Health Service Focus

An anti-adhesive strategy against bacterial attachment

Professor of biomedical surfaces at the University of Nottingham Morgan Alexander leads the team that recently discovered a new bacteria-resistant material. Here he discusses the implications of the research with NHE.

A medical device that could repel bacteria from ever attaching to a surface, reducing contagion and improving care across the NHS, has to be the holy grail of infection prevention.

The culmination of around seven years’ work, new materials have recently been discovered that can repel bacteria – with significant implications for use in the health service.

The University of Nottingham has been undertaking the research to identify materials with an application in medical use, where infections are a daily challenge.

Funded by the Wellcome Trust and in collaboration with MIT (Massachusetts Institute of Technology), the work focused on developing a urinary catheter that prevents the attachment of bacteria through a non-killing strategy.

A single implement was chosen for development, but the technology could be applied to all sorts of medical instruments and devices.

NHE spoke to Professor Morgan Alexander about this significant step forward in the field of infection prevention. He said: “We took the approach that we would like to use a different strategy of us preventing attachment and therefore preventing the formation of the biofilm, the environment which bacteria use to protect themselves against host immune defences and systemic antibiotics which are applied to reduce infections.”

Most approaches simply set out to kill bacteria once they have attached.

Optimal infection prevention

Most devices were originally developed and manufactured for their medical benefits, not necessarily their ability to prevent infection.

Professor Alexander explained: “People found silicone, decided it was a good elastic material with chemical resistance and thought they would try using it in the body. Maybe not surprisingly, such materials are not optimal in other senses, such as resisting bacterial attachments. The main consideration at the time would have been, ‘I’ve got to patch someone up, what can we use?’ and they go and have a look – I’ve heard this anecdotally – and put it in.”

The project therefore looked into new materials based upon a specific property; preventing bacterial attachments from forming.

Finding effective materials was complicated by the limited understanding around bacteria behaviour.

Prof Alexander acknowledged that it wasn’t known how bacteria colonise certain materials, and therefore the scientists did not know what particular surface chemistry was needed before they set out to find it.

He described the process they took: “We set out on a high-throughput approach for drug discovery, whereby you take a very large number of different chemistries and screen them to see which has the desired property. We proposed that we would find something better than we have currently.”

Fortunately, the team has found materials with a resistance to bacteria, superior to current solutions.

The new mechanism deters bacteria from attaching to surfaces, and has undergone testing in the lab before being manufactured into actual devices.

Licence to kill

Preventing bacterial attachment and biofilm formation allows the subject’s host defences to naturally clear the bacteria, rather than them finding shelter on the foreign object which was inserted.

Another potential benefit could be stemming the rise in bacterial resistance to antibiotics, as the host immune system deals with the problem without the need for antibiotics.

Using antibiotics only when completely necessary should help slow the development of antibiotic-resistant strains of bacteria.

Antibiotics can always be used to kill any strains of bacteria which do manage to adhere to the material.

Prof Alexander said: “We haven’t investigated that at all but that’s something for the future as we put these into trials and see how they perform in different medical environments, different scenarios.”

Surface chemistry

The process the researchers undertook was taken from the drug discovery field, where high frequency drug discovery has been “routine for many years in industry and academia to a degree”.

He added: “The critical difference is they are trying to discover a drug which normally you can work with as a solution, and the reaction will always be the same.

“What we had to really work hard with is that when we make materials, making the material differently could lead to the material having a different surface chemistry and therefore different performance.

“When you’re trying to discover new materials, it’s not as simple as saying ‘I know what I’ve put on that spot, it is X, and if it prevents bacterial attachment, X is good’ – you actually have to analyse the surface chemistry of that material to make sure you know what it is about the surface chemistry.

“Surface chemistry when it’s on a spot compared to when it’s on the catheter may be different. We spent almost eight years developing the high frequency surface characterisation, highthroughput screening and between the two of them we carried out detailed surface chemical analysis on each of the spots and then correlated it with the performance, bringing together an understanding of what it is about that material surface chemistry which allows it to perform in the way it does.”

Despite the breakthrough discovery, Prof Alexander was keen to emphasise the future research that needed to be done, to gain a better understanding of the materials and how they work.

He said: “We know the structural signature of what’s good in terms of the surface, [but] the exact biochemical mechanism by which they work is yet to be elucidated. That’s going to be a significant amount of work, more research, although that doesn’t prevent the application of these materials.”

Tell us what you think – have your say below, or email us directly at [email protected]