A common antibacterial substance found in toothpaste may combat life-threatening diseases such as cystic fibrosis (CF) when combined with another drug already approved by the Food and Drug Administration (FDA), according to Michigan State University. When triclosan, which reduces or prevents bacteria from growing, is combined with an antibiotic called tobramycin, it kills the cells that protect the CF bacteria, known as Pseudomonas aeruginosa, by up to 99.9%.
CF is a common genetic disease, with one in every 2,500 to 3,500 people diagnosed with it at an early age. It results in a thick mucus in the lungs that becomes a magnet for bacteria. These bacteria are difficult to kill because they are protected by a biofilm that allows the disease to thrive even when treated with antibiotics.
“The problem that we’re really tackling is finding ways to kill these biofilms,” said microbiology professor and lead author of the study Chris Waters, PhD.
According to Waters, there are many common biofilm-related infections that people get such as ear infections and swollen, painful gums caused by gingivitis. But more serious, potentially fatal diseases also are possible including endocarditis and infections from artificial hip and pacemaker implants.
The researchers grew 6,000 biofilms in petri dishes and added in tobramycin along with many different compounds to see what worked better at killing the bacteria. Twenty-five potential compounds were effective, but one stood out.
“It’s well known that triclosan, when used by itself, isn’t effective at killing Pseudomonas aeruginosa,” said coauthor Alessandra Hunt, DDS, MS, PhD, a post-doctoral associate of microbiology and molecular genetics. “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 been used for more than 40 years in soaps, makeup, and other commercial products because of its antibacterial properties. The FDA recently limited its use in soaps and hand sanitizers due to insufficient data on its increased effectiveness and concerns about overuse. But it has been found to be safe and highly effective in toothpaste for fighting gingivitis, and it is still approved for use.
“Limiting its use is the right thing to do,” said coauthor Michael Maiden, a graduate student in medicine. “The key is to avoid creating resistance to a substance, so when it’s found in numerous products, the chances of that happening increase.”
Tobramycin is the most widely used CF treatment, but it typically doesn’t clear the lungs of infection, Waters said. Patients generally inhale the drug yet find themselves chronically infected their whole lives, eventually needing a lung transplant.
“Most transplants aren’t a viable option, though, for these patients, and those who do have a transplant see a 50% failure rate within five years,” said Waters. “The other issue is that tobramycin can be toxic itself.”
Known side effects of tobramycin include kidney toxicity and hearing loss.
“Our tricolosan 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,” said Hunt.
Within the next year, the researchers will begin testing the effectiveness of the combination therapy on mice with hopes of it heading to a human trial soon after since both drugs are already approved by the FDA. Still, Maiden noted that brushing your teeth with toothpaste with triclosan won’t help treat lung infections.
“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,” said Maiden. “We think this can save lives.”
The study, “Triclosan Is an Aminoglycoside Adjuvant for the Eradication of Pseudomonas aeruginosa Biofilms,” was published by Antimicrobial Agents and Chemotherapy. It was funded by the National Institutes of Health, Cystic Fibrosis Foundation, and Hunt for a Cure.
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