The solution could address the global crisis of chronic antibiotic-resistant infections affecting hundreds of people around the globe.
Understanding Biofilms and Their Impact on Antibiotic Resistance
Bacteria secrete a substance which forms a protective matrix or layer around them – this is known as biofilms. These biofilms protect the bacteria from human immune cells and antimicrobial drugs. This leads to antimicrobial resistance.
The biofilms are difficult to remove without mechanically breaking them up – which is hard to do inside the body.
How the Drug Delivery System Works to Disrupt Biofilms
Oxford researchers have engineered antibiotic-loaded nanoparticles that, when activated by ultrasound, vaporise and physically disrupt biofilms whilst releasing drugs directly to the infection site.
The ultrasound can focus deep inside the body and target the infections non-invasively.
Promising Results in Combatting Chronic Infections
Professor of Biomaterials Eleanor Stride, principal investigator of the project, said: “Innovative solutions are desperately needed to extend the action of life-saving antibiotics. Our findings are very promising, as treatment of chronic infections associated with biofilm production continues to be a challenge in the face of spreading antimicrobial resistance worldwide. The methods we used in this study were designed with clinical use in mind, and we look forward to developing this drug delivery system further for application in healthcare settings.”
Testing the Drug Delivery System on Bacterial Strains
The nanoparticles were tested on bacterial strains such as E. coli and MRSA. With bacteria that did not form biofilms, the combination of the nanoparticles and ultrasound reduced the antibiotic concentration required to prevent their growth by more than 10-fold compared to conventional treatment.
Improved Efficacy in Biofilm Infections
In biofilm infections, the combination was even more effective, reducing the antibiotic concentration needed by more than 40-fold, and eliminating 100% of bacteria at clinically feasible doses. It was effective against dormant bacteria that can survive after treatment that cause recurring infection. The nanoparticles reduced the drug concentration needed to eliminate dormant bacteria by 25-fold compared to free antibiotics.
Next Steps in Developing the Drug Delivery System
The team is now working to develop the nanoparticle manufacturing method so that they can be tested clinically as soon as possible.
