Microbes may protect babies from infection

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Colonies of Clostridium difficile bacteria.
Credit: CDC/ Dr. Gilda Jones

From mood manipulation to yo-yo dieting, our intestinal flora has been shown to have a significant impact on the rest of our body. And now, a new study in mice has shown that particular gut bacteria can provide newborns with vital protection against infection.

In reseach published in Science, an international team of researchers found that a bacterium known as Clostridia helped mouse pups not only to digest food but to be protected from infection.

Mice born without Clostridia were vulnerable to invading bacteria, similar to those known to cause sickness in human babies, leading the researchers to suggest that the discovery could provide new insight into ways of protecting human infants from such illnesses.

“Newborns are very susceptible to infections in the first year of life,” says Gabriel Nunez from the University of Michigan, one of the authors of the study. “This work suggests that the lack of protective bacteria in the gut microbiota is a mechanism for that susceptibility.”

The research team began by breeding mice in a germ-free environment. This allowed them to track the changes to mouse health when those lacking natural gut bacteria obtained transplanted microbes from other mice.

Faecal samples taken from 4-day-old and 16-day-old mice were harvested and transplanted into germ-free mice. By infecting these mice with a strain of Salmonella, the researchers found that 50% of mice with the 4-day-old microbes perished, while all those transplanted with the 16-day old microbes lived.

Similar results were observed when the mice were exposed to Citrobacter rodentium – a bacteria similar to the E. coli that causes sickness in humans. Mice transplanted with the 16-day old microbe samples had higher survival rates than those that received the 4-day old microbes.

The researchers then transplanted microbes from newborn mice into germ-free mice, but added Clostridia bacteria into the mix.

They then exposed these mice to C. rodentium and found that only mice transplanted with added Clostridia were able to resist infection.

The team are now conducting further research to uncover the role of Clostridia in defending against infection, with human clinical trials a possibility if the bacterium’s protective potential bears fruit in further animal studies.

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