Candida biome of severe early childhood caries (S-ECC) and its cariogenic virulence traits

Abstract

The protected niche of deep-caries lesions is a distinctive ecosystem. We assessed the Candida biome and its cariogenic traits from dentin samples of 50 children with severe-early childhood caries (S-ECC). Asymptomatic, primary molars belonging to International Caries Detection and Assessment-ICDAS caries-code 5 and 6 were analyzed, and C. albicans (10-isolates), C. tropicalis (10), C. krusei (10), and C. glabrata (5) isolated from the lesions were then evaluated for their biofilm formation, acidogenicity, and the production of secreted hydrolases: hemolysins, phospholipase, proteinase and DNase. Candida were isolated from 14/43 ICDAS-5 lesions (32.5%) and 44/57 ICDAS-6 lesions (77.2%). Compared to, ICDAS-5, a significantly higher frequency of multi-species infestation was observed in ICDAS-6 lesions (p=0.001). All four candidal species (above) showed prolific biofilm growth, and an equal potency for tooth demineralization. A significant interspecies difference in the mean phospholipase, as well as proteinase activity was noted (p < 0.05), with C. albicans being the predominant hydrolase producer. Further, a positive correlation between phospholipase and proteinase activity of Candida-isolates was noted (r = 0.818, p < 0.001). Our data suggest that candidal mycobiota with their potent cariogenic traits may significantly contribute to the development and progression of S-ECC.

Keywords: Candida species; acidogenicity; biofilm; calcium-release; dentin caries; haemolysin; hydrolases; phopholipase; protease; severe early childhood caries (S-ECC).

Figure 1.

Distribution of Candida species according to ICDAS caries lesion severity code 5 (distinct cavity with visible dentin) and caries code 6 (extensive caries lesion involving half/more than half of tooth)

Figure 2.

Biofilm formation by Candida species (C. albicans n = 10; C. krusei n = 10; C. tropicalis n = 10; C. glabrata n = 5) at 24 hand 48 h; *P value < 0.05 (ANOVA)

Figure 3.

(a–d) Ca++ release assay and pH changes initiated by four different Candida species during tooth-demineralization evaluation (3a, C. albicans n = 10; 3b, C. krusei n = 10; 3c, C. tropicalis n = 10; 3d, C. glabrata n = 5)

Figure 4.

Haemolysin, phospholipase and proteinase production by the four different Candida species isolated from deep dentin caries lesions of children with S-ECC

Figure 5.

Correlation between the Pz value of proteinase and phospholipase enzyme activity of 29/35 clinical isolates belonging to C. albicans, C. krusei, C. tropicalis and C. glabrata species (P < 0.001; R² = 0.812)