A mouse model designed to mimic therapeutic antibiotic use in human children shows that commonly used antibiotics can alter the development of mouse pups, reports a paper published in Nature Communications. Early-life antibiotic use temporarily accelerated total body mass and bone growth in the young mice, and caused long-term changes in gut microbiome diversity and population structure.

Antibiotic use in the United States is highest in children under 10 who, collectively, receive more than 40 million courses per year. Previous research has looked at how low-level, continuous dosage affects animals; however, as humans usually receive 10- to 100-fold higher antibiotic exposures for short courses to treat acute infections, the relevance of these studies to human antibiotic use is unclear.

To better understand how human antibiotic use may affect microbiota and development, Martin Blaser and colleagues developed a mouse model that mimics early-life therapeutic-dose antibiotic treatment. They administered amoxicillin and tylosin to the mice as these antibiotic classes are the most commonly prescribed to children. They find that treatment early in life leads to short-term increases in body weight and bone growth in the mice. Longer-term changes, which remained for months after antibiotic exposure, were observed in gut microbiome diversity and composition. These effects were dependent on the number of courses and class of antibiotic. Although it is unclear if the effects on bone growth and body mass are to do with microbiota, these findings indicate a need to re-examine antibiotic guidelines and risks in the human population.