The Relationship of Collagen-Binding Protein Positive (Cbp+) Streptococcus mutans Serotypes and Candida spp. in Severe Early Childhood Caries

Objective: To evaluate the prevalence and distribution of Streptococcus mutans serotypes (c, e, f, and k), collagen-binding protein(Cbp) genes (Cbp-positive [Cbp+]; Cnm and Cbm), and Candida species in occlusal and proximal dentinal caries lesions ofchildren with severe early childhood caries (S-ECC). To further contextualize our findings, we also performed a scoping reviewof the literature on S. mutans serotypes, Cbp+ strains, and/or Candida species in pediatric caries.
Methods: Infected dentin samples were collected from occlusal and proximal caries lesions of 18 children aged 48–71 monthswith S-ECC. Microbiological and molecular analyses included culture-based identification of Candida species on CHROMagar,multiplex PCR for species differentiation, species-specific PCR for S. mutans serotyping, and real-time PCR for detection of Cbpgenes (Cnm and Cbm). Statistical comparisons were conducted between lesion sites, and exploratory association analyses wereperformed based on relative PCR detection levels (cycle threshold [ΔCt]-based).
Results: All samples tested positive for S. mutans, with serotypes c, e, and k being the most prevalent. Serotypes c and e weredetected at higher levels in occlusal lesions, whereas serotype k was more prevalent in proximal lesions. Candida albicans was thepredominant fungal species and was frequently co-detected with multiple S. mutans serotypes in both lesion types. Exploratoryassociation analysis showed no strong serotype-Candida associations in occlusal lesions; however, proximal lesions demonstrateda higher degree of co-detection between serotype k and C. albicans in proximal lesions (r = 0.74). This exploratory observationsuggests a possible site-specific microbial interaction.
Conclusion: Distinct microbial profiles were observed in occlusal and proximal dentinal lesions of children with S-ECC. Thedistribution patterns of S. mutans serotypes and the frequent co-detection of Candida species support the concept of niche-specificmicrobial ecosystems within advanced dentinal lesions. Further studies with larger cohorts, caries-free controls, and functionalapproaches are warranted to clarify the biological significance of these site-specific co-occurrence patterns.