Skip to main content
Move the World.
A Hidden Benefit of Banned Antimicrobial Soap: Treating Cystic Fibrosis Infections
A chest x-ray from a cystic fibrosis patient suffering from a drug-resistant pseudomonas infection. Credit: Freethink

Maybe you’ve had the experience of wading in a stream and struggling to keep your balance on the slick rocks, or forgetting to brush your teeth in the morning and feeling a slimy coating in your mouth. These are examples of bacterial biofilms that are found anywhere a surface is exposed to bacteria in a moist environment.

Besides leading to falls in streams or creating unhealthy teeth, biofilms can cause large problems when they infect people. Biofilms, multicellular communities of bacteria that can grow on a surface encased in their own self-produced matrix of slime, can block immune cells from engulfing and killing the bacteria or prevent antibodies from binding to their surface.

On top of this, bacteria in a biofilm resist being killed by antibiotics due to the sticky nature of the matrix and activation of inherent resistant mechanisms, such as slow-growing cells or the ability to pump antibiotics out of the cell.

Biofilms are one of the primary growth modes of bacteria, but all antibiotics currently used clinically were developed against free-swimming planktonic bacteria. This is why they do not work well against biofilms.

My laboratory studies how and why bacteria make biofilms, and we develop new therapeutics to target them. Because antibiotic resistance is the most problematic aspect of biofilms during infections, we set out to identify novel molecules that could enhance antibiotic activity against these communities.

We discovered that an antimicrobial that has recently obtained a bad reputation for overuse in many household products could be the secret sauce to kill biofilms.

The hunt for antibiotic superchargers

Dr. Alessandra Agostinho Hunt measures
biofilm formation of Psuedomonas
aerugionsa by pipetting in the purple
dye crystal violet to stain the
microbial structure.

Dr. Alessandra Agostinho Hunt measures
biofilm formation of Psuedomonas
aerugionsa by pipetting in the purple
dye crystal violet to stain the
microbial structure. Credit: Derrick Turner/MSU

To find such compounds, we developed an assay to grow plates of 384 tiny biofilms of the bacterium Pseudomonas aeruginosa. We did this to screen for molecules that enhance killing by the antibiotic tobramycin. We chose this bacterium and this antibiotic as our test subjects because they are commonly associated with cystic fibrosis lung infections and treatment.

People with cystic fibrosis (CF) are at particular risk from biofilm-based infections. These infections often become chronic in the lungs of cystic fibrosis patients and are often never cleared, even with aggressive antibiotic therapy.

After we screened 6,080 small molecules in the presence of tobramycin, we found multiple compounds that showed the antibiotic enhancement activity we were searching for. Of particular interest was the antimicrobial triclosan because it has been widely used in household products like toothpaste, soaps and hand sanitizers for decades, indicating that it had potential to be safely used in CF patients. Triclosan has also garnered a bad reputation due to its overuse, and states like Minnesota have banned it from these products. The Food and Drug Administration banned its use from hand soaps in September 2016. This ruling was not based on safety concerns, but rather because the companies that made these products did not demonstrate higher microbial killing when triclosan was added, compared to the base products alone.

Another fact that piqued our interest is that P. aeruginosa is resistant to triclosan. Indeed, treatment with either tobramycin or triclosan alone had very little activity against P. aeruginosa biofilms, but we found that the combination was 100 times more active, killing over 99 percent of the bacteria.

We further studied this combination and found that it worked against P. aeruginosa and other bacterial species that had been isolated from the lungs of CF patients. The combination also significantly enhanced the speed of killing so that at two hours of treatment, virtually all of the biofilm is eradicated.

Our efforts are now focused on pre-clinical development of the tobramycin-triclosan combination. For CF, we envision patients will inhale these antimicrobials as a combination therapy, but it could also be used for other applications such as diabetic non-healing wounds.

Although questions about the safety of triclosan have emerged in the mainstream media, there are actually dozens of studies, including in humans, concluding that it is well tolerated, summarized in this extensive EU report from 2009. My laboratory completely agrees that triclosan has been significantly overused, and it should be reserved to combat life-threatening infections.

The next steps for development are to initiate safety, efficacy and pharmacological studies. And thus far, our own studies indicate that triclosan is well tolerated when directly administered to the lungs. We hope that in the near future we will have enough data to initiate clinical trials with the FDA to test the activity of this combination in people afflicted with biofilm-based infections.

We think our approach of enhancing biofilm activity with the addition of novel compounds will increase the usefulness of currently used antibiotics. Learning about how these compounds work will also shed light on how bacterial biofilms resist antibiotic therapy.The Conversation

Chris Waters is an Associate Professor of Microbiology at Michigan State University. This article first appeared on the The Conversation.

Up Next

Dope Science
Psychedelic Mushrooms Explained
Psychedelic Mushrooms Explained
Dope Science
Psychedelic Mushrooms Explained
Psychedelic mushrooms, AKA magic mushrooms or psilocybin mushrooms, are currently being researched as a treatment for depression, addiction, and more.

Psychedelic mushrooms, AKA magic mushrooms or psilocybin mushrooms, are currently being researched as a treatment for depression, addiction, and more.

Future of Medicine
The First Universal Flu Vaccine Could Be Coming Soon
The First Universal Flu Vaccine Could Be Coming Soon
Future of Medicine
The First Universal Flu Vaccine Could Be Coming Soon
After flu season, vaccines are outdated and researchers must predict next year’s virus. But soon, we may have a universal flu vaccine that doesn't expire.

After flu season, vaccines are outdated and researchers must predict next year’s virus. But soon, we may have a universal flu vaccine that doesn't expire.

Dope Science
New Promise for Psychedelics and Depression
studying psychedelics and depression
Dope Science
New Promise for Psychedelics and Depression
New findings on psychedelics and depression show the benefits of microdosing, and could present more effective treatment options.
By Kurt Hackbarth

New findings on psychedelics and depression show the benefits of microdosing, and could present more effective treatment options.

How a Smartphone Can Detect a Deadly Disease, without a Lab, for Free
How a Smartphone Can Detect a Deadly Disease, without a Lab, for Free
Watch Now
How a Smartphone Can Detect a Deadly Disease, without a Lab, for Free
This app tests for anemia, and it's nearly as good as the gold-standard lab test.
Watch Now

Anemia affects up to ⅓ of the world’s population, but tests are expensive and require complicated devices. Now, an app is able to screen for anemia without even drawing blood. It’s the brainchild of Rob Mannino, a postdoctoral fellow at the Georgia Institute of Technology who has anemia himself. He wanted to fight the disease, so he teamed up with Wilbur Lam, an associate professor at Emory. Recognizing the number of...

Dispatches
Training the Body to Fight Off Drug-Resistant Bacteria
Training the Body to Fight Off Drug-Resistant Bacteria
Dispatches
Training the Body to Fight Off Drug-Resistant Bacteria
A new strategy, called host-targeted defense, could help solve antibiotic resistance by upgrading the immune system.
By Zahidul Alam

A new strategy, called host-targeted defense, could help solve antibiotic resistance by upgrading the immune system.

What Is Cystic Fibrosis—And What Is It Like?
What Is Cystic Fibrosis—And What Is It Like?
What Is Cystic Fibrosis—And What Is It Like?
What you need to know about this genetic disease, explained by someone who knows it inside and out.
By Ella Balasa

What you need to know about this genetic disease, explained by someone who knows it inside and out.

Fighting Superbugs with Viruses
Fighting Superbugs with Viruses
Watch Now
Fighting Superbugs with Viruses
This Yale scientist's experimental treatment is a Texas woman's last resort.
Watch Now

Ben Chan searches sewers, lakes, and pig farms all around the world for bacteriophages (bacteria-destroying viruses) that could help fight antibiotic-resistant bacteria, also known as “superbugs.” Paige is a young woman in Texas with cystic fibrosis who is suffering from a drug-resistant infection; Ben’s experimental phage therapy is her last resort. We follow Ben as he travels from his laboratory at Yale to Lubbock,...

Dispatches
Two Billion People Have TB. What Should We Do about It?
Two Billion People Have TB. What Should We Do about It?
Dispatches
Two Billion People Have TB. What Should We Do about It?
In the fight against TB, sometimes it's better to just get along.

In the fight against TB, sometimes it's better to just get along.