Role of vertical and horizontal microbial transmission of antimicrobial resistance genes in early life: insights from maternal-infant dyads

Early life represents a critical window for metabolic, cognitive and immune system development, which is influenced by the maternal microbiome as well as the infant gut microbiome. Antibiotic exposure, mode of delivery and breastfeeding practices modulate the gut microbiome and the reservoir of antibiotic resistance genes (ARGs). Vertical and horizontal microbial gene transfer during early life and the mechanisms behind these transfers are being uncovered. In this review, we aim to provide an overview of the current knowledge on the transfer of antibiotic resistance in the mother-infant dyad through vertical and horizontal transmission and to highlight the main gaps and challenges in this area.