The objective of this pilot study was to assess the fecal microbiome and different immunological parameters in infant feces and maternal milk from mother–infant pairs in which the infants were suffering from different gastrointestinal disorders (colic, non-IgE-mediated cow milk protein allergy (CMPA), and proctocolitis). A cohort of 30 mother–infant pairs, in which the infants were diagnosed with these gastrointestinal disorders or included as healthy controls, were recruited. Bacterial composition of infant feces and breast milk was determined by metataxonomic sequencing. Immunological compounds were quantified using multiplexed immunoassays. A higher abundance of Eggerthellaceae, Lachnospiraceae and Peptostreptococcaceae, and lower abundance of Bifidobacterium and higher abundance of Rothia were registered in fecal samples from the CMPA group. Eggerthellaceae was also significantly more abundant in milk samples of the CMPA group. There were no differences in the concentration of immunological compounds in infant fecal samples between the four groups. In contrast, differences were found in the concentration and/or frequency of compounds related to acquired immunity and granulocyte colony stimulating factor (GCSF) in breast milk samples. In conclusion, a few microbial signatures in feces may explain part of the difference between CMPA and other infants. In addition, some milk immunological signatures have been uncovered among the different conditions addressed in this pilot study.

Human milk microbiota is a unique bacterial community playing a relevant role in infant health, but its composition depends on different factors (woman health, lactation stage, and geographical lactation). However, information is lacking regarding some other factors that may affect the bacterial community of human milk. In this study we aimed to study the impact of the sample collection method and the skimming procedure using culture-dependent and culture-independent techniques to study the human milk microbial profile. One set of milk samples was provided by women (n = 10) in two consecutive days; half of the samples were collected the first day by manual expression and the other half on the second day by pumping. The rest of the participants (n = 17) provided milk samples that were fractionated by centrifugation; the bacterial profiles of whole milk and skimmed milk were compared by culture techniques in 10 milk samples, while those of whole milk, fat and skimmed milk were subjected to metataxonomic analysis in seven samples. Globally, the results obtained revealed high interindividual variability but that neither the use of single-use sterile devices to collect the sample nor the skimming procedure have a significant impact of the microbial profile of human samples.

Breastfeeding is the best way to feed an infant, although it can also be a source of abiotic contaminants such as heavy metals or bisphenol A (BPA). The early life exposure to these compounds can lead to serious toxic effects in both the short and long-term. These substances can reach breast milk through the mother’s habits, diet being one of the main routes of exposure. The aim of the present work was to analyse possible associations between the dietary habits of women and the content of major trace elements, BPA, fatty acids and lipids, and the microbiological and immunological profiles of human milk. Possible associations between major trace elements and BPA and the lipid, microbiological and immunological profiles were also analysed. The results of this study support that the microbiological composition of human milk is associated with the dietary habits of the women, and that the consumption of canned drinks is related to the presence of BPA in human milk. Furthermore, some relationships were found between the amount of major trace elements and the microbiological and immunological profile of the milk samples. Finally, the presence of BPA was associated with changes in the immunological profile of human milk.