Signatures of the maternal-infant oral microbiome in contexts of imprisonment and social vulnerability.

INTRODUCTION: The oral microbiome is a dynamic ecosystem that develops in early life through physiological processes and environmental exposures and plays a key role in oral and systemic health. In socially vulnerable settings, such as prisons, altered living conditions may shape the establishment of the pediatric oral microbiome. This study aimed to characterize the oral microbiome signatures in mothers, children, and pregnant women living in prisons, and to explore microbial variation in relation to confinement-related living conditions.

METHODS: A cross-sectional study was conducted that included the entire maternal-child population (n = 43 samples) residing in five prisons and social reintegration centers in the State of Mexico. Saliva and oral biofilm samples were collected from mothers (n = 19), children (n = 19), and pregnant women (n = 5). The taxonomic composition was evaluated by sequencing the 16S rRNA gene. Analyses of alpha diversity (Shannon index), beta diversity (weighted UniFrac), and differential abundance (DESeq2) were performed.

RESULTS: A shared core microbiome, dominated by Streptococcus and Veillonella, was identified in all groups. However, significant differences in microbial diversity were observed according to prison (p = 0.03) and population group (p = 0.01). Children exhibited the lowest diversity and a pronounced dominance of Streptococcus (58%), consistent with microbiome profiles in the early stages of life but consistent with early-life microbiome profiles. Mothers showed a greater abundance of opportunistic environmental taxa, including Pseudomonas (13.2%) and Raoultella (5.2%). Pregnant women showed the greatest diversity and a distinctive signature characterized by enrichment of Actinomyces and Leptotrichia. Beta diversity analyses revealed partial overlap between mothers and children, suggesting shared microbial patterns potentially related to common living conditions.

CONCLUSION: These findings provide an exploratory characterization of the oral microbiome in mothers, children, and pregnant women living in prison settings. The lower diversity observed in children, along with the presence of opportunistic environmental taxa, underscores the importance of accounting for confinement-related living conditions in oral health research and prevention strategies for historically marginalized populations. Future comparative and longitudinal studies are needed to clarify the relationship between prison-specific conditions and variation in the oral microbiome.