The study, published today in the journal EMBO reports, found that two widely-used antibiotics alter the bacterial ecosystem in the intestines of mice, and that in turn can result not only in more cases of asthma, but more severe cases as well.
The researchers say the same antibiotics — streptomycin and vancomycin — didn't lead to more asthma in adult mice, indicating that early life is a critical period for establishing a healthy immune system.
The report's author, microbiologist Brett Finlay, says the use of antibiotics and modern sanitation methods are hindering the development of intestinal bacteria that may be critical to an effective immune system.
He says asthma cases have not increased significantly in developing countries where antibiotics aren't used as much, thus allowing the normal development of intestinal bacteria.
Asthma cases around the world are increasing about 50 per cent every decade, mostly among children in industrialized countries, and the Asthma Society of Canada says about 12 per cent of children in Canada suffer from the condition.