Disinfectants designed to keep bacteria out of homes and hospitals could be fuelling the growth of superbugs, a study suggests.
Scientists from the National University of Ireland in Galway found that exposing infectious bacteria to increasing amounts of disinfectant turned the bugs into hardy survivors.
Not only did they become immune to the cleansing chemicals, but they developed resistance to a commonly prescribed antibiotic, ciprofloxacin. This was despite the bugs not having previously encountered the drug.
The findings could have important implications for controlling the spread of hospital infections.
The scientists carried out the tests on Pseudomonas aeruginosa, a bacterium that causes a wide range of infections in people with weak immune systems.
Sufferers of diseases like cystic fibrosis and diabetes are also vulnerable to the bug, which is responsible for many hospital-acquired infections.
Lead scientist Dr Gerard Fleming said: "In principle this means that residue from incorrectly diluted disinfectants left on hospital surfaces could promote the growth of antibiotic-resistant bacteria.
"We need to investigate the effects of using more than one type of disinfectant on promoting antibiotic-resistant strains," he said. "This will increase the effectiveness of our defence against hospital-acquired infections."