Breastfeeding premature infants affects the microbiota composition of breast milk

Aim: To determine whether and how breast feeding of premature infants influences the human milk (HM) bacterial communities. Methods: HM samples before and after breastfeeding were collected from 40 preterm infant mothers at 24-36(6/7) weeks of gestational age in the neonatal intensive care unit of our hospital. Of these 40 babies, 11 at 24-27(6/7) weeks of gestational age and 12 at 28-31(6/7) weeks were grouped into an extremely premature (EPM) group and a very premature (VPM) group, respectively. In addition, 11 with a birth weight (BWT) of 1000 g <= BWT < 1500 g were classified as a very low birth weight (VLBW) group and 12 with BWT < 1000 g an extremely low birth weight (ELBW) group. Breast feeding and kangaroo mother care were given once a day for 7 days, from 14 to 21 days of age. The bacterial composition of HM was analyzed using high-throughput sequencing before and after feeding. Results: Linear discriminant analysis effect size of HM samples before and after feeding showed that Bacillus, Prevotella and Fusobacterium were significantly enriched in HM before breastfeeding (P < 0.05). Post-feeding HM for the EPM group showed significant enrichment in Lactobacillales, Streptococcus, Desulfuromonadales, Ruminococcus, Geobacteraceae, Geobacter and Elizabethkingia_meningoseptica (P < 0.05). Bacillus was significantly enriched in the HM for EPM group before feeding (P < 0.05). For mothers with VLBW infants, Bacillus was enriched before feeding, while Lactobacillales was predominant after feeding (P < 0.05). There was a moderate correlation between the diversity of HM bacteria and infant development and immune outcomes. Conclusion: Breastfeeding of preterm infants can significantly affect the bacterial diversity in HM.