July 24 (UPI) -- The increased risk of type 1 diabetes has been associated with one course of antibiotics in childhood, according to a study with mice.
Previously, researchers at New York University School of Medicine had found that exposure to multiple courses of antibiotics accelerated the disease's onset. But their current findings, which were published Tuesday in eLife, found one single course significantly boosted the risk and severity.
"Our findings confirm earlier work showing that antibiotics can increase risk for type 1 diabetes," lead study author Dr. Xuesong Zhang, an assistant professor of medicine at NYU School of Medicine, said in a press release. "Even a single early-life course may perturb the intestinal microbiome in ways that lead to long-term consequences in the intestinal wall, including immune cell changes and damage to the pancreas."
The number of people with type 1 diabetes has doubled in recent decades as children's exposure to antibiotics has increased, the researchers said. On average, children receive three courses in their first two years of life.
The study examined the intestinal microbiome, which is the mix of bacterial species that live in the digestive tract.
In type 1 diabetes, immune cells that normally control invading microbes instead destroy insulin-producing cells in the pancreas. The pancreas then produces little or no insulin, which is a hormone that controls the level of sugar in the blood.
Researchers analyzed millions of pieces of bacterial DNA in samples taken from the study mice by using genomic and statistical techniques. In pasty studies, key DNA sequences were matched to known bacterial species.
In the new study, they were able to define each mouse's microbiome and watch the effect of antibiotics on each one.
Four bacterial species groups -- Enterococcus, Blautia, Enterobacteriaceae and Akkermansia -- were significantly more abundant in the guts of mice treated with the single course of antibiotics.
Although they normally are harmless, species called pathobionts cause disease when environmental factors like antibiotics alter the normal balance.
Also, four different groups -- S24-7, Clostridiales, Oscillospira and Ruminococcus -- were significantly smaller in mice treated with antibiotic compared with normal mice during the developmental postbirth time window.
Because they may be protective against type 1 diabetes, researchers said they could be a focus of future development of probiotics to restore healthy species in newborns.
The results "are a model of the pervasive effects that antibiotic courses may have on children, causing immune systems to develop abnormally on the way to serious illness," said senior study investigator Dr. Martin J. Blaser, director of the Human Microbiome Program at NYU School of Medicine.