infants – Lacto Bacto

Breastfeeding
Credit: Wikimedia Commons/ Anton Nosik

It has long been known that breast milk contains hundreds of microbial species (the milk microbiome), which help seed the infant's gut microbiome. Over the weeks and months of breast feeding, the microbial species in the milk change. All this is normal and good.

A recent study of human breast milk examined the species in breast milk and found that that the species could be viewed as a microbial ecosystem - one that is important in helping seed the infant's gut. The milk contained species that are considered beneficial (e.g., Bifidobacterium), but also some that can be viewed as not beneficial (e.g., E.coli). The milk was from healthy mother-infant pairs, so it was clear that this variety was normal.

Researchers analyzed 507 breast milk and infant stool samples from 195 healthy mother-infant pairs at one, three, and six months postpartum. They found characteristic mixes of bacteria dominated by Bifidobacteria (especially B. longum, B. breve, and B. bifidum). More than half of the milk samples contained B. longum, and that same species was abundant in over 98% of the infants' gut microbiomes.

The paper mentioned that numerous times they found the exact same bacterial strain in both the mother and infant pairs - thus evidence that the mothers transmitted that bacteria to the babies in the breast milk (this is referred to as vertical transmission).

From Medical Xpress: Breast milk microbes help shape infants' gut microbiomes, study finds

Most conversations about breast milk tend to focus on topics like nutrients, antibodies and bonding time rather than bacteria. But it turns out that human milk carries its own tiny community of microbes, and those passengers may help shape a baby's developing gut microbiome—which in turn can impact nutrient absorption, metabolic regulation, immune system development, and more. ...continue reading "Breast Milk Transmits Important Bacteria to the Infant Gut Microbiome"

Yes, even healthy newborns have a diversity of viruses in the gut - this is their virome (community of viruses), and it undergoes changes over time. In fact, the entire infant microbiome (community of microbes) is highly dynamic and the composition of bacteria, viruses and bacteriophages changes with age. One interesting finding is that initially newborn babies have a lot of bacteriophages (viruses that infect bacteria), but that these decline over the first two years of age. From Medical Xpress:

Viruses flourish in guts of healthy babies

Bacteria aren't the only nonhuman invaders to colonize the gut shortly after a baby's birth. Viruses also set up house there, according to new research at Washington University School of Medicine in St. Louis. All together, these invisible residents are thought to play important roles in human health.The study, published online Sept. 14 in Nature Medicine, reports data from eight healthy infants and is one of the first surveys of viruses that reside in the intestine. The investigators analyzed stool samples to track how the babies' bacterial gut microbiomes and viromes changed over the first two years of life.

"We are just beginning to understand the interplay between all the different types of life within our gut," said senior author Lori R. Holtz, MD, assistant professor of pediatrics. "They are not stand-alone communities. We also are seeing that the environment of the infant gut is extremely dynamic, which differs from the relative stability that has been shown in adults."The earliest stool samples were taken at 1-4 days of life, and even at this early time point, Holtz noted, viruses were present. ...continue reading "Viruses Live in The Guts of Healthy Babies"