Common disinfectant found in soap, toothpaste could be causing antibiotic resistance

A common ingredient of soap and toothpaste could be causing antibiotic resistance and fuelling the spread of superbugs, according to new research.Researchers found that triclosan, a chemical found in soap, toothpaste and cleaning products, could be making bacteria more immune to antibiotics.

A new British study found that bacteria exposed to triclosan could become more resistant to a group of antibiotics known as quinolones.Quinolones are a common antibiotic used to treat urinary tract infections, sinusitis, bronchitis and pneumonia.

The warning comes just a year after the use of triclosan in antibacterial soap was banned by the United States (US) Food and Drug Administration (FDA).Now researchers have found evidence that the chemical could be linked to an increase in antibiotic resistance among superbugs.

Researchers studying the stomach bug Escherichia coli in the lab found that triclosan could cause antibiotic resistance via a phenomenon known as ‘cross-resistance’.Cross-resistance is a term used to describe how exposure to one substance can cause bacteria to become immune to a similar substance that it hasn’t encountered before.

Researchers discovered that bacteria exposed to triclosan may also evolve resistance to quinolones. Quinolones kill bacteria by targeting a chemical involved with Deoxy ribonucleic Acid (DNA)/genetic material replication.

When a bacterial cell divides into two, a copy of its DNA is made to pass on to the new daughter cell.Quinolones stop DNA from being replicated, which causes the bacteria to cease dividing and die off.

But the researchers found that bacteria is able to evolve special defences to resist attack by quinolones. Bugs can evade the antibiotics by evolving new mutations which stop quinolones from destroying its DNA.

And these mutations also make the bacteria resistant to treatment with triclosan, the researchers found.Researchers warned that the phenomenon may also happen in reverse, with exposure to triclosan causing bacteria to evolve mutations which can protect them against quinolones.

Dr. Mark Webber, of the Institute of Food Research at the University of Birmingham, said: ‘The worry is that this might happen in reverse and triclosan exposure might encourage growth of antibiotic resistant strains.

“We found this can happen in E. coli. As we run out of effective drugs, understanding how antibiotic resistance can happen and under what conditions is crucial to stopping selection of more resistant bacteria.”

The World Health Organisation has previously warned that antibiotic resistance is one of the biggest threats to global health.Co-author Professor Laura Piddock, of the Institute of Microbiology and Infection at the University of Birmingham, said: “The link between quinolone and triclosan resistance is important as triclosan has become ubiquitous in the environment and even human tissues in the last 20 years.

“Given the prevalence of triclosan and other antimicrobials in the environment, a greater understanding of the impact they can have on bacteria and how exposure to these antimicrobials may impact the selection and spread of clinically relevant antibiotic resistance is needed.”