The development of the oral resistome during the first decade of life

Abstract Antibiotic overuse has promoted the spread of antimicrobial resistance (AMR) with significant health and economic consequences. Surveillance of resistance reservoirs, like the rarely explored oral microbiome, is necessary to combat AMR. We characterised the development of the paediatric oral resistome and investigated its role in dental caries in 221 twin children sampled over the first decade of life. From 535 oral metagenomes, we identified 309 antimicrobial resistance genes (ARGs), which significantly clustered by age, with the influence of host genetics on antimicrobial resistance increasing over time. Our results suggest the mobilisation potential of ARGs increased with age as Tn916 transposase was co-located with more species and ARGs as children grew. Dental caries compared to health was associated with a depletion of ARGs and species, which was reversed when restored. Our results highlight the dynamic nature of the paediatric oral resistome, and its potential role in transmission of AMR and dysbiosis.