In The Field

ESA 2009: Sweater by grandma; gut flora by mom

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A session this morning took on one intimate intersection between ecology and medicine. As Brendan Bohannan put it, “Some of the most exciting and interesting communities to study have been right under our noses all this time. In fact, they have been in our noses, and our guts, and the rest of our bodies.”

The microbes of the human biology form diverse communities, and each is a miniature ecosystem, presumably following all the same basic rules as the large ecosystems outside our windows. These communities do much more than merely hitch a ride. They help train human immune systems, help suck nutrients out of food, and so on.

For example, babies usually get their first gut microbes from the vaginal canal, as they are born. Babies born via Cesarean section bypass the canal, and tend to have predictably different communities of gut microbes until they are seven years old. According to Deborah Wohl, there is some research to suggest that Cesarean babies as a consequence have slightly higher rates of immune-related conditions such as asthma, eczema and allergies.

One fascinating talk was about catheter infections, which are apparently very common in hospitals. The general idea about them is that the urethra is more or less sterile, so the infection must proceed when microbes climb up the inside of the catheter tube and reach the bladder, where they then cause harm. But in a small pilot study, Betsy Foxman and her colleagues found evidence to suggest that microbial communities on the inside of catheter were stable over time, whereas communities on the outside of the tube—the surface touching the urethra tissue—shifted from day to day. She suggests that infection may result from disturbances in the regular microbial community inside the urethra.

And other conditions, including inflammatory colitis, periodontal disease, and bacterial vaginosis may not be the result of one bad pathogen coming from the outside, but disturbances in the normal microbial communities of the colon, mouth and vagina. Future treatment may look more like ecological restoration than the blunt instrument of antibiotics.

So is the medical establishment ready for ecological medicine? The panel was hopeful. Patrick Seed, an infectious disease specialist, said “One might argue that really the future is going to be restoring ecology with things like anti-virulence drugs. But even with that precise knife, if you take out a member of the community, my guess it that you will affect the community very broadly. We need to feed the good bacteria—keystone or cornerstone organisms that bring about a healthy ecology.”

See also: Why your teeth are like tropical islands.

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