Oral Candida-biome and Early Childhood Caries: A Systematic Review and Meta-Analysis

OBJECTIVE

Candida is a common fungal pathogen in the oral cavity, with Candida albicans being the most prevalent species. Some studies report a correlation between Candida prevalence and dental caries experience in preschoolers, while others report no such association. This systematic review and meta-analysis aimed to evaluate the association of Candida-biome with Early Childhood Caries (ECC) in preschool children.

METHODS

Seven databases were searched for studies evaluating the correlation between Candida and ECC in healthy preschool children under 71 months of age. Dual independent screening, data extraction, bias risk assessment, meta-analysis, and quality evaluation of evidence were conducted.

RESULTS

The review included 20 studies with 12 reporting a positive association between Candida prevalence and ECC. The prevalence of Candida albicans in ECC ranged from 60%-84% across sample sites. Certain specific species, including C. dubliniensis and atypical non-albicans Candida (NAC), were also associated with caries severity in preschoolers. The pooled odds ratio (OR) estimate was 7.98 (95%CI; 3.84-16.58) for Candida-biome in plaque samples (I² = 84%), and 9.42 (95%CI: 4.15- 21.40) for Candida-biome in saliva sample (I² = 50%). These results suggest that children with Candida-biome in plaque and saliva have higher odds of having ECC than caries-free children.

CONCLUSIONS

Children with Candida-biome in plaque and saliva samples have a higher risk of Early Childhood Caries, predominantly associated with Candida albicans. Standardised methodologies for evaluating and comparing data on Candida species and ECC are recommended for future studies.

A comparative study of microbial changes in dental plaque before and after single- and multiappointment treatments in patients with severe early childhood caries

BACKGROUND

The status of dental caries is closely related to changes in the oral microbiome. In this study, we compared the diversity and structure of the dental plaque microbiome in children with severe early childhood caries (S-ECC) before and after general anaesthesia and outpatient treatment.

METHODS

Forty children aged 3 to 5 years with S-ECC who had completed whole-mouth dental treatment under general anaesthesia (C1) or in outpatient settings (C2) were selected, 20 in each group. The basic information and oral health status of the children were recorded, and the microbial community structure and diversity of dental plaque before treatment (C1, C2), the day after treatment(C2_0D), 7 days after treatment (C1_7D, C2_7D), 1 month after treatment (C1_1M, C2_1M), and 3 months after treatment (C1_3M, C2_3M) were analysed via 16 S rRNA high-throughput sequencing technology.

RESULTS

(1) The alpha diversity test showed that the flora richness in the multiappointment group was significantly greater at posttreatment than at pretreatment (P < 0.05), and the remaining alpha diversity index did not significantly differ between the 2 groups (P > 0.05). The beta diversity analysis revealed that the flora structures of the C1_7D group and the C2_3M group were significantly different from those of the other time points within the respective groups (P < 0.05). (2) The core flora existed in both the pre- and posttreatment groups, and the proportion of their flora abundance could be altered depending on the caries status of the children in both groups. Leptotrichia abundance was significantly (P < 0.05) lower at 7 days posttreatment in both the single- and multiappointment groups. Corynebacterium and Corynebacterium_matruchotii were significantly more abundant in the C1_1M and C1_3M groups than in the C1 and C1_7D groups (P < 0.05). Streptococcus, Haemophilus and Haemophilus_parainfluenzae were significantly more abundant in the C1_7D group than in the other groups (P < 0.05).

CONCLUSION

A single session of treatment under general anaesthesia can cause dramatic changes in the microbial community structure and composition within 7 days after treatment, whereas treatment over multiple appointments may cause slow changes in oral flora diversity.

Efficacy of Oxy-Ionic Solutions With Varying pH Levels Against Streptococcus mutans In Vitro

Background Chlorhexidine (CHX) is a widely used antimicrobial agent known for its ability to inhibit cariogenic bacteria, reduce plaque formation, neutralize acidity, and promote remineralization. However, the effectiveness of oxy-ionic solutions at different pH levels as an alternative antimicrobial treatment requires further exploration. This study aims to compare the antimicrobial effects of oxy-ionic solutions at various pH levels with those of CHX and fluoride. Methodology This study employed disc diffusion tests to measure the inhibition zone diameters of each solution and broth dilution assays to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results The oxy-ionic solutions exhibited varying degrees of antimicrobial effectiveness depending on their pH levels. The solution at pH 5 demonstrated the best antimicrobial performance among the oxy-ionic solutions, with inhibition zones comparable to those of CHX. The MIC and MBC values indicated that oxy-ionic solutions in mildly acidic environments generally resulted in better antimicrobial activity. Conclusions The study concludes that while CHX remains highly effective against cariogenic bacteria, oxy-ionic solutions, particularly at pH 5, offer a promising alternative. The antimicrobial efficacy of oxy-ionic solutions is influenced by their pH levels. Further research is recommended to explore the long-term effects and clinical applications of oxy-ionic solutions in maintaining oral health and preventing disease.

The Evolving Microbiome of Dental Caries

Dental caries is a significant oral and public health problem worldwide, especially in low-income populations. The risk of dental caries increases with frequent intake of dietary carbohydrates, including sugars, leading to increased acidity and disruption of the symbiotic diverse and complex microbial community of health. Excess acid production leads to a dysbiotic shift in the bacterial biofilm composition, demineralization of tooth structure, and cavities. Highly acidic and acid-tolerant species associated with caries include Streptococcus mutans, Lactobacillus, Actinomyces, Bifidobacterium, and Scardovia species. The differences in microbiotas depend on tooth site, extent of carious lesions, and rate of disease progression. Metagenomics and metatranscriptomics not only reveal the structure and genetic potential of the caries-associated microbiome, but, more importantly, capture the genetic makeup of the metabolically active microbiome in lesion sites. Due to its multifactorial nature, caries has been difficult to prevent. The use of topical fluoride has had a significant impact on reducing caries in clinical settings, but the approach is costly; the results are less sustainable for high-caries-risk individuals, especially children. Developing treatment regimens that specifically target S. mutans and other acidogenic bacteria, such as using nanoparticles, show promise in altering the cariogenic microbiome, thereby combatting the disease.

Evaluation of Changes in Oral Microflora in Children with Early Childhood Caries after Full Mouth Rehabilitation

Aim

To evaluate the change in microflora in children suffering from severe early childhood caries (ECC) after full mouth rehabilitation.

Materials and methods

A total of 60 children, aged 3-5 years suffering from severe ECC who fulfilled the inclusion and exclusion criteria were included in the study. Pooled plaque samples were taken and subjected to quantitative reverse transcriptase polymerase chain reaction (PCR) to obtain baseline mean values of Streptococcus mutans (S. mutans), Streptococcus sobrinus (S. sobrinus), Candida albicans (C. albicans), and Candida dubliniensis (C. dubliniensis) before full mouth rehabilitation was done under general anesthesia. Posttreatment samples were collected at 6, 12, and 18 months. Wilcoxon signed-rank test was used to compare the mean values of S. mutans, S. sobrinus, C. albicans, and C. dubliniensis before and after full mouth rehabilitation.

Results

A total of 60 patients recruited for the study were present at the follow-up at 6 and 12 months. At 18 months, 55 patients returned, and five were lost due to follow-up. A statistically significant reduction was seen in all microorganisms at 6, 12, and 18 months compared to baseline values. At 18 months a slight increase in S. mutans, S. sobrinus, and C. albicans was seen. C. dubliniensis was not detected in any cases after full mouth rehabilitation. Caries recurrence was seen in four patients at 18 months.

Conclusion

Significant reduction of S. mutans, S. sobrinus, C. albicans, and C. dubliniensis was seen at 6, 12, and 18 months. A complete reduction of only C. dubliniensis was seen. A significant but not permanent reduction of S. mutans, S. sobrinus, and C. albicans. Caries recurrence was seen in 7.27% of patients at 18 months.

How to cite this article

Mathew MG, Jeevanandan G, Rathod NN. Evaluation of Changes in Oral Microflora in Children with Early Childhood Caries after Full Mouth Rehabilitation. Int J Clin Pediatr Dent 2024;17(1):21-25.

Catalase produced by Candida albicans protects Streptococcus mutans from H2O2 stress-one more piece in the cross-kingdom synergism puzzle

Co-infection with Streptococcus mutans and Candida albicans is associated with dental caries, and their co-cultivation results in enhanced biofilm matrix production that contributes to increased virulence and caries risk. Moreover, the catalase-negative S. mutans demonstrates increased oxidative stress tolerance when co-cultivated in biofilms with C. albicans, a catalase-producing yeast. Here, we sought to obtain mechanistic insights into the increased H2O2 tolerance of S. mutans when co-cultivated with clinical isolates of Candida glabrata, Candida tropicalis, and C. albicans. Additionally, the C. albicans SC5314 laboratory strain, its catalase mutant (SC5314Δcat1), and S. mutans UA159 and its glucosyltransferase B/C mutant (UA159ΔgtfB/C) were grown as single- and dual-species biofilms. Time-kill assays revealed that upon acute H2O2 challenge, the survival rates of S. mutans in dual-species biofilms with the clinical isolates and C. albicans SC5314 were greater than when paired with SC5314Δcat1 or as a single-species biofilm. Importantly, this protection was independent of glucan production through S. mutans GtfB/C. Transwell assays and treatment with H2O2-pre-stimulated C. albicans SC5314 supernatant revealed that this protection is contact-dependent. Biofilm stability assays with sublethal H2O2 or peroxigenic Streptococcus A12 challenge resulted in biomass reduction of single-species S. mutans UA159 and dual-species with SC5314Δcat1 biofilms compared to UA159 biofilms co-cultured with C. albicans SC5314. S. mutans oxidative stress genes were upregulated in single-species biofilms when exposed to H2O2, but not when S. mutans was co-cultivated with C. albicans SC5314. Here, we uncovered a novel, contact-dependent, synergistic interaction in which the catalase of C. albicans protects S. mutans against H2O2. IMPORTANCE It is well established that co-infection with the gram-positive caries-associated bacterium Streptococcus mutans and the yeast pathobiont Candida albicans results in aggressive forms of caries in humans and animal models. Together, these microorganisms form robust biofilms through enhanced production of extracellular polysaccharide matrix. Further, co-habitation in a biofilm community appears to enhance these microbes' tolerance to environmental stressors. Here, we show that catalase produced by C. albicans protects S. mutans from H2O2 stress in a biofilm matrix-independent manner. Our findings uncovered a novel synergistic trait between these two microorganisms that could be further exploited for dental caries prevention and control.

Incidence and risk factors of unplanned retreatment following dental general anesthesia in children with severe early childhood caries

Objective

This study aimed to retrospectively describe the unplanned retreatment of dental general anesthesia (DGA) in children with severe early childhood caries (S-ECC) and explore potential factors that may influence the outcome of DGA treatment.

Methods

Medical records of children with S-ECC who received DGA treatment were screened, and necessary data were extracted. The Kaplan-Meier method and Cox proportional hazards model were used to estimate the DGA survival rate and explore the potential factors affecting the success rate of DGA treatment.

Results

Medical records of 852 children were included; 509 (59.7%) children with 1,212 (10.7%) teeth underwent unplanned retreatment. Restoration failure (30.12%) and new caries (29.46%) accounted for the most significant proportion of all failures. The median survival times were 510 and 1,911 days at the child and tooth levels, respectively. Unplanned retreatment risk was associated with the age of S-ECC children, frequency of follow-up, and fluoride application (hazard ratio = 0.97, 0.78, 0.69, P < 0.001).

Conclusion

The treatment outcome of DGA administered to children with S-ECC was satisfactory at the tooth level from the perspective of the incidence of unplanned retreatment. Restoration failure was the main reason for the high unplanned retreatment rate. Strategies for a better outcome of DGA include improving the professional knowledge and skills of pediatric dentists and enhancing compliance of parents/patients. Health education and regular topical fluoride application may improve the success rate of DGA treatment.

Prediction of Future Caries in 1-Year-Old Children via the Salivary Microbiome

Dental caries is the most common chronic disease in children that causes negative effects on their health, development, and well-being. Early preventive interventions are key to reduce early childhood caries prevalence. An efficient strategy is to provide risk-based targeted prevention; however, this requires an accurate caries risk predictor, which is still lacking for infants before caries onset. We aimed to develop a caries prediction model based on the salivary microbiome of caries-free 1-y-old children. Using a nested case-control design within a prospective cohort study, we selected 30 children based on their caries status at 1-y follow-up (at 2 y old): 10 children who remained caries-free, 10 who developed noncavitated caries, and 10 who developed cavitated caries. Saliva samples collected at baseline before caries onset were analyzed through 16S rRNA gene sequencing. The results of β diversity analysis showed a significant difference in salivary microbiome composition between children who remained caries-free and those who developed cavitated caries at 2 y old (analysis of similarities, Benjamini-Hochberg corrected, P = 0.042). The relative abundance of Prevotella nanceiensis, Leptotrichia sp. HMT 215, Prevotella melaninogenica, and Campylobacter concisus in children who remained caries-free was significantly higher than in children who developed cavitated caries (Wilcoxon rank sum test, P = 0.024, 0.040, 0.049, and 0.049, respectively). These taxa were also identified as biomarkers for children who remained caries-free (linear discriminant analysis effect size, linear discriminant analysis score = 3.69, 3.74, 3.53, and 3.46). A machine learning model based on these 4 species distinguished between 1-y-old children who did and did not develop cavitated caries at 2 y old, with an accuracy of 80%, sensitivity of 80%, and specificity of 80% (area under the curve, 0.8; 95% CI, 44.4 to 97.5). Our findings suggest that these salivary microbial biomarkers could assist in predicting future caries in caries-free 1-y-old children and, upon validation, are promising for development into an adjunctive tool for caries risk prediction for prevention and monitoring.

Antifungal Susceptibility of Oral Candida Isolates from Mother-Infant Dyads to Nystatin, Fluconazole, and Caspofungin

The carriage of Candida albicans in children's oral cavities is associated with a higher risk for early childhood caries, so controlling this fungus in early life is essential for preventing caries. In a prospective cohort of 41 mothers and their children from 0 to 2 years of age, this study addressed four main objectives: (1) Evaluate in vitro the antifungal agent susceptibility of oral Candida isolates from the mother-child cohort; (2) compare Candida susceptibility between isolates from the mothers and children; (3) assess longitudinal changes in the susceptibility of the isolates collected between 0 and 2 years; and (4) detect mutations in C. albicans antifungal resistance genes. Susceptibility to antifungal medications was tested by in vitro broth microdilution and expressed as the minimal inhibitory concentration (MIC). C. albicans clinical isolates were sequenced by whole genome sequencing, and the genes related to antifungal resistance, ERG3, ERG11, CDR1, CDR2, MDR1, and FKS1, were assessed. Four Candida spp. (n = 126) were isolated: C. albicans, C. parapsilosis, C. dubliniensis, and C. lusitaniae. Caspofungin was the most active drug for oral Candida, followed by fluconazole and nystatin. Two missense mutations in the CDR2 gene were shared among C. albicans isolates resistant to nystatin. Most of the children's C. albicans isolates had MIC values similar to those from their mothers, and 70% remained stable on antifungal medications from 0 to 2 years. For caspofungin, 29% of the children's isolates showed an increase in MIC values from 0 to 2 years. Results of the longitudinal cohort indicated that clinically used oral nystatin was ineffective in reducing the carriage of C. albicans in children; novel antifungal regimens in infants are needed for better oral yeast control.

Gene expression analysis of toll like receptor 2 and 4, Dectin-1, Osteopontin and inflammatory cytokines in human dental pulp ex-vivo

BACKGROUND

Toll like receptors (TLR) 2 and 4 present on innate immune cells of the dental pulp detect cariogenic bacteria. Along with bacteria, C. albicans may also be present in dental caries. The presence of C. albicans can be detected by Dectin-1 a C type Lectin receptor. Expression of Dectin-1 in human pulpits has not been reported. Similarly, cytokines are released as a consequence of dental pulp inflammation caused by cariogenic bacteria. The T helper (Th) 1 inflammatory response leads to exacerbation of inflammation and its relationship with Osteopontin (OPN) is not known in pulp inflammation.

OBJECTIVE

The aim of this study was to observe the expression of Dectin-1, TLR-2, OPN and pro-inflammatory cytokines in irreversibly inflamed human dental pulp and to observe relationship between Dectin-1/TLR-2 and OPN/Pro-inflammatory cytokines in the presence of appropriate controls.

METHODS

A total of 28 subjects diagnosed with irreversible pulpitis were included in this ex-vivo study. Fifteen samples were subjected to standard hematoxylin and Eosin (H&E) and immunohistochemistry staining. Whereas, gene expression analysis was performed on 13 samples to observe mRNA expression of pro-inflammatory cytokines; tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1 beta (ß), IL-6 Dectin-1, OPN, TLR-2 and TLR-4. SPSS version 21 was used for statistical analysis. One way analysis of variance (ANOVA), Pearson correlation and Chi-square test were used at p ≤ 0.05.

RESULTS

Gene expressions of Dectin-1, TLR-2 and TLR-4 were observed in all samples. Dectin-1 and TLR-2 expressions were significantly correlated (r = 0.5587, p = 0.0002). Similarly, OPN and TNF-α expression showed a significant correlation (r = 0.5860, p = 0001). The agreement between histologic and clinical diagnosis was 69.2% in the cases of irreversible pulpitis.

CONCLUSION

Dectin-1 was expressed by inflamed human dental pulp. Dectin-1 and TLR-2 expression pattern was suggestive of a collaborative receptor response in inflamed pulp environment. OPN and TNF-α expressions showed a positive correlation indicating a possible relationship.

Does Early Childhood Caries Increase Caries Development among School Children and Adolescents? A Systematic Review and Meta-Analysis

The aim of this paper is to systematically review the literature to determine whether early childhood caries (ECC) is significantly associated with caries development in permanent teeth among school children and adolescents, and to identify the association of other risk factors over 24 months. A systematic literature search was performed in four electronic databases and via a manual search from inception to 28 July 2022. Independent study selection and screening, data extraction, evaluation of risk of bias using ROBINS-I tool and certainty of evidence with GRADE were performed. Ten cohort studies were included, all of which identified that ECC significantly increased the risk of caries in permanent teeth. Meta-analysis suggested children with ECC were three times more likely to develop caries in their permanent teeth (OR, 3.22; 95% CI 2.80, 3.71; p < 0.001), especially when the lesions were in primary molars and progressed to dentine. However, the certainty of evidence was substantially compromised by serious risk of bias and inconsistency between studies. There were inconsistent findings between socioeconomic or behavioural factors on caries development, which could not be pooled for meta-analyses. ECC significantly increases the likelihood of caries development in permanent teeth. Evidence on the association of socioeconomic and oral health behavioural factors is weak.

Vitamin D Supplementation, Characteristics of Mastication, and Parent-Supervised Toothbrushing as Crucial Factors in the Prevention of Caries in 12- to 36-Month-Old Children

Severe early childhood caries (S-ECC), defined as any sign of smooth-surface caries in a child younger than three years of age, remains a serious health issue. The aim of this study was to indicate oral health behaviours related to S-ECC. The study surveyed parents (socio-economic and medical factors, oral health behaviours) and clinically examined children including non-cavitated d1,2/cavitated d ≥ 3 lesions. %S-ECC, and caries indices (d1,2 d ≥ 3 mft and d1,2 d ≥ 3 mfs) were calculated. Spearman’s correlation and simple and multiple logistic regression were used to assess the relationships between various factors and S-ECC. A total of 496 children were examined. S-ECC occurred in 44.8%: d1,2 d ≥ 3 mft = 2.62 ± 3.88, d1,2 d ≥ 3 mfs = 4.46 ± 8.42. S-ECC was correlated with socio-economic factors, vitamin D supplementation, breastfeeding and using formula after the 18th month, and toothbrushing. Supplementation of vitamin D and toothbrushing tended to decrease the odds of S-ECC (OR = 0.49 (0.27−0.87); p = 0.016, OR = 0.46 (0.24−0.86) p = 0.015, respectively). Feeding exclusively with formula was observed to increase the odds of S-ECC (OR = 2.20 (1.29−3.76); p = 0.004). Consuming > three snacks daily (OR = 1.39 (0.97−1.98); p = 0.072) and the reluctance to eat resilient foods (OR = 1.63 (1.05−2.51); p = 0.028) were nullified by the confounding factors. Vitamin D supplementation, mastication of resilient food, breastfeeding in the first six months of a baby’s life, and parent-supervised toothbrushing are factors in the prevention of caries in toddlers. Breast- and bottle-feeding after the 18th month of life, the reluctance to eat solids, lack of vitamin D supplementation, hygienic neglect, and delay in introducing oral health behaviours may contribute to the development of caries in toddlers.

Clinical outcomes of dental treatment under general anesthesia and its effects on the caries activity and body growth of children: a 2-year retrospective study

OBJECTIVES

To analyze clinical outcomes of dental treatment under general anesthesia (DGA) and its effects on children's caries activity status and body growth within 2 years after the treatment.

MATERIALS AND METHODS

The case data and 2-year follow-up records of children who underwent DGA from February 2017 to February 2018 were collected and analyzed. The general characteristics of the sample, the success rates of treatment procedures, the caries recurrence rate, the caries activity test scores, and the BMI of all the children were described. The caries activity levels between children with and without caries recurrence at 24 months after DGA were compared before and after DGA to explore the relationship between caries activity level and caries recurrence. The correlation between BMI level and caries recurrence was explored using Cox regression analysis.

RESULTS

A total of 94 children consisting of 46 boys and 48 girls were included in this study. The average dmft score before DGA was 13.90. Within 2 years after the treatment, composite fillings and strip crowns of the anterior teeth achieved similar success rates, around 90%; SSCs showed a similar success rate to composite fillings of posterior teeth (P = 1.000); the clinical success rate of pulpectomy was 90.43%. All the children showed no caries relapse at 1 month after DGA. The number of children with caries relapse at 6-, 12-, and 24-month post-treatment was 24 (25.53%), 35 (37.23%), and 53 (56.38%), respectively. The caries activity scores at each follow-up were significantly lower than those before the treatment (P < 0.0001). Children with caries relapse within 2 years after DGA showed no significantly different caries activity scores than children without caries relapse before and after the treatment. The proportion of children with normal BMI at 12 months after DGA was significantly higher than that before DGA (P = 0.007), and the difference was still very significant at 24 months after DGA (P < 0.0001). Statistical results showed a correlation between BMI level before DGA and caries recurrence (P < 0.001).

CONCLUSIONS

Dental treatment under general anesthesia achieves acceptable clinical outcomes in this study. Children's caries activity scores decrease significantly. Low or high BMI levels before DGA drift towards normal after the treatment.

CLINICAL RELEVANCE

Acceptable outcomes are achieved within 2 years after dental treatment under general anesthesia. However, children with abnormal BMI before the treatment tend to have caries relapse.

Oral Candida Predicts Streptococcus mutans Emergence in Underserved US Infants

Despite the cariogenic role of Candida suggested from recent studies, oral Candida acquisition in children at high risk for early childhood caries (ECC) and its association with cariogenic bacteria Streptococcus mutans remain unclear. Although ECC disproportionately afflicts socioeconomically disadvantaged and racial-minority children, microbiological studies focusing on the underserved group are scarce. Our prospective cohort study examined the oral colonization of Candida and S. mutans among 101 infants exclusively from a low-income and racial-minority background in the first year of life. The Cox hazard proportional model was fitted to assess factors associated with the time to event of the emergence of oral Candida and S. mutans. Oral Candida colonization started as early as 1 wk among 13% of infants, increased to 40% by 2 mo, escalated to 48% by 6 mo, and remained the same level until 12 mo. S. mutans in saliva was detected among 20% infants by 12 mo. The emergence of S. mutans by year 1 was 3.5 times higher (hazard ratio [HR], 3.5; confidence interval [CI], 1.1-11.3) in infants who had early colonization of oral Candida compared to those who were free of oral Candida (P = 0.04) and 3 times higher (HR, 3.0; CI, 1.3-6.9) among infants whose mother had more than 3 decayed teeth (P = 0.01), even after adjusting demographics, feeding, mother's education, and employment status. Infants' salivary S. mutans abundance was positively correlated with infants' Candida albicans (P < 0.01) and Candida krusei levels (P < 0.05). Infants' oral colonization of C. albicans was positively associated with mother's oral C. albicans carriage and education (P < 0.01) but negatively associated with mother's employment status (P = 0.01). Future studies are warranted to examine whether oral Candida modulates the oral bacterial community as a whole to become cariogenic during the onset and progression of ECC, which could lead to developing novel ECC predictive and preventive strategies from a fungal perspective.

Susceptibility of Dental Caries Microcosm Biofilms to Photodynamic Therapy Mediated by Fotoenticine

Photodynamic therapy (PDT) mediated by Fotoenticine^® (FTC), a new photosensitizer derived from chlorin e-6, has shown in vitro inhibitory activity against the cariogenic bacterium Streptococcus mutans. However, its antimicrobial effects must be investigated on biofilm models that represent the microbial complexity of caries. Thus, we evaluated the efficacy of FTC-mediated PDT on microcosm biofilms of dental caries. Decayed dentin samples were collected from different patients to form in vitro biofilms. Biofilms were treated with FTC associated with LED irradiation and analyzed by counting the colony forming units (log10 CFU) in selective and non-selective culture media. Furthermore, the biofilm structure and acid production by microorganisms were analyzed using microscopic and spectrophotometric analysis, respectively. The biofilms from different patients showed variations in microbial composition, being formed by streptococci, lactobacilli and yeasts. Altogether, PDT decreased up to 3.7 log10 CFU of total microorganisms, 2.8 log10 CFU of streptococci, 3.2 log10 CFU of lactobacilli and 3.2 log10 CFU of yeasts, and reached eradication of mutans streptococci. PDT was also capable of disaggregating the biofilms and reducing acid concentration in 1.1 to 1.9 mmol lactate/L. It was concluded that FTC was effective in PDT against the heterogeneous biofilms of dental caries.

Machine Learning Approach Identified Multi-Platform Factors for Caries Prediction in Child-Mother Dyads

Untreated tooth decays affect nearly one third of the world and is the most prevalent disease burden among children. The disease progression of tooth decay is multifactorial and involves a prolonged decrease in pH, resulting in the demineralization of tooth surfaces. Bacterial species that are capable of fermenting carbohydrates contribute to the demineralization process by the production of organic acids. The combined use of machine learning and 16s rRNA sequencing offers the potential to predict tooth decay by identifying the bacterial community that is present in an individual’s oral cavity. A few recent studies have demonstrated machine learning predictive modeling using 16s rRNA sequencing of oral samples, but they lack consideration of the multifactorial nature of tooth decay, as well as the role of fungal species within their models. Here, the oral microbiome of mother–child dyads (both healthy and caries-active) was used in combination with demographic–environmental factors and relevant fungal information to create a multifactorial machine learning model based on the LASSO-penalized logistic regression. For the children, not only were several bacterial species found to be caries-associated (Prevotella histicola, Streptococcus mutans, and Rothia muciloginosa) but also Candida detection and lower toothbrushing frequency were also caries-associated. Mothers enrolled in this study had a higher detection of S. mutans and Candida and a higher plaque index. This proof-of-concept study demonstrates the significant impact machine learning could have in prevention and diagnostic advancements for tooth decay, as well as the importance of considering fungal and demographic–environmental factors.

Association of Candida albicans and Cbp+ Streptococcus mutans with early childhood caries recurrence

Early childhood caries (ECC) recurrence occurs in approximately 40% of treated cases within one year. The association of Streptococcus mutans and Candida albicans with the onset of ECC is well known. Also, S. mutans strains harboring collagen-binding proteins (Cbps) avidly bind to collagen-rich dentin and are linked to increased caries risk. Here, we investigated the presence of Cbp⁺ S. mutans and C. albicans in saliva and dental plaque of children with varying caries statuses, and their salivary microbiome. In this cross-sectional study, 143 children who were caries-free (n = 73), treated for ECC with no signs of recurrence after 6 months (n = 45), or treated for ECC and experiencing recurrence within 6 months following treatment (n = 25) were enrolled. Co-infection with C. albicans and S. mutans, especially Cbp⁺ S. mutans, was strongly associated with caries recurrence. Subjects of the recurrence group infected with Cbp⁺ S. mutans showed a greater burden of Candida spp. and of Mutans streptococci in dentin than those infected with Cbp^- strains. Salivary microbiome analysis revealed that Streptococcus parasanguinis was overrepresented in the caries recurrence group. Our findings indicate that Cbp⁺ S. mutans and C. albicans are intimately associated with caries recurrence, contributing to the establishment of recalcitrant biofilms.

Association of oral microbiota profile with sugar-sweetened beverages consumption in school-aged children

Evidence that common beverage consumption is associated with oral ecosystem. However, little is known about the effect of sugar-sweetened beverages (SSBs) on composition and functional potential of childhood oral microbiota. We aim to examine associations between SSBs consumption with oral microbiota diversity and function among school-aged children. Oral microbiota in buccal swab samples was collected from 180 children (11.3 ± 0.6 years) from an ongoing child growth and development cohort established in 2016, using 16S rDNA gene sequencing. Higher SSBs consumption (≥1 serving/day) was associated with lower oral microbiota richness and diversity. Children with higher SSBs consumption showed decreased abundance of genus Fusobacterium, Lachnoanaerobaculum, Soonwooa, Tannerella and Moraxella (p < 0.05). However, more SSBs intake selectively increases the dominance of aciduric bacteria (Neisseria and Streptococcus), which can lead to dental caries and other oral problems. Furthermore, PICRUSt analysis illustrated that oral microbiota was more conducive to the pathway activated of protein export (p = 0.020), D-glutamine and D-glutamate metabolism (p = 0.013), and pantothenate and CoA biosynthesis (p = 0.004), indicating vigorous microbial metabolism in oral bacterial community in higher SSBs intake groups. Overall, our finding suggests that higher SSBs consumption may disturb oral microecology and reduce diversity of microbiota during childhood, stimulating an increase in cariogenic genera, which contributes to increased susceptibility of SSBs-related oral diseases.

Anticaries activity of GERM CLEAN in Streptococcus mutans and Candida albicans dual-species biofilm

OBJECTIVE

To evaluate the antimicrobial effects of a peptide containing novel oral spray GERM CLEAN on dual-species biofilm formed by Streptococcus mutans and Candida albicans and to investigate whether GERM CLEAN inhibits the demineralization procedure of bovine enamel in vitro.

METHODS

The antimicrobial effects of GERM CLEAN on dual-species biofilm were analyzed by initial adherence rate calculation, water-insoluble exopolysaccharides quantification, total biomass quantification, and colony-forming units (CFUs) counting. Scanning electron microscopy and confocal laser scanning microscopy were applied to evaluate the impacts of GERM CLEAN on the biofilm structure. Further, the effects of GERM CLEAN on acidogenicity of dual-species were appraised via glycolytic pH drop analysis and hydroxyapatite dissolution measurement. The percentage of Surface Microhardness Reduction (%SMHR) evaluation, Atomic Force Micrograph (AFM) examination, and Transverse Microradiography (TMR) analysis after pH cycling were used to determine whether GERM CLEAN inhibited the demineralization of bovine enamel.

RESULTS

GERM CLEAN decreased the adherence rate, water-insoluble EPS production, biofilm formation, and acidogenicity of the dual-species. Moreover, GERM CLEAN significantly inhibited the demineralization status of bovine enamels.

CONCLUSION

This peptide containing novel oral spray GERM CLEAN has antimicrobial potential toward the dual-species. GERM CLEAN can also impede the demineralization procedure of enamel.

Oral microbiome: possible harbinger for children's health

The human microbiome functions as an intricate and coordinated microbial network, residing throughout the mucosal surfaces of the skin, oral cavity, gastrointestinal tract, respiratory tract, and reproductive system. The oral microbiome encompasses a highly diverse microbiota, consisting of over 700 microorganisms, including bacteria, fungi, and viruses. As our understanding of the relationship between the oral microbiome and human health has evolved, we have identified a diverse array of oral and systemic diseases associated with this microbial community, including but not limited to caries, periodontal diseases, oral cancer, colorectal cancer, pancreatic cancer, and inflammatory bowel syndrome. The potential predictive relationship between the oral microbiota and these human diseases suggests that the oral cavity is an ideal site for disease diagnosis and development of rapid point-of-care tests. The oral cavity is easily accessible with a non-invasive collection of biological samples. We can envision a future where early life salivary diagnostic tools will be used to predict and prevent future disease via analyzing and shaping the infant’s oral microbiome. In this review, we present evidence for the establishment of the oral microbiome during early childhood, the capability of using childhood oral microbiome to predict future oral and systemic diseases, and the limitations of the current evidence.

Identification of Non- Streptococcus mutans Bacteria from Predente Infant Saliva Grown on Mitis-Salivarius-Bacitracin Agar

Objective: Although mitis-salivarius-bacitracin (MSB) agar is a commonly used selective medium for detecting Streptococcus mutans in clinical studies, non-S. mutans microorganisms are cultivatable on MSB agar. Since few studies have identified non-S. mutans bacteria grown on MSB, this study aimed to identify and differentiate MSB-grown non-S. mutans bacteria from predente infants' oral cavity. Study design: The saliva from 51 predente infants were plated on MSB agars. Bacteria colonies were characterized based on their morphology under direct visualization and light microscopic observation. Colony PCR targeting S. mutans htrA locus and 16S rRNA DNA sequencing were used for further bacteria identification. Results: Overall, 80% of the predente infants had oral bacteria grown on the MSB agar. Nine bacteria were identified, including S. mutans, Staphylococcus epidermidis, Klebsiella quasi-pneumoniae, Klebsiella pneumoniae, Enterobacter kobei, Enterococcus faecalis, Staphylococcus hominis, Streptococcus anginosus and Phytobacter. The most frequently detected bacteria were S. epidermidis (41.5%), followed by E. kobei (24.4%), K. pneumoniae (17.1%) and S. mutans (9.8%.) Conclusions: Multiple non-S. mutans bacteria from infants' oral cavity could grow on MSB agar. Caution should be exercised in counting the colony forming units of S. mutans from oral samples on MSB agar to avoid overestimation by assuming that all colonies on the MSB agar are S. mutans. Using the colony morphological guide we summarized, these non-S. mutans bacteria could be distinguished from S. mutans. Our study provides a key reference to pediatric cariology clinical-epidemiological studies that commonly use MSB to identify/quantify S. mutans in infants and young children.

Oral health and Candida carriage in socioeconomically disadvantaged US pregnant women

Background

Despite the well-documented associations between poor maternal oral health and increased risk for adverse birth outcomes and dental caries in children after birth, prenatal oral health care is under-utilized, especially among the underserved population. In addition, oral Candida has recently been suggested as a potential culprit for children’s dental caries, with evident maternal contributions. Therefore, this study aimed to obtain epidemiological data on the oral health and oral Candida carriage in a cohort of underserved US pregnant women, and reveal factors associated with their oral Candida carriage.

Methods

Demographic-medical-oral hygiene practice data were collected. Comprehensive oral examination was conducted. Caries status and plaque index were recorded. Oral samples (saliva, plaque and swab) were processed to identify Candida species and Streptococcus mutans by culturing-dependent and -independent methods. Multiple logistic regression analyses were used to identify factors associated with oral Candida carriage and caries severity.

Results

Eighty-two socioeconomically disadvantaged women (48 pregnant and 34 non-pregnant) were enrolled. More pregnant women (79.1%) had > = 1 untreated decayed tooth when compared to their non-pregnant counterparts (47.1%) (p = 0.01). The average number of decayed teeth in pregnant and non-pregnant women was 3.9 and 3.1 (p > 0.05). Caries severity was positively associated with race (African American vs. white), plaque index and salivary Candida albicans level. C. albicans was the most predominant/abundant Candida strain, with cheek and tonsil as the most common colonized sites. The detection of C. albicans was 56%/56% in saliva and 40%/47% in plaque of the pregnant and non-pregnant groups, respectively. Study women’s oral Candida carriage is positively associated with hypertension [p = 0.03, odds ratio = 14.47(1.28, 163.51)], decayed teeth number [p = 0.04, odds ratio = 1.31 (1.01,1.69)] and salivary S. mutans level [p = 0.03, odds ratio = 4.80 (1.18–19.43)].

Conclusions

Socioeconomically disadvantaged US women are in need of improved prenatal oral health, a large proportion of them have untreated decayed teeth and high carriage of oral Candida. Due to the observed significant association between the decayed teeth number and oral Candida carriage, providing oral health care during pregnancy (including limiting decayed teeth) will not only improve women’s oral health, but also present as a promising approach to reduce oral Candida carriage in women.

Assessing the impact of curcumin on dual-species biofilms formed by Streptococcus mutans and Candida albicans

Streptococcus mutans and Candida albicans are often isolated from plaques associated with early childhood caries. However, there are limited studies examining how these microorganisms interact with one another and how best to manage them. Recent studies have shown that curcumin (CUR), a natural compound, has the potential to independently control both of these microorganisms. The purpose of this study was to investigate how S. mutans and C. albicans respond in mono‐ and dual‐species biofilms challenged with CUR. Quantitative biofilm biomass and viability were first evaluated and supported by live–dead PCR to assess biofilm composition. Confocal laser scanning microscopy (CLSM) was used to evaluate the exopolysaccharide (EPS) content and thickness of the biofilms, and the structure of the biofilms and morphology of the cells were observed by scanning electron microscopy (SEM). Quantitative real‐time PCR (qRT‐PCR) was applied to assess relative gene expression. The 50% minimum biofilm eradication concentration (MBEC₅₀) of CUR against S. mutans and C. albicans was 0.5 mM. The biomass and viability decreased after treatment with CUR both in dual‐species biofilms and in mono‐species biofilm. CUR inhibited S. mutans and C. albicans in both mono‐ and dual‐species biofilms. Streptococcus mutans was more sensitive to CUR in dual‐species biofilm than in mono‐species biofilms, whereas C. albicans was less sensitive in dual‐species biofilms. EPS production was decreased by CUR in both mono‐ and dual‐species biofilms, which coincided with the downregulation of glucosyltransferase and quorum sensing‐related gene expression of S. mutans. In C. albicans, the agglutinin‐like sequence family of C. albicans was also downregulated in dual‐species biofilms. Collectively, these data show the potential benefit of using a natural antimicrobial, CUR, to control caries‐related dual‐species plaque biofilms.

Bioactive molecule optimized for biofilm reduction related to childhood caries

Aim: To evaluate antimicrobial activity of a new nitrochalcone (NC-E08) against Candida albicans and Streptococcus mutans, and its toxicity. Materials & methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration/minimum fungicidal concentration (MFC) were determined against C. albicans and S. mutans, as well as antibiofilm potential and toxicity (human gingival fibroblast and Galleria mellonella). Infection and treatment were performed in G. mellonella. Results & conclusion: NC-E08 showed antimicrobial activity in C. albicans (MIC: 0.054 mM) and S. mutans (MIC: 0.013 mM); 10xMIC treatment reduced 4.0 log10 biofilms for both strains and there was a reduction in survival of mixed biofilms of C. albicans and S. mutans (6.0 and 4.0 log10, respectively). NC-E08 showed no cytotoxicity in human gingival fibroblast cells and G. mellonella. NC-E08 after larval infection protected them 90% (p < 0.05). Thus, is a promising one for the prevention and treatment of S. mutans and C. albicans infections.

Efficacy of an adenosine triphosphate meter for evaluating caries risk in clinical dental practice

BACKGROUND

Adenosine triphosphate bioluminescence (ATP-B) readings have been proposed as markers of caries risk. ATP readings may indicate bacteria or oral streptococci activity in microbial plaque. The authors of this study aimed to evaluate whether readings using a commercial ATP meter (CariScreen Testing Meter, Oral BioTech) are significantly different for patients with low, moderate, and high caries risk in the Caries Management by Risk Assessment Practice-Based Research Network study.

METHODS

Twenty practice-based research network dentists enrolled 460 patients; 271 returned for 2 or more semiannual follow-up visits over 2 years. Dentists were trained and calibrated to perform ATP-B testing and caries risk assessment (CRA) using established protocols. ATP-B readings were compared via CRA category (low, moderate, high). Generalized estimating equations were used to compare the risk of experiencing incident clinical outcomes (newly recorded decayed, missing, or restored tooth surfaces and CRA disease indicators) according to ATP-B reading at prior patient visits (≥ 1,500 versus < 1,500 relative light units).

RESULTS

Median ATP-B readings did not differ statistically significantly by clinician-assessed caries risk level (low, 2,323; moderate, 2,940; high, 3,217; P = .65). Adjusted for patient demographics and trial intervention assignment, higher readings were not associated with newly developed decayed, missing, or restored tooth surface (relative risk, 1.57; 95% confidence interval, 0.55 to 4.45) or disease indicators (relative risk, 1.08; 95% confidence interval, 0.85 to 1.37) at the following visit, whereas clinician-assessed caries risk level was strongly associated.

CONCLUSIONS

ATP-B readings poorly predicted caries risk and future clinical outcomes. CRA incorporating multiple risk, protective, and disease indicators has superior predictive performance.

PRACTICAL IMPLICATIONS

The findings of this study do not provide evidence supporting the use of ATP-B to predict caries risk.

Activity and distribution pattern of enzymes in the in-situ pellicle of children

OBJECTIVE

This study investigated, for the first time, pellicle enzymes with respect to their activity, distribution and fluorescence pattern in children with different caries experience.

DESIGN

In-situ pellicles were collected from 41 children (aged 4-6 years) with different caries status; 17 of them were caries-free (dmf = 0), 12 had dental restorations but no current caries (dmf ≥ 2) and 12 had at least two carious lesions (dmf ≥ 2). Bovine enamel samples were fixed on individual upper jaw braces for pellicle formation. After 30 min of intraoral exposure, the pellicle and saliva samples were analysed for the activities of amylase, lysozyme, peroxidase and glucosyltransferase (GTF). The distribution of these enzymes, including GTF-isoforms B, C and D, and the pellicle ultrastructure were examined by gold-immunolabelling and transmission electron microscopy (TEM). Furthermore, interactions between pellicle enzymes and adherent bacteria were visualised using combined fluorescence and immunofluorescence labelling.

RESULTS

There were no significant differences in the pellicle enzyme activities between the study groups. TEM analysis revealed the absence of GTF C and D in the pellicle of caries-active children. Amylase, peroxidase and GTF-isoforms showed a random distribution within the pellicle layer; lysozyme was found in the form of clusters. A similar ultrastructural pattern was observed for all subjects. Fluorescence labelling technique enabled visualisation of all enzymes, except for GTF B.

CONCLUSION

Pellicle enzyme activities and ultrastructure are not associated with children's caries status. Further investigation is needed to assess the influence of individual GTF-isoforms on caries susceptibility in children.

Prenatal Oral Health Care and Early Childhood Caries Prevention: A Systematic Review and Meta-Analysis

Despite the advancement of early childhood caries (ECC) prediction and treatment, ECC remains a significant public health burden in need of more effective preventive strategies. Pregnancy is an ideal period to promote ECC prevention given the profound influence of maternal oral health and behaviors on children's oral health. However, studies have shown debatable results with respect to the effectiveness of ECC prevention by means of prenatal intervention. Therefore, this study systematically reviewed the scientific evidence relating to the association between prenatal oral health care, ECC incidence, and Streptococcus mutans carriage in children. Five studies (3 randomized control trials, 1 prospective cohort study, and 1 nested case-control study) were included for qualitative assessment. Tested prenatal oral health care included providing fluoride supplements, oral examinations/cleanings, oral health education, dental treatment referrals, and xylitol gum chewing. Four studies that assessed ECC incidence reduction were included in meta-analysis using an unconditional generalized linear mixed effects model with random study effects and age as a covariate. The estimated odds ratio and 95% confidence intervals suggested a protective effect of prenatal oral health care against ECC onset before 4 years of age: 0.12 (0.02, 0.77) at 1 year of age, 0.18 (0.05, 0.63) at 2 years of age, 0.25 (0.09, 0.64) at 3 years of age, and 0.35 (0.12, 1.00) at 4 years of age. Children's S. mutans carriage was also significantly reduced in the intervention group. Future studies should consider testing strategies that restore an expectant mother's oral health to a disease-free state during pregnancy.

The Oral Microbiome in the Elderly With Dental Caries and Health

With the aging of the population, dental caries in the elderly has received increasing attention. A comprehensive study of the oral microbiome is required to understand its polymicrobial etiology. The results of previous studies are limited and remain controversial. In this study, subjects 60 years and older with and without caries were recruited. Unstimulated saliva and dental plaque were collected from each subject and the bacterial 16S rDNA was amplified using PCR and sequenced by Illumina MiSeq high-throughput sequencing. A total of 92 samples were collected from 24 caries patients and 22 healthy controls. Sequences clustered into 147,531 OTUs, representing 16 phyla, 29 classes, 49 orders, 79 families, 149 genera, and 305 species. All predominant phyla, including Proteobacteria, Bacteroidetes, Firmicutes, Fusobacteria, Actinobacteria, and Saccharibacteria, were largely consistent in different groups, but different relative abundances could be observed. The core microbiome was defined with 246 shared species among groups, which occupied 80.7% of all the species detected. Alpha diversity showed no significant differences in bacterial richness or diversity between caries patients and healthy controls, but distinction existed between samples collected from dental plaque and saliva. Beta diversity analysis was performed by PCoA and hierarchical clustering analysis, showing similar results that microorganisms vary between the two niches. The biomarkers of different groups were defined by LEfSe analysis to identify potential caries-related and health-related bacteria. The co-occurrence analysis of the predominant genera revealed significant interactions among oral microbiota and exhibited more complex and aggregated bacterial correlations in caries-free groups. Finally, the functional prediction of the microbiota present in oral samples was performed by PICRUSt, indicating vigorous microbial metabolism in the oral bacterial community. Our study provides thorough knowledge of the microbiological etiology of elderly individuals with caries and is expected to provide novel methods for its prevention and treatment.

Activity of quercetin and kaemferol against Streptococcus mutans biofilm

OBJECTIVE

Nidus Vespae (NV) is the honeycomb of Polistes Olivaceous, P. Japonicus Saussure, and Parapolybiavaria Fabricius. Previously, we have shown the extract and chemical fractions from NV demonstrated remarkable capacities of inhibiting the acid production of oral bacteria at sub-minimum inhibitory concentration (MIC) concentrations. In searching the most potent anti-caries compounds in NV, we further separated the NV Chl/MeOH fraction and obtained two purified compounds: quercetin and kaemferol. The objective of this study was to assess the effectiveness of quercetin and kaemferol against S. mutans biofilm formation.

METHODS

The MIC, minimum biofilm inhibition concentration (MBIC₅₀) and minimum biofilm reduction concentration (MBRC₅₀) against Streptococcus mutans were examined for NV-derived of quercetin and kaemferol. The effectiveness of inhibiting S. mutans biofilm formation was further examined using in vitro biofilm model.

RESULTS

Both quercetin and kaemferol compounds demonstrated anti-biofilm activities when compared to the negative control. They are capable of reducing biofilm dry-weight, total protein, viable cells measured by colony forming unit (CFU), insoluble and soluble glucans formation. The in situ culture pH was less acidic when the biofilms were treated by quercetin and kaemferol. The quercetin and kaemferol demonstrated comparable capability of S. mutans killing in biofilms, compared to chlorhexidine.

CONCLUSIONS

The results of this study showed inhibitory activity of quercetin and kaemferol against S. mutans biofilms, suggesting that quercetin and kaemferol might be considered as alternative anti-caries agents in searching novel anti-caries therapeutics.

Early Childhood Caries: Epidemiology, Aetiology, and Prevention

Early childhood caries (ECC) is one of the most prevalent diseases in children worldwide. ECC is driven by a dysbiotic state of oral microorganisms mainly caused by a sugar-rich diet. Additionally, poor oral hygiene or insufficient dental plaque removal leads to the rapid progression of ECC. ECC leads not only to dental destruction and pain with children, but also affects the quality of life of the caregivers. Children with extensive ECC are at high risk to develop caries with the permanent dentition or will have other problems with speaking and/or eating. To prevent ECC, several strategies should be taken into account. Children should brush their teeth with toothpastes containing gentle ingredients, such as mild surfactants and agents showing antiadherent properties regarding oral microorganisms. Parents/caregivers have to help their children with brushing the teeth. Furthermore, remineralizing and nontoxic agents should be included into the toothpaste formulation. Two promising biomimetic agents for children's oral care are amorphous calcium phosphate [Ca_x(PO₄)_yn H₂O] and hydroxyapatite [Ca₅(PO₄)₃(OH)].

RNA-Seq Reveals Enhanced Sugar Metabolism in Streptococcus mutans Co-cultured with Candida albicans within Mixed-Species Biofilms

Early childhood caries (ECC), which can lead to rampant tooth-decay that is painful and costly to treat, is one of the most prevalent infectious diseases affecting children worldwide. Previous studies support that interactions between Streptococcus mutans and Candida albicans are associated with the pathogenesis of ECC. The presence of Candida enhances S. mutans growth, fitness and accumulation within biofilms in vitro, although the molecular basis for these behaviors is undefined. Using an established co-cultivation biofilm model and RNA-Seq, we investigated how C. albicans influences the transcriptome of S. mutans. The presence of C. albicans dramatically altered gene expression in S. mutans in the dual-species biofilm, resulting in 393 genes differentially expressed, compared to mono-species biofilms of S. mutans. By Gene Ontology analysis, the majority of up-regulated genes were related to carbohydrate transport and metabolic/catabolic processes. KEGG pathway impact analysis showed elevated pyruvate and galactose metabolism, suggesting that co-cultivation with C. albicans influences carbohydrate utilization by S. mutans. Analysis of metabolites confirmed the increases in carbohydrate metabolism, with elevated amounts of formate in the culture medium of co-cultured biofilms. Moreover, co-cultivation with C. albicans altered transcription of S. mutans signal transduction (comC and ciaRH) genes associated with fitness and virulence. Interestingly, the expression of genes for mutacins (bacteriocins) and CRISPR were down-regulated. Collectively, the data provide a comprehensive insight into S. mutans transcriptomic changes induced by C. albicans, and offer novel insights into how bacterial–fungal interactions may enhance the severity of dental caries.

Candida albicans Carriage in Children with Severe Early Childhood Caries (S-ECC) and Maternal Relatedness

Introduction

Candida albicans has been detected together with Streptococcus mutans in high numbers in plaque-biofilm from children with early childhood caries (ECC). The goal of this study was to examine the C. albicans carriage in children with severe early childhood caries (S-ECC) and the maternal relatedness.

Methods

Subjects in this pilot cross-sectional study were recruited based on a convenient sample. DMFT(S)/dmft(s) caries and plaque scores were assessed during a comprehensive oral exam. Social-demographic and related background information was collected through a questionnaire. Saliva and plaque sample from all children and mother subjects were collected. C. albicans were isolated by BBL^™ CHROMagar^™ and also identified using germ tube test. S. mutans was isolated using Mitis Salivarius with Bacitracin selective medium and identified by colony morphology. Genetic relatedness was examined using restriction endonuclease analysis of the C. albicans genome using BssHII (REAG-B). Multilocus sequence typing was used to examine the clustering information of isolated C. albicans. Spot assay was performed to examine the C. albicans Caspofungin susceptibility between S-ECC children and their mothers. All statistical analyses (power analysis for sample size, Spearman’s correlation coefficient and multiple regression analyses) were implemented with SAS 9.4

Results

A total of 18 S-ECC child-mother pairs and 17 caries free child-mother pairs were enrolled in the study. Results indicated high C. albicans carriage rate in the oral cavity (saliva and plaque) of both S-ECC children and their mothers (>80%). Spearman’s correlation coefficient also indicated a significant correlation between salivary and plaque C. albicans and S. mutans carriage (p<0.01) and caries severity (p<0.05). The levels of C. albicans in the prepared saliva and plaque sample (1ml resuspension) of S-ECC children were 1.3 ± 4.5 x10⁴ cfu/ml and 1.2 ± 3.5 x10⁴ cfu/ml (~3-log higher vs. caries-free children). Among 18 child-mother pairs, >60% of them demonstrated identical C. albicans REAG-B pattern. C. albicans isolated from >65% of child-mother pairs demonstrated similar susceptibility to caspofungin in spot assay, while no caspofungin resistant strains were seen when compared with C. albicans wild-type strain SC5314. Interestingly, the regression analysis showed that factors such as antibiotic usage, birth weight, inhaler use, brushing frequency, and daycare attendance had no significant effect on the oral carriage of C. albicans in the S-ECC children.

Conclusions

Our results reveal that both the child with S-ECC and the mother were highly infected with C. albicans, while most of the strains were genetically related, suggesting that the mother might be a source for C. albicans acquisition in the oral cavity of children affected by the disease.

Prevalence of Candida albicans and Candida dubliniensis in caries-free and caries-active children in relation to the oral microbiota-a clinical study

OBJECTIVES

The correlation between caries and the oral prevalence of Candida spp. in children is contradictory in literature. Thereby, authors focused on Candida albicans as the most isolated Candida species from the oral cavity. Therefore, the aim of the present study was to compare caries-free and caries-bearing children regarding their oral carriage of Candida spp.

MATERIAL AND METHODS

Twenty-six caries-free (CF group) and 26 caries-active children (CA group) were included into this study. Three different types of specimens were assessed, saliva and plaque, and in the case of caries, infected dentine samples were microbiologically analyzed for aerobic and anaerobic microorganisms and their counts. Special attention was given to the differentiation between C. albicans and Candida dubliniensis. Additionally, different biochemical tests, VITEK 2 (VITEK®2, bioMérieux, Marcy-l'Etoile, France) and 16S and 18S ribosomal DNA (rDNA) sequencing, were applied for identification.

RESULTS

The detection of C. albicans did not differ between the CF and CA groups. C. dubliniensis was never detected in any specimen of the CF group, but occurred in one quarter of the CA group (27 % in plaque, 23 % in saliva), thus leading to a statistically significant difference between the two groups (p < 0.05). In six of these cases, C. dubliniensis was detected concomitantly in saliva and plaque and once only in plaque. CA group harbored statistically more Streptococcus mutans than the control group revealing a correlation between S. mutans and C. dubliniensis regarding the caries group.

CONCLUSIONS

This is the first study reporting a frequent detection of C. dubliniensis in caries-active children, which could have been underestimated so far due to difficulties in differentiation between this yeast species and C. albicans.

CLINICAL RELEVANCE

Microbiological diagnostic-especially of oral Candida species-is an important determinant for identifying etiological factors of dental caries in children.

Prevalence of oral Candida in the first year of life

Colonisation of the gastrointestinal tract is influenced by primary microbial exposure and bioactive factors in breastmilk. The aim was to explore the prevalence of oral Candida in the first year of life in relation to selected exposures. Oral Candida was studied in 100 healthy infants at 4 and 8 weeks, 3, 6 and 12 months of age and related to delivery mode, birth weight, infant health and feeding, antibiotics, antimycotics, steroids and probiotics in mother and infant, living conditions, maternal smoking and infections The association between lactoferrin and antisecretory factor in breastmilk and maternal serum haemoglobin, transferrin, and ferritin levels in relation to oral Candida was also explored. About 11% to 15% of the infants had oral Candida at the respective age. Colonisation was fairly stable until 6 months of age. There was no conclusive impact of the investigated exposures at entry. Infants with a furry pet at home had a lower frequency of Candida at 3 months, (P < 0.05) whereas all but one colonised infant had older siblings at 12 months (P < 0.01). Lactoferrin in breastmilk was negatively associated with colonisation at 6 months of age. It is concluded that 11 to 15% had oral Candida. Exposure to furry pets and siblings impacted oral Candida.