Genotyping of Streptococcus mutans by using arbitrarily primed polymerase chain reaction in children with Down Syndrome

A Comparative Evaluation of Physical Parameters of Saliva and Correlation with Periodontal Condition in Down Syndrome Children and Healthy Controls

AIM

The aim of this study was to assess the significance and role of physical parameters of saliva on periodontal health in children with Down syndrome (DS).

MATERIALS AND METHODS

A comparative evaluation of physical parameters of saliva such as flow rate, viscosity, pH, quantity and buffering capacity, and buffer capacity was carried out using GC Saliva-Check Buffer kit and correlated with periodontal condition examined using community periodontal index of treatment needs (CPITN) in 40 DS subjects (group I) and 40 healthy controls (group II) aged 8-15 years.

RESULTS

Down syndrome subjects had a low resting salivary flow rate, moderately acidic saliva, very low quantity of stimulated saliva, and low buffering capacity. On correlating salivary parameters with the periodontal condition, DS subjects with CPITN code 1 had low resting salivary flow rate, normal viscosity, moderately acidic pH, very low quantity of stimulated saliva, and low buffering capacity. Down syndrome subjects with CPITN code 2 had low resting flow rate, increased viscosity, very low quantity of stimulated saliva, low buffering capacity, and moderately acidic pH. Healthy controls with CPITN code 0 had normal resting flow rate, viscosity of saliva, quantity of stimulated saliva, buffering capacity, and moderately acidic pH.

CONCLUSION

Compared to healthy controls, DS subjects showed decreased values for resting flow rate, pH, quantity of stimulated saliva, and buffering capacity. A statistically significant correlation was observed between the physical parameters of saliva and periodontal condition in DS subjects (p < 0.05).

CLINICAL SIGNIFICANCE

Periodontal diseases start at a very early age and periodontal health deteriorates at a faster rate in DS children for which saliva also plays its part. Prime importance should be given to frequent oral hygiene and preventive measures in DS children thus preventing accumulation of debris and plaque.

Molecular Detection of Streptococcus downii sp. nov. from Dental Plaque Samples from Patients with Down Syndrome and Non-Syndromic Individuals

A new bacterial species has recently been identified in the dental plaque of an adolescent with Down syndrome. The species is known as Streptococcus downii sp. nov. (abbreviated to S. downii), and it inhibits the growth of S. mutans and certain periodontal pathogens. The aim of this study was to determine the distribution of S. downii in the oral cavity of individuals with Down syndrome. Methods: A specific polymerase chain reaction for the operon of bacteriocin (class IIb lactobin A/cerein 7B family) was designed to detect S. downii in individuals with Down syndrome (n = 200) and in the general population (n = 100). We also compared the whole genome of S. downii and the regions related to its bacteriocins against 127 metagenomes of supragingival plaque of the “Human Microbiome Project”. Results: We detected the specific gene of the S. downii bacteriocin in an individual with Down syndrome (Cq, 34.52; GE/μL, 13.0) and in an individual of the non-syndromic control group (Cq, 34.78 Cq; GE/μL, 4.93). The prevalence of S. downii was ≤1% both in Down syndrome and in the general population, which did not allow for clinical-microbiological correlations to be established. This result was confirmed by detecting only one metagenome with an ANIm with approximately 95% homology and with 100% homology with ORFs that code class IIb lactobiocin A/cerein 7B bacteriocins among the 127 metagenomes of the “Human Microbiome Project” tested. Conclusions: The detection rate of S. downii in the supragingival dental plaque was very low, both in the Down syndrome individuals and in the non-syndromic controls. A clinical-microbiological correlation could therefore not be established.

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

Aim

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

Materials and methods

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

Results

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

Interpretation and conclusion

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

Genotypic diversity and acidogenicity of Streptococcus mutans in Down syndrome children

AIMS

To evaluate the genotypic diversity and acidogenicity of Streptococcus mutans (S. mutans) and the potential association of these factors with dental caries experience in children with DS compared to non-DS children (controls).

METHODS AND RESULTS

Seventeen children (age 6-12 years) with high salivary S. mutans counts (> 2.5 × 10⁵ CFU/mL) were selected and divided into two groups: DS and non-DS. Five children in each group were caries-free, while the remainder had elevated caries experience. S. mutans isolates were obtained from each participant. The genotypic profile of the isolates was analyzed with the AP-PCR methodology. The acidogenicity of a representative strain from each genotype of S. mutans was also evaluated. DS children had 16 different S. mutans genotypes, while the control group had 21. Twelve genotypes were present in both groups and one of them was associated with caries-free status (P < .05). Although the acidogenicity of the genotypes found in DS children was significantly lower (P < .05) compared to controls, this fact was not associated with caries experience in both groups.

CONCLUSIONS

DS children have a lower S. mutans genotypic diversity and genotypes with lower acidogenicity than those of non-DS children. However these findings were not associated with their caries experience.

Reduced salivary flow rate and high levels of oxidative stress in whole saliva of children with Down syndrome

AIM

To investigate salivary parameters between children with Down Syndrome (DS) and without DS.

MATERIALS AND METHODS

Stimulated whole saliva was collected from 18 children with DS and 23 without DS. Salivary flow rate, pH, and salivary buffering capacity were determined. Cariogenic microorganisms were quantified by culture, and periodontopathogens by quantitative real-time polymerase chain reaction. The antioxidant profile was quantified spectrophotometrically, while malondialdehyde (MDA) was quantified by high-performance liquid chromatography. Data were analyzed by Mann-Whitney test and Spearman correlation (α = 0.05).

RESULTS

Salivary flow rate was significantly lower in DS than in controls (p < 0.0001). Significant higher difference was observed for total protein dosage (p < 0.0001), superoxide dismutase activity (SOD) (p = 0.0002), and MDA (p < 0.001) in DS group.

CONCLUSIONS

Reduced salivary flow rate might be an important factor in oral diseases development. High salivary levels of SOD and MDA show the significant influence of the oxidative stress and the early-onset periodontal disease in DS people.

Salivary density of Streptococcus mutans and Streptococcus sobrinus and dental caries in children and adolescents with Down syndrome

Streptococcus mutans and Streptococcus sobrinus are strongly associated with dental caries. However, the relationship between oral streptococci and dental caries in children with Down syndrome is not well characterized.

Dental caries and associated factors in twins with Down syndrome: a case report

Down syndrome (DS) is the most common genetic disorder in humans, but its incidence in monozygotic twins is extremely rare. The aim of this study was to determine the factors associated with dental caries in a pair of monozygotic twin girls with DS, where one had caries experience and the other did not. Clinical examination, salivary Streptococcus mutans (S. mutans) levels and their genotypic diversity, the biochemical composition of the dental biofilm, the frequency of sucrose consumption, and toothbrushing habits were assessed from the twin girls. Twin with caries experience showed higher levels of S. mutans in the saliva and lower concentrations of calcium, phosphate, and fluoride and higher concentrations of extracellular polysaccharides in the biofilm compared to her sister. Genotypic diversity of S. mutans was also higher in the twin with caries experience. Dental biofilm composition showed different patterns of cariogenicity between the two sisters, which may also by itself explain the difference in the dental caries between them.

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

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

Dental caries in individuals with Down syndrome: a systematic review

BACKGROUND

Many studies have shown a lower experience of caries in people with Down syndrome compared to individuals without Down syndrome, but this issue has not been critically evaluated.

AIM

To conduct a systematic review of the international literature on dental caries experience in people with Down syndrome.

DESIGN

Three online databases (PubMed, LILACS, and Cochrane) were used to identify relevant studies on caries experience in people with Down syndrome published until May 2015. PICO (Patient/Population, Intervention, Comparison group, and Outcome) criteria were used to screen studies by title and abstract. An assessment of the methodological study quality was performed according to the modified Newcastle-Ottawa Scale.

RESULTS

The search resulted in 226 studies. Thirteen publications were included in the systematic review. Ten studies reported results of lower caries experience in individuals with Down syndrome in at least one age group studied. Three studies reported no differences in caries experience among the groups. All studies, however, included in this systematic review had limitations that increased the likelihood of bias in the study results.

CONCLUSION

There is no scientific evidence to support the hypothesis that people with Down syndrome have a lower experience of caries than non-syndromic individuals.

Association between Dental Caries and Down Syndrome: A Systematic Review and Meta-Analysis

Scientific evidence of susceptibility to dental caries in the population with Down Syndrome (DS) is limited and conflicting, making it difficult to establish firm conclusions. The aim of this systematic review and meta-analysis was to obtain scientific evidence of the possible association between dental caries and individuals with DS, compared to individuals without DS (control). An electronic search of five databases was performed, with no language or publication date restrictions. The studies were selected by two independent reviewers (Kappa = 0.83). The systematic review included 13 studies, while eight studies were included in the meta-analysis. The studies are presumably all at risk of bias given their observational character. Two of these evaluated the presence or absence of caries in permanent and deciduous teeth, and six evaluated the mean DMFT index in permanent teeth. Combined odds ratios (OR), standard difference, standard error and a 95% confidence interval (CI) were obtained. The vast majority of the studies found that individuals from control groups had more carious lesions or caries experience than those with DS. The results were statistically significant in seven studies (p<0.05). Meta-analysis of two studies revealed that individuals with DS had a lower dental caries than those in the control group (OR = 0.36; 95% CI = 0.22-0.57). In six studies, individuals with DS had a significantly lower mean DMFT index than individuals from the control group (Sd = -0.18; SE = 0.09; 95% CI = -0.35--0.02). The quality of the studies varied and in general had a high risk of bias. Scientific evidence suggests that individuals with DS have fewer dental caries than individuals without DS.

Low levels of caries in aggressive periodontitis: A literature review

This article is a traditional literature review on caries levels in aggressive periodontitis. Aggressive periodontitis generally affects systemically healthy individuals aged <30 years (older individuals can also be affected) and is characterized by a young age of onset, rapid rate of disease progression, and familial aggregation of cases. Dental caries is caused by the dissolution of enamel by acid-producing bacteria present in the plaque biofilm, especially when the biofilm reaches critical mass due to improper oral hygiene. The association between caries level and aggressive periodontitis has long been debated. Initial research indicated that caries levels were high in patients with aggressive periodontitis, but high-quality studies have consistently shown that caries and aggressive periodontitis are inversely related. A recent in vitro study showed that Streptococcus mutans was killed more readily in the saliva of patients with aggressive periodontitis and Aggregatibacter actinomycetemcomitans positivity than in patients with A. actinomycetemcomitans negativity. Other mechanisms possibly explaining the inverse relationship between caries and aggressive periodontitis in cases of Down's syndrome are also discussed in this literature review. The usefulness of caries level in the diagnosis of aggressive periodontitis in developing countries such as India, where the disease is diagnosed primarily on the basis of clinical and radiographic features and familial history is also discussed.

Expression of interferon-γ, interferon-α and related genes in individuals with Down syndrome and periodontitis

BACKGROUND

Recently, attenuation of anti-inflammatory and increase of pro-inflammatory mediators was demonstrated in individuals with Down syndrome (DS) in comparison with euploid patients during periodontal disease (PD), suggesting a shift to a more aggressive inflammation in DS.

AIM

To determine the influence of DS in the modulation of interferons (IFNs) signaling pathway in PD.

MATERIALS AND METHODS

Clinical periodontal assessment was performed and gingival tissue samples obtained from a total of 51 subjects, including 19 DS individuals with PD, 20 euploid individuals with PD and 12 euploid individuals without PD. Expression levels of interferon-gamma (IFNG) and interferon-alpha (IFNA), and their receptors IFNGR1, IFNGR2, IFNAR1 and IFNAR2, the signaling intermediates Janus kinase 1 (JAK1), signal transducer and activator of transcription 1 (STAT1) and interferon regulatory factor 1 (IRF1) were determined using real time quantitative polymerase chain reaction (qPCR).

RESULTS

Clinical signs of periodontal disease were markedly more severe in DS and euploid patients with PD in comparison to euploid and periodontally healthy patients. There was no difference on mRNA levels of IFNA, IFNG, INFGR2, IFNAR1 and IFNAR2 between DS and euploid individuals, even though some of these genes are located on chromosome 21. STAT1 and IRF1 mRNA levels were significantly lower in DS patients in comparison with euploid individuals with PD. In euploid individuals, PD was associated with an increased expression of IFNGR1, IFNGR2, IFNAR1, STAT1 and IRF1.

CONCLUSIONS

Reduced expression of STAT1 and IRF1 genes indicate an impaired activation of IFNs signaling in individuals with DS and PD. Expression of IFNA, IFNG and IFN receptors was not altered in DS patients, indicating that indirect mechanisms are involved in the reduced activation of IFN signaling.

Reduced salivary flow and colonization by mutans streptococci in children with Down syndrome

OBJECTIVES

Although individuals with Down syndrome have considerable oral disease, the prevalence of dental caries in this group is low. The present study aimed to compare known risk factors for dental caries development in children with Down syndrome and a matched population (siblings). In both populations, the number of acidogenic microorganisms, such as mutans streptococci, lactobacilli and Candida species, and the paraffin-stimulated pH, flow rate and IgA concentration in whole saliva were evaluated and compared.

METHOD

Saliva was collected, and the caries index was evaluated in 45 sibling pairs aged between 6 and 18 years old. The salivary IgA concentration was determined by immunoturbidimetry. Salivary mutans streptococci, lactobacilli and Candida species were quantified on mitis salivarius agar containing bacitracin and 20% sucrose, rogosa agar supplemented with glacial acetic acid and sabouraud agar supplemented with chloramphenicol, respectively.

RESULTS

Down syndrome children had a higher caries-free rate (p<0.05) and lower salivary mutans streptococci counts (p<0.03) compared to their siblings. Similar numbers of lactobacilli and Candida species were found in both groups. Salivary flow rates were 36% lower in Down syndrome children compared to their siblings (p<0.05). The salivary pH did not differ between Down syndrome children and controls. The Down syndrome children had an IgA secretion rate 29% lower than that of their siblings, but this difference was not statistically significant.

CONCLUSIONS

In conclusion, the lower number of mutans streptococci in the saliva may be one of the factors contributing to the lower caries rate observed in Down syndrome children, despite evidence of hyposalivation.

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

A comparison of the sialochemistry, oral pH, and oral health status of Down syndrome children to healthy children

BACKGROUND

The aetiology of low caries incidence in Down syndrome (DS) children is not entirely clear. Aim. To compare sialochemistry and oral mucosal pH between Down syndrome children with caries (DS-Ca) and caries free (DS-CaF), and healthy children with caries (C-Ca) and caries free (C-CaF).

DESIGN

The study group comprised 70 children with DS (mean age 4.41 +/- 1.9 years); 32 healthy children (mean age 9.22 +/- 2.7 years) served as control. Groups were further subdivided according to caries status: DS-Ca, DS-CaF, C-Ca and C-CaF. Sialochemistry analysis included calcium (Ca), sodium (Na), potassium (K), and chloride (Cl). Mucosal pH, plaque and gingival indices (PI and GI), and caries status were recorded.

RESULTS

DMFT/dmft were significantly lower in the DS group. Cl and Ca levels were significantly higher in the DS-Ca compared to the C-Ca and the C-CaF children. Na and K were significantly higher in DS-Ca group compared to DS-CaF group. PI and GI were significantly higher in DS-C children compared to DS-CaF children.

CONCLUSIONS

DS may manifest itself in the salivary glands. Consequently, different electrolyte salivary environment may form, leading to lower caries rates among DS children.

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.

Genotypes of Streptococcus mutans in saliva versus dental plaque

OBJECTIVE

The aim of this study was to investigate whether genotypes of Streptococcus mutans strain can be detected as effectively in saliva samples as in plaque samples from buccal surfaces and occlusal surface fissures of permanent first molars.

DESIGN

The study included 20 school children aged 6-7 years who were positive for mutans streptococci. Samples of stimulated saliva and of dental plaque on buccal surfaces and occlusal surface fissures of permanent first molars were collected. Samples were cultivated in MSB agar. Up to nine isolates compatible with mutans streptococci were obtained and identified by means of biochemical tests. All isolates identified as S. mutans were genotyped by arbitrarily primed polymerase chain reaction.

RESULTS

A total of 28 genotypes of S. mutans were isolated: 23 in saliva samples, 23 in buccal surface plaque samples, and 16 in plaque samples from occlusal surface fissures.

CONCLUSIONS

Although, saliva sampling did not reveal all genotypes isolated, it was equally as effective as plaque sampling from the buccal surfaces of permanent first molars, and more effective than plaque sampling from fissures on their occlusal surfaces.