Bacterial composition of the human milk microbiome across lactation

Research has illustrated the presence of a diverse range of microbiota in
human milk. The composition of the milk microbiome varies across
different stages of lactation, emphasizing the need to consider
the lactation stage when studying its composition. Additionally,
the transfer of both milk and skin microbiota during
breastfeeding is crucial for understanding their collective impact
on infant health and development. Further exploration of the
complete breastfeeding microbiome is necessary to unravel the
role these organisms play in infant development. We aim to
longitudinally assess the bacterial breastfeeding microbiome
across stages of lactation. This includes all the bacteria that
infants are exposed to during breastfeeding, such as bacteria
found within human milk and any bacteria found on the breast and
nipple. Forty-six human milk samples were collected from 15 women
at 1, 4, 7, and 10 months postpartum. Metagenomic analysis of the
bacterial microbiome for these samples was performed by CosmosID
(Rockville, MD) via deep sequencing. Staphylococcus epidermidis
and Propionibacteriaceae species are the most abundant bacterial
species from these samples. Samples collected at 10 months showed
higher abundances of Proteobacteria, Streptococcaceae,
Lactobacillales, Streptococcus, and Neisseria mucosa compared to
other timepoints. Alpha diversity varied greatly between
participants but did not change significantly over time. As the
bacterial breastfeeding microbiome continues to be
studied, bacterial contributions could be used to predict and
reduce health risks, optimize infant outcomes, and design
effective management strategies, such as altering the maternal
flora, to mitigate adverse health concerns.