Two recent studies provided information on the transmission of bacteria from mother to newborn.
The first one, from Milani et al., found with PCR analysis of the mother’s stool and milk samples and of the infant’s stool samples, that a Bifidobacterium breve and Bifidobacterium longum subsp. longum strain were transmitted from mother to child, and were persistent in the child’s gut 6 months later.
The second study, from Dotterud et al., used 16S ribosomal RNA in a randomized controlled trial to confirm that probiotic strains given in milk to pregnant women from 36 weeks of gestation to 3 months postnatally (while breastfeeding) were present in the mother’s own stool. One of the probiotic strains was recovered in the stool of the children at 10 days and 3 months of age, but there were no differences between the gut microbiota of the children in the control group and those in the probiotic group at 1 and 2 years of age. The authors concluded that there was no long-term vertical transmission of the probiotic strains.
Milani C, Mancabelli L, Lugli GA, Duranti S, Turroni F, Ferrario C, Mangifesta M, Viappiani A, Ferretti P, Gorfer V, Tett A, Segata N, van Sinderen D, & Ventura M. Exploring vertical transmission of bifidobacteria from mother to child. Appl Environ Microbiol. 2015 Jul 31. pii: AEM.02037-15. [Epub ahead of print]
Dotterud CK, Avershina E, Sekelja M, Simpson MR, Rudi K, Storrø O, Johnsen R, & Øien T. Does Maternal Perinatal Probiotic Supplementation Alter the Intestinal Microbiota of Mother and Child? J Pediatr Gastroenterol Nutr. 2015 Aug;61(2):200-7. doi: 10.1097/MPG.0000000000000781.