http://www.nytimes.com/2012/06/19/scien ... wanted=all
Early in the first trimester of pregnancy, she found, the diversity of vaginal bacteria changes significantly. Abundant species become rare, and vice versa.
One of the dominant species in the vagina of a pregnant woman, it turns out, is Lactobacillus johnsonii. It is usually found in the gut, where it produces enzymes that digest milk. It’s an odd species to find proliferating in the vagina, to say the least. Dr. Aagaard-Tillery speculates that changing conditions in the vagina encourage the bacteria to grow. During delivery, a baby will be coated by Lactobacillus johnsonii and ingest some of it. Dr. Aagaard-Tillery suggests that this inoculation prepares the infant to digest breast milk.
The scientists reared mice that lacked any microbiome. In their guts and lungs, the germ-free mice developed abnormally high levels of immune cells called invariant natural killer T cells. Normally, these cells trigger a swift response from the immune system against viruses and other pathogens. In Dr. Blumberg’s microbe-free mice, however, they caused harmful inflammation. As adults, the mice were more likely to suffer from asthma and inflammatory bowel disease.
This experiment parallels studies of children in recent years. Children who take high levels of antibiotics may be at greater risk of developing allergies and asthma later on, many researchers have suggested.
Dr. Blumberg and his colleagues found that they could prevent the mice from becoming ill by giving them bacteria while they were still young. Acquiring a microbiome as an adult did not help the rodents.
I wonder if giving bacteria at age 5 can still affect the microbiome?