Genetic Profiling of the Oral Microbiota Associated with Severe Early-Childhood Caries

Abstract

The determination of the composition of the microbial community in the oral cavity is usually based on cultivation methods; however, nearly half of the bacteria in the saliva and the dental plaque are not cultivable. In this study, we evaluated the difference in oral microbial diversity between children with severe early-childhood caries (S-ECC) and caries-free (CF) controls by means of a cultivation-independent approach called denaturing gradient gel electrophoresis (DGGE). Pooled dental plaque samples were collected from 20 children aged 2 to 8 years. Total microbial genomic DNA was isolated from those subjects, and a portion of the 16S rRNA gene locus was PCR amplified by using universal primers. We observed that the mean species richness of the bacterial population was greater in the CF children (n ‫؍‬ 12) (42 ؎ 3.7) than in the S-ECC children (n ‫؍‬ 8) (35 ؎ 4.3); the difference was statistically significant (P ‫؍‬ 0.005). The overall diversity of plaque samples as measured by the Shannon index was 3.5 for the S-ECC group and 3.7 for the CF group (P ‫؍‬ 0.004). Differences in DGGE profiles were distinguished on the basis of a cluster analysis. Sequence analysis of excised DGGE bands consisted of 2.7 phylotypes, on average. After adjusting for the number of observed bands, we estimated that the S-ECC group exhibited 94.5 total phylotypes and that the CF group exhibited 113.4. These results suggest that the microbial diversity and complexity of the microbial biota in dental plaque are significantly less in S-ECC children than in CF children.

Association of oral streptococci community dynamics with severe early childhood caries as assessed by PCR-denaturing gradient gel electrophoresis targeting the rnpB gene

“…These findings imply that the onset of dental caries has an association with a lower diversity of oral streptococci, which is consistent with a cross-section study of preschool children in the various stages of dental caries (Jiang et al, 2011). According to these findings and the previous studies, we infer that the decline in streptococcal diversity in S-ECC plaques is possible because of shifts in the balance of the resident plaque microbiota (Jiang et al, 2011;Li et al, 2007;Ling et al, 2010). Bacterial species present in the dental biofilm communities have cooperative or competitive interactions with other members (Guo et al, 2014).…”

“…Such data could reflect the general microbial composition in dental plaque of the exposed tooth surface, compared with sitespecific plaque sampling, for which data reflect only the situation of specific colonized sites (Tanzer et al, 2001). Previously, we and others demonstrated that PCR-DGGE is a valuable tool for intuitively observing the dynamics of microbial communities composing the dental plaque of children (Jiang et al, 2011;Li et al, 2007;Ling et al, 2010;Tao et al, 2013). In the present study, we sequenced the rnpB gene combined with DGGE to evaluate the diversity and dynamics of oral streptococci associated with S-ECC.…”

“…Previous studies by our group (Tao et al, 2013) and others (Jiang et al, 2011;Li et al, 2007;Ling et al, 2010) demonstrated the superior utility of PCR-denaturing gel gradient electrophoresis (PCR-DGGE) relative to other methods in evaluating the oral microbiota composition. With this approach, microbial profiles of plaques or saliva from various individuals can be compared, and shifts in the ecological balance of the biofilms can be evaluated.…”

Hypoplasia-associated Severe Early Childhood Caries – A Proposed Definition

“…MS in levels over 1% of the total biota are considered a risk indicator for caries (Loesche, 1986). Microbes other than, or in addition to, MS, which preferentially colonize retentive sites include the lactobacilli (Li et al, 1994;Marchant et al, 2001;Becker et al, 2002;Gross et al, 2010;Yang et al, 2010) and possibly several novel species of microbes (Li et al, 2007;Tanner et al, 2011). It is also noteworthy that the overall microbial diversity in plaque of children with S-ECC (HAS-ECC) is significantly less diverse than that of caries-free controls (Li et al, 2007).…”

Exploring the oral bacterial flora: current status and future directions

“…could be implicated as aetiological agents of dental caries. It has also been shown that the bacterial diversity in severe early childhood caries is less than that of caries-free tooth surfaces (Li et al, 2007). Upon analysis of 1285 bacterial 16S rDNA sequences from 42 individuals, Aas et al (2008) showed that nearly half of the bacteria from the caries lesions are yet to be identified.…”