The microbiota of young children from tooth and tongue samples

Evaluation of microbiome in primary and permanent dentition in grade C periodontitis in young individuals

BACKGROUND

The aim of the present study was to evaluate the subgingival microbiome in patients with grade C molar-incisor pattern periodontitis (C-MIP) affecting the primary or permanent dentitions.

METHODS

DNA was isolated from subgingival biofilm samples from diseased and healthy sites from 45 C-MIP patients and subjected to phylogenetic microarray analysis. C-MIP sites were compared between children affected in the primary to those affected in the permanent dentitions. Within-subject differences between C-MIP-affected sites and dentition-matched healthy sites were also evaluated.

RESULTS

C-MIP sites of subjects affected in the primary dentition showed partially overlapping but distinct microbial communities from C-MIP permanent dentition sites (p < 0.05). Differences were due to increased levels in primary C-MIP sites of certain species of the genera Capnocytophaga and Leptotrichia, while C-MIP permanent dentition sites showed higher prevalence of Filifactor alocis. Aggregatibacter actinomycetemcomitans (Aa) was among species seen in high prevalence and levels in both primary and permanent C-MIP sites. Moreover, both permanent and primary C-MIP sites showed distinct microbial communities when compared to dentition-matched healthy sites in the same subject (p < 0.01).

CONCLUSIONS

Primary and permanent teeth with C-MIP showed a dysbiotic microbiome, with children affected in the primary dentition showing a distinct profile from those affected in the permanent dentition. However, Aa was enriched in both primary and permanent diseased sites, confirming that this microorganism is implicated in C-MIP in both dentitions.

Bacterial Sialic Acid Catabolism at the Host–Microbe Interface

Sialic acids consist of nine-carbon keto sugars that are commonly found at the terminal end of mucins. This positional feature of sialic acids contributes to host cell interactions but is also exploited by some pathogenic bacteria in evasion of host immune system. Moreover, many commensals and pathogens use sialic acids as an alternative energy source to survive within the mucus-covered host environments, such as the intestine, vagina, and oral cavity. Among the various biological events mediated by sialic acids, this review will focus on the processes necessary for the catabolic utilization of sialic acid in bacteria. First of all, transportation of sialic acid should be preceded before its catabolism. There are four types of transporters that are used for sialic acid uptake; the major facilitator superfamily (MFS), the tripartite ATP-independent periplasmic C4-dicarboxilate (TRAP) multicomponent transport system, the ATP binding cassette (ABC) transporter, and the sodium solute symporter (SSS). After being moved by these transporters, sialic acid is degraded into an intermediate of glycolysis through the well-conserved catabolic pathway. The genes encoding the catabolic enzymes and transporters are clustered into an operon(s), and their expression is tightly controlled by specific transcriptional regulators. In addition to these mechanisms, we will cover some researches about sialic acid utilization by oral pathogens.

Distribution characteristics of oral microbiota and its relationship with intestinal microbiota in patients with type 2 diabetes mellitus

Introduction

Type 2 diabetes mellitus (T2DM) has a high incidence rate globally, increasing the burden of death, disability, and the economy worldwide. Previous studies have found that the compositions of oral and intestinal microbiota changed respectively in T2DM; whether the changes were associated or interacted between the two sites and whether there were some associations between T2DM and the ectopic colonization of oral microbiota in the gut still need to be identified.

Research design and methods

We performed a cross-sectional observational study; 183 diabetes and 74 controls were enrolled. We used high-throughput sequencing technology to detect the V3-V4 region of 16S rRNA in oral and stool samples. The Source Tracker method was used to identify the proportion of the intestinal microbiota that ectopic colonized from the oral cavity.

Results

The oral marker bacteria of T2DM were found, such as Actinobacteria, Streptococcus, Rothia, and the intestinal marker bacteria were Bifidobacterium, Streptococcus, and Blautia at the genus level. Among them, Actinobacteria and Blautia played a vital role in different symbiotic relationships of oral and intestinal microbiota. The commonly distributed bacteria, such as Firmicutes, Bacteroidetes, and Actinobacteria, were found in both oral and intestine. Moreover, the relative abundance and composition of bacteria were different between the two sites. The glycine betaine degradation I pathway was the significantly up-regulated pathway in the oral and intestinal flora of T2DM. The main serum indexes related to oral and intestinal flora were inflammatory. The relative abundance of Proteobacteria in the intestine and the Spirochete in oral was positively correlated, and the correlation coefficient was the highest, was 0.240 (P<0.01). The proportion of ectopic colonization of oral flora in the gut of T2DM was 2.36%.

Conclusion

The dysbacteriosis exited in the oral and intestine simultaneously, and there were differences and connections in the flora composition at the two sites in T2DM. Ectopic colonization of oral flora in the intestine might relate to T2DM. Further, clarifying the oral-gut-transmitting bacteria can provide an essential reference for diagnosing and treating T2DM in the future.

Comparison of the Level of Staphylococcus Aureus and Escherichia Coli in Complete Cleft Infants With Normal Infants

BACKGROUND

There are many types of oral bacteria, and they differ between healthy children and children with an oral cleft. The purpose of this study was to compare the level of Staphylococcus aureus and Escherichia coli in complete cleft infants with normal infants.

MATERIALS AND METHODS

Fifty-two Iraqi infants had participated in this study (26 infants were with cleft and 26 infants were the control healthy group), the study group included 13 infants with class III Veau's palatal classification, and 13 with class IV Veau's palatal classification). All are aged from 1 day to 4 months. They were selected and submitted to a questionnaire and clinical examination and bacterial examination. Data description, analysis and presentation were performed using statistical package for social science (SPSS version 21).

RESULTS

The counting and colonization of S. aureus and GV- (E. coli) were higher in cleft group than in control group.

Relationships Between Diurnal Changes of Tongue Coating Microbiota and Intestinal Microbiota

The oral cavity and the intestine are the main distribution locations of human digestive bacteria. Exploring the relationships between the tongue coating and gut microbiota, the influence of the diurnal variations of the tongue coating microbiota on the intestinal microbiota can provide a reference for the development of the disease diagnosis and monitoring, as well as the medication time. In this work, a total of 39 healthy college students were recruited. We collected their tongue coating microbiota which was collected before and after sleep and fecal microbiota. The diurnal variations of tongue coating microbiota are mainly manifested on the changes in diversity and relative abundance. There are commensal bacteria in the tongue coating and intestines, especially Prevotella which has the higher proportion in both sites. The relative abundance of Prevotella in the tongue coating before sleep has a positive correlation with intestinal Prevotella; the r is 0.322 (p < 0.05). Bacteroides in the intestine had the most bacteria associated with the tongue coating and had the highest correlation coefficient with Veillonella in the oral cavity, which was 0.468 (p < 0.01). These results suggest that the abundance of the same flora in the two sites may have a common change trend. The SourceTracker results show that the proportion of intestinal bacteria sourced from tongue coating is less than 1%. It indicates that oral flora is difficult to colonize in the intestine in healthy people. This will provide a reference for the study on the oral and intestinal microbiota in diseases.

Acquisition and establishment of the oral microbiota

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

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.

Home sampling is a feasible method for oral microbiota analysis for infants and mothers

OBJECTIVES

Large longitudinal cohort studies in infants are needed to understand oral microbiome maturation in relation to general health. The logistics of such studies are complex and costs involved high. Methods like home sampling by caretakers might be a solution to these issues. This study aimed to evaluate feasibility of home sampling by caretakers and to assess which oral niche provides the most reliable sample.

METHODS

In this cross-sectional study 30 mothers and their infants aged 2-15 months participated. Swabs of the tongue, buccal mucosa, saliva, and dental plaque of the mother and the infant were collected by the mother after watching an instruction video. Thereafter, the trained researcher repeated the sample collection. Variations on the sampling protocol were listed. Bacterial DNA was quantified and microbial composition was assessed using 16S rDNA amplicon sequencing.

RESULTS

None of the sampled niches appeared to be unfeasible based on interviews and observed variations on protocol. No significant differences in bacterial DNA concentration between operators (mother and researcher) were found. In infant's saliva, Shannon diversity of samples collected by the researcher was significantly higher than those collected by mothers (p = 0.0009) and the bacterial composition was influenced by variations on sampling protocol (p = 0.01).

CONCLUSIONS

Home sampling by caretakers is a feasible method for oral sample collection in infants and mothers. Oral samples collected by mothers resemble samples collected by a trained researcher, with the tongue sample being the most similar and saliva the least.

CLINICAL SIGNIFICANCE

Home sampling can simplify longitudinal oral microbiota collection.

A longitudinal study of the development of the saliva microbiome in infants 2 days to 5 years compared to the microbiome in adolescents

Understanding oral microbiota programming attracts increasing interest due to its importance for oral health and potential associations with systemic diseases. Here the oral microbiota was longitudinally characterized in children from 2 days (n = 206) to 5 years of age and in young adults (n = 175) by sequencing of the v3-v4 region of the 16S rRNA gene from saliva extracted DNA. Alpha diversity increased by age, with 2-day- and 3-month-old infants in one sub-group, and 18-month- and 3-year-old children in another. Firmicutes decreased up to 3 years of age, whereas Proteobacteria, Actinobacteria, Bacteroidetes and Fusobacteria abundances increased. Abiotrophia, Actinomyces, Capnocytophaga, Corynebacterium, Fusobacterium, Kingella, Leptotrichia, Neisseria and Porphyromonas appeared from 18-months of age. This was paralleled by expansions in the core microbiome that continued up to adulthood. The age-related microbiota transformation was paralleled by functional alterations, e.g., changed metabolic pathways that reflected e.g., breastfeeding and increasing proportions of anaerobic species. Oral microbiotas differed by feeding mode and weakly by mode of delivery, but not gender, pacifier use or cleaning method or probiotic intake. The study shows that the saliva microbiota is diverse 2 days after birth and under transformation up to 5 years of age and beyond, with fluctuations possibly reflecting age-related environmental influences.

Rapid Multiplex Real-Time PCR Method for the Detection and Quantification of Selected Cariogenic and Periodontal Bacteria

Dental caries and periodontal diseases are associated with a shift from symbiotic microbiota to dysbiosis. The aim of our study was to develop a rapid, sensitive, and economical method for the identification and quantification of selected cariogenic and periodontal oral bacteria. Original protocols were designed for three real-time multiplex PCR assays to detect and quantify the ratio of 10 bacterial species associated with dental caries (“cariogenic” complex) or periodontal diseases (red complex, orange complex, and Aggregatibacter actinomycetemcomitans). A total number of 60 samples from 30 children aged 2–6 years with severe early childhood caries and gingivitis were tested. In multiplex assays, the quantification of total bacterial (TB) content for cariogenic bacteria and red complex to eliminate differences in quantities caused by specimen collection was included. The mean counts for the TB load and that of ten evaluated specimens corresponded to previously published results. We found a significant difference between the microbial compositions obtained from the area of control and the affected teeth (p < 0.05). Based on this comprehensive microbiological examination, the risk of dental caries or periodontal inflammation may be determined. The test could also be used as a tool for behavioral intervention and thus prevention of the above-mentioned diseases.

Effect of CPP-ACP on Streptococcus mutans in saliva of high caries-risk preschool children: a randomized clinical trial

PURPOSE

The aim of this study was to assess the efficacy of CPP-ACP in reducing salivary S. mutans levels and compare its effect as a dentifrice to use of a fluoride dentifrice alone, or with the sequential use of a combination of both agents (fluoride, then CPP-ACP) in three groups of preschool children over a 6-month period.

METHODS

This was a double-blinded clinical trial, the sample (n = 127, age 4.6 ± 0.47 years), with high caries risk, was randomized into three groups which applied different agents twice daily; fluoride toothpaste (500 ppm, n = 50), CPP-ACP (10% w/v, n = 38), and combination group (n = 39) applied fluoride, then CPP-ACP. S. mutans salivary levels were measured by GC Saliva-Check Mutans^™.

RESULTS

Within groups, a significant decrease in S. mutans-positive children (SMPC) occurred in fluoride and combination groups at 3-months, (P < 0.05), and in all groups at 6-months, (P < 0.05). The highest reduction in SMPC occurred in the CPP-ACP group, however, there were no significant differences in SMPC between groups at all study intervals, (P > 0.05).

CONCLUSION

Although all agents were effective, CPP-ACP showed the highest reduction in SMPC over 6-months.

The Oral Bacterial Microbiome of Interdental Surfaces in Adolescents According to Carious Risk

Adolescence is closely associated with a high risk of caries. The identification of specific bacteria in an oral microniche, the interdental space of the molars, according to carious risk can facilitate the prediction of future caries and the anticipation of the progression or stabilization of caries in adolescents. A cross-sectional clinical study according to the bacteriological criteria of interdental healthy adolescents and carious risk factors-low and high-using a real-time polymerase chain reaction technique was conducted. The presence of 26 oral pathogens from the interdental microbiota of 50 adolescents aged 15 to 17 years were qualitatively and quantitatively analyzed. Bacteria known to be cariogenic (Bifidobacterium dentium, Lactobacillus spp., Rothia dentocariosa, Streptococcus cristatus, Streptococcus mutans, Streptococcus salivarius, Streptococcus sobrinus, and Streptococcus wiggsiae) did not present differences in abundance according to carious risk. Periodontal bacteria from the red complex are positively correlated with carious risk. However, only 3 bacteria-S. sobrinus, E corrodens and T. forsythia-presented a significant increase in the highest group. Estimating the risk of caries associated with bacterial factors in interdental sites of molars in adolescents contributes to the better definition of carious risk status, periodicity and intensity of diagnostic, prevention and restorative services.

Periodontal pathogenic bacteria among high school children in Saudi Arabia

BACKGROUND

The periodontal tissues are continuously exposed to specific bacterial components that have the ability to alter many local functions. Normal endogenous infections in healthy mouths cause disease when their numbers increase significantly.

OBJECTIVE

Determine the percentage of different periodontal pathogenic bacteria and their association with periodontal status.

DESIGN

Cross-sectional, analytical.

SETTINGS

School children of both genders in Saudi Arabia.

PATIENTS AND METHODS

Clinical examination consisted of measurement of the gingival and periodontal supporting tissue including attachment loss, probing pocket depth and furcation involvement following the National Health and Nutrition Examination Survey (NHANES) and taking samples of the subgingival bacterial flora.

MAIN OUTCOME MEASURES

The percentage of periodontal pathogenic bacteria and its association with periodontal status in Saudi Arabia.

SAMPLE SIZE

Bacterial samples were collected from 277 subjects.

RESULTS

Aggregatibacter actinomycetemcomitans was present in 21.7% of the subjects, Porphyromonas gingivalis in 21.3%; Tannerella forsythia in 10.1%; Treponema denticola in 34.7% and Prevotella inter-media in 12.3%. The red complex bacteria were found in 2.9% of the subjects.

CONCLUSIONS

The percentages of bacteria varied but only T denticola was significantly associated with periodontal breakdown. In addition, the presence of more than 2 of the 5 species tested were significantly associated with tissue damage.

LIMITATIONS

Cannot be generalized to all of Saudi Arabia. Larger controlled studies are needed.

CONFLICT OF INTEREST

None.

Aggregatibacter actinomycetemcomitans (Aa) Under the Radar: Myths and Misunderstandings of Aa and Its Role in Aggressive Periodontitis

Aggregatibacter actinomycetemcomitans (Aa) is a low-abundance Gram-negative oral pathobiont that is highly associated with a silent but aggressive orphan disease that results in periodontitis and tooth loss in adolescents of African heritage. For the most part Aa conducts its business by utilizing strategies allowing it to conceal itself below the radar of the host mucosal immune defense system. A great deal of misinformation has been conveyed with respect to Aa biology in health and disease. The purpose of this review is to present misconceptions about Aa and the strategies that it uses to colonize, survive, and evade the host. In the process Aa manages to undermine host mucosal defenses and contribute to disease initiation. This review will present clinical observational, molecular, and interventional studies that illustrate genetic, phenotypic, and biogeographical tactics that have been recently clarified and demonstrate how Aa survives and suppresses host mucosal defenses to take part in disease pathogenesis. At one point in time Aa was considered to be the causative agent of Localized Aggressive Periodontitis. Currently, it is most accurate to look at Aa as a community activist and necessary partner of a pathogenic consortium that suppresses the initial host response so as to encourage overgrowth of its partners. The data for Aa's activist role stems from molecular genetic studies complemented by experimental animal investigations that demonstrate how Aa establishes a habitat (housing), nutritional sustenance in that habitat (food), and biogeographical mobilization and/or relocation from its initial habitat (transportation). In this manner Aa can transfer to a protected but vulnerable domain (pocket or sulcus) where its community activism is most useful. Aa's “strategy” includes obtaining housing, food, and transportation at no cost to its partners challenging the economic theory that “there ain't no such thing as a free lunch.” This “strategy” illustrates how co-evolution can promote Aa's survival, on one hand, and overgrowth of community members, on the other, which can result in local host dysbiosis and susceptibility to infection.

Comparison of Salivary pH Changes after Consumption of Two Sweetened Malaysian Local Drinks among Individuals with Low Caries Experience: A Pilot Study

Background

Regular consumption of sweetened beverages has been associated with dental caries, which is mediated through salivary pH. The salivary pH changes among individuals with low caries experience after consumption of two local sweetened drinks is compared.

Methods

In this block randomised controlled parallel group, an open-label pilot study of 49 participants aged 21–25 were selected. The participants were randomised into three groups: mineral water, chocolate drink and sirap bandung. One day prior to the test, scaling was done and the participants did not eat or drink anything on the test day till the saliva sample collection was done. Salivary pH was measured at baseline and after the consumption of the drinks with a glass electrode digital pH meter at five-minute interval for half an hour. The statistical significance was assessed at the level of 5%.

Results

After consumption of chocolate drink and sirap bandung, the salivary pH dropped from a baseline of 7.09 for chocolate drink and 7.13 for sirap bandung to 6.69 for chocolate and 6.86 for sirap bandung. This difference was statistically significant (P < 0.001).

Conclusion

Sweetened milk based local drinks can increase the caries susceptibility. In the community, information about limiting the intake of sweetened drinks should be reinforced.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Transmission of mutans streptococci in mother-child pairs

BACKGROUND & OBJECTIVES

Dental caries is an infectious, transmissible disease. Maternal transfer of mutans streptococci (MS) has been a subject of research. The aim of this study was to evaluate the transmission of MS from mother to children through genetic analysis.

METHODS

Thirty mother-child pairs were included and divided into three groups according to the age of the children. Saliva samples were collected and MS colonies from each mother-child pair were isolated. After inoculation and incubation, MS colonies were submitted to amplification technique by polymerase chain reaction (PCR) for identification and arbitrarily primed PCRs (AP-PCRs) to determine various MS genotypes.

RESULTS

From birth to six months of age, 30 per cent of children exhibited MS colonization, and by the age of 30 months, 100 per cent harboured the bacteria (P < 0.001). Factors associated with MS colonization were eruption of teeth (P < 0.001), feeding habits with mean colony count being significantly lower in breast-fed as compared to bottle-fed children (P < 0.001) and a significant association between mean MS count of child and mother's practice of sharing spoon with child (P < 0.001). The AP-PCR fingerprinting profile analysis showed 17 MS groups (clusters) containing identical or highly related isolates in mother-child pairs with a high level of similarity (77.27 %).

INTERPRETATION & CONCLUSIONS

The presence of matching MS genotypes suggested vertical transmission from mothers to children. Feeding habits, gum cleaning and number of erupted teeth in children had significant effect on MS colonization. There is a need to develop strategies to present MS colonization in children.

A Comparative Study of Oral Microbiota in Infants with Complete Cleft Lip and Palate or Cleft Soft Palate

Few reports have been published on the early microbiota in infants with various types of cleft palate. We assessed the formation of the oral microbiota in infants with complete cleft lip and palate (CLP n = 30) or cleft soft palate (CSP n = 25) in the neonatal period (T1 time) and again in the gum pad stage (T2 time). Culture swabs from the tongue, palate, and/or cleft margin at T1 and T2 were taken. We analysed the prevalence of the given bacterial species (the percentage) and the proportions in which the palate and tongue were colonised by each microorganism. At T1, Streptococcus mitis (S. mitis) were the most frequently detected in subjects with CLP or CSP (63% and 60%, resp.). A significantly higher frequency of methicillin-sensitive Staphylococcus aureus (S. aureus MSSA) was observed in CLP compared to the CSP group. At T2, significantly higher percentages of S. mitis, S. aureus MSSA, Staphylococcus epidermidis, and members of the Enterobacteriaceae family were noted in CLP infants compared to the CSP. S. mitis and Streptococcus sanguinis appeared with the greatest frequency on the tongue, whereas Streptococcus salivarius was predominant on the palate. The development of the microbiota in CLP subjects was characterised by a significant increase in the prevalence of pathogenic bacteria.

Salivary microbiomes of indigenous Tsimane mothers and infants are distinct despite frequent premastication

Background

Premastication, the transfer of pre-chewed food, is a common infant and young child feeding practice among the Tsimane, forager-horticulturalists living in the Bolivian Amazon. Research conducted primarily with Western populations has shown that infants harbor distinct oral microbiota from their mothers. Premastication, which is less common in these populations, may influence the colonization and maturation of infant oral microbiota, including via transmission of oral pathogens. We collected premasticated food and saliva samples from Tsimane mothers and infants (9–24 months of age) to test for evidence of bacterial transmission in premasticated foods and overlap in maternal and infant salivary microbiota. We extracted bacterial DNA from two premasticated food samples and 12 matched salivary samples from maternal-infant pairs. DNA sequencing was performed with MiSeq (Illumina). We evaluated maternal and infant microbial composition in terms of relative abundance of specific taxa, alpha and beta diversity, and dissimilarity distances.

Results

The bacteria in saliva and premasticated food were mapped to 19 phyla and 400 genera and were dominated by Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. The oral microbial communities of Tsimane mothers and infants who frequently share premasticated food were well-separated in a non-metric multi-dimensional scaling ordination (NMDS) plot. Infant microbiotas clustered together, with weighted Unifrac distances significantly differing between mothers and infants. Infant saliva contained more Firmicutes (p < 0.01) and fewer Proteobacteria (p < 0.05) than did maternal saliva. Many genera previously associated with dental and periodontal infections, e.g. Neisseria, Gemella, Rothia, Actinomyces, Fusobacterium, and Leptotrichia, were more abundant in mothers than in infants.

Conclusions

Salivary microbiota of Tsimane infants and young children up to two years of age do not appear closely related to those of their mothers, despite frequent premastication and preliminary evidence that maternal bacteria is transmitted to premasticated foods. Infant physiology and diet may constrain colonization by maternal bacteria, including several oral pathogens.

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.

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.

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.

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.

Antibiogram pattern of oral microflora in periodontic children of age group 6 to 12 years: a clinicomicrobiological study

AIM

The study was carried out to see the diversity of oral microflora and its antibiotic sensitivity test in children of age group 6 to 12 years was carried.

MATERIALS AND METHODS

Total 50 patients of age group 6 to 12 years were analyzed for their oral microflora and then checked for the antibiotic susceptibility test. The samples that were collected were incubated at 37°C for 48 hours. Once dispersed samples were taken and Gram staining was done, also they were spread on to a number of freshly prepared agar plates and incubated to allow cells to form microbial colony.

RESULTS

The result showed microflora common in all types, Gram-positive facultative anaerobic rods and cocci. In normal children Gram-positive facultative anaerobic and fermenting cocci were predominant where as in children with caries growth of microbiota that were Gram-negative and positive, capnophilic, motile and anaerobic rods and cocci belonging to members of genera S. mutans and A. actinomycetemcomitans was seen.

CONCLUSION

By the present study it has been concluded that the number of bacteria determined by microscopic counts was twice as high in caries patients as in healthy sites, and also recommended that amoxicillin, ampicillin and amikacin are the most effective antibacterial drugs for the treatment of dental caries.

Microbiota-targeted therapies: an ecological perspective

The connection between disease and the disruption of homeostatic interactions between the host and its microbiota is now well established. Drug developers and clinicians are starting to rely more heavily on therapies that directly target the microbiota and on the ecology of the microbiota to understand the outcomes of these treatments. The effects of those microbiota-targeted therapies that alter community composition range in scale from eliminating individual strains of a single species (for example, with antibacterial conjugate vaccines) to replacing the entire community with a new intact microbiota (for example, by fecal transplantation). Secondary infections linked to antibiotic use provide a cautionary tale of the unintended consequences of perturbing a microbial species network and highlight the need for new narrow-spectrum antibiotics with rapid companion diagnostics. Insights into microbial ecology will also benefit the development of probiotics, whose therapeutic prospects will depend on rigorous clinical testing. Future probiotics may take the form of a consortium of long-term community residents: "a fecal transplant in a capsule." The efficacy of microbiota-targeted therapies will need to be assessed using new diagnostic tools that measure community function rather than composition, including the temporal response of a microbial community to a defined perturbation such as an antibiotic or probiotic.

Quantification of subgingival bacterial pathogens at different stages of periodontal diseases

Anaerobic gram-negative oral bacteria such as Treponema denticola, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Campylobacter rectus, and Fusobacterium nucleatum are closely associated with periodontal diseases. We measured the relative population (bacterial levels) of these oral pathogens in subgingival tissues of patients at different stages of Korean chronic periodontal diseases. We divided the individuals into those with chronic gingivitis (G), moderate periodontitis (P1), severe periodontitis (P2), and normal individuals (N) (n = 20 for each group) and subgingival tissue samples were collected. We used real-time PCR with TaqMan probes to evaluate the change of periodontal pathogens among different stages of periodontitis. Bacterial levels of A. actinomycetemcomitans and C. rectus are significantly increased in individuals with chronic gingivitis and moderate periodontitis, but unchanged in severe periodontitis patients. These results suggest that analyzing certain bacterial levels among total oral pathogens may facilitate understanding of the role of periodontal bacteria in the early stages of periodontitis.

Bacterial-killing effect of atmospheric pressure non-equilibrium plasma jet and oral mucosa response

Recently, plasma sterilization has attracted increasing attention in dental community for the atmospheric pressure non-equilibrium plasma jet (APNPs), which is driven by a kilohertz pulsed DC power, may be applied to the dental and oral diseases. However, it is still in doubt whether APNPs can effectively kill pathogenic bacteria in the oral cavity and produce no harmful effects on normal oral tissues, especially on normal mucosa. The aim of this study was to evaluate the bacterial-killing effect of APNPs in the biofilms containing a single breed of bacteria (Porphyromonas gingivalis, P.g.), and the pathological changes of the oral mucosa after treatment by APNPs. P.g. was incubated to form the biofilms in vitro, and the samples were divided into three groups randomly: group A (blank control); group B in which the biofilms were treated by APNPs (the setting of the equipment: 10 kHz, 1600 ns and 8 kV); group C in which the biofilms were exposed only to a gas jet without ignition of the plasma. Each group had three samples and each sample was processed for up to 5 min. The biofilms were then fluorescently stained, observed and photographed under a laser scanning confocal microscope. In the animal experiment, six male Japanese white rabbits were divided into two groups randomly (n=3 in each group) in terms of the different post-treatment time (1-day group and 5-day group). The buccal mucosa of the left side and the mucosa of the ventral surface of the tongue were treated by APNPs for 10 min in the same way as the bacterial biofilm experiment in each rabbit, and the corresponding mucosa of the other sides served as normal control. The clinical manifestations of the oral mucosa were observed and recorded every day. The rabbits were sacrificed one or five day(s) after APNPs treatment. The oral mucosa were harvested and prepared to haematoxylin and eosin-stained sections. Clinical observation and histopathological scores were used to assess mucosal changes. The results showed the obvious P.g. biofilms were formed at 10 days, and most of the bacteria in groups A and C were alive under a laser scanning confocal microscope, but the bacteria in the group B were almost all dead. In animal experiment, no ulcers, anabrosis and oral mucositis were found in both the 1-day and 5-day groups. The average mucous membrane irritation index was -0.83 and -0.67 in the 1-day and 5-day groups, respectively, suggesting that no intense mucosal membrane irritation responses occurred. It was concluded that APNPs could effectively kill P.g. in the biofilms and did not cause any pathological changes in the normal mucosa, suggesting that the plasma jet (APNPs) may be applied to oral diseases as a novel sterilization device in the future.

Detection of periodontal pathogens in newborns and children with mixed dentition

We report the age-related prevalence of red complex periodontal pathogens, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, along with four strains of orange complex pathogens. The bacteria present in samples isolated from tongue, cheek, and subgingival sulcus in edentulous newborns and children with mixed dentition were monitored by polymerase chain reaction (PCR). P. gingivalis was not detected in any site of any subject in the two groups tested. However, T. denticola was not only found in the 6-13 years age group, but also in edentulous newborns at a relatively high prevalence, indicating non-dentition-related colonization by T. denticola. Campylobacter rectus, Prevotella intermedia, T. forsythia, Eikenella corrodens, and Parvimonas micra were found in the oral cavity of most subjects belonging to the 6-13 years age group compared to newborns. This suggested a pronounced association between these colonizing bacteria and the presence of teeth. There was also a strong relation between T. denticola and T. forsythia for their prevalence in the subgingival sulcus of the 6-13 years age group (p < 0.0001), but not in the other sites tested, suggesting that the colonization of dentition-related T. forsythia may be associated with the increased prevalence of non-dentition-related T. denticola in the subgingival sulcus. Overall, these results suggest that dentition is a key determinant of bacterial colonization, especially orange complex bacteria and the red complex bacterium T. forsythia.

Analysis of oral microbiota in children with dental caries by PCR-DGGE and barcoded pyrosequencing

Oral microbiota plays a vital role in maintaining the homeostasis of oral cavity. Dental caries are among the most common oral diseases in children and pathogenic bacteria contribute to the development of the disease. However, the overall structure of bacterial communities in the oral cavity from children with dental caries has not been explored deeply heretofore. We used high-throughput barcoded pyrosequencing and PCR-denaturing gradient gel electrophoresis (DGGE) to examine bacterial diversity of oral microbiota in saliva and supragingival plaques from 60 children aged 3 to 6 years old with and without dental caries from China. The multiplex barcoded pyrosequencing was performed in a single run, with multiple samples tagged uniquely by multiplex identifiers. As PCR-DGGE analysis is a conventional molecular ecological approach, this analysis was also performed on the same samples and the results of both approaches were compared. A total of 186,787 high-quality sequences were obtained for evaluating bacterial diversity and 41,905 unique sequences represented all phylotypes. We found that the oral microbiota in children was far more diverse than previous studies reported, and more than 200 genera belonging to ten phyla were found in the oral cavity. The phylotypes in saliva and supragingival plaques were significantly different and could be divided into two distinct clusters (p < 0.05). The bacterial diversity in oral microbiome analyzed by PCR-DGGE and barcoded pyrosequencing was employed to cross validate the data sets. The genera of Streptococcus, Veillonella, Actinomyces, Granulicatella, Leptotrichia, and Thiomonas in plaques were significantly associated with dental caries (p < 0.05). The results showed that there was no one specific pathogen but rather pathogenic populations in plaque that significantly correlated with dental caries. The enormous diversity of oral microbiota allowed for a better understanding of oral microecosystem, and these pathogenic populations in plaque provide new insights into the etiology of dental caries and suggest new targets for interventions of the disease.

Putative respiratory chain of Porphyromonas gingivalis

The electron transfer chain in Porphyromonas gingivalis, or periodontopathogens, has not yet been characterized. P. gingivalis, a strict anaerobic bacteria and the second colonizer of the oral cavity, is considered to be a major causal agent involved in periodontal diseases. Primary colonizers create a favorable environment for P. gingivalis growth by decreasing oxygen pressure. Oxygen does not appear to be the final electron acceptor of the respiratory chain. Fumarate and cytochrome b have been implicated as major components of the respiratory activity. However, the P. gingivalis genome shows many other enzymes that could be implicated in aerobic or nitrite respiration. Using bioinformatic tools and literature studies of respiratory pathways, the ATP synthesis mechanism from the sodium cycle and nutrients metabolism, the putative respirasome of P. gingivalis has been proposed.

Oral microbiota of children in a school-based dental clinic

OBJECTIVES

Dental caries disproportionately affects disadvantaged subjects. This study hypothesized that there were greater caries extent and higher levels of caries-associated and anaerobic subgingival bacterial species in oral samples of Hispanic and immigrant children compared with non-Hispanic and US born children.

METHODS

Children from a school-based dental clinic serving a community with a large Hispanic component were examined, and the extent of caries was recorded. Microbial samples were taken from teeth and the tongues of children. Samples were analyzed using DNA probes to 18 oral bacterial species.

RESULTS

Seventy five children were examined. Extent of caries increased with child age in immigrant, but not in US born or Hispanic children. There were no differences in the microbiota based on ethnicity or whether the child was born in US or not. There was a higher species detection frequency from teeth than tongue samples. Levels of Streptococcus mutans and other Streptococcus spp increased with caries extent. Prevotella intermedia, Tannerella forsythia and Selenomonas spp were detected at low levels in these children.

CONCLUSIONS

We conclude that, while there was a high rate of dental caries in disadvantaged school children, there were no differences in the caries-associated microbiota, including S. mutans, based on ethnicity or immigration status. Furthermore, while anaerobic subgingival, periodontal pathogens were also detected in children, there was no difference in species detection based on ethnicity or immigration status. Increased levels of streptococci, including S. mutans, however, were detected with high caries levels. This suggested that while it is beneficial to target preventive and treatment programs to disadvantaged populations, there is likely no additional benefit to focus on subgroups within a population already at high risk for dental disease.

Oral health in children guidelines for pediatricians

Dental caries in the primary dentition can have significant damaging effects on a childs growth due to impairment of oral functions. Since the first encounter of a child to a medical environment is often through pediatricians and medical practitioners, it is important that they be aware of the prevention of oral disease that begins early in life. The aim of this article is to diminish the existing ambiguity among pediatricians and medical practitioners regarding oral disease and its prevention.

Enterobacteriaceae and pseudomonadaceae on the dorsum of the human tongue

OBJECTIVE

The aim of this study was to correlate the presence of Enterobacteriaceae, Pseudomonadaceae, Moraxellaceae and Xanthomonadaceae on the posterior dorsum of the human tongue with the presence of tongue coating, gender, age, smoking habit and denture use.

MATERIAL AND METHODS

Bacteria were isolated from the posterior tongue dorsum of 100 individuals in MacConkey agar medium and were identified by the API 20E system (Biolab-Mérieux).

RESULTS

43% of the individuals, presented the target microorganisms on the tongue dorsum, with greater prevalence among individuals between 40 and 50 years of age (p = 0.001) and non-smokers (p=0.0485).

CONCLUSIONS

A higher prevalence of Enterobacteriaceae and Pseudomonadaceae was observed on the tongue dorsum of the individuals evaluated. There was no correlation between these species and the presence and thickness of tongue coating, gender and presence of dentures.

A novel sialic acid utilization and uptake system in the periodontal pathogen Tannerella forsythia

Tannerella forsythia is a key contributor to periodontitis, but little is known of its virulence mechanisms. In this study we have investigated the role of sialic acid in biofilm growth of this periodontal pathogen. Our data show that biofilm growth of T. forsythia is stimulated by sialic acid, glycolyl sialic acid, and sialyllactose, all three of which are common sugar moieties on a range of important host glycoproteins. We have also established that growth on sialyllactose is dependent on the sialidase of T. forsythia since the sialidase inhibitor oseltamivir suppresses growth on sialyllactose. The genome of T. forsythia contains a sialic acid utilization locus, which also encodes a putative inner membrane sialic acid permease (NanT), and we have shown this is functional when it is expressed in Escherichia coli. This genomic locus also contains a putatively novel TonB-dependent outer membrane sialic acid transport system (TF0033-TF0034). In complementation studies using an Escherichia coli strain devoid of its outer membrane sialic acid transporters, the cloning and expression of the TF0033-TF0034 genes enabled an E. coli nanR nanC ompR strain to utilize sialic acid as the sole carbon and energy source. We have thus identified a novel sialic acid uptake system that couples an inner membrane permease with a TonB-dependent outer membrane transporter, and we propose to rename these novel sialic acid uptake genes nanO and nanU, respectively. Taken together, these data indicate that sialic acid is a key growth factor for this little-characterized oral pathogen and may be key to its physiology in vivo.

Microbial risk markers for childhood caries in pediatricians' offices

Dental caries in pre-school children has significant public health and health disparity implications. To determine microbial risk markers for this infection, this study aimed to compare the microbiota of children with early childhood caries with that of caries-free children. Plaque samples from incisors, molars, and the tongue from 195 children attending pediatricians' offices were assayed by 74 DNA probes and by PCR to Streptococcus mutans. Caries-associated factors included visible plaque, child age, race, and snacking habits. Species were detected more frequently from tooth than tongue samples. Lactobacillus gasseri (p < 0.01), Lactobacillus fermentum, Lactobacillus vaginalis, and S. mutans with Streptococcus sobrinus (all p < 0.05) were positively associated with caries. By multifactorial analysis, the probiotic Lactobacillus acidophilus was negatively associated with caries. Prevotella nigrescens was the only species (p < 0.05) significantly associated with caries by the 'false discovery' rate. Analysis of the data suggests that selected Lactobacillus species, in addition to mutans streptococci, are risk markers for early childhood caries.

The Bifidobacterium dentium Bd1 genome sequence reflects its genetic adaptation to the human oral cavity

Bifidobacteria, one of the relatively dominant components of the human intestinal microbiota, are considered one of the key groups of beneficial intestinal bacteria (probiotic bacteria). However, in addition to health-promoting taxa, the genus Bifidobacterium also includes Bifidobacterium dentium, an opportunistic cariogenic pathogen. The genetic basis for the ability of B. dentium to survive in the oral cavity and contribute to caries development is not understood. The genome of B. dentium Bd1, a strain isolated from dental caries, was sequenced to completion to uncover a single circular 2,636,368 base pair chromosome with 2,143 predicted open reading frames. Annotation of the genome sequence revealed multiple ways in which B. dentium has adapted to the oral environment through specialized nutrient acquisition, defences against antimicrobials, and gene products that increase fitness and competitiveness within the oral niche. B. dentium Bd1 was shown to metabolize a wide variety of carbohydrates, consistent with genome-based predictions, while colonization and persistence factors implicated in tissue adhesion, acid tolerance, and the metabolism of human saliva-derived compounds were also identified. Global transcriptome analysis demonstrated that many of the genes encoding these predicted traits are highly expressed under relevant physiological conditions. This is the first report to identify, through various genomic approaches, specific genetic adaptations of a Bifidobacterium taxon, Bifidobacterium dentium Bd1, to a lifestyle as a cariogenic microorganism in the oral cavity. In silico analysis and comparative genomic hybridization experiments clearly reveal a high level of genome conservation among various B. dentium strains. The data indicate that the genome of this opportunistic cariogen has evolved through a very limited number of horizontal gene acquisition events, highlighting the narrow boundaries that separate commensals from opportunistic pathogens.

Distribution of periodontopathic bacterial species in Japanese children with developmental disabilities

Background

Recent developments in molecular biological techniques have enabled rapid detection of periodontopathic bacterial species in clinical specimens. Accumulated evidence suggests that detection of specific bacterial species enables identification of subjects at high risk for the onset of periodontitis. We investigated the distribution of 10 selected periodontopathic bacterial species in dental plaque specimens obtained from children with disabilities who were attending daycare centers.

Methods

A total of 187 children (136 boys, 51 girls) aged 1-6 years old and diagnosed with such disabilities as mental retardation, cerebral palsy, and autism, participated in the study. Subgingival dental plaque specimens were collected from the buccal side of the maxillary left second primary molar after a clinical examination. Bacterial DNA was extracted from the specimens and PCR analyses were carried out to detect 10 selected periodontopathic species using specific primers for each. In addition, statistical analyses were performed to analyze the correlations among clinical parameters and the detected species.

Results

The most frequently detected species was Capnocytophaga sputigena (28.3%), followed by Aggregatibacter actinomycetemcomitans (20.9%) and Campylobacter rectus (18.2%). Eikenella corrodens, Capnocytophaga ochracea, and Prevotella nigrescence were detected in approximately 10% of the specimens, whereas Treponema denticola, Tannerella forsythia, and Prevotella intermedia were rarely found, and Porphyromonas gingivalis was not detected in any of the subjects. The total numbers of detected species were positively correlated with the age of the subjects. There were 10 subjects with positive reactions for T. denticola and/or T. forsythia, in whom the total number of bacterial species was significantly higher as compared to the other subjects. Furthermore, subjects possessing C. rectus showed significantly greater values for periodontal pocket depth, gingival index, and total number of species.

Conclusion

We found that approximately one-fourth of the present subjects with disabilities who possessed at least one of T. denticola, T. forsythia, and C. rectus were at possible risk for periodontitis. Follow-up examinations as well as preventive approaches should be utilized for such individuals.

Prospects for the development of probiotics and prebiotics for oral applications

There has been a paradigm shift towards an ecological and microbial community-based approach to understanding oral diseases. This has significant implications for approaches to therapy and has raised the possibility of developing novel strategies through manipulation of the resident oral microbiota and modulation of host immune responses. The increased popularity of using probiotic bacteria and/or prebiotic supplements to improve gastrointestinal health has prompted interest in the utility of this approach for oral applications. Evidence now suggests that probiotics may function not only by direct inhibition of, or enhanced competition with, pathogenic micro-organisms, but also by more subtle mechanisms including modulation of the mucosal immune system. Similarly, prebiotics could promote the growth of beneficial micro-organisms that comprise part of the resident microbiota. The evidence for the use of pro or prebiotics for the prevention of caries or periodontal diseases is reviewed, and issues that could arise from their use, as well as questions that still need to be answered, are raised. A complete understanding of the broad ecological changes induced in the mouth by probiotics or prebiotics will be essential to assess their long-term consequences for oral health and disease.

Oropharyngeal flora in healthy infants: observations and implications for cystic fibrosis care

OBJECTIVE

The purpose of this preliminary study was to determine normal oropharyngeal flora in healthy, non-CF infants in order to help care givers better interpret culture results obtained from infants with CF.

METHODS

Oropharyngeal cultures were obtained from 104 healthy infants <12 months old. Cultures were obtained using the same methods as for CF patients and were inoculated onto routine CF culture media. Approximately 20 infants from each of 5 age groups (0-2 days, 3 days to <3 months, 3 months to <6 months, 6 months to <9 months or 9 months to <1 year) were included in the well child sample. In addition, we reviewed serial results of upper airway cultures obtained during the first year of life from 20 CF-affected infants whose diagnosis was suggested by newborn screening.

RESULTS

Well infants in the first 48 hr of life had very few pathogenic organisms found in their oropharyngeal cultures; 1/21 had S. aureus. Of the 83 samples from infants over 48 hr of age, we found that 27% (23/83) had S. aureus in their oropharyngeal cultures. Many infants had polymicrobial cultures. Eleven percent of culture samples had E. coli, E. cloacae, H. influenzae, or M. catarrhalis. Three of 83 cultures were positive for non-mucoid Ps. aeruginosa (3.6%), while 2 others were positive for Ps. putida.

CONCLUSION

Healthy infants can have multiple gram-negative and gram-positive organisms recovered from their oropharynx. S. aureus and enteric gram-negative organisms, including non-mucoid Ps. aeruginosa, can be found in the oropharynx of well children up to 1 year of age. Care should be taken to not over interpret the presence of some of these organisms in the oropharyngeal cultures of asymptomatic CF infants.

Distribution of selected cariogenic bacteria in five different intra-oral habitats in young children

BACKGROUND

Knowledge of the colonization patterns and composition of the oral microbiota can lead to a better understanding of disease initiation.

AIM

The aim of this study was to examine the distribution of selected cariogenic bacteria in samples from five different oral habitats in young Greek children.

DESIGN

Ninety-three children 3-12 years old (mean + SD 7.9 +/- 2.5) (60.2% male, 39.8% female) participated and split into three different age groups: primary (3-6 years), early mixed (6-9 years), and mixed dentition (9-12 years). Samples for bacterial enumeration were taken from saliva, supragingival and subgingival plaque, tongue dorsum, and soft tissues from each child, and were further analysed using checkerboard DNA-DNA hybridization.

RESULTS

Mean counts and proportions of all the test bacteria differed significantly among sample locations. Cariogenic bacteria were present in almost all healthy children. Mean proportions of Streptococcus mutans isolated from soft tissue and Streptococcus sanguinis from soft tissue, subgingival and saliva samples increased significantly with age, whereas the opposite was seen for Lactobacillus acidophilus.

CONCLUSIONS

Cariogenic bacteria were present in almost all young children. Soft tissues, saliva, and tongue were more often colonized by cariogenic streptococcal species than teeth. These surfaces may serve as reservoirs for oral pathogens, requiring attention during preventive interventions.

Quantitative real-time polymerase chain reaction for Streptococcus mutans and Streptococcus sobrinus in dental plaque samples and its association with early childhood caries

BACKGROUND

Streptococcus mutans and Streptococcus sobrinus are closely associated with the development of early childhood caries (ECC). Recently, quantitative real-time polymerase chain reaction (qRT-PCR) has been used for rapid and accurate quantification of these bacterial species.

AIM

This study aims to detect quantitatively the levels of S. mutans and S. sobrinus in plaque samples by qRT-PCR, and to assess their association with the prevalence of ECC in Korean preschool children.

DESIGN

One hundred and five children (71 months old or younger) were examined and classified into three groups (caries-free, ECC, severe ECC). Dental plaque samples were collected and qRT-PCR was conducted using oligonucleotide primers specific for glucosyltransferase gene (S. mutans-gtfB, S. sobrinus-gtfU) and universal primer. Pearson's correlation test was conducted to evaluate the relationship between the dmfs (decayed, missing, or filled surfaces primary teeth) scores and the microbiological findings.

RESULTS

There was a significant difference between the levels of S. mutans and S. sobrinus in the plaque samples of the three groups (P < 0.05). The proportion of S. sobrinus to S. mutans showed strong correlation to the dmfs scores (r = 0.748, P < 0.05).

CONCLUSIONS

The qRT-PCR results of this study showed that children with ECC had higher level of S. mutans and S. sobrinus in their dental plaque samples. The children with higher ratio of S. sobrinus to S. mutans in their dental plaque showed higher incidence of ECC.

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.

Similarity of bacterial populations in saliva from African-American mother-child dyads

Using PCR-based denaturing gradient gel electrophoresis analyses of oral bacterial samples in 20 mother-child dyads, this study demonstrated a high degree of similarity of bacterial compositions between the mothers and their children; the two may share as much as 94% of their oral bacterial spectra, including cariogenic species.

Loss of bacterial diversity during antibiotic treatment of intubated patients colonized with Pseudomonas aeruginosa

Management of airway infections caused by Pseudomonas aeruginosa is a serious clinical challenge, but little is known about the microbial ecology of airway infections in intubated patients. We analyzed bacterial diversity in endotracheal aspirates obtained from intubated patients colonized by P. aeruginosa by using 16S rRNA clone libraries and microarrays (PhyloChip) to determine changes in bacterial community compositions during antibiotic treatment. Bacterial 16S rRNA genes were absent from aspirates obtained from patients briefly intubated for elective surgery but were detected by PCR in samples from all patients intubated for longer periods. Sequencing of 16S rRNA clone libraries demonstrated the presence of many orally, nasally, and gastrointestinally associated bacteria, including known pathogens, in the lungs of patients colonized with P. aeruginosa. PhyloChip analysis detected the same organisms and many additional bacterial groups present at low abundance that were not detected in clone libraries. For each patient, both culture-independent methods showed that bacterial diversity decreased following the administration of antibiotics, and communities became dominated by a pulmonary pathogen. P. aeruginosa became the dominant species in six of seven patients studied, despite treatment of five of these six with antibiotics to which it was sensitive in vitro. Our data demonstrate that the loss of bacterial diversity under antibiotic selection is highly associated with the development of pneumonia in ventilated patients colonized with P. aeruginosa. Interestingly, PhyloChip analysis demonstrated reciprocal changes in abundance between P. aeruginosa and the class Bacilli, suggesting that these groups may compete for a similar ecological niche and suggesting possible mechanisms through which the loss of microbial diversity may directly contribute to pathogen selection and persistence.