Researchers also warned that the drugs’ effects on bacteria in the gut could make the disease more deadly.
Although the scientists’ research examined the results in mice, they stressed the principle could also apply to humans.
The team discovered that when bacteria living in a mouse’s gut detect a virus, they send out a chemical signal. This activates a defensive immune reaction in the lungs.
When mice with healthy gut bacteria were infected with the flu, about 80% of them survived. But only a third remained alive if they were given antibiotics before being infected. Dr Andreas Wack, from the Francis Crick Institute in London, which carried out the study, said: “Gut bacteria send a signal that prevents the virus from multiplying so quickly.
“It takes around two days for immune cells to mount a response in which time the virus is multiplying. Two days after infection, antibiotic-treated mice had five times more virus in their lungs. To face this bigger threat, the immune response is much stronger and more damaging, leading to more severe symptoms.”
He added: “Inappropriate use not only promotes antibiotic resistance and kills helpful gut bacteria, but may also leave us more vulnerable to viruses.” He called for further studies to test the findings, which were published in the journal Cell Reports. Daily Mail