Study: Most common antibiotic drug may cause permanent side effects in children

A recent study proves that early exposure to antibiotics destroys good bacteria in the digestive system and can lead to asthma and allergies. The study, published in the journal Mucosal Immunology, provides the strongest evidence to date that the long-established link between early antibiotic exposure and later asthma and allergy onset is causal. "The practical implications are simple," said senior author Martin Blaser, director of the Rutgers Center for Advanced Biotechnology and Medicine. "As long as you can avoid antibiotics in young children, it may increase the risk of major, long-term problems with allergies or asthma. According to the study authors, from Rutgers University, New York University and the University of Zurich, antibiotics are "one of the most used drugs in children, affecting gut microbial communities and metabolic function. These changes in microbiota structure can affect the host's immunity". In the first phase of the experiment, five-day-old mice were given water, azithromycin or amoxicillin. After the mice became adults, the scientists exposed them to a common allergen produced by house dust mites. Mice that had been given any kind of antibiotic, especially azithromycin, had an enhanced immune response -- an allergy. Phases two and three of the experiment tested the hypothesis that certain healthy gut bacteria that are essential for normal immune system development are killed by early (but not later) exposure to antibiotics, which can lead to allergies and asthma . Lead author Timothy Borbet initially transferred bacteria-rich fecal samples from the first group of mice to a second group of adult mice that had not been previously exposed to any bacteria or germs. Some have obtained samples from mice given azithromycin or amoxicillin in early childhood. Others obtained normal samples from mice that had received water. The researchers found that mice that received antibiotic-altered samples were no more likely than others to develop an immune response to house dust mites, just as those who received antibiotics as adults were no more likely to develop asthma or allergies than those who did not receive antibiotics. . For the next generation, however, things are different. The offspring of mice that received the antibiotic-altered sample had a greater response to house dust mites than those whose parents received samples that were not altered by the antibiotic, just as mice that initially received antibiotics in infancy were more responsive to house dust mites than mice that received water. Allergen reactions are much the same. "It 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 was affected by antibiotics. Everything else about the mice was the same." Blaser added: "These experiments provide strong Strong evidence that antibiotics cause unwanted immune responses through their effects on gut bacteria, but only when gut bacteria are altered in early childhood."