01:47pm Sunday 20 August 2017

Bacteria-resistant materials offer new weapon in fight against hospital infections

The new polymers are designed to be used for coating medical devices and could one day lead to a significant reduction in hospital infections and medical device failures.

Medical-device-associated infections can lead to systemic infections or device failure, costing the NHS £1 billion a year. They are caused by the formation of bacterial communities known as biofilms on the surface of devices such as urinary and venous catheters. Biofilms are less susceptible to antibiotics and the bodies’ own natural defences, which makes them particularly difficult to fight.

To find the materials, the researchers simultaneously screened thousands of different chemistries, using a process that was initially developed by experts at MIT, and tested their reaction to bacteria. Using this technique they identified a new class of polymers that are able to repel bacteria and prevent them from forming biofilms.

The research, which was supported by a Translation Award from the Wellcome Trust, was led by Professor Morgan Alexander and Professor Martyn Davies in the School of Pharmacy and Professor Paul Williams in the School of Molecular Medical Sciences.

Their discovery marks a breakthrough that could not have been achieved with conventional materials development or the current understanding of how bacteria interact with non-living surfaces.

Professor Alexander said: “This is a major scientific breakthrough – we have discovered a new group of structurally related materials that dramatically reduce the attachment of pathogenic bacteria. We could not have found these materials using the current understanding of bacteria-surface interactions.

“The technology developed with the help of MIT means that hundreds of materials could be screened simultaneously to reveal new structure-property relationships. In total, thousands of materials were investigated using this high-throughput materials discovery approach, leading to the identification of novel materials resisting bacterial attachment. This could not have been achieved using conventional techniques.”

In the laboratory, the team were able to reduce the numbers of bacteria growing on a surface by up to 96.7 per cent compared with a commercially available silver-containing catheter. The materials were also effective at resisting bacterial attachment in a mouse implant infection model.

The new materials prevent infection by stopping biofilm formation at the earliest possible stage – when the bacteria first attempt to attach themselves to the device. Stopping the bacteria from attaching to the surface in this way enables the body’s own immune system to kill the bacteria before they have time to generate biofilms.

Ted Bianco, Director of Technology Transfer at the Wellcome Trust, said: “Infections caused by microbial biofilms binding to the surface of implants often cannot be treated with conventional antibiotics. This makes them a significant challenge in patient care, particularly for those with inserted medical devices like catheters, heart valves and prosthetic joints.

“The discovery of these new polymers is a great example of how advances in materials science are being exploited in our efforts to improve the performance of critical medical components. Just as materials science gave us the non-stick saucepan, so we look forward to the day of the ‘non-stick’ medical device.”

Bacterial attachment and subsequent biofilm formation are key challenges to the performance of medical devices. This is early stage research, but the initial results are very promising. The next stage of this research will be to develop the manufacture of these coatings to enable the performance of these materials to be assessed clinically, and the inventors are in discussions with several medical device companies.

The results of the £1.3m four-year research project are published this week in the journal ‘Nature Biotechnology’. The findings also have implications for water purification systems, food preparation surfaces and utensils, and any other surface where bacterial adhesion is problematic.

Image: Ultrasound catheter. Credit: Wellcome Images.

Reference

Hook AL et al. Combinatorial discovery of polymers resistant to bacterial attachment. Nature Biotechnology 2012 (epub ahead of print).

Wellcome Trust, Gibbs Building


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