Our Symbiotic Selves

Heidi Nelson, M.D.

Heidi Nelson, M.D., is director of the Microbiome Program in the Center for Individualized Medicine.

Harnessing the power of our microbial companions

As much as we would like to think so, our body is not our own. We are covered in microbes.

They live on and even in us. In fact, for every human cell in our body, there are 10 microbial cells, covering our skin, informing our immune system and helping us turn food into nutrients.

These cells form their own microscopic communities, or microbiomes, which are ecosystems that live in symbiosis with our cells. Unfortunately, these ecosystems can fall out of balance when certain microbes grow out of control, causing illness and disease. For instance, one microbe in the intestine, Clostridium difficile, can cause dangerous colon inflammation, and even death, if it grows unchecked.

The standard protocol is to give antibiotics that kill broad populations of bacteria, including the ones making people sick. The Center for Individualized Medicine is finding better solutions in certain cases. To treat serious intestinal infections, Mayo Clinic researchers are exploring ways to harvest the healthy and balanced microbiome of a donor and use it to restore the microbiome in sick patients.

With benefactor support, researchers are sequencing the genetic code of the entire microbiome of 100 patients who have had Clostridium difficile infection. The researchers are comparing it with the microbiome of healthy people.

This will help determine whether an individual has a healthy community of intestinal bacteria or one that puts him or her at an increased risk of getting Clostridium difficile. This kind of information could help get the right treatment to the patient early and spare serious life-threatening complications.

"We have a dense population of bacteria in all parts of our body, with the largest majority being in our intestines and on our skin," says Heidi Nelson, M.D., the Fred C. Andersen Professor and director of the Center for Individualized Medicine's Microbiome Program. "Sequencing opens the door to a whole new horizon of understanding what bacteria are there and what they're doing there."

This knowledge will improve both diagnostic tests and treatment options. And it promises to lead to specific probiotics — delivered through pill or suppository — that will return a patient's microbiome to a healthy, vibrant state.