Disinfectants likely to promote growth of superbugs

LONDON - Using disinfectants could cause bacteria to become resistant to antibiotics as well as the disinfectant itself, according to new research, a finding that may have important implications on how the spread of infection is managed in hospitals.

National University of Ireland (NUI) researchers found that by adding increasing amounts of disinfectant to lab cultures of Pseudomonas aeruginosa, the bacteria could adapt to survive not only the disinfectant but also ciprofloxacin - a commonly-prescribed antibiotic - even without being exposed to it.

Gerard Fleming of NUI, who led the study, said: “What is more worrying is that bacteria seem to be able to adapt to resist antibiotics without even being exposed to them.”

Researchers showed that the bacteria had adapted to more efficiently pump out antimicrobial agents (disinfectant and antibiotic) from the bacterial cell.

The adapted bacteria also had a mutation in their DNA that allowed them to resist ciprofloxacin-type antibiotics specifically.

Pseudomonas aeruginosa is an opportunistic bacterium that can cause a wide range of infections in people with weak immune systems and those with diseases such as cystic fibrosis and diabetes.

It is a cause of hospital-acquired infections. Disinfectants are used to kill bacteria on surfaces to prevent their spread. If the bacteria manage to survive and go on to infect patients, antibiotics are used to treat them.

Bacteria that can resist both these control points may be a serious threat to hospital patients, said an NUI release.

The study showed that when very small non-lethal amounts of disinfectant were added to the bacteria in culture, the adapted bacteria were more likely to survive compared to the non-adapted bacteria.

These findings are slated for publication in the January issue of Microbiology.