Mother\'s milk contains diverse bacterial communities, although their impact on microbial colonization in very-low-birth-weight (VLBW, <1,500 g) infants remains unknown. Here, we examine relationships between the microbiota in preterm mother\'s milk and the VLBW infant gut across initial hospitalization (n = 94 mother-infant dyads, 422 milk-stool pairs). Shared zero-radius operational taxonomic units (zOTUs) between milk-stool pairs account for ∼30%-40% of zOTUs in the VLBW infant\'s gut. We show dose-response relationships between intakes of several genera from milk and their concentrations in the infant\'s gut. These relationships and those related to microbial sharing change temporally and are modified by in-hospital feeding practices (especially direct breastfeeding) and maternal-infant antibiotic use. Correlations also exist between milk and stool microbial consortia, suggesting that multiple milk microbes may influence overall gut communities together. These results highlight that the mother\'s milk microbiota may shape the gut colonization of VLBW infants by delivering specific bacteria and through intricate microbial interactions.

BACKGROUND: Infants requiring neonatal care often face initial breastfeeding challenges, leading them to receive expressed breast milk from their mother or donor milk. While emphasizing the mother\'s own milk as the gold standard for infant nutrition, the utilization of donor milk stands as the preferred alternative over infant formula due to its numerous benefits. To facilitate the provision of donor milk to preterm and ill infants in neonatal units, the active participation of women willing to contribute their breast milk is crucial. This study aims to enhance the understanding of women\'s experiences in the donation process, thereby contributing to efforts aiming at alleviating the shortage of donated breast milk by improve the care and support for breast milk donors.
METHODS: This descriptive qualitative study took an inductive approach based on individual semi-structured interviews conducted during 2021 with 15 breast milk donors in Sweden. The data were analysed with thematic analysis.
RESULTS: Two themes were identified in the analysis: motivation to donate and challenges to overcome. Many of the women struggled to overcome the apparent challenges of not only starting the process of donating breast milk but also maintaining it. Despite the strain, they were motivated to donate their breast milk and seeking information by themselves to do something important for someone else. Only a few of the women talked about the financial benefits of donating breast milk; donating seemed to be mostly based on altruistic reasons.
CONCLUSIONS: Despite the challenges posed by COVID-19 restrictions, time consumption, and the hard work of sterilizing pump utensils, women continued to donate their milk driven by altruism. To enhance donor support and increase milk donation, several improvements are suggested: providing comprehensive information and resources, simplifying the donation process, offering flexible scheduling, and recognizing donors\' contributions.

Human milk reduces risk for necrotizing enterocolitis in preterm infants. Necrotizing enterocolitis occurs in the ileocecal region where thousands of milk protein-derived peptides have been released from digestion. Digestion-released peptides may exert bioactivity, such as antimicrobial and immunomodulatory activities, in the gut. In this study, we applied mass spectrometry-based peptidomics to characterize peptides present in colostrum before and after in vitro digestion. Sequence-based computational modeling was applied to predict peptides with antimicrobial activity. We identified more peptides in undigested samples, yet the abundances were much higher in the digested samples. Heatmapping demonstrated highly different peptide profiles between undigested and digested samples. Four peptides (αS1-casein [157-163], αS1-casein [157-165], β-casein [153-159] and plasminogen [591-597]) were selected, synthesized and tested against common pathogenic bacteria associated with necrotizing enterocolitis. All four exhibited bacteriostatic, though not bactericidal, activities against Klebsiella aerogenes, Citrobacter freundii and Serratia marcescens, but not Escherichia coli.

Holder pasteurization (HoP) enhances donor human milk microbiological safety but damages many bioactive milk proteins. Though ultraviolet-C irradiation (UV-C) can enhance safety while better preserving some milk proteins, it has not been optimized for dose or effect on a larger array of bioactive proteins. We determined the minimal UV-C parameters that provide >5-log reductions of relevant bacteria in human milk and how these treatments affect an array of bioactive proteins, vitamin E, and lipid oxidation. Treatment at 6000 and 12 000 J/L of UV-C resulted in >5-log reductions of all vegetative bacteria and bacterial spores, respectively. Both dosages improved retention of immunoglobulin A (IgA), IgG, IgM, lactoferrin, cathepsin D, and elastase and activities of bile-salt-stimulated lipase and lysozyme compared with HoP. These UV-C doses caused minor reductions in α-tocopherol but not γ-tocopherol and no increases in lipid oxidation products. UV-C treatment is a promising approach for donor human milk processing.

Toxic trace elements could enter human milk through mothers\' food consumption, drinking water, air, or incidental soil ingestion, and are of concern to the nursing infant.
To determine the concentration of toxic trace elements (lead and arsenic) in Peruvian mothers\' milk and their association with blood concentrations in their own infants 3-20 months old.
This exploratory, cross-sectional study, carried out in Peru, included breastfeeding mother/child dyads (N = 40). Following standardized protocols, biospecimens of human milk and child\'s blood were collected.
Lead and arsenic concentrations in milk were above the method detection limits in 73% and 100% of samples with median concentrations of 0.26 µg/L (IQR = 0.10, 0.33 µg/L) and 0.73 µg/L (IQR = 0.63, 0.91 µg/L), respectively. Concentrations of lead and arsenic in blood were 2.05 µg/dL (SD = 1.35), and 1.43 µg/dl (geometric mean: SD = 1.39), respectively. Blood lead concentrations in 12.5% (n = 5) of the samples were above the U.S. Center for Disease Control and Prevention reference value (< 3.5 µg/dl), and over half of arsenic concentrations were above the acceptable levels of < 1.3 µg/dl (Mayo Clinic Interpretative Handbook). Our results showed that for every one-month increase in age, lead blood concentrations increased by 0.1 µg/dl (p = 0.023). Additionally, every 1 µg/L increase in the mother\'s milk arsenic was associated with a 1.40 µg/dl increase in the child\'s blood arsenic concentration.
Implementing effective interventions to decrease the toxic exposure of reproductive-aged women is needed in Peru and worldwide.

Donor human milk banks use Holder pasteurization (HoP; 62.5°C, 30 min) to reduce pathogens in donor human milk, but this process damages some bioactive milk proteins.
We aimed to determine minimal parameters for high-pressure processing (HPP) to achieve >5-log reductions of relevant bacteria in human milk and how these parameters affect an array of bioactive proteins.
Pooled raw human milk inoculated with relevant pathogens (Enterococcus faecium, Staphylococcus aureus, Listeria monocytogenes, Cronobacter sakazakii) or microbial quality indicators (Bacillus subtilis and Paenibacillus spp. spores) at 7 log CFU/mL was processed at 300-500 MPa at 16-19°C (due to adiabatic heating) for 1-9 min. Surviving microbes were enumerated using standard plate counting methods. For raw milk, and HPP-treated and HoP-treated milk, the immunoreactivity of an array of bioactive proteins was assessed via ELISA and the activity of bile salt-stimulated lipase (BSSL) was determined via a colorimetric substrate assay.
Treatment at 500 MPa for 9 min resulted in >5-log reductions of all vegetative bacteria, but <1-log reduction in B. subtilis and Paenibacillus spores. HoP decreased immunoglobulin A (IgA), immunoglobulin M (IgM), immunoglobulin G, lactoferrin, elastase and polymeric immunoglobulin receptor (PIGR) concentrations, and BSSL activity. The treatment at 500 MPa for 9 min preserved more IgA, IgM, elastase, lactoferrin, PIGR, and BSSL than HoP. HoP and HPP treatments up to 500 MPa for 9 min caused no losses in osteopontin, lysozyme, α-lactalbumin and vascular endothelial growth factor.
Compared with HoP, HPP at 500 MPa for 9 min provides >5-log reduction of tested vegetative neonatal pathogens with improved retention of IgA, IgM, lactoferrin, elastase, PIGR, and BSSL in human milk.

Ethanol intoxications in newborns are generally due to false preparation of formula with alcoholics or alcohol consumption by the breastfeeding mothers. Rarely, intoxications occur in hospitalized newborns, e.g., from excessive use of alcoholic hand sanitizers. We herein report a strange case of acute ethanol intoxications in our NICU.
An extremely premature infant (23 0/7 weeks gestational age, birthweight 580 g) suffered from repeated life-threatening events with hemodynamic compromise, apnea, and lactic acidosis while being treated in our neonatal intensive care unit (NICU). Symptomatic treatment with intravenous fluids and, if necessary, intubation and catecholamine therapy led to recovery after several hours each time. The episodes eventually turned out to be severe ethanol intoxications brought about by breast milk contaminated with ethanol. The breast milk was supplied by the infant\'s mother, who consumed non-trivial amounts of alcohol to build up her strength and make herself produce more milk, which was recommended to her by a family member. Additionally, she supplemented her own mother\'s milk with cow\'s milk because she was worried her baby was underserved with her milk. The mother admitted to this in intensive conversations with our team and a professional translator.
This unique case underlines how different cultural dynamics can attribute to life-threatening events in the care of premature infants. It is important for us to emphasize that intensive communication and building a confident relationship with the parents of patients is essential to the work on NICUs. Child safeguarding issues and possibilities of intoxications have to stay in mind even in a supposedly safe space like the NICU.

Nutrient fortifiers are added to human milk to support the development of very-low-birth-weight infants. Currently, bovine-milk-based fortifiers (BMBFs) are predominantly administered, with increasing interest in adopting human-milk-based fortifiers (HMBFs). Although beneficial for growth, their effects on the gastrointestinal microbiota are unclear. This triple-blind, randomized clinical trial (NCT02137473) tested how nutrient-enriching human milk with HMBF versus BMBF affects the gastrointestinal microbiota of infants born < 1,250 g during hospitalization. HMBF-fed infants (n = 63, n = 269 stools) showed lower microbial diversity, altered microbial community structure, and changes in predicted microbial functions compared with BMBF-fed infants (n = 56, n = 239 stools). HMBF-fed infants had higher relative and normalized abundances of unclassified Enterobacteriaceae and lower abundances of Clostridium sensu stricto. Post hoc analyses identified dose-dependent relationships between individual feed components (volumes of mother\'s milk, donor milk, and fortifiers) and the microbiota. These results highlight how nutrient fortifiers impact the microbiota of very-low-birth-weight infants during a critical developmental window.

OBJECTIVE: Breast milk is the best source of nutrition for a newborn during the first six months of his or her life. However there is a possibility that breast milk may contain pollutants such as metals. The current meta-analytic study assessed the concentration of potentially toxic elements (PTEs), including lead (Pb), cadmium (Cd), arsenic (As), Iron (Fe), Zinc (Zn), copper (Cu), and nickel (Ni), in mothers\' milk.
METHODS: The literature studies regarding the concentrations of PTEs in the breast milk of mothers were collected from international databases such as PubMed, Scopus, Web of Science, and Embase. Afterward, the Total Target Hazard Quotient (TTHQ) by Monte Carlo Simulation (MCS) model was used to assess the non-carcinogenic risk.
CONCLUSIONS: According to 42 of the 836 retrieved articles, the PTE concentrations in mother\'s milk were as follows: Cu (1.84 mg/kg) > Zn (1.80 mg/kg) > Fe (1.03 mg/kg) > Ni (0.60 mg/kg) > Pb (0.10 mg/kg) > As (0.15 mg/kg) ≈ Cd (0.15 mg/kg). Based on the containment type, the highest concentrations of As (2.80 mg/kg), Cd (0.07 mg/kg), and Pb (2.68 mg/kg) were related to Western Pacific Region (WPRO), European Region (EURO), and WPRO, respectively. In addition, for trace elements, Eastern Mediterranean Region (EMRO) was the region with the highest concentrations of Cu (3.56 mg/kg), Fe (2.78 mg/kg), Ni (3.13 mg/kg), and Zn (5.58 mg/kg) were related to Lastly, the non-carcinogenic risk assessment of the PTEs in breast milk indicated different risk patterns in various countries, and the calculated TTHQ level in infants was below 1.
CONCLUSIONS: Overall, human breast milk was generally safe for infants to consume and poses no risks to their health.

The child microbiome, including gut and skin communities, is shaped by a multitude of factors, and breastfeeding is one of the most essential. Food allergy (FA) and atopic dermatitis (AD) are among the most common diseases in pediatrics, with the prevalence of each up to 6% and 20%, respectively. Therefore, we aimed at finding differences between the fecal and skin microbiomes of FA and AD patients in the context of breastfeeding, by means of the Illumina sequencing of 16S rRNA gene fragment libraries amplified from the total DNA isolated from samples collected from allergic and healthy infants. We also analyzed milk samples from the mothers of the examined children and searched for patterns of incidence suggesting milk influence on an infant\'s allergy status. Here we show that a mother\'s milk influences her child\'s fecal and skin microbiomes and identify Acinetobacter as the taxon whose abundance is correlated with milk and child-derived samples. We demonstrate that breastfeeding makes allergic children\'s fecal and skin communities more similar to those of healthy infants than in the case of formula-feeding. We also identify signature taxa that might be important in maintaining health or allergy development.