In the intensive care nursery at Duke University Medical Center, doctors and nurses attend to premature infants in rows of incubators surrounded by ventilators and monitors. As new parents holding packages of breast milk watch their tiny babies, neonatologist Susan LaTuga makes her rounds, checking vital signs and evaluating how the infants tolerate feeding. She consults with nurses, dietitians, and pharmacists about the course of the day’s treatment for the babies, some of whom weigh as little as one pound and were born as much as 17 weeks early.
At the end of her shift, LaTuga stops at a freezer and inspects stool samples from some of the infants that are at the center of a remarkable new study. Across the Duke campus, technicians are waiting to analyze them with a powerful gene sequencer capable of penetrating the hidden world of the billions of microorganisms growing inside each infant.
LaTuga is one of several medical researchers at Duke working with microbial ecologists to study the development of the human microbiome—the enormous population of microbes, including bacteria, fungi, and viruses, that live in the human body, predominantly in the gut. There are 20 times as many of these microbes as there are cells in the body, up to 200 trillion in an adult, and each of us hosts at least 1,000 different species. Seen through the prism of the microbiome, a person is not so much an individual human body as a superorganism made up of diverse ecosystems, each teeming with microscopic creatures that are essential to our well-being. “Our hope is that if we can understand the normal microbial communities of healthy babies, then we can manipulate unhealthy ones,” LaTuga says.
The Duke study is just one of many projects begun in the past five years that use genetic sequencing to explore how the diversity of the microbiome impacts our health. Two of the largest efforts are the Human Microbiome Project, funded by the National Institutes of Health (See “Your Microbial Menagerie,” page 4), and the European Union’s Metagenomics of the Human Intestinal Tract. Although these groups have only just begun to publish their findings, it is already clear that the microbiome is much more complex and very likely more critical to human health than anyone suspected. Understanding and controlling the diversity of our germs, as opposed to assaulting them with antibiotics, could be the key to a range of future medical treatments.
In-depth analysis of the human body’s microflora has been possible only in the past few years—a by-product of the same new gene sequencing techniques that have allowed scientists to cheaply and accurately identify the DNA of the human genome. “Gene sequencing has opened a huge door to how complex these communities are,” says Patrick Seed, a Duke pediatrician specializing in infectious disease, who with biologist Rob Jackson is a lead investigator of the premature infant study.
