Assessment of the bacterial diversity of breast milk of healthy women by quantitative real-time PCR

Breast milk has been described as a source of bacteria influencing the development of the infant gut microbiota. Up to the present, few studies have been focused on the application of culture-independent techniques to study bacterial diversity in breast milk. In this context, the aim of this study was to characterize the breast milk microbiota of healthy women by applying the quantitative real-time PCR technique (qRTi-PCR). A total of 50 breast milk samples were analysed by qPCR to assess the presence of different bacterial genera or clusters, including the Bifidobacterium, Lactobacillus, Staphylococcus, Bacteroides, Enterococcus, Streptococcus, Clostridium cluster IV and Clostridium cluster XIVa-XIVb groups. Staphylococcus, Streptococcus, Bifidobacterium and Lactobacillus were the predominant groups and were detected in all the samples. Clostridium XIVa-XIVb and Enterococcus were detected in most of the samples in contrast to the Bacteroides and Clostridium cluster IV groups. Our results confirm the abundance of bacterial DNA in breast milk samples and suggest that the qRTi-PCR technique has a huge potential in the microbiological analysis of human milk. qRTi-PCR allowed the detection of bacterial DNA of streptococci, staphylococci, lactic acid bacteria and bifidobacteria in the samples of human milk, which confirms that breast milk can be an important source of bacteria and bacterial DNA to the infant gut.