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 Immunologyprovided the strongest evidence to date that there is a long-observed causal connection between early childhood antibiotic exposure and the later development of asthma and allergies.
According to lead author Martin Blaser, director of the Rutgers Center for Biotechnology and Advanced Medicine, “The practical implication is simple: Avoid using antibiotics in children whenever possible, as it can increase the risk of significant long-term health problems. ”. allergies or asthma.
In the study, researchers from Rutgers University, New York University and the University of Zurich noted that antibiotics are among the most commonly used drugs in children, but they affect the populations and functions of the gut microbiota. These changes in the microbiota structure can affect immunity later on.
In the first part of the experiment, five-day-old mice were given water or the antibiotics azithromycin or amoxicillin. After the mice matured, the researchers exposed them to a common allergen derived from house dust mites. Mice that received one of the two antibiotics, especially azithromycin, had high rates of immune responses, i.e. allergies.
The second and third parts of the experiment tested the hypothesis that early (but not later) exposure to antibiotics causes allergies and asthma, killing some healthy gut bacteria that support proper immune system development.
The researchers first transferred bacteria-rich fecal samples from the first group of mice to a second group of adult mice without prior exposure to any bacteria or germs. Some received samples from mice given azithromycin or amoxicillin in childhood. Others received normal samples from mice that received only water.
“Antibiotics cause unwanted immune responses through their effect on gut bacteria, but only in early childhood”
The mice who received samples altered with antibiotics were not more likely than other mice to develop immune responses to domestic octopus mites, just as people who receive antibiotics in an adult age are not more likely to develop asthma or allergies than they they don’t.
However, things were different for the next generation. The pups of mice that received samples altered by antibiotics reacted more to house dust mites than those whose parents received samples not altered by antibiotics, just as mice that were originally given antibiotics as babies reacted more to the allergen than those that received samples that were altered by antibiotics. by antibiotics. they received water.
“This was a carefully controlled experiment,” says Blaser. “The only variable in the first part was exposure to antibiotics. The only variable in the next two parts was whether the mixture of gut bacteria was 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 through their effect on gut bacteria, but only if they are stopped in early childhood.”
REFERENCE
Influence of early life gut microbiota on immune responses to an inhaled allergen