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

Abstract

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.

Figure 1

Microbiological analysis of saliva and plaque samples from caries free (CF), caries experienced—no recurrence (CE-NR), and active recurrent caries (CR) groups. Panels A and B depict Mutans streptococci and Candida spp. counts in saliva samples and in healthy plaque (H), white spot lesion plaque (WS) and cavitated dentin plaque (D) from the study groups, respectively. The CFU counts among the three caries status groups were compared using general linear mixed modeling, controlling by age. Data shown are mean  ± SD values of log total colony count of Mutans streptococci and Candida spp. colonies.

Figure 2

Microbiological analysis of plaque samples collected from subjects with active recurrent caries (CR group). Graph shows Mutans streptococci and Candida spp. counts in healthy plaque (H), white spot lesion plaque (WS) and cavitated dentin plaque (D) of CR subjects in relation to infection with S. mutans strains harboring either cnm or cbm genes (Cbp⁺). The CFU counts of the Cbp⁺ and Cbp^- CR subjects were compared using general linear mixed modeling. Data shown are mean  ± SD values of log total colony count of Mutans streptococci and Candida spp. colonies.

Figure 3

Shannon alpha diversity and Beta diversity metrics of the salivary microbiome of children who were caries free (CF), caries experienced—no recurrence (CE-NR) and had active recurrent caries (CR). (A) Violin plot depicting Shannon alpha diversity measures for each sample category was analyzed by paired Kruskal–Wallis test. CR group has a significantly higher alpha diversity when compared to CF and CE-NR. (B) Beta diversity was compared by using Principal Coordinate Analysis and the strength of the differences were tested by Permutational Analysis of Variance. No differences were observed in Beta diversity among the groups.

Figure 4

Distribution of the top 25 most abundant taxa across the caries free (CF), caries experienced—no recurrence (CE-NR) and active recurrent caries (CR) groups using rarefied taxon counts. The chart shows mean taxon counts for sample group. Means are shown as relative proportions.