Factors that Are Associated with Increased Lactic Acid Bacteria Presence in Donated Human Milk

<b><i>Background:</i></b> Probiotic bacteria isolated from human milk can have a preventive effect against necrotizing enterocolitis and other risks of prematurity. The aim of the study is to identify the possible factors that can influence the presence of lactic acid bacteria (LAB) in donated human milk (DHM). <b><i>Methods:</i></b> Next-generation sequencing and selective microbiological culturing of samples from pools of raw DHM were performed. Data on the donors, their children, and the milk are correlated with the microbiological findings. A regression model is performed, to predict the probability of the presence of the genera <i>Lactobacillus</i> and <i>Bifidobacterium</i>. <b><i>Results:</i></b> The abundance of the genus <i>Bifidobacterium</i> positively correlated with the donor's body mass index (<i>p</i> = 0.050). The abundance of the <i>Lactobacillus</i> positively correlated with the lactation age (<i>p</i> = 0.007) and negatively with the total bacterial count on blood agar (<i>p</i> = 0.001). The abundance of the <i>Bifidobacterium</i> positively correlated with the growth on selective transgalactosylated oligosaccharides-propionate agar media (<i>p</i> = 0.036). In the regression model for predicting the probability of the presence of LAB, the feeding mode and the length of storage in the milk bank proved to be statistically significant predictors. <b><i>Conclusion:</i></b> The results of this study indicate that mature DHM, that has a lower bacterial count, that was stored in the milk bank for a shorter time after pool formation and that is donated from a mother exclusively breastfeeding her infant is assumed to have both LAB.