Method: The study population comprised 42 S-ECC and 40 caries-free children (2-6 years old). Over 5,000 isolates from plaque cultured anaerobically on blood (pH 7), and acid (pH 5) agars were identified by comparing partial 16S rRNA sequences with taxa/species in the Forsyth Human Oral Microbiome Database. The microbiotas in samples were clustered by disease category and isolation medium using principal component analysis and two-way cluster analysis.
Result: The microbiotas of blood and acidic agars grouped separately by cluster analysis. There was some overlap in the microbiotas of S-ECC and caries-free samples isolated on blood. In contrast, samples cultured on the acidic agar clustered into two major groups, one of S-ECC and another of caries-free children. When analyzed separately, three clusters were formed in both S-ECC and caries-free children. Species detected in the two major clusters were similar from both S-ECC and caries-free children. From the S-ECC children the third, loosely-grouped, cluster comprised of Streptococcus mutans, Scardovia wiggsiae, Streptococcus intermedius and Veillonella atypica. From caries-free children, the third cluster included S. intermedius and V. atypica with 3 unnamed Actinomyces species, Streptococcus gordonii, Streptococcus mitis, Streptococcus thermophilus, Veillonella parvula and Veillonella dispar.
Conclusion: Microbial complexes varied between S-ECC and caries-free children although the majority of taxa detected grouped similarly in both disease categories. A microbial complex containing S. mutans and Scardovia wiggsiae was detected in the S-ECC children but not observed in the caries-free children.