Disinfectants make superbugs resistant to antibiotics

Disinfectants designed to keep bacteria out of hospitals and homes could effectively train bacteria to become resistant to antibiotics, despite not having previously encountered the drug, according to research published in the January issue of Microbiology. Scientists found that exposing infectious bacteria to increasing amounts of disinfectant turned the bugs into hardy survivors.

The findings could have important implications for how the spread of infection is managed in hospital settings. The scientists, led by Dr Gerard Fleming from the National University of Ireland in Galway, found that the bacterium Pseudomonas aeruginosa adapted to disinfectant exposure by improving its ability to pump antimicrobial agents out of its cells.  The adapted bacteria also had a mutation in their DNA that allowed them to resist ciprofloxacin-type antibiotics specifically.

Exposure to small, non-lethal amounts of disinfectant encouraged the survival of resistant bacteria, Dr Fleming said. “In principle this means that residue from incorrectly diluted disinfectants left on hospital surfaces could promote the growth of antibiotic-resistant bacteria. What is more worrying is that bacteria seem to be able to adapt to resist antibiotics without even being exposed to them.”

 Pseudomonas aeruginosa is a bacteria most likely to infect those who are already seriously ill, particularly among those with weak immune systems such as HIV or cancer patients, as well as people with severe burns, diabetes or cystic fibrosis.

Dr Fleming also said: “We need to investigate the effects of using more than one type of disinfectant on promoting antibiotic-resistant strains. This will increase the effectiveness of both our first and second lines of defense against hospital-acquired infections.”