than the numbers colonizing the dentures of stomatitis subjects. The proportions and frequency of isolation of mutans streptococci, lactobacilli, bifidobacteria and yeasts were significantly (P < 0.

Oral Bifidobacteria: caries-associated bacteria in older adults.

Bifidobacteria are aciduric bacteria that might play a role in the caries process. To test the hypothesis that Bifidobacteria behave as caries-associated organisms, as predicted by the ecological plaque hypothesis, we determined salivary levels of Bifidobacteria and caries-associated organisms for 156 older adults. Salivary levels of Bifidobacteria, mutans streptococci, lactobacilli, and yeasts were correlated with each other (p < 0.