Antibiotics can leave the lung vulnerable to flu viruses, leading to significantly worse infections and symptoms, according to a study. The research, published in the journal Cell Reports, discovered that signals from gut bacteria help to maintain a first line of defence in the lining of the lung. When mice with healthy gut bacteria were infected with the flu, around 80% of them survived. However, only a third survived if they were given antibiotics before being infected.

"We found that antibiotics can wipe out early flu resistance, adding further evidence that they should not be taken or prescribed lightly," Andreas Wack, who led the research at Francis Crick Institute in the UK. "Inappropriate use not only promotes antibiotic resistance and kills helpful gut bacteria, but may also leave us more vulnerable to viruses. This could be relevant not only in humans but also in livestock animals," Wack said.