Scientists at the University of Nottingham have discovered surface patterns that can drastically reduce bacteria's ability to multiply on plastics, which means that infections on medical devices, such as catheters, could be prevented.
The findings of the study, which are published in Nature Communications, show that when bacterial cells encounter patterned grooves on a surface, they lose their ability to form biofilms. Biofilms are surface associated slime-cities which help protect the bacteria from the body's natural defences against infection. This in turn means the infection is effectively prevented before it can become fully established and would also positively activate the immune system to get rid of any individual bacteria that were there.
The study was led by Professor Paul Williams in the School of Life Sciences, along with Professor Morgan Alexander in the School of Pharmacy, and colleagues in the School of Computer Science at the University of Nottingham with Jan DeBoer in the Netherlands. It was funded by the ESPRC and the Wellcome Trust.
Many medical implants are made of plastics, such as catheters and breathing tubes, and are commonplace in hospitals. Once bacteria have stuck to the plastic surface and developed into a biofilm, they can be very difficult to treat with antibiotics.
For this reason, a lot of effort has gone into reducing the likelihood of bacteria attaching to such devices by incorporating antibiotics, and other antimicrobials into the plastic.
In this new study, the team describe how they identified patterns that prevented biofilm formation by screening over 2000 designs made in different plastics including polyurethane, which is commonly used to make medical devices.
On the best biofilm inhibitory pattern, they discovered that small crevices in the raised patterns trapped the bacterial cells, tricking them into producing a lubricant which stops them sticking to the plastic surface. This in turn blocks biofilm formation and makes it easier for the host's immune defences cells to clear the infecting bacteria and so prevent infection.
Professor Williams, an expert in Molecular Microbiology, said: "Previous research has shown that introducing antibiotics to medical devices has flaws, such as driving the development of antibiotic resistance. Our study took this idea one step further as we wanted to find out if we could create a simple landscape on a catheter, made of the same material that bacteria didn't like and couldn't form biofilms on.
"We tested different species of bacteria on over 2000 different shapes. We had to use machine learning to figure out which of these shapes was best at preventing biofilms forming. We then looked at why certain bacteria didn't like this surface.
Our findings could help to reduce the high number of infections in healthcare settings associated with medical devices. Not only could this method prevent bacteria sticking but also activate the body's immune system to kill any bacteria that have stuck to the surface.
Using physically pattered surfaces has the advantage over coating approaches that it can be applied to existing device materials, reducing the barrier to commercial application. Our discovery could save the NHS a lot of money.
The researchers hope to expand this in current UKRI funding to practical medical devices in collaboration with medical device companies.
