Sound and timely microbial gut colonization completes newborn’s healthy metabolic programming and manifests in infant appropriate growth and weight development. Feces, collected at 3, 30, and 90 days after birth from 60 breastfed Slovenian newborns, was submitted to microbial DNA extraction and qPCR quantification of selected gut associated taxa. Multivariate regression analysis was applied to evaluate microbial dynamics with respect to infant demographic, environmental, clinical characteristics and first year growth data. Early microbial variability was marked by the proportion of Bacilli, but diminished and converged in later samples, as bifidobacteria started to prevail. The first month proportions of enterococci were associated with maternity hospital locality and supplementation of breastfeeding with formulae, while Enterococcus faecalis proportion reflected the mode of delivery. Group Bacteroides-Prevotella proportion was associated with infant weight and ponderal index at first month. Infant mixed feeding pattern and health issues within the first month revealed the most profound and extended microbial perturbations. Our findings raise concerns over the ability of the early feeding supplementation to emulate and support the gut microbiota in a way similar to the exclusively breastfed infants. Additionally, practicing supplementation beyond the first month also manifested in higher first year weight and weight gain Z-score.

Microbial communities inhabiting the breast milk microenvironment are essential in supporting mammary gland health in lactating women and in providing gut-colonizing bacterial 'inoculum' for their infants’ gastro-intestinal development. Bacterial DNA was extracted from colostrum samples of 45 healthy Slovenian mothers. Characteristics of the communities in the samples were assessed by polymerase chain reaction (PCR) coupled with denaturing gradient gel electrophoresis (DGGE) and by quantitative real-time PCR (qPCR). PCR screening for the prevalence of bacteriocin genes was performed on DNA of culturable and total colostrum bacteria. DGGE profiling revealed the presence of Staphylococcus and Gemella in most of the samples and exposed 4 clusters based on the abundance of 3 bands: Staphylococcus epidermidis/Gemella, Streptococcus oralis/pneumonia and Streptococcus salivarius. Bacilli represented the largest proportion of the communities. High prevalence in samples at relatively low quantities was confirmed by qPCR for enterobacteria (100%), Clostridia (95.6%), Bacteroides-Prevotella group (62.2%) and bifidobacteria (53.3%). Bacterial quantities (genome equivalents ml^-1) varied greatly among the samples; Staphylococcus epidermidis and staphylococci varied in the range of 4 logs, streptococci and all bacteria varied in the range of 2 logs, and other researched groups varied in the range of 1 log. The quantity of most bacterial groups was correlated with the amount of all bacteria. The majority of the genus Staphylococcus was represented by the species Staphylococcus epidermidis (on average 61%), and their abundances were linearly correlated. Determinants of salivaricin A, salivaricin B, streptin and cytolysin were found in single samples. This work provides knowledge on the colostrum microbial community composition of healthy lactating Slovenian mothers and reports bacteriocin gene prevalence.

Commentary: Relationship between Milk Microbiota, Bacterial Load, Macronutrients, and Human Cells during Lactation

Background/Objectives: Diaper dermatitis (DD) is a common dermatological condition that is often exacerbated by antibiotics. Probiotics may restore microbiota balance and influence the incidence of DD. This study aimed to evaluate whether 6 weeks of Limosilactobacillus (L.) reuteri DSM 17938 supplementation during and after antibiotic treatment affects the incidence of DD. Methods: A secondary analysis of a randomised, double-blind, placebo-controlled trial that included 89 term neonates treated with antibiotics during the first 3 weeks of life was conducted. Neonates were assigned to receive either a probiotic supplement or a placebo for a total of 6 weeks. DD incidence, onset of DD, and skin care data were collected for 87 infants. Faecal samples were collected 6 weeks after study enrolment to analyse the composition of gut microbiota. Results: Twenty-four (28%) infants developed DD, of whom six (25%) had fungal DD. There was no significant difference in the incidence of DD or fungal DD between the probiotic and placebo groups (30% vs. 25% and 7% in both groups, respectively). Probiotic supplementation had no significant effect on the gut microbiota composition or diversity. In an exploratory binary logistic regression analysis based on six fungal DD events, probiotic supplementation was not associated with fungal DD, whereas breastfeeding was associated with lower odds of fungal DD; however, the overall model was not statistically significant, and this finding should be interpreted with caution because of the small number of events. Conclusions: In this exploratory secondary analysis, supplementation with L. reuteri DSM 17938 was not associated with a reduced incidence of DD or alterations in gut microbiota composition in antibiotic-treated neonates. Breastfeeding was associated with lower odds of fungal DD; however, this finding should be confirmed in larger, adequately powered studies.