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Christopher Campbell
In up to 80% of chronic infections, bacteria form biofilms – a slimy substance secreted by the bacteria which forms a protective matrix around them. Biofilms are a major contributor to antimicrobial resistance as they protect bacteria from both human immune cells and antimicrobial drugs, increasing their resistance to treatment by up to 1000-fold. Biofilms are very difficult to remove without mechanically breaking them up, which is not straightforward to do inside the body.
To address this, a team from Oxford's Department of Engineering Science and the Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences (NDORMS) have engineered antibiotic-loaded nanoparticles. When activated by ultrasound, these rapidly vaporise and thus both physically disrupt biofilms and release drugs directly at the infection site. Ultrasound can be precisely focused deep inside the body, which is a key advantage for targeting infections non-invasively.
Professor Eleanor Stride, Professor of Biomaterials, University of Oxford and 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 system further for application in healthcare settings.'
The nanoparticles were tested against 10 clinical bacterial strains, including E. Coli and methicillin-resistant Staphylococcus aureus (MRSA), delivering four different antibiotics. 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.
Read the full story on the University of Oxford website.