Exposure to antibiotics in early childhood linked to later development of asthma and allergies

Early exposure to antibiotics kills healthy bacteria in the digestive tract and can cause asthma and allergies, a new study shows.

The study, published in Mucosal Immunology, has provided the strongest evidence yet that the long-observed connection between antibiotic exposure in early childhood and the later development of asthma and allergies is causal.

The practical implication is simple: avoid the use of antibiotics in young children whenever possible because it can increase the risk of significant long-term problems with allergy and/or asthma.”

Martin Blaser, lead author, director of the Center for Biotechnology and Advanced Medicine at Rutgers

In the study, the researchers, who came from Rutgers, New York University and the University of Zurich, noted that antibiotics, “among the most commonly used medications in children, affect gut microbiome communities and metabolic functions. These changes in the structure of the microbiota can affect the host.” immunity”.

In the first part of the experiment, five-day-old mice were given water, azithromycin or amoxicillin. After the mice matured, the researchers exposed them to a common allergen derived from house dust mites. Mice that had received either antibiotic, especially azithromycin, showed elevated rates of immune responses -; i.e. allergies.

The second and third parts of the experiment tested the hypothesis that early exposure to antibiotics (but not later exposure) causes allergies and asthma by killing some healthy gut bacteria that support proper immune system development .

Lead author Timothy Borbet first transferred bacteria-rich fecal samples from the first set of mice to a second set of adult mice with no prior exposure to any bacteria or germs. Some received samples from mice that received azithromycin or amoxicillin during childhood. Others received normal samples from mice that had received water.

Mice given antibiotic-altered samples were no more likely than other mice to develop immune responses to house dust mites, just as people who receive antibiotics in adulthood are no more likely to develop asthma or allergies than those who do not.

Things were different, however, for the next generation. Offspring of mice that received antibiotic-altered samples reacted more to house dust mites than those whose parents received antibiotic-unaltered samples, as did mice that originally received antibiotics as infants. they reacted more to the allergen than those who received water.

“This was a carefully controlled experiment,” Blaser said. “The only variable in the first part was antibiotic exposure. The only variable in the second two parts was whether the mix of gut bacteria had been affected by the antibiotics. Everything else in the mice was identical.

Blaser added that “these experiments provide strong evidence that antibiotics cause unwanted immune responses to develop through their effect on gut bacteria, but only if the gut bacteria are altered in early childhood.”


Journal reference:

Borbet, TC, et al. (2022) Influence of early gut microbiota on immune responses to an inhaled allergen. Immunology of the mucosa. doi.org/10.1038/s41385-022-00544-5.

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