Poster Topical Area: Maternal, Perinatal and Pediatric Nutrition

Location: Hall D

Poster Board Number: 366

P13-108 - Bacterial Composition of Expressed Human Milk Collected Under Two Real-Life Conditions - a Randomized, Controlled Trial

Sunday, Jun 10
8:00 AM – 6:00 PM

Objective: Women use a wide range of practices for pumping, handling, and storing their milk. The effects of these practices on the bacterial composition of the milk are unclear. Our objective was to characterize and compare the bacterial composition of human milk pumped under 2 real-life conditions.


Methods: We conducted a randomized trial (Milk in Life Conditions, MiLC) comparing bacterial communities in milk expressed using 2 pump and collection kit set ups. Lactating mothers (n=52) fully expressed the same breast in 2 consecutive pumping sessions at home, once with their own pumps and collection kits ("own" supplies) and once with a hospital-grade pump (Medela Symphony) and sterile collection kits ("sterile" supplies). Randomization was used to determine the pump set up participants used first. Thirty mL of milk were retained for analysis. Bacterial composition was assessed by aerobic culturing and deep sequencing of the V1-V3 region of the bacterial 16S rRNA gene amplified from DNA extracted from this milk.


Results: Milk collected with mothers' own supplies contained ~5.6 times more total culturable aerobic bacteria than milk collected with sterile supplies (8.1 x 10e4 v. 1.4 x 10e4 cfu/mL, respectively; p<0.0001). Growth on selective media for Streptococcus, Staphylococcus, and gram-negative aerobic bacteria accounted for ~100% of total cultured aerobes in milk collected with sterile supplies, but only ~55% of cultured aerobes collected with mother's own supplies. Analysis of 16S rRNA sequences revealed an effect of pump and collection kit set up on the relative abundances of several taxa. Proteobacteria were 4.75 times more (p<0.0001) and Firmicutes were 1.6 times less abundant (p<0.0001), respectively, in milk collected with own v. sterile supplies. At the genus level, Acinetobacter and Enterobacter were 68 (p<0.0001) and 20 (p=0.02) times more abundant, respectively, and Staphylococcus and Streptococcus 1.7 (p=0.008) and 1.9 (p=0.003) times less abundant, respectively, in milk collected with own v. sterile supplies.


Conclusion: The bacterial composition of milk collected with mothers' own pumps and collection kits is significantly different from that of milk collected with hospital-grade pumps and sterile collection kits. Whether these differences influence infant health requires further study.



Funding Source:

Funded in part by NIH T32-DK007158, USDA/Hatch NYC-399346, travel grant from Larsson-Rosenquist Family Foundation, McNair Scholars Program, NIGMS NIH P30 GM103324, and the Idaho Agricultural Experiment Station.

CoAuthors: Dainelle Allen – Cornell University; Michelle McGuire, PhD – Washington State University; Mark McGuire, PhD – University of Idaho; Anthony Hay, PhD – Cornell University; Kathleen Rasmussen, ScD – Cornell University

Sarah M. Reyes

Doctoral Candidate
Cornell University
Ithaca, New York