Antibiotics cause changes in gastrointestinal tract microbes and alter immune system responses, making people more sensitive to common allergens, says a University of Michigan Health System study.
The findings with laboratory mice may help explain the growing number of people with asthma, allergies and inflammatory diseases.

“We all have a unique microbial fingerprint - a specific mix of bacteria and fungi living in our stomach and intestines,” researcher Gary B. Huffnagle, an associate professor of internal medicine and of microbiology and immunology, said in a prepared statement.

“Antibiotics knock out bacteria in the gut, allowing fungi to take over temporarily until the bacteria grow back after the antibiotics are stopped. Our research indicates that altering intestinal microflora this way can lead to changes in the entire immune system, which may produce symptoms elsewhere in the body,” Huffnagle said.

If confirmed in human studies, these findings could help clarify why rates of asthma, allergies and other chronic inflammatory diseases have greatly increased over the past 40 years, when there’s been widespread use of antibiotics, Huffnagle said.

The study was to be presented May 26 at the American Society for Microbiology meeting in New Orleans.