A recent study demonstrates that early exposure to antibiotics destroys beneficial bacteria in the digestive system and can cause asthma and allergies.
The research, which was published in the journal Mucosal Immunology, has offered the strongest evidence to date that the long-recognized link between early antibiotic exposure and the later onset of asthma and allergies is causative.
“The practical implication is simple: Avoid antibiotic use in young children whenever you can because it may elevate the risk of significant, long-term problems with allergy and/or asthma,” said senior author Martin Blaser, director of the Center for Advanced Biotechnology and Medicine at Rutgers.
The study’s authors, from Rutgers University, New York University, and the University of Zurich, stated that antibiotics, “among the most used medications in children, affect gut microbiome communities and metabolic functions. These changes in microbiota structure can impact host immunity.”
Five-day-old mice were given water, azithromycin, or amoxicillin in the first stage of the experiment. After the mice reached adulthood, scientists exposed them to a common allergen produced by house dust mites. Mice that had taken either antibiotic, particularly azithromycin, had heightened immunological responses — i.e., allergies.
The second and third stages of the experiment tested the hypothesis that certain healthy gut bacteria that are critical for proper immune system development are killed by early exposure to antibiotics (but not later exposure), which results in allergies and asthma.
Timothy Borbet, the lead author, initially transferred fecal samples rich in bacteria from the first group of mice to a second group of adult mice with no previous exposure to any bacteria or germs. Some received samples from mice given azithromycin or amoxicillin in infancy. Others received normal samples from mice that had received water.
Mice that received 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 don’t.
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 samples unaltered by antibiotics, just as mice that originally received antibiotics as babies reacted more to the allergen than those that received water.
“This was a carefully controlled experiment,” said Blaser. “The only variable in the first part was antibiotic exposure. The only variable in the second two parts was whether the mixture of gut bacteria had been affected by antibiotics. Everything else about the mice was identical.
Blaser added that “these experiments provide strong evidence that antibiotics cause unwanted immune responses to develop via their effect on gut bacteria, but only if gut bacteria are altered in early childhood.”
Sci Tech Daily, 15 September 2022