A natural bacterial inoculum in maternal milk

PÉREZ, P. F.; DORÉ, J.; LECLERC, M. ; LEVENEZ, F. ; BENYACOUB, J. ; SERRANT, P. ; SEGURA-ROGGERO, I. ; SCHIFFRIN, E. J. AND DONNET-HUGHES, A.

Barcelona

Congreso; 40th Annual Meeting of the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN); 2007

Aim: To study the presence and origin of a bacterial inoculum in maternal milk. Methods: The presence of viable bacteria in the milk and peripheral blood of healthy mothers was determined by plating. In addition, Temporal Temperature Gradient-Gel Electrophoresis (TTGE) was used to examine bacterial ribosomal DNA (rDNA) content in maternal peripheral blood mononuclear cells, milk cells and faeces as well as in the corresponding infant faeces. Blood from non-gravid, non-lactating women served as a control. Bacterial translocation to extraintestinal tissues was also evaluated in virgin, pregnant and lactating mice. Results: The total number of viable bacteria in breast milk was <103cfu/mL but maternal blood and milk cells contained the DNA of diverse enteric bacteria. Some bacterial DNA signatures were common to infant feces and to samples of maternal origin. Bacterial translocation to mesenteric lymph nodes and the mammary gland occurs during late pregnancy and early lactation in mice. Summary: Bacterial translocation is increased during pregnancy and lactation in mice. Human breast milk cells contain a low number of viable bacteria but a range of bacterial DNA that is also found in maternal blood cells. Conclusion: Our results suggest that during lactation, bacterial components are transported from the intestine to the lactating breast within host cells. The consequences of this trafficking for the mother and her baby are not known. We speculate that it educates the neonatal immune system to recognise specific molecular motifs of bacteria and to respond appropriately to pathogens and commensals.