Antibiotics and asthma

By Siouxsie Wiles 19/03/2012

Administering antibiotics in infancy leads to enhanced susceptibility to asthma

At least in mice. Brett Finlay and colleagues, at the University of British Columbia, report in the journal EMBO Reports that treating baby mice with the antibiotic vancomycin not only changed the types of bacteria found in the gut, but was also associated with an increased susceptibility to asthma.

The researchers added one of two different antibiotics, streptomycin and vancomycin, into the animals drinking water. One group of mice were exposed to the antibiotic from during pregnancy (so potentially in the womb) while the other group weren’t exposed till they were 7 weeks old (teenagers by mouse standards). After exposure, the researchers used an experimental asthma model in which animals are sensitised to the protein ovalbumin* (OVA) by giving them two injections into the peritoneal cavity (the space around their abdominal organs). They are then exposed to OVA again a few weeks later by getting them to breathe it in. By measuring the number of immune cells in the lungs, the researchers are able to measure the degree of allergic response AKA asthma.

The bottom line? Nothing much happened to mice fed on streptomycin, while baby but not adult mice fed on vancomycin had a reduced diversity of bacteria in their guts, a reduction in a subset of key regulatory immune cells and increased inflammatory cells in their lungs after exposure to OVA. The researchers therefore propose that vancomycin administered early in life selects for a community of microbes that disrupt the balance of proinflammatory and regulatory immune responses and that this can lead to syndromes like asthma.

Yet another reason to avoid antibiotics unless they are really needed!

* The main protein found in egg white.