Genotypic diversity of mutans streptococci in Brazilian nursery children suggests horizontal transmission

The contribution of maternal factors to the oral microbiota of the child: Influence from early life and clinical relevance

The mother represents one of the earliest sources of microorganisms to the child, influencing the acquisition and establishment of its microbiota in early life. However, the impact of the mother on the oral microbiota of the child from early life until adulthood remains to unveil. This narrative review aims to: i) explore the maternal influence on the oral microbiota of the child, ii) summarize the similarity between the oral microbiota of mother and child over time, iii) understand possible routes for vertical transmission, and iv) comprehend the clinical significance of this process for the child. We first describe the acquisition of the oral microbiota of the child and maternal factors related to this process. We compare the similarity between the oral microbiota of mother and child throughout time, while presenting possible routes for vertical transmission. Finally, we discuss the clinical relevance of the mother in the pathophysiological outcome of the child. Overall, maternal and non-maternal factors impact the oral microbiota of the child through several mechanisms, although the consequences in the long term are still unclear. More longitudinal research is needed to unveil the importance of early-life microbiota on the future health of the infant.

A preliminarily Investigation on Oral Colonization and Counts of Streptococcus mutans and Streptococcus mitis in a Group of Predentate Infants in Relation to Some Maternal and Infant Factors (A Longitudinal Observational study)

Aim

Bacterial colonization of infants' oral cavities is a key factor for future caries risk. This study sought to longitudinally assess oral bacterial colonization in a group of predentate infants in relation to some mother and infant factors.

Materials and methods

A total of 50 mother-infant pairs were enrolled. When infants were 3-month-old, data were collected about some infant and mother factors; additionally, maternal Decayed, Missing, and Filled Teeth (DMFT) scores and salivary samples of mothers and infants were obtained. At 6 months of infant's age, another infants' salivary samples were obtained. Saliva was cultured to detect and quantify Streptococcus mutans (S. mutans) and Streptococcus mitis (S. mitis).

Results

Streptococcus mitis (S. mitis) was detected in all infants at 3 months. 74 and 96% of infants acquired S. mutans at 3 and 6 months, respectively. S. mutans detection was significantly higher with higher maternal DMFT scores, salivary S. mutans counts, and lower S. mitis counts, as well as when infants were given sugar-containing complementary foods/drinks. At 3-6 months, infants' S. mutans counts were significantly positively correlated with maternal S. mutans counts and DMFT scores and negatively correlated with maternal S. mitis counts. The opposite was evident for infants' S. mitis counts. Regression analysis showed that increased maternal DMFT scores and S. mutans counts, and Cesarean delivery were strong predictors for increased infant's S. mutans counts. While increased DMFT scores and maternal S. mutans counts were strong predictors for reduced infant's S. mitis counts.

Conclusion

Poor maternal oral health, early introduction of sugars in the diet, and probably Cesarean delivery can negatively impact infants' oral bacterial colonization and possibly future caries risk.

Clinical significance

Understanding factors associated with oral colonization of both caries-producing and protective flora in infants of different populations is important for caries prevention. This, in turn, can aid tailoring oral health promotion programs for expectant mothers.

How to cite this article

Wassel MO, Salman NS, Metwalli NE. A preliminarily Investigation on Oral Colonization and Counts of Streptococcus mutans and Streptococcus mitis in a Group of Predentate Infants in Relation to some Maternal and Infant Factors (A Longitudinal Observational study). Int J Clin Pediatr Dent 2023;16(1):79-86.

Vertical and Horizontal Transmission of Streptococcus Mutans and Effective Factors: An In Vivo Study

Aim:

The degree of vertical (intrafamilial) and horizontal (extrafamilial) transfer of Streptococcus mutans ( S. mutans) to a child shows differences according to cultures. The wrong care habits may result in transfer of S. mutans. The aim of this study was to determine the vertical and horizontal transmission of S. mutans to a child and effective factors.

Materials and Methods:

Mothers and kindergarten staff of 37 children aged between 4 and 5 years who initially started in two kindergartens (Group 1, n = 19; Group 2, n = 18) were included in this in vivo study according to 95% reliability and 80% theoretical power. Intraoral examination of mothers and children made according to the World Health Organization criteria (dmf-t/DMF-T) was done, following which mothers were asked to fill questionnaire forms including knowledge and attitudes of them about oral/dental health care. 1 mL saliva samples received from children/mothers/staff were examined microbiologically in order to isolate and quantify S. mutans. Arbitrarily primed polymerase chain reaction analysis was done to determine the genetic characteristics of S. mutans. All examinations were repeated to evaluate the horizontal transmission in the fifth month. Parametric tests ( t-test and two-way analysis of variance) were employed for comparison of the variables that meet the normality assumption and nonparametric tests (Mann–Whitney) were also used.

Results:

It was observed that there is a statistically significant correlation between mother DMF-T values and mother–child S. mutans similarity level ( P < .05). There is a statistically positive correlation between the habits of using a common fork, spoon, glass, and mother–child similarity level.

Conclusion:

Vertical and horizontal transfers occurred in Turkish families in order to prevent the transfer of S. mutans; wrong baby care habits that may lead to the transfer of S. mutans, which is the main factor in case of tooth decay, should be avoided.

Genetic diversity of Streptococcus mutans serotype c isolated from white spot and cavitated caries lesions from schoolchildren

OBJECTIVE

To determine the genetic diversity of Streptococcus mutans (S. mutans) serotype c isolated from white spot and cavitated caries lesions of schoolchildren.

METHODS

S. mutans isolates were obtained and identify by Polymerase Chain Reaction (PCR) from 28 schoolchildren. A total of 92 S. mutans isolates, identified as serotype c by PCR, were analyzed by pulsed field gel electrophoresis after digestion of genomic DNA with SmaI enzyme. 62 isolates were obtained from white spot and cavitated caries lesions of schoolchildren that presented both lesions simultaneously and 30 isolates were from saliva and biofilm samples of schoolchildren without dental caries. Cluster analyses were performed using the Dice coefficient of the BioNumerics software version 6.0.

RESULTS

It was possible to determine the serotype in 190 isolates out of 255 isolates identified as S. mutans. Serotype c was the most frequent (n = 139), followed by serotype f (n = 31) and serotype e (n = 20). After analyzing the dendograms of the 92 serotype c isolates, this study identified three strains present in both types of lesions, two strains specific to the type of lesion: one strain from the white spot lesion and one strain from the cavitated caries lesion, and five strains specific to children with caries versus four strains for children without caries.

CONCLUSION

S. mutans serotype c genetic variability is similar in terms of the number of strains present according to the caries status and type of lesion.

Genotypic diversity of Streptococcus mutans isolated from preschoolers with and without early dental care

Abstract Introduction Streptococcus mutans (S. mutans) exhibits extensive genotypic diversity, but the role of this variation is poorly understood. Objective To evaluate the genotypic diversity of S. mutans in preschoolers with and without early dental care and to associate it with dental caries experience. Material and method Twenty children, aged five year old, with history of dental care since they were one year old (G1) and 20 children without history of dental care (G2) were included. Their oral health status was assessed by the dmft index. S. mutans samples were isolated from the saliva and analysed by polymerase chain reaction. A total of 339 S. mutans isolates (173 from G1 and 166 from G2) were genotyped by random amplified polymorphic DNA with arbitrary primers OPA-02 and OPA-13. Result The results revealed 75 distinct genotypes of S. mutans in G1 and 73 in G2. Furthermore, G1 and G2 subjects harboured one to eight and one to seven distinct genotypes of S. mutans, respectively. A statistically significant association (P=0.021) and a moderate correlation (r= 0.503) were observed between dental caries experience and genotypic diversity of S. mutans in G1. Conclusion From the limitations of the study design, we just can hypothesize that actions of early dental care carried out by an educative-preventive program can contribute to a distinct oral microbiota.

Comparative Analysis of the Microbial Profiles in Supragingival Plaque Samples Obtained From Twins With Discordant Caries Phenotypes and Their Mothers

Early childhood caries (ECC), the most frequent disease of oral cavity in preschool children, is the consequence of microbial, genetic, biochemical, socioeconomic, physical, environmental and health-influencing behavioral factors. To investigate the role of the oral microbiome and the impact of host and environmental factors in the occurrence and development of ECC, we studied the supragingival plaques of 14 twin pairs and a set of triplets with discordant caries phenotypes and 15 mothers, applying the Human Oral Microbe Identification using Next Generation Sequencing technique (HOMINGS). A total of 2,293,650 reads revealed 11 phyla, 116 genera, and 139 species of micromiome. Comparative analysis between the caries and caries-free group at species level revealed that the relative abundance of Streptococcus mutans, Lactobacillus fermentum, Actinomyces islaelii, Neisseria sica, and Veilonella dispar was much higher in caries group (P < 0.0001). Furthermore, monozygotic twins exhibited a higher degree of similarity than dizygotic twins. Finally, we analyzed the relationship between environmental factors and the oral microbiome, and our results indicat that the frequency of taking sweet food is associated with ECC. We conclude the following. First, the occurrence of Streptococcus mutans, Lactobacillus fermentum, Neisseria sica, and Veilonella dispar is strongly associated with the occurrence of ECC. Second, host genetic factors influence the oral microbiome composition, while environmental and behavioral factors like the frequency of taking sweet foods have an impact on the distribution of caries-related bacteria.

Early Childhood Caries

Early childhood caries (ECC) is a common childhood disease with highest prevalence found in poor, socially disadvantaged, and minority groups. The main risk factors for ECC are frequent sugar consumption, lack of tooth brushing, and enamel hypoplasia. Contributory factors include environmental and psychosocial stresses that modify caregiver behaviors. Strategies for prevention include preventing mutans streptococci transmission, restricting dietary sugars, tooth brushing, topical fluoride applications, and early dental examinations. This article provides an overview of ECC based on current understanding of its cause, prevention, and management.

Contribution of Streptococcus Mutans Virulence Factors and Saliva Agglutinating Capacity to Caries Susceptibility in Children: A Preliminary Study

BACKGROUND

Many factors contribute to caries development in humans, such as diet, host factors - including different saliva components - and the presence of acidogenic bacteria in the dental biofilm, particularly Streptococcus mutans (S. mutans). Despite the influence of S. mutans in caries, this bacterium is also prevalent among healthy individuals, suggesting the contribution of genetic variation on the cariogenic potential. Based on this hypothesis, the present work investigated the influence of S. mutans virulence factors and saliva agglutinating capacity on caries susceptibility in children.

STUDY DESIGN

Saliva samples of 24 children from low income families (13 caries-free and 11 caries-active individuals) were collected and tested for their ability to agglutinate S. mutans. The bacteria were isolated from these samples and analyzed for the presence of the gene coding for mutacin IV (mut IV). Biofilm formation and acid tolerance were also investigated in both groups (caries-free and caries-active).

RESULTS

Saliva samples from caries-free children showed an increased capacity to agglutinate S. mutans (p=0.006). Also, bacteria isolated from the caries-free group formed less biofilm when compared to the caries-active group (p=0.04). The presence of mut IV gene did not differ between bacteria isolated from caries-free and caries-active individuals, nor did the ability to tolerate an acidic environment, which was the same for the two groups.

CONCLUSIONS

Altogether, the results suggest that the adhesive properties of S. mutans and the agglutinating capacity of the saliva samples correlated with the presence of caries lesions in children.

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.

Streptococcus mutans in Mother-Child Dyads and Early Childhood Caries: Examining Factors Underlying Bacterial Colonization

This study investigated the association between colonization of mother-child dyads with Streptococcus mutans (SM) and early childhood caries (ECC), with consideration of the mediator and confounders, using a theoretical model. Four hundred mothers and their children from São Luís, Brazil, were included in the study. A diagram based on directed acyclic graphs was elaborated to analyze the association between SM colonization of the mother, mediated by child SM, and ECC. Other maternal (socioeconomic, waist circumference, sugar consumption, DMFT index, and visible plaque) and child factors (sugar consumption, visible plaque, and child age) composed the theoretical model. A total effect model (maternal SM on ECC) and a direct effect model, adjusted by the mediation effect of child SM (maternal SM via child SM) on ECC, were analyzed. The outcome of interest in this study was ECC (number of teeth with caries experience, dmft), which was analyzed as a discrete variable by Poisson regression. The Paramed test was used to analyze mediation. The following variables were associated with ECC in the total effect model: maternal SM, maternal waist circumference ≥80 cm, DMFT, maternal visible plaque, child age ≥4 years, and increased sugar consumption of the child (>3 times/day). In the direct effect model, high maternal SM levels remained associated with ECC, while moderate and high colonization of the child with SM was also associated with ECC. Child SM colonization just partially mediated the effect of maternal SM on ECC (33%). Thus, factors other than the mechanism of bacterial colonization should be considered in mother-child dyads, including eating habits, oral hygiene practices, and a family history of caries.

Early Childhood Caries: Prevalence, Risk Factors, and Prevention

Early childhood caries (ECC) is major oral health problem, mainly in socially disadvantaged populations. ECC affects infants and preschool children worldwide. The prevalence of ECC differs according to the group examined, and a prevalence of up to 85% has been reported for disadvantaged groups. ECC is the presence of one or more decayed, missing, or filled primary teeth in children aged 71 months (5 years) or younger. It begins with white-spot lesions in the upper primary incisors along the margin of the gingiva. If the disease continues, caries can progress, leading to complete destruction of the crown. The main risk factors in the development of ECC can be categorized as microbiological, dietary, and environmental risk factors. Even though it is largely a preventable condition, ECC remains one of the most common childhood diseases. The major contributing factors for the for the high prevalence of ECC are improper feeding practices, familial socioeconomic background, lack of parental education, and lack of access to dental care. Oral health plays an important role in children to maintain the oral functions and is required for eating, speech development, and a positive self-image. The review will focus on the prevalence, risk factors, and preventive strategies and the management of ECC.

The Oral Microbiome in Health and Its Implication in Oral and Systemic Diseases

The oral microbiome can alter the balance between health and disease, locally and systemically. Within the oral cavity, bacteria, archaea, fungi, protozoa, and viruses may all be found, each having a particular role, but strongly interacting with each other and with the host, in sickness or in health. A description on how colonization occurs and how the oral microbiome dynamically evolves throughout the host's life is given. In this chapter the authors also address oral and nonoral conditions in which oral microorganisms may play a role in the etiology and progression, presenting the up-to-date knowledge on oral dysbiosis as well as the known underlying pathophysiologic mechanisms involving oral microorganisms in each condition. In oral pathology, oral microorganisms are associated with several diseases, namely dental caries, periodontal diseases, endodontic infections, and also oral cancer. In systemic diseases, nonoral infections, adverse pregnancy outcomes, cardiovascular diseases, and diabetes are among the most prevalent pathologies linked with oral cavity microorganisms. The knowledge on how colonization occurs, how oral microbiome coevolves with the host, and how oral microorganisms interact with each other may be a key factor to understand diseases etiology and progression.

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.

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.

Mother-to-child transmission of mutans streptococci

Mutans streptococci (MS) are the major group of pathogens implicated in dental caries. Like other infectious diseases, transmission of the causative microorganisms is the initial and essential step that should be understood relative to disease control and prevention. This review summarizes current knowledge regarding MS transmission, especially from mothers to their children. Included are methods used to study transmission, sources of MS, initial acquisition, factors concerning transmission and prevention of transmission. Information accumulated over many decades showed the involvement of MS transmission in the pathogenesis of caries, hence several preventive measurements have been proposed. Nevertheless, some essential aspects remain to be elucidated for more benefits of practical application.

Risk factors for early colonization of mutans streptococci - a multiple logistic regression analysis in Swedish 1-year-olds

BACKGROUND

Mutans streptococci (MS) are closely related to the development of dental caries and are usually established in the oral cavity during early childhood. The aim of the study was to identify factors associated with the presence of MS in Swedish 1-year-olds.

METHODS

Parents completed a questionnaire on different caries-associated factors and an oral bacterial sample was collected from 1,050 (526 boys, 524 girls) 1-year-olds. Multiple logistic regression analyses were performed to identify risk factors for colonization with MS.

RESULTS

MS were found in 27% of the 1-year-olds with teeth. High or very high MS scores (2-3) were found in 72 (7%) of the children. MS score was correlated to the number of erupted teeth (p < 0.001). No difference due to gender was found. Multiple logistic regression analysis showed that presence of bacteria was associated with: caries in a sibling, other beverages than water between meals, and more than 8 erupted teeth. High or very high MS scores (2-3) were associated with other beverages than water between meals, and more than 8 erupted teeth.

CONCLUSIONS

Number of teeth present, diet and family aspects were factors associated with presence of MS in 1-year-olds. To develop high or very high MS scores, the number of erupted teeth and dietary habits are important.

Acquisition and maturation of oral microbiome throughout childhood: An update

Traditional microbiology concepts are being renewed since the development of new microbiological technologies, such as, sequencing and large-scale genome analysis. Since the entry into the new millennium, a lot of new information has emerged regarding the oral microbiome. This revision presents an overview of this renewed knowledge on oral microbial community acquisition in the newborn and on the evolution of this microbiome to adulthood. Throughout childhood, the oral microbial load increases, but the microbial diversity decreases. The initial colonizers are related to the type of delivery, personal relationships, and living environment. These first colonizers seem to condition the subsequent colonization, which will lead to more complex and stable ecosystems in adulthood. These early oral microbial communities, therefore, play a major role in the development of the adult oral microbiota and may represent a source of both pathogenic and protective microorganisms in a very early stage of human life. The implications of this knowledge on the daily clinical practice of odontopediatrics are highlighted.

Caries-risk profile variations after short-term use of 5000 ppm fluoride toothpaste

OBJECTIVE

To assess the caries risk following 6 weeks' use of 5000 ppm F toothpaste using 'Cariogram' software.

MATERIALS AND METHODS

A total of 34 participants, 17 mothers and their teenage children, were enrolled in a 6-week clinical trial in which they were given 5000 ppm F toothpaste. They were followed consecutively for 6 weeks with visits that were 2 weeks apart (four in total). A clinical examination was done at baseline and salivary chair-side tests to record the buffer capacity and mutans streptococci (MS) and lactobacilli (LB) counts were performed at each visit. Based on these data, seven caries-related variables were collected and inserted into the Cariogram software to calculate the actual chance of avoiding caries.

RESULTS

The use of 5000 ppm F toothpaste resulted in a statistically significant modification of the caries-risk profile, increasing the actual chance of avoiding caries in the future among the mothers and teenagers at each visit following baseline (p < 0.01). The changes essentially related to the salivary parameters (buffer capacity, MS and LB counts). A statistically significant linear trend was observed for MS counts (p < 0.01) and the number of subjects with a salivary concentration of MS < 10(3) increased at each visit. The same trend was also observed for LB and buffer capacity scores (p = 0.04 and p = 0.03, respectively).

CONCLUSIONS

The short-term use of 5000 ppm F toothpaste is able to reduce the caries risk, which can be clearly demonstrated using 'Cariogram' software.

Current state of topical antimicrobial therapy in management of early childhood caries

The treatment of early childhood caries can have a significant economical burden and treatment relapses are frequent. Effective intervention by means of topical antimicrobial agents can reduce the burden of early childhood caries. The main aim in prevention and treatment should focus on inhibition of the growth of oral bacteria. This is a comprehensive review of the literature on the various antimicrobial agents which are proven to be effective in management of this carious progression. The review identified that there is a significant data to suggest use of antimicrobial agents in management of early childhood caries. Antimicrobial agents aid in better management of patients with early carious lesion. The relapse rates are less, when the treatment is combined with the use of antimicrobial agent.

Characteristics of Streptococcus mutans genotypes and dental caries in children

This longitudinal cohort study evaluated the diversity, commonality, and stability of Streptococcus mutans genotypes associated with dental caries history. Sixty-seven 5- and 6-yr-old children, considered as being at high caries risk, had plaque collected from baseline through 36 months for S. mutans isolation and genotyping using repetitive extragenic palindromic-PCR (4,392 total isolates). Decayed, missing, or filled surfaces (dmfs (primary teeth)/DMFS (secondary teeth)) for each child were recorded at baseline. At baseline, 18 distinct genotypes were found among 911 S. mutans isolates from 67 children (diversity), and 13 genotypes were shared by at least two children (commonality). The number of genotypes per individual was positively associated with the proportion of decayed surfaces (p-ds) at baseline. Twenty-four of the 39 children who were available at follow-up visits maintained a predominant genotype for the follow-up periods (stability) and this was negatively associated with the p-ds. The observed diversity, commonality, and stability of S. mutans genotypes represent a pattern of dental caries epidemiology in this high-caries-risk community, which suggests that fewer decayed surfaces are significantly associated with lower diversity and higher stability of S. mutans genotypes.

Oral health care for children - a call for action

Oral health is a fundamental component of overall health. All children and youth should have access to preventive and treatment-based dental care. Canadian children continue to have a high rate of dental disease, and this burden of illness is disproportionately represented by children of lower socioeconomic status, those in Aboriginal communities and new immigrants. In Canada, the proportion of public funding for dental care has been decreasing. This financial pressure has most affected low-income families, who are also less likely to have dental insurance. Publicly funded provincial/territorial dental plans for Canadian children are limited and show significant variability in their coverage. There is sound evidence that preventive dental visits improve oral health and reduce later costs, and good evidence that fluoridation therapy decreases the rate of dental caries, particularly in high-risk populations. Paediatricians and family physicians play an important role in identifying children at high risk for dental disease and in advocating for more comprehensive and universal dental care for children.

Effects of xylitol wipes on cariogenic bacteria and caries in young children

The aim of the study was to investigate the efficacy of the use of xylitol-containing tooth-wipes in preventing dental caries in young children. In a double-blinded randomized controlled clinical trial, 44 mothers with active caries and their 6- to 35-month-old children were randomized to xylitol-wipe or placebo-wipe groups. The children's caries scores were recorded at baseline and 1 year. Salivary levels of mutans streptococci and lactobacilli were enumerated at baseline, 3, 6, and 12 months. Data were analyzed by intent-to-treat modeling with imputation for caries lesions and a linear mixed-effect model for bacterial levels. Significantly fewer children in the xylitol-wipe group had new caries lesions at 1 year compared with those in the placebo-wipe group (P < 0.05). No significant differences between the two groups were observed in levels of mutans streptococci and lactobacilli at all time-points. Daily xylitol-wipe application significantly reduced the caries incidence in young children as compared with wipes without xylitol, suggesting that the use of xylitol wipes may be a useful adjunct for caries control in infants (Clinicaltrials.gov registration number CT01468727).

Horizontal transmission of Streptococcus mutans in schoolchildren

Objetive: The aim of this study was to analyze possible horizontal transmission patterns of S. mutans among 6-7-yr-old schoolchildren from the same class, identifying genotypes and their diversity and relationship with caries disease status. Study Design: Caries indexes and saliva mutans streptococci and lactobacilli counts were recorded in 42 schoolchildren. Mutans streptococci colonies were identified by means of biochemical tests and all S. mutans strains were genotyped by arbitrarily primed polymerase chain reaction. A child was considered free of S. mutans when it could not be isolated in 3 samples at 1-week intervals. Results: S. mutans was isolated in 30 schoolchildren: 20 having one genotype and 10 two genotypes. Higher mutans streptococci and caries index values were found in those with two genotypes. Five genotypes were isolated in more than 1 schoolchild and one of these was isolated in 3 schoolchildren. Our results suggest that horizontal transmission may take place. Conclusion: Schoolchildren aged 6-7 yrs may be the source of mutual transmission of S. mutans.

Key words:Streptococcus mutans, Horizontal transmission, AP-PCR, genotyping

Children with severe early childhood caries: pilot study examining mutans streptococci genotypic strains after full-mouth caries restorative therapy

PURPOSE

Genotypic strains of mutans streptococci (MS) may vary in important virulence properties and be differentially affected by specific components of full-mouth caries restorative therapy. The purpose of this pilot study was to identify mutans streptococci strains that predominate following caries restorative therapy.

METHODS

Plaque from 7 children with severe early childhood caries was collected before and following therapy. MS isolates (N=828) were subjected to polymerase chain reaction (PCR) and arbitrarily primed-PCR (AP-PCR) for assignment within MS strains. Determining the longitudinal changes in MS strain distribution over time within each patient required the isolation of larger numbers of isolates per patient, but from fewer patients.

RESULTS

Up to 39 genotypic strains of Streptococcus mutans and Streptococcus sobrinus, and 7 genotypic strains of non-MS streptococci were identified by AP-PCR and 16S ribosomal rRNA gene sequencing. The number of MS strains isolated from each patient were 3 to 7 prior to treatment, diminishing to 1 to 2 dominant MS strains in most patients 6 months following therapy.

CONCLUSIONS

Caries restorative therapy resulted in shifts of specific mutans streptococcus and non-mutans streptococcus strains. The implications are that caries restorative therapy affects the distribution of MS strains, and that well-accepted practices for caries prevention should be more closely examined for efficacy.

Genetic diversity of plaque mutans streptococci with rep-PCR

Mutans streptococci (MS) are key organisms associated with the etiology of dental caries. Using probabilities that were tested by oversampling, we designed this study to determine the minimal number of MS isolates from an individual required to evaluate diversity of genotypes. MS isolates were genotyped by repetitive extragenic palindromic-polymerase chain-reaction (rep-PCR). Analysis of 20 isolates from individuals resulted in a mean of 1.6 and 2.4 genotypes in children (N = 12) and adults (N = 10), respectively. In a follow-up study, reducing the number of isolates to 7-10 resulted in a theoretical probability of up to 78% for detecting up to 4 genotypes. A mean of 1.5 genotypes was found in 35 children and 10 adults. These findings provide evidence for the design of studies of MS genotyping that can serve as a model for the analysis of genotypes within individuals.

Horizontal transmission of mutans streptococci in children

It has not been established whether transmission of mutans streptococci occurs between unrelated children older than 4 years of age. The aim of the study was to investigate the possible transmission of mutans streptococci genotypes from child to child in kindergarten. We studied 96 children (ages 5-6 yrs) in three San Francisco Bay Area public schools. Mutans streptococci colonies from each child were isolated from selective culture on Mitis Salivarius Sucrose Bacitracin agar. We used arbitrary primed polymerase chain reactions to determine the mutans streptococci genotypes. Two children (not siblings) in each of the three schools (6%) shared an identical amplitype of S. mutans, unique to each pair. The 19 S. sobrinus amplitypes were found in 12 children, and all were unique to each child. The presence of matching genotypes of S. mutans demonstrates horizontal transmission of this species between unrelated children aged 5-6 years.

Genotypic Diversity of Streptococcus mutans in Caries-Free and Caries-Active Preschool Children

Aim. The aim of the present paper was to evaluate the genotypic diversity of S. mutans in caries-free and caries-active preschool children in Brazil. Design. Twenty-eight preschool children were examined regarding caries experience by the dmft index. DNA from 280 isolates of S. mutans was extracted. S. mutans evaluated using to the PCR method, with primers for the glucosyltransferase gene. The genetic diversity of S. mutans isolates was analyzed by arbitrary primed-PCR (AP-PCR) reactions. The differences between the diversity genotypic and dmft/caries experience were evaluated by χ2 test and Spearman's correlation. Results. The Spearman correlation test showed a strong association between genotypic diversity and caries experience (r = 0.72; P < .001). There were more S. mutans genotypes in the group of preschool children with dental caries, compared with the caries-free group. Among the children with more than 1 genotype, 13 had dental caries (2 to 5 genotypes) and 4 were caries-free (only 2 genotypes). Conclusion. Our results support the previous findings of genetic diversity of S. mutans in preschool children being associated with dental caries. The investigation of such populations may be important for directing the development of programs for caries prevention worldwide.

Comparative whole-genome analysis of Streptococcus mutans isolates within and among individuals of different caries status

INTRODUCTION

Genotypic analyses of Streptococcus mutans using fingerprinting methods depend on a few genetic loci being different but do not reveal the underlying genome-wide differences between strains.

METHODS

We used comparative genomic hybridization (CGH) with 70-mer oligonucleotide microarrays containing open reading frames (ORFs) from S. mutans strain UA159 to examine the genetic diversity of 44 isolates from nine children selected from a local study population in Eastern Iowa.

RESULTS

Unique strains (clones) within each child initially identified by arbitrary-priming polymerase chain reaction were confirmed by CGH. There was a wide range of variation in the hybridization patterns of the 1948 ORFs among the test isolates examined. Between 87 and 237 ORFs failed to give a positive signal among individual isolates. A total of 323 of the UA159 ORFs were absent from one or more of the test strains. These 323 variable genes seemed to be distributed across the entire UA159 genome and across all the predicted functional categories.

CONCLUSION

This set of very close geographically and temporally collected S. mutans isolates had a degree of gene content variation as high as a previously examined global set of strains. Comparing the frequency of these variable genes, the majority of which have unknown function, among strains of different origins (i.e. different caries status) could help to determine their relevance in S. mutans cariogenicity.

Evidence-based caries, risk assessment, and treatment

Dental caries is a dietary and host-modified biofilm disease process, transmissible early in life that, if left untreated, will cause destruction of dental hard tissues. If allowed to progress, the disease will result in the development of caries lesions on tooth surfaces, which initially are noncavitated (eg, white spots), and eventually can progress to cavitation. The "medical model," where the etiologic disease-driving agents are balanced against protective factors, in combination with risk assessment, offers the possibility of patient-centered disease prevention and management before there is irreversible damage done to the teeth. This article discusses how to use evidence supporting risk assessment and management strategies for the caries process.

Prospective study of potential sources of Streptococcus mutans transmission in nursery school children

Transmission of Streptococcus mutans, a major dental caries pathogen, occurs mainly during the first 2.5 years of age. Children appear to acquire S. mutans mostly from their mothers, but few studies have investigated non-familial sources of S. mutans transmission. This study prospectively analysed initial S. mutans oral colonization in 119 children from nursery schools during a 1.5-year period and tracked the transmission from child to child, day-care caregiver to child and mother to child. Children were examined at baseline, when they were 5-13 months of age, and at 6-month intervals for determination of oral levels of S. mutans and development of caries lesions. Levels of S. mutans were also determined in caregivers and mothers. A total of 1392 S. mutans isolates (obtained from children, caregivers and mothers) were genotyped by arbitrarily primed PCR and chromosomal RFLP. Overall, 40.3 % of children were detectably colonized during the study, and levels of S. mutans were significantly associated with the development of caries lesions. Identical S. mutans genotypes were found in four nursery cohorts. No familial relationship existed in three of these cohorts, indicating horizontal transmission. Despite high oral levels of S. mutans identified in most of the caregivers, none of their genotypes matched those identified in the respective children. Only 50 % of children with high levels of S. mutans carried genotypes identified in their mothers. The results support previous evidence indicating that non-familial sources of S. mutans transmission exist, and indicate that this bacterium may be transmitted horizontally between children during the initial phases of S. mutans colonization in nursery environments.

Maternal transmission of mutans Streptococci in severe-early childhood caries

PURPOSE

This study utilized multiple genetic analyses to detect evidence of maternal MS acquisition in children with S-ECC.

METHODS

Twenty-seven mother/child pairs were selected from children with 5-ECC preceding dental rehabilitation under general anesthesia. Plaque samples were collected from the mother, child, and the child's carious lesion. Arbitrarily primed-polymerase chain reaction (AP-PCR) genotyped 6-8 MS isolates from each plaque sample, and unique genotypes were identified. Representative MS isolates with unique genotypes were characterized by pulsed-field gel electrophoresis (PFGE). Cluster analysis using the Dice band-based similarity coefficient was used to generate dendrograms from gel bonding patterns. A Dice coefficient >70% indicated similarity or match among PFGE genotypes.

RESULTS

In 26% (7/27) of mother/child pairs, all of the child's isolates matched the mother. In 15% (4/27), some of the child's genotypes matched the mother, and in 59% (16/27), no isolates matched the mother. Maternal transmission was a mode of MS acquisition in 41% (11/27) of mother/child pairs, while acquisition from non-maternal sources occurred in 74% (20/27).

CONCLUSIONS

MS genotypes that did not match maternal strains were identified in the majority of children (74%) within this S-ECC population. Evidence of maternal transmission was detected in 41% of mother/child pairs.

Genotypic diversity of S. mutans in dental biofilm formed in situ under sugar stress exposure

In situ dental biofilm composition under sugar exposure is well known, but sugar effect on the genotypic diversity of S. mutans in dental biofilm has not been explored. This study evaluated S. mutans genotypic diversity in dental biofilm formed in situ under frequent exposure to sucrose and its monosaccharide constituents (glucose and fructose). Saliva of 7 volunteers was collected for isolation of S. mutans and the same volunteers wore intraoral palatal appliances, containing enamel slabs, which were submitted to the following treatments: distilled and deionized water (negative control), 10% glucose + 10% fructose (fermentable carbohydrates) solution or 20% sucrose (fermentable and EPS inductor) solution, 8x/day. After 3, 7 and 14 days, the biofilms were collected and S. mutans colonies were isolated. Arbitrarily primed polymerase chain reaction (AP-PCR) of S. mutans showed that salivary genotypes were also detected in almost all biofilm samples, independently of the treatment, and seemed to reflect those genotypes present at higher proportion in biofilms. In addition to the salivary genotypes, others were found in biofilms but in lower proportions and were distinct among treatment. The data suggest that the in situ model seems to be useful to evaluate genotypic diversity of S. mutans, but, under the tested conditions, it was not possible to clearly show that specific genotypes were selected in the biofilm due to the stress induced by sucrose metabolism or simple fermentation of its monosaccharides.

Knowledge and attitude of parents or caretakers regarding transmissibility of caries disease

Dental caries is a transmissible infectious disease in which mutans streptococci are generally considered to be the main etiological agents. Although the transmissibility of dental caries is relatively well established in the literature, little is known whether information regarding this issue is correctly provided to the population. The present study aimed at evaluating, by means of a questionnaire, the knowledge and usual attitude of 640 parents and caretakers regarding the transmissibility of caries disease. Most interviewed adults did not know the concept of dental caries being an infectious and transmissible disease, and reported the habit of blowing and tasting food, sharing utensils and kissing the children on their mouth. 372 (58.1%) adults reported that their children had already been seen by a dentist, 264 (41.3%) answered that their children had never gone to a dentist, and 4 (0.6%) did not know. When the adults were asked whether their children had already had dental caries, 107 (16.7%) answered yes, 489 (76.4%) answered no, and 44 (6.9%) did not know. Taken together, these data reinforce the need to provide the population with some important information regarding the transmission of dental caries in order to facilitate a more comprehensive approach towards the prevention of the disease.

Transcriptional analysis of gtfB, gtfC, and gbpB and their putative response regulators in several isolates of Streptococcus mutans

BACKGROUND

Streptococcus mutans, a major dental caries pathogen, expresses several virulence genes that mediate its growth, accumulation on tooth surfaces, and acid-mediated tooth demineralization. GtfB and GtfC catalyze the extracellular synthesis of water-insoluble glucan matrix from sucrose, and are essential for accumulation of bacteria in the dental biofilm. GbpB, an essential protein of S. mutans, might also mediate cell-surface interaction with glucan.

AIM/METHODS

In this study, we determined the transcription levels of gtfB, gtfC, and gbpB, and several putative transcriptional response regulators (rr) at different phases of planktonic growth in 11 S. mutans strains.

RESULTS

Activities of gtfB and gtfC were growth-phase dependent and assumed divergent patterns in several strains during specific phases of growth, while gbpB activities appeared to be under modest influence of the growth phase. Transcription patterns of the rr vicR, covR, comE, ciaR, and rr1 were growth-phase dependent and some of these genes were expressed in a highly coordinated way. Each rr, except comE, was expressed by all the strains. Patterns of virulence and regulatory genes were, however, strain-specific.

CONCLUSIONS

The findings suggest that mechanisms controlling virulence gene expression are variable among genotypes, providing the notion that the genetic diversity of S. mutans may have important implications for understanding mechanisms that regulate the expression of virulence genes in this species.

Case definition, aetiology and risk assessment of early childhood caries (ECC): a revisited review

AIM

To provide a review of the existing literature on early childhood caries (ECC) with particular reference on the nomenclature, case definition, epidemiology, etiology and risk assessment.

METHODS

An electronic search was used to identify and critically review papers that have been published and are pertinent to the above issues, evaluate and compile the reported evidence.

RESULTS

The term ECC has been adopted to more accurately describe dental caries that affects primary dentitions, replacing previously used terminology that associated the disease with the nursing habit. Suggested ECC case definition uses caries patterns as defining criteria, however, further refinement to include different clinical expressions of a varying severity is necessary. Significant percentages of preschool child populations are affected by ECC today, with the disease concentrating disproportionately in deprived families. Early colonization by mutans streptococci (MS) is associated with increased ECC development, with bacteria being transmitted in both vertical and horizontal ways. Dietary factors related to sugar consumption predispose to early MS colonization and establishment and increase the risk for ECC development, being part of the causal chain. Inappropriate bottle and breast-feeding behaviors also increase the risk, without showing a direct causal relationship. High risk children belong to ethnic minority groups and to low income families with poor parental behaviors and attitudes.

CONCLUSIONS

Further high-quality studies are needed to explore the role bacteria other than MS may play in caries initiation and progression, elucidate the interaction of the saliva immune defence system with a potentially defective tooth, and investigate the effect distant behavioral factors have on the causal chain that leads to ECC development.

[[Streptococcus mutans Acquisition and Dental Caries Development in First-Born Children].]

OBJECTIVE: To evaluate the moment of streptococcus mutans (SM) acquisition, caries development and their associate variables along 23 months, in first-born children of low socioeconomic status families, starting at 7 months of age. METHOD: The sample was chosen based on highly SM-colonized mothers, including all members of 14 families living in the same houses. The study included 14 mothers, 14 fathers and 14 first-borns and 8 relatives (mostly grandparents). Initial clinical examinations and radiographs determined the caries indices and periodontal conditions of the adults. SM count in all adults was made in the first 2 visits. The children were examined for SM count, number of teeth and number of carious lesions, in 4 visits. RESULTS: SM prevalence was high in the adults, being absent in only one of the parents. SM was found in 1, 2, 3 and 10 children in the first, second, third and fourth visits. Dental caries was detected in only 3 children in the last visit (at 30 months), who presented significantly higher SM scores than the children without caries in the same visit. CONCLUSION: A low income social condition and mothers highly colonized by SM do not mean necessarily early SM colonization and high caries activity in children with oral homecare. Caries development is significantly associated with high SM scores in the children.

Streptococcus mutans clonal variation revealed by multilocus sequence typing

Streptococcus mutans is the major pathogen of dental caries, a biofilm-dependent infectious disease, and occasionally causes infective endocarditis. S. mutans strains have been classified into four serotypes (c, e, f, and k). However, little is known about the S. mutans population, including the clonal relationships among strains of S. mutans, in relation to the particular clones that cause systemic diseases. To address this issue, we have developed a multilocus sequence typing (MLST) scheme for S. mutans. Eight housekeeping gene fragments were sequenced from each of 102 S. mutans isolates collected from the four serotypes in Japan and Finland. Between 14 and 23 alleles per locus were identified, allowing us theoretically to distinguish more than 1.2 x 10(10) sequence types. We identified 92 sequence types in these 102 isolates, indicating that S. mutans contains a diverse population. Whereas serotype c strains were widely distributed in the dendrogram, serotype e, f, and k strains were differentiated into clonal complexes. Therefore, we conclude that the ancestral strain of S. mutans was serotype c. No geographic specificity was identified. However, the distribution of the collagen-binding protein gene (cnm) and direct evidence of mother-to-child transmission were clearly evident. In conclusion, the superior discriminatory capacity of this MLST scheme for S. mutans may have important practical implications.

Genotypic diversity of Streptococcus mutans in 3- to 4-year-old Chinese nursery children suggests horizontal transmission

OBJECTIVE

The aims of this study were to investigate the colonisation of Streptococcus mutans and to determine the possibility of horizontal transmission in Chinese nursery children.

DESIGN

Fifty-six children aged between 3 and 4 years old from a nursery were included in this study. Twenty-four children were from the day and night nursery class, the others were from the day nursery class. Dental plaque samples were collected with sterile toothpicks and cultured on S. mutans-selective tryptone-yeast-cystine agar supplemented with 0.2U/ml bacitracin and 15% sucrose. The typical isolates of S. mutans were identified by classical microbiological methods and genotyped by arbitrarily primed PCR (AP-PCR) and restriction fragment length polymorphism analysis.

RESULTS

S. mutans was isolated from 41 of the 56 children. The prevalence of S. mutans was higher in the children from day nursery class, compared with the children from day and night nursery class (P<0.05). A total of 140 S. mutans isolates from 41 children were analysed by AP-PCR, and 88 different amplitypes were identified. Of 41 children with S. mutans isolates, 82.9% carried two or more genotypes. Two genotypes of S. mutans were repeatedly isolated among 13 children in the day and night nursery class, and one genotype was isolated from two children in the day nursery class.

CONCLUSION

The presence of matching genotypes of S. mutans among children attending the same nursery suggests the possibility of horizontal transmission.

Genetic diversity of competence gene loci in clinical genotypes of Streptococcus mutans

The frequencies of 21 competence genes were analyzed in 94 genotypes of Streptococcus mutans. These include those of a main regulatory system (comCDE), structural, and other regulatory orthologues identified in the genome of strain UA159. PCR and Southern blot analysis revealed that all genes are widespread within the species.

Colonization and vertical transmission of Streptococcus mutans in Turkish children

The aim of the study was to establish the colonization of Streptococcus mutans and to determine the possibility of intra-familial transmission in a group of Turkish children and their parents. A total of 56 children participated in the study together with their parents (20 fathers and 49 mothers). Saliva samples were collected from the individuals and cultivated on S. mutans selective TYCSB agar. The typical isolates of S. mutans were identified by using classical microbiological methods, as well as molecular typing of S. mutans clones which was performed by using AP PCR with OPA5 primer for the detection of transmission. The vertical transmission of salivary S. mutans was detected among 14 mother-father-child, 35 mother-child (one twins) and 6 father-child combinations. The homologies of strain types were recorded as 24% and 16.6% for mother-child and father-child combinations, respectively. A significant positive correlation (p<0.001) was found between the infected children and their parents with high S. mutans counts.