Friday, October 9, 2009

Preemies' Intestinal Microorganisms Surprising

A research pediatrician and an ecologist are joining forces at Duke to improve the prospects for very premature infants by exploring which bacteria first colonize their intestines.

"We hope this will allow us to ask if there are organisms that, when acquired early, provide early warning or reduce the risk of serious disease," said Patrick Seed, an assistant professor of pediatrics, molecular genetics and microbiology at the Duke Medical Center.

"We're examining which microbes are there, what's their relative abundance and how quickly do pathogenic organisms appear," added Robert Jackson, a Biology and Nicholas School of the Environment professor of biology and global climatic change. He provided Seed with DNA detection tools originally developed to identify which species of microorganisms live in soil samples.

While all babies are thought to be sterile in the womb, they are immediately exposed to their mother's microbes during delivery and through nursing as well as via tender loving handling by relatives, Seed said.

As a result, by the time researchers can assess them, these recent arrivals already have thriving microbial mixtures living in their intestines.

"Living with microbes is a fundamental part of the human experience," Seed said. The growing microbe collections are generally user-friendly species needed for digestion. But bad actors can quickly be acquired in some cases, sometimes causing problems such as diarrhea.

By contrast, the tiny very premature infants arriving months too early are immediately isolated and treated with antibiotics to ward off infections. Even nursing is delayed. Instead, they are initially nourished through a catheter. Thus protected, preemies should enter the world as blank slates for microbes.

So Seed is applying Jackson's molecular toolkit on preemies' stool samples to establish which bacterial varieties are first taking up residence in their immature intestines. As a result, perhaps treating physicians would better know which problem species to anticipate. "Or perhaps we can identify which kinds of organisms could form cornerstones for healthy bacterial communities," Seed said.

So far, Seed has surveyed 11 infants, two of those in great detail, several weeks after their premature deliveries and after they were taken off antibiotics. While Jackson's DNA tests are revealing some diversity in bacterial populations, each baby's gut seems to be harboring the same "predominant organisms," according to Seed.

"I'm just surprised that the infants' immature systems wouldn't give more organisms a chance to move in, he said. "However, this also seems like a real opportunity. We may have more of a chance in the future to help babies develop 'healthy' groups of microbes that promote growth and development while keeping the particularly dangerous players out," Seed said.

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