The role of breastfeeding in modulating antimicrobial resistance in neonates: a systematic review

Abstract: Antimicrobial resistance (AMR) is a growing health concern in neonates. Breastfeeding potentially plays a pivotal role in modulating neonatal gut microbiota, thereby influencing the acquisition and transmission of AMR genes (ARGs). This systematic review evaluates the links between breastfeeding and the origin of neonatal gut microbiota and AMR. Selection of pertinent studies published between 2015 and 2025 focusing on major outcome measures of neonatal AMR and ARG transfer was performed on scholarly databases. Following quality assessment, 22 studies met the inclusion criteria for further consideration. Evidence consistently demonstrates that breast milk is an active contributor to the microbial and genetic landscape of the neonatal gut microbiome. Further, studies implicated breast milk as a source of ARG transfer in neonates. Other reports indicated that exclusive breastfeeding and human milk-associated bioactive compounds promoted the colonization of beneficial commensals, limited colonization of multidrug-resistant species, and suppressed horizontal transfer of ARGs. Interestingly, maternal factors, such as maternal antibiotic history, lifestyle, and overall health status, appeared to influence the links between breast milk and transmission and impact of ARGs in neonates. In conclusion, while breastfeeding-based strategies are important to neonatal AMR mitigation, further mechanistic studies are required to establish causal pathways. Impact: Breastfeeding has an active role in altering neonatal gut microbiota and influences antimicrobial resistance (AMR) acquisition. This review synthesizes evidence from 2015–2025 indicating that breastfeeding is both a source of antimicrobial resistance genes (ARGs) and contains bioactive components that suppress ARG transmission and promote beneficial colonization. Maternal factors, such as antibiotic exposure, lifestyle, and overall health, potently influence these links. Mechanistic comprehension of the links between breastfeeding, neonatal microbiome, and AMR acquisition may allow identification of prevention strategies against neonatal infections. The analyses underscore the need for longitudinal, mechanistic studies to determine causal relationships and long-term effects of breastfeeding on neonatal AMR.