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United States researchers have found that a common antibacterial found in toothpaste may help treat cystic fibrosis (CF) when combined with an FDA-approved drug already used to treat the disease.

CF is a common genetic disease, with one in every 2,500 to 3,500 people diagnosed with it at an early age. It causes a thick mucus in the lungs which attract the bacteria Pseudomonas aeruginosa. These bacteria are notoriously difficult to kill due to their protective slimy barrier known as a biofilm. Even antibiotics are ineffective, allowing the disease to thrive.

Michigan State University researchers have been looking into how to kill these biofilms in order to treat CF and started by growing 6,000 biofilms in petri dishes.

The team then added the antibiotic tobramycin to the dishes, along with a variety of different compounds to see if any of the combinations were effective at killing the bacteria.

Tobramycin is currently the most widely used treatment for CF, but it is not without its problems. Lead author Chris Waters explains that not only does it often fail to clear the lungs of infection, meaning many patients will eventually need a lung transplant, but it can also be toxic, with known side effects including kidney toxicity and hearing loss.

However, the team found that when tobramycin and other compounds were used together, 25 of the potential compounds were effective in killing the biofilms.

But it was triclosan, a common ingredient in toothpaste, which was found to be most effective, killing the bacteria by up to 99.9 percent when combined with tobramycin.

“It’s well known that triclosan, when used by itself, isn’t effective at killing Pseudomonas aeruginosa,” said co-author Alessandra Hunt said. “But when I saw it listed as a possible compound to use with tobramycin, I was intrigued. We found triclosan was the one that worked every time.”

Triclosan has already been used for more than 40 years in soaps, makeup and other commercial products because of its antibacterial properties. However, the FDA recently ruled to limit its use in soaps and hand sanitizers due to insufficient data on its increased effectiveness and concern that it was being overused.

It is still approved for use in toothpaste as evidence suggests that triclosan is safe and highly effective in fighting gingivitis, which is also another common biofilm-related infection.

“Limiting its use is the right thing to do,” commented co-author Michael Maiden. “The key is to avoid creating resistance to a substance so when it’s found in numerous products, the chances of that happening increase.”

“Our triclosan finding gives doctors another potential option and allows them to use significantly less of the tobramycin in treatment, potentially reducing its use by 100 times,” added Hunt.

Within the next year the team will conduct further research into the combined treatment, and they hope that human trials will soon follow since both drugs are already FDA approved.

“We’re working to get this potential therapy approved so we can provide a new treatment option for CF patients, as well as treat other biofilm infections that are now untreatable. We think this can save lives,” says Hunt.

The research was published in the journal Antimicrobial Agents and Chemotherapy. JB

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