The Relationship of Collagen‐Binding Protein Positive (Cbp ⁺ ) <i>Streptococcus mutans</i> Serotypes and <i>Candida</i> 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 of children with severe early childhood caries (S‐ECC). To further contextualize our findings, we also performed a scoping review of 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 months with 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 Cbp genes (Cnm and Cbm). Statistical comparisons were conducted between lesion sites, and exploratory association analyses were performed 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 were detected at higher levels in occlusal lesions, whereas serotype k was more prevalent in proximal lesions. Candida albicans was the predominant fungal species and was frequently co‐detected with multiple S. mutans serotypes in both lesion types. Exploratory association analysis showed no strong serotype‐ Candida associations in occlusal lesions; however, proximal lesions demonstrated a higher degree of co‐detection between serotype k and C. albicans in proximal lesions ( r = 0.74). This exploratory observation suggests a possible site‐specific microbial interaction. Conclusion Distinct microbial profiles were observed in occlusal and proximal dentinal lesions of children with S‐ECC. The distribution patterns of S. mutans serotypes and the frequent co‐detection of Candida species support the concept of niche‐specific microbial ecosystems within advanced dentinal lesions. Further studies with larger cohorts, caries‐free controls, and functional approaches are warranted to clarify the biological significance of these site‐specific co‐occurrence patterns.