Characteristics of Streptococcus mutans genotypes and dental caries in children

Intraspecies interactions of Streptococcus mutans impact biofilm architecture and virulence determinants in childhood dental caries

Early childhood dental caries (ECC) is the most common chronic disease among children with a heavy disease burden among low socioeconomic populations. Streptococcus mutans is most frequently associated with initiation of ECC. Many studies report children with multiple S. mutans strains (i.e., genotypes) having greater odds of developing ECC, studies investigating intraspecies interactions in dental caries are lacking. In this study, the impact of intraspecies interactions on cariogenic and fitness traits of clinical S. mutans isolates are investigated using in-vitro and in-vivo approaches. Initially clinical S. mutans isolates of 10 children from a longitudinal epidemiological study were evaluated. S. mutans strains (G09 and G18, most prevalent) isolated from one child were used for subsequent analysis. Association analysis was used to determine if presence of multiple S. mutans genotypes within the first-year of colonization was associated with caries. Biofilm analysis was performed for single and mixed cultures to assess cariogenic traits, including biofilm biomass, intra-polysaccharide, pH, and glucan. Confocal Laser Scanning Microscopy (CLSM) and time-lapse imaging were used to evaluate spatial and temporal biofilm dynamics, respectively. A Drosophila model was used to assess colonization in-vivo. Mean biofilm pH was significantly lower in co-cultured biofilms as compared with monoculture biofilms. Doubling of S. mutans in-vitro biofilms was observed by CLSM and in-vivo colonization in Drosophila for co-cultured S. mutans. Individual strains occupied specific domains in co-culture and G09 contributed most to increased co-culture biofilm thickness and colonization in Drosophila. Biofilm formation and acid production displayed distinct signatures in time-lapsed experiments.

Microbiological evaluation in invisible aligner chemical cleaning methods against Candida albicans and Streptococcus mutans

INTRODUCTION

This study aimed to assess the efficacy of chemical agents in removing Candida albicans and Streptococcus mutans biofilm from invisible aligners.

METHODS

The samples were made of EX30 Invisalign trays, biofilm was cultured by standardized suspensions of C. albicans ATCC strain and S. mutans clinical strain on the sample. The treatments used were 0.5% sodium hypochlorite (NaClO) (20 minutes), 1% NaClO (10 minutes), chlorhexidine (5 minutes), peroxide (15 minutes), and orthophosphoric acid (15 seconds). The control group received phosphate-buffered saline for 10 minutes. The colony-forming units per milliliter of each microorganism were determined by serial dilutions seeded in plates with selective culture mediums for each one. Data were analyzed by the Kruskal-Wallis and Conover-Iman tests at an α of 0.05.

RESULTS

For the C. albicans biofilm group, the control group had 9.7 Log10 of microorganism growth, and all treatment groups had statistically significant biofilm reduction, in which chlorhexidine presented the highest inhibition of 3 Log10, followed by alkaline peroxide and orthophosphoric acid both with 2.6 Log10, 1% NaClO (2.5 Log10), and 0.5% NaClO (2 Log10). As for S. mutans, the control group had 8.9 Log10 of growth, and a total microorganism inhibition was reached by chlorhexidine, 1% NaClO, and orthophosphoric acid, whereas alkaline peroxide inhibited growth to 7.9 Log10 and 0.5% NaClO 5.1 Log10.

CONCLUSIONS

Within the limitations, chlorhexidine and orthophosphoric acid had greater efficacy in both biofilms. In addition, 1% NaClO and alkaline peroxide also had significant effects; therefore, their incorporation aligners disinfection protocols are valid.

Oral Microbiome Traits of Type 1 Diabetes and Phenylketonuria Patients in Latvia

Some metabolic disorder treatments require patients to follow a specific diet or to consume supplements that, over time, can lead to oral microbiome alterations. Well-known disorders requiring such treatment are phenylketonuria (PKU), an inborn error of amino acid metabolism, and type 1 diabetes (T1D), a metabolic disorder that requires a specific diet regimen. Therefore, the aim of this study was to investigate the oral health and microbiome characteristics that might contribute to caries activity and periodontal disease risk in PKU and T1D patients. In this cross-sectional study, 45 PKU patients, 24 T1D patients, and 61 healthy individuals between the ages of 12 and 53 years were examined. Their anamnestic data and dental status were assessed by one dentist. Microbial communities were detected from saliva-isolated DNA using 16S rRNA gene V3-V4 sequencing on Illumina MiSeq sequencing platform. Results revealed that the PKU patient group displayed the highest number of extracted teeth (on average 1.34), carious teeth (on average 4.95), and carious activity (44.44% of individuals) compared to the T1D and CTRL groups. The lowest numbers of filled teeth (on average 5.33) and extracted teeth (on average 0.63) per individual were observed in T1D patients. Gingivitis appeared more often in the T1D group; however, possible risk of periodontal disease was seen in both the T1D and PKU patient groups. The highest number of differentially abundant genera was detected in the PKU group (n = 20), with enrichment of Actinomyces (p_adj = 4.17 × 10^-22), Capnocytophaga (p_adj = 8.53 × 10^-8), and Porphyromonas (p_adj = 1.18 × 10^-5) compared to the CTRL group. In conclusion, the dental and periodontal health of PKU patients was found to be significantly inferior compared to T1D patients and healthy controls. T1D patients showed early signs of periodontal disease. Several genera that correlate with periodontal disease development were found in both groups, thus suggesting that T1D and PKU patients should seek early and regular dental advice and be educated about proper oral hygiene practices.

Cinnamomum: The New Therapeutic Agents for Inhibition of Bacterial and Fungal Biofilm-Associated Infection

Due to the potent antibacterial properties of Cinnamomum and its derivatives, particularly cinnamaldehyde, recent studies have used these compounds to inhibit the growth of the most prevalent bacterial and fungal biofilms. By inhibiting flagella protein synthesis and swarming motility, Cinnamomum could suppress bacterial attachment, colonization, and biofilm formation in an early stage. Furthermore, by downregulation of Cyclic di‐guanosine monophosphate (c‐di‐GMP), biofilm-related genes, and quorum sensing, this compound suppresses intercellular adherence and accumulation of bacterial cells in biofilm and inhibits important bacterial virulence factors. In addition, Cinnamomum could lead to preformed biofilm elimination by enhancing membrane permeability and the disruption of membrane integrity. Moreover, this substance suppresses the Candida species adherence to the oral epithelial cells, leading to the cell wall deformities, damage, and leakages of intracellular material that may contribute to the established Candida’s biofilm elimination. Therefore, by inhibiting biofilm maturation and destroying the external structure of biofilm, Cinnamomum could boost antibiotic treatment success in combination therapy. However, Cinnamomum has several disadvantages, such as poor solubility in aqueous solution, instability, and volatility; thus, the use of different drug-delivery systems may resolve these limitations and should be further considered in future investigations. Overall, Cinnamomum could be a promising agent for inhibiting microbial biofilm-associated infection and could be used as a catheter and other medical materials surface coatings to suppress biofilm formation. Nonetheless, further in vitro toxicology analysis and animal experiments are required to confirm the reported molecular antibiofilm effect of Cinnamomum and its derivative components against microbial biofilm.

Assessment of Diversity and Fidelity of Transmission of Streptococcus mutans Genotypes in American Indian and Southeast Iowa Mother-Child Dyads

Early childhood caries (ECC) is a common chronic infectious disease of childhood with a complex etiology and many contributing risk factors. Its prevalence is greater in certain racial and ethnic minority groups and populations with low socioeconomic status. Among the species of bacteria that contribute to the progression of dental caries, Streptococcus mutans (SM) has long been considered a primary etiological agent of the disease. We report here on the genotypic diversity, commonality, and fidelity of mother-child transmission of S. mutans in mother-child dyads in two high-risk populations.

Methods

Thirty-eight mother-child dyads from a Southeast Iowa population and 40 dyads from a Northern Plains American Indian Tribe were selected for a comparison of S. mutans genotype profiles within and between populations. S. mutans was isolated from whole mouth plaque samples collected from each subject. DNA was extracted and AP-PCR using OPA2 primer was performed. Amplified DNA was electrophoresed and images of the resulting patterns were compared via GelCompar®IIv6.5 software.

Results

Thirty unique S. mutans genotypes were identified from the 1,638 S. mutans isolates analyzed. Fifteen genotypes (50%) were seen in both cohorts, while 11 were unique to the American Indian (AI) cohort and 4 were unique to the Southeast Iowa (SEI) population. Within the AI cohort, 61.5% (16/26) of the S. mutans genotypes identified were seen in ≥2 individuals and 14 of the 26 (53.8%) were seen in ≥2 dyads. In the SEI cohort, 78.9% (15/19) of the S. mutans genotypes identified were seen in ≥2 individuals and 13 of the 19 (68.4%) were present in ≥2 dyads. Fifty-seven percent of AI children and 23% of SEI children displayed fidelity of mother-child transmission of ≥1 S. mutans genotype.

Conclusion

In comparing the populations, we observed large variation in genotypic diversity and fidelity of mother-child transmission, while the amount of commonality seen in both cohorts was similarly high in both groups. This study furthers our understanding of the genotypic diversity of S. mutans in both of these populations and provides a basis for further comparison to other populations at greater risk for developing ECC.

Estimating Genotypic Diversity of Streptococcus mutans Isolated From Caries-Active and Caries-Free Individuals Among Indian Population

Purpose

To identify the genetic characterization of S mutans strains isolated from the caries-free and caries-active population using arbitrarily primed -polymerase chain reaction (AP-PCR).

Materials and methods

Thirty-five subjects with a decayed missing and filled teeth (DMFT) score of 0 were allocated to the caries-free group and 35 subjects with a DMFT score greater than four were allocated to the caries-active group and salivary samples were collected. The samples were processed and the colony forming units (CFU) of S mutans were determined for all the samples. About three colonies resembling S mutans from each subject were subjected to deoxyribonucleic acid (DNA) isolation, a purification process was performed, and DNA was analyzed by AP-PCR.

Results

Among the 210 isolates from 35 caries-active and 35 caries-free subjects that were analyzed by AP-PCR, 41.9% had a single genotype, 25.8% had two genotypes, 19.4% had three genotypes, 9.7% had four genotypes and 3.2% had more than four genotypes among the caries-free group. Among the caries-active group, 54.3% had a single genotype, 25.7% had two genotypes, 14.3% had three genotypes and 5.7% had four genotypes.

Conclusion

The study concluded that different genotypic pattern was present in caries-free and caries-active subjects which indicate the occurrence of genetic polymorphism among the S mutans strains. There was no particular genotype of S mutans that was uniquely present in subjects in caries-active and caries-free individuals.

Tropical Oral Disease: Analysing Barriers, Burden, Nutrition, Economic Impact, and Inequalities

Traditionally, a healthy mouth is a good indicator of good general health. Poor oral hygiene reflects the health of the oral cavity and is a risk factor for overall health. Although oral diseases like dental decay and periodontitis are prevalent, awareness of oral diseases is still limited. Oral disorders include a wide range of diseases that may not be confined to the oral anatomical structures but may be manifestations of systemic diseases. Identification of the risk factors of dental and oral diseases, including socio-economic determinants, plays a major role in the type of oral health care, and in the promotion of dental health awareness. This article reviews oral diseases in the Caribbean and aims to raise awareness of this subject while suggesting a research agenda for the region.

Streptococcus Mutans Infections in Infants and Related Maternal/Child Factors

Objective

The aim of the study was to investigate the maternal-child S. mutans infection, mutual interaction and potential risk factors altering this interaction.

Material and methods

A total of 160 mothers who were paired with their children were recruited. Saliva from mothers and children was collected and S. mutans categorized levels were analyzed. A questionnaire was used to collect maternal and child conventional caries risk factors. A proportional odds regression model was used to investigate whether the level of infection of mothers would similarly affect the level of infection of their children, thus adjusting for other risk factors.

Results

The average age of mothers was 28.1 years and children had a median age of 5.1 months. Paired mother-child S. mutans cross-classification into non-infected and infected subjects showed no agreement in mutual contamination. Maternal infection of the child was highest when the mother was infected with 10^>3 S. mutans/ml of saliva. The results obtained by the regression model showed that none of the potential risk factors influenced the level of infection in the child.

Conclusion

Mothers with a high S. mutans level increase the risk of S. mutans acquisition for her five- month- old child but no evidence was found that other maternal/child factors may influence this.

Children's detailed non-water beverage consumption habits and longitudinal early childhood caries experiences

OBJECTIVES

Sugar-sweetened beverages and dental caries are prevalent among children. Measurement choices could explain their inconsistent relationships. This study evaluated associations between detailed baseline non-water beverage consumption (NWBC) behaviors and longitudinal early childhood caries (ECC) experiences in young, high-caries risk children.

METHODS

Researchers followed poor, rural, African Americans, recruited at 8-18 months old from Uniontown, Alabama, through convenience sampling, annually for 5 years (N = 66). Baseline questionnaires obtained demographics, oral hygiene, and daily dietary histories, including beverage types, frequencies, and NWBC behaviors of intake speed (intermittent/rapid), container (bottles/non-bottles), and bedtime beverages (yes/no). Dentists conducted examinations annually to determine decayed, missing, filled (carious) surfaces (dmfs) scores, producing increments (dmfs_final - dmfs_initial ). Age-adjusted logistic regressions estimated odds ratios (OR) and 95% confidence intervals (95% CI) for ECC (carious: incidence >0 versus caries-free: incidence = 0) with NWBC behavior then NWBC frequency, individually and conditional on NWBC behaviors, exposures.

RESULTS

NWBC behaviors were not associated with ECC; juice was significant (OR: 2.0, 95% CI: 1.0, 4.2). Adjusting for intake speed, juice persisted as a risk factor (OR: 2.1, 95% CI: 1.0, 4.3), remaining suggestive after controlling for container or bedtime beverages (OR: 2.0, 95% CI: 0.9, 4.3; OR: 1.9, 95% CI: 0.9, 4.0, respectively). Container could be an effect modifier (OR_bottle : 3.5, 95% CI: 0.8, 16.2 vs. OR_non-bottle : 1.5, 95% CI: 0.6, 3.7). Milk was not associated with ECC.

CONCLUSIONS

Independently, NWBC behaviors are insufficient in evaluating NWBC/ECC relationships; beverage type, frequency, and consumption behaviors, collectively, can better evaluate associations.

Overestimation of Early Childhood Caries Using the dmfs Index

Purpose: The preferred epidemiological caries assessment method is the decayed, missing, and filled surfaces (dmfs) score, which records all crowned/missing primary teeth's surfaces as carious. The purpose of this study was to evaluate the dmfs score's accuracy in capturing caries-affected (versus treated) surfaces of crowned/extracted teeth. Methods: A high-caries risk cohort of children, eight to 18 months old at baseline, were recruited from a nonfluoridated, rural, minority, and low-income community. Oral examinations occurred every 12 months for five years, identifying children with at least one caries-related crown/extraction (N equals 45). Observed scoring counted all crowned/extracted surfaces as carious. Private dentists' clinical records were also reviewed to determine how many surfaces were carious at crown/extraction appointments (53 actual scores for n equals 19). Differences in actual and observed scoring were evaluated (sign test; α equals 0.05 with two-tailed P-values). Results: Most children in the study group had more than one crown/extraction. Actual scoring revealed two to three fewer carious surfaces per tooth than observed scoring; cumulatively, observed scoring added two to 27 more surface counts per participant (P<0.001). Conclusions: Observed scoring exaggerated early childhood caries burdens when crowns/extractions were prevalent. Modified dmfs scoring, individualized or population-corrected crown/extraction counts, could more accurately estimate disease.

DNA finger printing of S. Mutans present in the saliva of caries active children and those associated with intellectual disability - An RAPD analysis

Aim

The aim of this study is, to evaluate and compare the diversity of S. Mutans genotypes with respect to caries activity among normal children and intellectually disabled children, which would enable the clinician to plan better strategies for early caries detection, management and prevention.

Materials and methods

Genotyping of S. Mutans was done by collecting the saliva samples from 40 caries active children (20 normal and 20 children associated with intellectual disability by Rapid amplified polymorphic DNA analysis using three arbitrarily primers (P1, P2, P3). Rapid amplified polymorphic DNA (RAPD) is preferred because of its reliability, reproducibility in generating genetic fingerprints of Streptococcus isolates.

Results

Number of bacterial counts in Group I showed a mean of 111.6500 followed by the Group II with a mean of 102.6500. Therefore, the difference in the number of bacterial counts was not significant between the two groups (p < 0.001). Genotype encoding Primer 1 was present in almost 82.5% of the total population of both groups. Genotype encoding Primer 2 was present in 95% of the total population. Whereas, Genotype encoding Primer 3 was present in 20% of children associated with intellectual disability and 95% of normal children.

Interpretation and conclusion

There was no significant difference in S. Mutans count of normal caries active children to that of caries active children with intellectual disability, but, there was a significance difference in the distribution of S. Mutans genotypes in both the groups.

Streptococcus mutans isolated from children with severe-early childhood caries form higher levels of persisters

OBJECTIVES

Dental caries is the most common chronic infectious disease in children. Streptococcus mutans, the main cariogenic bacterial species, produces persisters, nongrowing dormant variants of regular cells associated with chronicity of diseases. We hypothesized that the recurrent nature of caries, particularly within populations with high-caries risk, is due partly to specific phenotypic features of S. mutans such as its ability to form persisters. We aimed to investigate the genotypic and phenotypic differences between the S. mutans from children with severe early-childhood caries (S-ECC) and those without caries.

METHODS

S. mutans from plaque samples of caries-free (CF) and S-ECC children were tested for their ability to adapt to a lethal pH in an acid tolerance response assay. The persister levels of S. mutans isolates was quantified in both groups.

RESULTS

S. mutanswas identified in all 23 S-ECC but only 6 of the 21 CF subjects. In most subjects, only one dominant S. mutans genotype was detected. No statistically significant differences in the mean survival percentage of S. mutans were observed between the two groups at a lethal pH of 3.5. However, the dominant genotype within a particular S-ECC subject exhibited a higher percentage of cell survival compared to those in the CF group. In S-ECC patients, S. mutans isolates displayed a ∼15-fold higher persistence phenotype than S. mutans isolates from CF patients.

CONCLUSIONS

The ability of S. mutans to produce high levels of persisters may contribute to part of an individual's ability to control caries disease activity and recurrent lesions.

Metagenome sequencing-based strain-level and functional characterization of supragingival microbiome associated with dental caries in children

Studies of the microbiome associated with dental caries have largely relied on 16S rRNA sequence analysis, which is associated with PCR biases, low taxonomic resolution, and inability to accurately study functions. Here, we employed whole metagenome shotgun sequencing, coupled with high-resolution analysis algorithm, to analyze supragingival microbiomes from 30 children with or without dental caries. A total of 726 bacterial strains belonging to 406 species, in addition to 34 bacteriophages were identified. A core bacteriome was identified at the species and strain levels. Species of Prevotella, Veillonella, as yet unnamed Actinomyces, and Atopobium showed strongest association with caries; Streptococcus sp. AS14 and Leptotrichia sp. Oral taxon 225, among others, were overabundant in caries-free. For several species, the association was strain-specific. Furthermore, for some species, e.g. Streptococcus mitis and Streptococcus sanguinis, sister strains showed differential associations. Noteworthy, associations were also identified for phages: Streptococcus phage M102 with caries and Haemophilus phage HP1 with caries-free. Functionally, potentially relevant features were identified including urate, vitamin K2, and polyamine biosynthesis in association with caries; and three deiminases and lactate dehydrogenase with health. The results demonstrate new associations between the microbiome and dental caries at the strain and functional levels that need further investigation.

Photodynamic therapy mediated by chlorin-type photosensitizers against Streptococcus mutans biofilms

Photodynamic therapy (PDT) can be used for the control of oral pathogens and different photosensitizers (PS) have been investigated. This study evaluated the efficacy of PDT against Streptococcus mutans biofilms using two second-generation PS derived from chlorin: Photoditazine® (PDZ) and Fotoenticine® (FTC). These PS were compared to methylene blue (MB), a dye with proven antimicrobial activity against S. mutans. Suspensions of S. mutans were cultured in contact with bovine tooth disks for biofilm formation. After 48 h, the biofilms were treated with PDZ (0.6 mg/mL), FTC (0.6 mg/mL) or MB (1 mg/mL) and submitted to laser irradiation (660 nm, 50 mW/cm²). The biofilms were quantified by the determination of CFU/mL count and analyzed by scanning electron microscopy (SEM). All PS used for PDT reduced the number of S. mutans, with a statistically significant difference compared to the untreated groups. PDT achieved microbial reductions of 4 log with MB and 6 log with PDZ, while the use of FTC resulted in the complete elimination of S. mutans biofilms. SEM analysis confirmed the CFU/mL results, showing that all PS, particularly FTC, were able to detach the biofilms and to eliminate the bacteria. In conclusion, PDT mediated by chlorin-type PS exhibited greater antimicrobial activity against S. mutans than MB-mediated PDT, indicating that these PS can be useful for the control of dental caries.

Oral health status in historic population: Macroscopic and metagenomic evidence

Recent developments in High-Throughput DNA sequencing (HTS) technologies and ancient DNA (aDNA) research have opened access to the characterization of the microbial communities within past populations. Most studies have, however, relied on the analysis of dental calculus as one particular material type particularly prone to the molecular preservation of ancient microbial biofilms and potential of entire teeth for microbial characterization, both of healthy communities and pathogens in ancient individuals, remains overlooked. In this study, we used shotgun sequencing to characterize the bacterial composition from historical subjects showing macroscopic evidence of oral pathologies. We first carried out a macroscopic analysis aimed at identifying carious or periodontal diseases in subjects belonging to a French rural population of the 18th century AD. We next examined radiographically six subjects showing specific, characteristic dental pathologies and applied HTS shotgun sequencing to characterize the microbial communities present in and on the dental material. The presence of Streptococcus mutans and also Rothia dentocariosa, Actinomyces viscosus, Porphyromonas gingivalis, Tannerella forsythia, Pseudoramibacter alactolyticus, Olsenella uli and Parvimonas micra was confirmed through the presence of typical signatures of post-mortem DNA damage at an average depth-of-coverage ranging from 0.5 to 7X, with a minimum of 35% (from 35 to 93%) of the positions in the genome covered at least once. Each sampled tooth showed a specific bacterial signature associated with carious or periodontal pathologies. This work demonstrates that from a healthy independent tooth, without visible macroscopic pathology, we can identify a signature of specific pathogens and deduce the oral health status of an individual.

Genotypic characterization and comparison of Streptococcus mutans in American Indian and Southeast Iowa children

Early childhood caries is a complex health care issue that has a multifactorial etiology. One aspect of this etiology is the colonization and propagation of acidogenic bacteria at an early age. There have been several bacterial species associated with caries but 1 common species is Streptococcus mutans. Here, we describe genotypic diversity and commonality of Streptococcus mutans recovered from children representing 2 groups with similar socioeconomic demographics: a Northern Plains American Indian Tribe and a Southeast Iowa population. Forty 36‐month‐old American Indian children were selected from a cohort of 239 mothers and children, and forty 2‐ to 5‐year‐old children from Southeast Iowa were selected to compare the genotypic profiles of Streptococcus mutans recovered from each child's plaque. S. mutans isolates were selected from whole mouth plaque samples; DNA was extracted and amplified via AP‐PCR to show specific genotype patterns. These patterns were compared with GelComparIIv6.5 gel analysis software. We found 18 distinct genotypes from 524 isolates; 13 of which were common between the 2 communities. Five genotypes were unique to only the American Indian children while the Southeast Iowa children harbored no unique genotypes. Although the American Indian children had some genotypes that were not present in the Southeast Iowa children, these were not widely distributed among the community. Furthermore, the levels of genotypic diversity and commonality were similar between the 2 populations. This study sets the groundwork for a comprehensive comparison of genotypes and caries among larger subsections of both populations.

Genotypic diversity and phenotypic traits of Streptococcus mutans isolates and their relation to severity of early childhood caries

BACKGROUND

Early childhood caries (ECC) is an aggressive condition that can affect teeth of young children. This study aimed to evaluate genotypic diversity and phenotypic traits of S. mutans isolated from dental biofilms of children with different caries status in comparison with caries free (CF) children.

METHODS

Streptococcus mutans strains were isolated from supragingival biofilm samples of CF, ECC and severe-ECC (S-ECC) children and genotyped by arbitrary-primer polymerase chain reaction - AP-PCR. S. mutans genotypes were tested for their ability to reduce the suspension pH through glycolysis, to tolerate extreme acid challenge and by their ability to form biofilm. Response variables were analyzed by ANOVA/Tukey or Kruskal-Wallis/Mann-Whitney tests at a 5% of significance.

RESULTS

There was an increase in the prevalence of Streptococcus mutans in biofilms with the severity of dental caries. No differences in genotypic diversity and in acidogenicity of genotypes were found among CF, ECC and S-ECC children. S mutans strains with genotypes more characteristic for ECC and S-ECC children formed more biofilms than those identified in CF children. The strains isolated from S-ECC children were highly acid tolerant.

CONCLUSION

Although S. mutans genotypic diversity was similar among the groups of children, phenotypic traits of S. mutans, especially the acid tolerance response, could explain the severity of early childhood caries.

Association Between Early Childhood Caries and Colonization with Streptococcus mutans Genotypes From Mothers

PURPOSE

The purpose of this study was to evaluate Streptococcus mutans genotypes (GT) between mother and child (M-C) in a high caries risk cohort to explore the association with early childhood caries (ECC).

METHODS

Sixty-nine infants (each approximately one year old) had periodic oral examinations (dmfs) and microbial samples collected from dental plaque, saliva, and other oral surfaces. Their mothers had an examination and plaque collected. S mutans isolates were genotyped using repetitive extragenic palindromic-PCR (rep-PCR). Statistical analyses were conducted for associations of S mutans in M-C dyads with caries outcomes.

RESULTS

Twenty-seven S mutans genotypes (GT) from 3,414 isolates were identified. M-C were categorized as GT match (n equals 40) or no-match (n equals 29). When modeling the severity of ECC at 36 months (approximately four years old), the estimated dmfs in the match group was 2.61 times that of the no-match group (P=.014).

CONCLUSIONS

Colonization of children with Streptococcus mutans genotypes that matched with mothers was shown to be highly associated with early childhood caries. Although the data suggest vertical transmission of S mutans in 40 of 69 children that shared GT with their mother, it is possible that other individuals transmitted the S mutans. Nonetheless, these findings support the importance of the mother's oral microbial status as a contributing influence to their children's oral health.

Xylitol in preventing dental caries: A systematic review and meta-analyses

Xylitol is a sugar alcohol having the properties that reduce levels of mutans streptococci (MS) in the plaque and saliva. To assess the role of xylitol in preventing dental caries. Systematic review and meta-analysis developed by Cochrane cooperation were adapted. Electronic search was carried out in PubMed through the period up to 2014. Included clinical studies were done on (1) humans (2) participants include both individuals and as pairs (mother-child) (3) participants using orthodontic appliances (4) xylitol dispensed in any form (5) compare the effect of xylitol on dental caries and on other phenotype that determines the preventive effect on dental caries, such as decayed, missing, and filled (DMF/dmf) and salivary or plaque MS level. Twenty articles of the 477 articles initially identified. Among 20 studies indexed, 16 articles were accessed, systematically reviewed, and the meta-analysis was carried out. The evaluation of quality of the studies was done using risk of bias assessment tool. The quality of the studies was high risk and unclear risk for six and five trials. The meta-analysis shows a reduction in DMF/dmf with the standard mean (SM) of -1.09 (95% confidence interval [95% CI], -1.34, -0.83) comparing xylitol to all controls. The effect of DMF/dmf reduction by xylitol to fluoride varnish was with the SM of -1.87 (95% CI, -2.89, -0.84). The subgroup analysis, there was a reduction in MS count with SM of 0.30 (95% CI, 0.05, 0.56) when compared with all other caries preventive strategies; however, it was insignificant. Xylitol was found to be an effective strategy as self-applied caries preventive agent.

Bactericidal dental nanocomposites containing 1,2,3-triazolium-functionalized POSS additive prepared through thiol-ene click polymerization

OBJECTIVE

Deterioration of mechanical strength for the dental composite containing ionic bactericidal compounds restricts the widespread utilization of this class of useful materials. This problem is originated from the reduction of the intermolecular interaction of polymeric network due to plasticization effect of absorbed water molecules penetrated between the chain segments. The main goal of this study is the synthesis of the highly efficient bactericidal additive with low hydrophilicity and consequently the least adverse effect on the final mechanical strength of the dental composite.

METHODS

The bactericidal 1, 2, 3-triazolium functional groups were chemically anchored on the surface of hydrophobic POSS nanoparticles (Triazolium-POSS) and incorporated into a dental restorative system composed of a ternary thiol-allyl ether-methacrylate resin and glass fillers. A similar system was also prepared, in which the POSS additive was replaced with quaternized dimethyl aminoethyl methacrylate monomer (DMAEMA-BC). The chemical structure of POSS derivatives was evaluated by ¹HNMR and FTIR spectra. The water uptake of dental composites was evaluated at days 1 and 14 after immersion into water. The bactericidal activity of composite specimens against Streptococcus mutans (ATCC 35668) was determined based on ASTM E 2180 - 07. The flexural properties of samples were investigated through three-point bending assay and the shrinkage-strain of photo-cured resins was measured using the bonded-disk technique. The degree of conversion (DC %) of methacrylate functions was followed by FTIR spectroscopy. MTT assay was performed to investigate the cytocompatibility of samples.

RESULTS

Regardless of the partial increase in water uptake for Triazolium-POSS-containing sample, this parameter was much favor than the composite made from DMAEMA-BC. Therefore, the lower decline in flexural properties was recorded under the wet condition for the former system. Incorporation of Triazolium-POSS had no significant effect on shrinkage strain and cytocompatibility of composite specimen, meanwhile, a higher degree of conversion of methacrylate functional groups was recorded. The Triazolium-POSS-containing nano composite showed significantly higher bactericidal activity against Streptococcus mutans than another studied model system.

SIGNIFICANCE

The new derivative of bactericidal POSS nanoparticles decorated with 1, 2, 3-Triazolium moieties is a highly efficient bactericidal compound. If Triazolium-POSS is incorporated into a proper dental resin formulation, it can provide a strong bactericidal activity for dental materials; in the meantime, it leads to minimum deterioration of their mechanical strength due to its low water uptake.

Genetic Diversity and Evidence for Transmission of Streptococcus mutans by DiversiLab rep-PCR

This two-part study investigated the genetic diversity and transmission of Streptococcus mutans using the DiversiLab repetitive extragenic palindromic PCR (rep-PCR) approach. For children with S. mutans and participating household members, analysis for evidence of unrelated child-to-child as well as intra-familial transmission was evaluated based on commonality of genotypes. A total of 169 index children and 425 household family members from Uniontown, Alabama were evaluated for genetic diversity using rep-PCR. Thirty-four unique rep-PCR genotypes were observed for 13,906 S. mutans isolates. For transmission, 117 child and household isolates were evaluated for shared genotype (by child and by genotype cases, multiple matches possible for each child). Overall, children had 1-9 genotypes and those with multiple genotypes were 2.3 times more likely to have caries experience (decayed, missing and filled teeth/surfaces>0). Only 28% of children shared all genotypes within the household, while 72% had at least 1 genotype not shared with anyone in the household. Children had genotype(s) not shared with any household members in 157 cases. In 158 cases children and household members shared a genotype in which 55% (87/158 cases) were shared with more than one family member. Children most frequently shared genotypes with their mothers (54%; 85/158), siblings (46%; 72/158) and cousins (23%; 37/158). A reference library for S. mutans for epidemiological surveillance using the DiversiLab rep-PCR approach is detailed. The genetic diversity of S. mutans in this population demonstrated frequent commonality of genotypes. Evidence for both child-to-child and intra-familial transmission of S. mutans was observed by rep-PCR.

Dental Caries in High-risk, School-age African American Children in Alabama: A Six-year Prospective

PURPOSE

The purpose of this study was to assess the prevalence and incidence of dental caries in school-age African American children who received semi-annual fluoride varnish applications.

METHODS

A cohort of six-year-old high caries-risk African American children (n equals 98) was recruited in Uniontown, Ala., USA, and followed for six years. Oral examinations were done annually by three trained/calibrated dentists. Tooth surfaces with cavitated caries, teeth missing due to caries, and teeth with filled surfaces were recorded using World Health Organization criteria. Also, as part of the study, children received periodic oral health instruction, fluoride varnish applications, and referrals to dentists starting at baseline.

RESULTS

The person-level prevalence of decayed, missing, and filled surfaces of primary and permanent teeth (dmfs/DMFS) was: 61.2 percent at mean age of 5.9 years old (n equals 98, mean dmfs/DMFS equals 11.6); 63.8 percent at 6.7 years old (n equals 80, mean dmfs/ DMFS equals 13.2); 70.6 percent at 7.8 years old (n equals 68, mean dmfs/DMFS equals 14.2); 65.7 percent at 8.8 years old (n equals 68, mean dmfs/DMFS equals 11.8); 55.6 percent at 9.7 years old (n equals 63, mean dmfs/DMFS equals 8.8); 40.3 percent at 10.7 years old (n equals 62, mean dmfs/DMFS equals 3.4); and 37.1 percent at 11.7 years old (n equals 62, mean dmfs/DMFS equals 2.3). The six-year person-level incidence of dmfs/DMFS was 32.3 percent (mean dmfs/DMFS equals 1.6) from 5.9 to 11.7 years old (<small>N</small> equals 62).

CONCLUSIONS

In spite of the oral health education and fluoride varnish applications, there was substantial new dental caries in this high-risk sample. Additional studies evaluating risk factors for caries development are ongoing.

Assessment of clonality and serotypes of Streptococcus mutans among children by multilocus sequence typing

Studies using multilocus sequence typing (MLST) have demonstrated that Streptococcus mutans isolates are genetically diverse. Our laboratory previously demonstrated clonality of S. mutans using MLST but could not discount the possibility of sampling bias. In this study, the clonality of randomly selected S. mutans plaque isolates from African-American children was examined using MLST. Serotype and the presence of collagen-binding proteins (CBPs) encoded by cnm/cbm were also assessed. One-hundred S. mutans isolates were randomly selected for MLST analysis. Sequence analysis was performed and phylogenetic trees were generated using start2 and mega. Thirty-four sequence types were identified, of which 27 were unique to this population. Seventy-five per cent of the isolates clustered into 16 clonal groups. The serotypes observed were c (n = 84), e (n = 3), and k (n = 11). The prevalence of S. mutans isolates of serotype k was notably high, at 17.5%. All isolates were cnm/cbm negative. The clonality of S. mutans demonstrated in this study illustrates the importance of localized population studies and are consistent with transmission. The prevalence of serotype k, a recently proposed systemic pathogen, observed in this study, is higher than reported in most populations and is the first report of S. mutans serotype k in a United States population.

Assessment of two multilocus sequence typing (MLST) schemes available for Streptococcus mutans

OBJECTIVE

Two multilocus sequencing typing (MLST) schemes are currently available for Streptococcus mutans. The first, introduced by Nakano et al. in 2007, consists of 8 conserved housekeeping genes. The second, introduced in 2010 by Do et al., includes 6 housekeeping genes and 2 putative virulence genes. The purpose of the current study was to compare the two MLST schemes for use in validating repetitive extragenic palindromic polymerase chain reaction (rep-PCR) genotypes.

DESIGN

Thirty-three S. mutans isolates, representing the 11 most commonly occurring rep-PCR genotype groups, were selected for MLST. MLST was performed with SYBR Green™ PCR with published primers for both MLST schemes. Amplicons were purified, sequenced, and data checked against the www.PubMLST.org database for allelic and sequence type (ST) assignment. Discriminatory power, congruence, and convenience criteria were evaluated. Concatenated sequences for each scheme were analyzed using MEGA to generate phylogenetic trees using minimum evolution with bootstrap.

RESULTS

No significant difference in discriminatory power was observed between the two MLST schemes for S. mutans. Clonal clusters were consistent for both schemes. Overall, MLST demonstrated marginally greater discriminatory power than rep-PCR; however all methods were found to be congruent. New alleles and ST are reported for each scheme and added to the PubMLST database.

CONCLUSIONS

Clonality, supported by both methods and rep-PCR, indicates S. mutans genotypes are shared between unrelated subjects. Both Nakano and Do schemes demonstrates similar genotype discrimination for S. mutans isolates suggesting each are well designed and may be used to verify rep-PCR genotypes.

Factors associated with early childhood caries incidence among high caries-risk children

OBJECTIVES

To assess the relationships between different behavioral factors and Early Childhood Caries (ECC) in African-American pre-school children.

METHODS

Ninety-six African-American children aged 3-22 months old at baseline were recruited from a high caries risk, non-fluoridated African-American community in Uniontown, Alabama. The children had dental examinations annually following World Health Organization (WHO) criteria at mean ages 1.1, 2.0, 3.1 and 4.0 years. All children received fluoride varnish application at each study visit. Parents provided oral hygiene and dietary information semiannually by completing questionnaires. Area-under-the-curve (AUC) with the trapezoidal rule was used to summarize longitudinal exposure data. Bivariate and multivariable relationships between ECC incidence and behavioral risk factors were assessed using logistic regression and negative binomial modeling for dichotomous and count dependent variables, respectively, with the independent variables defined at age 1, age 3 and as the AUC.

RESULTS

Greater frequency of toothbrushing and greater AUC composite of daily frequency of consumption of 100% juices were associated with lower incidence of dental caries (P-values = 0.01 and 0.049, ORs = 0.34 and 0.37, respectively). Greater AUC of daily frequency of consumption of sweetened foods and history of a previous visit to a dentist by age 3 were associated with greater incidence of ECC (ORs = 9.22 and 4.57, P-values = 0.002 and 0.03, respectively).

CONCLUSION

For these children living in a non-fluoridated community, more frequent consumption of sweetened food, less frequent consumption of 100% juice, less frequent toothbrushing, and reporting a previous visit to a dentist were significantly associated with greater ECC incidence.

Genotypic characterization of initial acquisition of Streptococcus mutans in American Indian children

Background

Severe-early childhood caries (S-ECC) is one of the most common infectious diseases in children and is prevalent in lower socio-economic populations. American Indian children suffer from the highest levels of S-ECC in the United States. Members of the mutans streptococci, Streptococcus mutans, in particular, are key etiologic agents in the development of caries. Children typically acquire S. mutans from their mothers and early acquisition is often associated with higher levels of tooth decay.

Methods

We have conducted a 5-year birth cohort study with a Northern Plains Tribe to determine the temporality and fidelity of S. mutans transmission from mother to child in addition to the genotypic diversity of S. mutans in this community. Plaque samples were collected from 239 mother/child dyads at regular intervals from birth to 36 months and S. mutans were isolated and genotyped by arbitrarily primed-polymerase chain reaction (AP-PCR).

Results

Here we present preliminary findings from a subset of the cohort. The focus for this paper is on initial acquisition events in the children. We identified 17 unique genotypes in 711 S. mutans isolates in our subset of 40 children, 40 mothers and 14 primary caregivers. Twelve of these genotypes were identified in more than one individual. S. mutans colonization occurred by 16 months in 57.5% of the children and early colonization was associated with higher decayed, missing and filled surface (DMFS) scores (p=0.0007). Children colonized by S. mutans shared a common genotype with their mothers 47.8% of the time. While multiple genotypes were common in adults, only 10% of children harbored multiple genotypes.

Conclusion

These children acquire S. mutans at an earlier age than the originally described ‘window of infectivity’ and often, but not exclusively, from their mothers. Early acquisition is associated with both the caries status of the children and the mothers.

Experiences with the Streptococcus Mutans in Lakota Sioux (SMILeS) Study: Risk factors for Caries in American Indian Children 0-3 Years

Severe Early Childhood Caries (S-ECC) is a terribly aggressive and devastating disease that is all too common in lower socio-economic children, but none more so that what is encountered in American Indian Tribes. Nationwide, approximately 27% of 2-5 year olds have decay while 62% percent of American Indian/Alaska Native children in the same age group have a history of decay (IHS 2010, NHANES 1999-2002). We have conducted a study of children from birth to 36 months of age on Pine Reservation to gain a better understanding of the variables that come into play in the development of this disease, from transmission and acquisition of Streptococcus mutans genotypes from mother to child to multiple dietary and behavioral components. This article describes how we established a direct partnership with the Tribe and the many opportunities and challenges we faced in performing this 5-year field study.

Streptococcus mutans wall-associated protein A promotes TLR4-induced dendritic cell maturation

Dendritic cells orchestrate innate and adaptive immune responses, which are central to establishing efficient responses to vaccination. Wall-associated protein A (WapA) of Streptococcus mutans was previously used as a vaccine in animal studies for immunization against dental caries. However, as a cell surface protein, whether WapA activates innate immune responses and the effects of WapA on DCs remain unclear. In this study, WapA was cloned into the GST fusion vector pEBG, which can be expressed efficiently in mammalian cells. We found that when added before stimulation with LPS, purified WapA-GST protein increased TLR4-induced NF-κB and MAPK signalling pathway activation. Pretreatment with WapA-GST also increased LPS-induced proinflammatory cytokine production by DCs, including IL-12, IL-6 and TNF-α. Furthermore, expression of the DC maturation markers CD80/86, CD40 and MHC II was also increased by WapA pretreatment. These data indicate that WapA is recognized by DCs and promotes DC maturation.

Mutans streptococci enumeration and genotype selection using different bacitracin-containing media

The primary etiological agents associated with dental caries include the mutans streptococci (MS) comprised of Streptococcus mutans and Streptococcus sobrinus. The effective cultivation and isolation of MS are necessary for the study of MS, including their proper clinical assessment in the epidemiological study of dental caries. Several selective media have been developed for the isolation, enumeration, and characterization of MS. However, inhibition of MS may occur, reducing counts and perhaps limiting selection of some strains. The purpose of this study was to compare five culture media containing bacitracin recommended for the isolation of MS. Five commonly used bacitracin-containing media (MSB, MSKB, GTSB, TYS20B, and TYCSB) used for MS isolation were quantitatively evaluated. Standard plate counts were performed in duplicate for 2 prototype MS strains (S. mutans UA159 and S. sobrinus 6715) and for MS isolates from clinical saliva samples obtained from 16 children (approximate age 5years) to determine total plate counts, and total S. mutans counts. Selected isolates (n=249) from all five media for 5 saliva samples were further confirmed as S. mutans with real-time PCR then subsequently evaluated qualitatively with rep-PCR for genotype determination. All media resulted in variable enumeration with no significant difference in MS counts. MS prototype strains grew well on all five media; clinical isolates demonstrated more variability in counts but no overall significant differences were found. MSB demonstrated comparable ability to grow S. mutans but allowed for more non-S. mutans growth. All 5 media identified a consistent predominant genotype by rep-PCR. Recovery of minor genotypes was not inhibited by media type.

A QM/MM MD study of the pH-dependent ring-opening catalysis and lid motif flexibility in glucosamine 6-phosphate deaminase

QM/MM MD and MM MD simulations reveal pH-dependent proton-shuttle ring-opening mechanisms of GlcN6P and dynamical behavior of the lid motif inSmuNagB.