Mother's own milk microbiome does not associate with necrotising enterocolitis in preterm infants

Preterm infants who are fed mother's own milk (MOM) have a decreased risk to develop necrotising enterocolitis (NEC). Such protection might be mediated by various MOM bioactive components such as human milk oligosaccharides (HMOs), but also the microbial community. Here, we used 16S rRNA gene sequencing to compare MOM microbiome composition between 48 NEC infants and 62 matched controls. No significant differences in the MOM microbiome composition were observed between NEC and control infants. A general stability in the MOM microbiome was observed over time and the viability of abundant genera was verified by culturing. Potential correlations between the MOM microbiome, HMO profiles, and the infant gut microbiome were also investigated. The only significant correlations observed were found between Acinetobacter in the infant gut and Acinetobacter and Staphylococcus in MOM. This is the first study integrating MOM microbiome with HMO profiles and infant gut microbiome in a preterm cohort. The results suggest MOM exerts its protective effects against NEC through bioactive components, rather than by directly seeding the infant gut.