The Composition of Human Milk and Infant Faecal Microbiota Over the First Three Months of Life: A Pilot Study

Kiera Murphy,Catherine Stanton,Carol-Anne O’Shea,Eugene M Dempsey,David Curley,R Paul Ross,C Anthony Ryan,Tom F O’Callaghan,Paul W O’Toole

doi:10.1038/srep40597

Abstract

Human milk contains a diverse array of bioactives and is also a source of bacteria for the developing infant gut. The aim of this study was to characterize the bacterial communities in human milk and infant faeces over the first 3 months of life, in 10 mother-infant pairs. The presence of viable Bifidobacterium and Lactobacillus in human milk was also evaluated. MiSeq sequencing revealed a large diversity of the human milk microbiota, identifying over 207 bacterial genera in milk samples. The phyla Proteobacteria and Firmicutes and the genera Pseudomonas, Staphylococcus and Streptococcus were the predominant bacterial groups. A core of 12 genera represented 81% of the microbiota relative abundance in milk samples at week 1, 3 and 6, decreasing to 73% at week 12. Genera shared between infant faeces and human milk samples accounted for 70–88% of the total relative abundance in infant faecal samples, supporting the hypothesis of vertical transfer of bacteria from milk to the infant gut. In addition, identical strains of Bifidobacterium breve and Lactobacillus plantarum were isolated from the milk and faeces of one mother-infant pair. Vertical transfer of bacteria via breastfeeding may contribute to the initial establishment of the microbiota in the developing infant intestine.

Highlights

Microbial colonisation of the neonatal gut exerts a major effect on host health status[1,2]
Reads were classified into 1313 observed operational taxonomic units (OTUs) for human milk and 264 OTUs for infant faeces at a 3% similarity cut-off
Differences have been reported in the microbiota composition of breast-fed infants versus formula-fed with the former suffering from less allergies and gastrointestinal infections[3,4]

Summary

Introduction

Microbial colonisation of the neonatal gut exerts a major effect on host health status[1,2]. It has been reported that human milk is in itself a source of commensal bacteria that may colonise the infant gut. The maternal gut has been suggested as a source, with bacteria entering the mammary glands via the entero-mammary pathway, a route that involves phagocytic dendritic cells penetrating the gut epithelium and trafficking bacteria through the circulatory system[17,18,19]. This is important since manipulation of the maternal microbiota could be used to promote an optimal human milk microbiome

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