Donor Human Milk Bacterial Microbiota Composition is Shaped by Breastfeeding Mode.

This article focuses on profiling the bacterial composition of donor human milk (DHM) samples from Shanghai, China, and identifying factors influencing its microbiota. In a cross-sectional study of 252 milk samples from healthy donors at the Shanghai Donor Human Milk Bank, 16S rRNA sequencing revealed that the predominant bacterial phyla were Firmicutes, Proteobacteria, Bacteroidota, and Actinobacteriota, with key genera including Staphylococcus, Achromobacter, Streptococcus, and Acinetobacter. Breastfeeding mode emerged as a pivotal determinant: indirect breastfeeding was independently associated with lower bacterial diversity and higher relative abundance of Staphylococcus, while preterm birth and Cesarean section were also linked to increased Staphylococcus levels. Additionally, milk protein content correlated positively with Lactobacillus and Enterococcus abundance, which declined as lactation progressed. These findings suggest that breastfeeding practices significantly shape the human milk microbiota, with implications for optimizing donor milk collection and use.