Too Many Childhood Antibiotics Affects Bone Growth

Researchers from New York University’s Langone Medical Center have further evidence that multiple courses of antibiotics in childhood may significantly impact bone development. The study was led by Martin Blaser, M.D., the Muriel G. and George W. Singer Professor of Translational Medicine, director of the NYU Human Microbiome Program at NYU School of Medicine.

According to the June 30, 2015 news release, female mice that were administered two classes of childhood antibiotics gained more weight and developed larger bones than untreated mice. Both of the antibiotics also disrupted the gut microbiome.

“The mice received three short courses of amoxicillin, tylosin (not used in children but represents another common antibiotic class called the macrolides, which is increasingly popular in pediatrics), or a mixture of both drugs. To mimic the effects of pediatric antibiotic use, the researchers gave the animals the same number of prescriptions and the same therapeutic dose that the average child receives in the first two years of life. A control group of mice received no drugs at all.”

Although Dr. Blaser cautioned that the study was limited to mice, he said that it’s important to note that the results are in line with results from multiple other studies pointing toward significant effects on children exposed to antibiotics early in life. “We have been using antibiotics as if there was no biological cost.”

The study supports Dr. Blaser’s prior work showing that “antibiotic exposure during a critical window of early development disrupts the bacterial landscape of the gut and permanently reprograms the body’s metabolism, setting up a predisposition for obesity. The new study found that short, high-dose pulses of tylosin had the most pronounced and long-lasting effect on weight gain, while amoxicillin had the biggest effect on bone growth—a prerequisite for increased height.”

The research team found that tylosin had a larger impact on the maturity of the microbiome compared with amoxicillin. “We also see that the effect is cumulative, ” said lead co-author Laura M. Cox, Ph.D., an adjunct instructor in the Department of Medicine at NYU School of Medicine. “So the number of courses of antibiotics matters.”

Dr. Blaser told OTW, “This was the third study that we have conducted in mice comparing receipt of early life antibiotics or not. In all three studies, we have seen evidence for accelerated bone growth. So there was no surprise from this study, but rather consistency with the other study results, regardless of variation in study protocol.”

“These studies provide evidence that such issues as bone maturation and length are not fixed in early childhood, but that microbes are playing a role in choreographing development. This may lead to new approaches to issues on the quantity, quality and location of new bone growth in infants.”