The Body as Bacterial Landlord

Robert Lee Hotz has written an extremely fascinating look at our bacterial over-lords. If I wasn’t so busy, I’d love to create a treatment of this concept for a possible sci-fi thriller. Or something. Too interesting not to research further.

When scientists discovered that bacteria, not stress, caused most stomach ulcers, the insight overturned a century of medical dogma, transformed clinical practice and garnered a 2005 Nobel Prize for the two researchers who made the connection so many others had missed. After people adopted antibiotics to treat gastric distress, though, microbiologist Martin Blaser and his colleagues at New York University began to document an odd medical trend.

Ulcers did drop dramatically, as expected. So did the incidence of stomach cancer. As the bacteria, called Helicobacter pylori, virtually disappeared among children, however, cases of asthma tripled. So did rates of hay fever and allergies, such as eczema. Among adults, gastric reflux disease became more common, as did some forms of esophageal cancer, researchers noted.

To Dr. Blaser’s way of thinking, antibiotics and other sanitation measures are eliminating the harm these bacteria cause at the expense of the protection they provide us.

The human body teems with so many microbes that they outnumber our own cells ten to one. Vast schools of bacteria are in us and around us, like fish nuzzling a coral reef. “They are not simply along for the ride,” says Stanford University microbiologist David Relman. “They are interacting with us.”

Yet almost all of them are still unknown to science, since most cannot be grown and studied in the laboratory. In ways mysterious to medicine, this microbial menagerie of fellow travelers in and on us is controlling our health, affecting obesity, cancer and heart disease, among others.

[From The Body as Bacterial Landlord –]

Our constant interference with the body through use of anti-biotics has real consequences:

…As many as 500 species of bacteria may inhabit our guts, like H.pylori. Maybe 500 or so other species make themselves at home in our mouth, where each tooth has its own unique bacterial colony, Dr. Relman recently determined. No one knows how many species we contain in all. This past August, researchers at Kings College London identified yet another new species of oral bacteria between the tongue and cheek.

Until recently, half of humanity harbored these H. pylori stomach bacteria, according to a 2002 study in the New England Journal of Medicine. Indeed, we appear to have evolved together. Among those born in the U.S. during the 1990s, however, only 5% or so still carry these microbes, largely due to the indiscriminate use of antibiotics.

After analyzing health records of 7,412 people collected by the National Center for Health Statistics, Dr. Blaser and NYU epidemiologist Yu Chen reported this summer in the Journal of Infectious Diseases that children between three and 13 years old who tested positive for H. pylori bacteria were 59% less likely to have asthma. They also were 40% to 60% less likely to have hay fever or rashes.

Bacteria has evolved for billions of years, and is now an essential part of the human body

Last week, University of Chicago immunologist Alexander Chervonsky and his collaborators at Yale University reported that doses of the right stomach bacteria can stop the development of Type 1 diabetes in lab mice.

“By changing who is living in our guts, we can prevent Type 1 diabetes,” Dr. Chervonsky says.

Other bacteria are just as crucial to our well-being, feeding us the calories from food we can’t digest on our own, bolstering our immune systems, tending our skin and dosing us with vitamins, such as B-6 and B-12, which we are unable to synthesize unaided.

And there is work being done attempting to categorize the bacteria, and figure out what exactly each contributes to our body:

For the first time, researchers are attempting to identify and analyze the types of bacteria that live within us, in an effort that makes the Human Genome Project look like child’s play. Instead of sequencing the genes of one microbe at a time, researchers in a five-year, $125 million NIH effort called the Human Microbiome Project are analyzing entire communities of mixed bacteria at once, in a technique called metagenomics.

To start, researchers at the Baylor College of Medicine in Houston, the Washington University School of Medicine in St. Louis, the Broad Institute in Cambridge, Mass., and the J. Craig Venter Institute in Rockville, Md., are sequencing the genomes of 200 microbe species isolated from 250 healthy volunteers. They are sampling bacteria from the skin, gut, vagina, mouth and nose, then attempting to identify them by cataloging variations in a single gene sequence that all bacteria share.

If I was in school right now, this might be a very tempting field to enter.
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