Microbial Risk Indicators of Early Childhood Caries

Abstract

The aim of this study was to use molecular identification methods, such as 16S RNA gene sequence and reverse-capture checkerboard hybridization, for identification of the bacteria associated with dental caries and with dental health in a subset of 204 twins aged 1.5 to 7 years old. A total of 448 plaque samples (118 collected from caries-free subjects and 330 from caries-active subjects) were used for analysis. We compared the bacteria found in biofilms of children exhibiting severe dental caries, with different degrees of lesion severity, with those found in biofilms of caries-free children. A panel of 82 bacterial species was selected, and a PCR-based reverse-capture checkerboard method was used for detection. A simple univariate test was used to determine the overabundance and underabundance of bacterial species in the diseased and in the healthy groups. Features identified with this univariate test were used to construct a probabilistic disease prediction model. Furthermore, a method for the analysis of global patterns of gene expression was performed to permit simultaneous analysis of the abundance of significant species by allowing cross-bacterial comparisons of abundance profiles between caries-active and caries-free subjects. Our results suggested that global patterns of microbial abundance in this population are very distinctive. The top bacterial species found to be overabundant in the caries-active group were Actinomyces sp. strain B19SC, Streptococcus mutans, and Lactobacillus spp., which exhibited an inverse relationship to beneficial bacterial species, such as Streptococcus parasanguinis, Abiotrophia defectiva, Streptococcus mitis, Streptococcus oralis, and Streptococcus sanguinis.

Functional profiles of coronal and dentin caries in children

“…Abiotrophia defectiva was detected in caries-free sites, although not significantly associated with health. This previously ‘aberrant Streptococcus species’ is clinically associated with bacterial endocarditis and has been observed in health compared with early childhood caries [39] as in the current study.…”

Acid-resistant genes of oral plaque microbiome from the functional metagenomics

“…Further, expression of the gene in question and successful translation may not be efficient in the E. coli host since some gram-positive proteins are toxic when translated within E. coli . An alternative explanation might be the limitations of the samples and method: (i) Studies have confirmed that S. mutans is not the only predominant caries-pathogenic bacterium [14,15]; depending on individual patients, it might not be the principal ECC bacterium [42]. Hence, in this study, the abundance of S. mutans might only occupy a small fraction of the collected caries samples, limiting the genetic information in our library and reducing the chance of obtaining functional genes.…”

Heritability of Oral Microbial Species in Caries-Active and Caries-Free Twins

“…The abundance (levels) of 82 oral bacterial species or groups were detected using the reverse capture checkerboard hybridization assay (Corby et al, 2005b;Paster et al, 1998). Briefly, the amplified product for each sample was PCR amplified using a forward primer labeled with digoxigenin and a universally-conserved reverse primer.…”

“…Sensitivity and specificity of the model were measured using the area under the receiver/operator curve (ROC). Methods for computational analysis of microbial expression used in this study have been reported in detail elsewhere (Corby et al, 2005b). Significant oral health-associated species predicted by this model were used for computing heritability estimates.…”

“…While disease-associated flora are recognized for a variety of conditions, we hypothesized that the indigenous microflora of caries-free children may be protective, thereby decreasing the risk for dental caries onset. In this light, we previously reported that caries susceptibility may be explained by the relative overabundance and/or underabundance in levels of disease-associated and health-associated microflora (Corby et al, 2005b). The purpose of this study was to assess the heritability of colonization of oral microbial species in biofilms of the primary dentition using twin models.…”