Antibiotics overuse may alter children's development

Repeated use of common antibiotics may have a significant effect on a child's development and cause side effects such as weight gain and growth of larger bones, a new study in mice has warned.
In the study, female mice treated with two classes of widely used childhood antibiotics gained more weight and developed larger bones than untreated mice.
Both of the antibiotics also disrupted the gut microbiome, the trillions of microbes that inhabit the intestinal tract, researchers found.
Overall, the mice received three short courses of amoxicillin (a broad-spectrum antibiotic), tylosin (which isn't 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 paediatric 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.
Martin Blaser, director of the New York University Human Microbiome Programme, and the study's senior author, said the results agree with multiple other studies pointing towards significant effects on children exposed to antibiotics early in life.

He noted that the cumulative data could help shape guidelines governing the duration and type of paediatric prescriptions.
"We have been using antibiotics as if there was no biological cost," said Blaser.

The study supports previous research by Blaser's group suggesting that antibiotic exposure during a critical window of early development disrupts the bacterial landscape of the gut and permanently reprogrammes 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.
Based on extensive DNA sequencing data, the study showed that both antibiotics also disrupted the gut microbiome.
"They changed the ecology of the microbiome in terms of the richness of the organisms, the diversity, and also what we call the community structure, or the nature of its composition," Blaser said.

Tylosin, the researchers found, had a much bigger impact on the maturity of the microbiome compared with amoxicillin.
"We also see that the effect is cumulative," said lead coauthor Laura M Cox, an adjunct instructor in the Department of Medicine at NYU School of Medicine.
"So the number of courses of antibiotics matters," she said.
The study was published in the journal Nature Communications.