Coatings & surface treatment
Serratia marcescens can be a cause of catheter- associated infections.
Depending on the application, the team might want something that releases the drug a little more quickly or slowly. For instance, orthopaedic surgeons often need a coating that will protect the implant during the operation itself, releasing its antibiotic payload within about a week. A catheter, for its part, needs to retain the antimicrobial on the surface, so that it isn’t flushed out when the patient urinates.
As well as exploring different medical applications, Nichol is working with his colleague Dr Sarah Forbes on incorporating something called ‘quorum sensing inhibitors’ (QSIs). Quorum sensing is a form of chemical communication between cells, which allows bacteria to coordinate their behaviours. Inhibiting this process can silence the so-called crosstalk, meaning biofilm communities are prevented from forming. Kelly Capper-Parkin, one of Forbes’ doctoral students, examined various types of QSIs in her thesis. She found that cinnamaldehyde, a component of cinnamon essential oil, worked especially well to stop biofilm formation. The compound was paired with silver nitrate, a commonly used biocide, and incorporated into a sol-gel coating. This approach, she thinks, shows great potential for creating a truly anti-infective catheter.
30% 120
Urinary tract infections as a percentage of total infections reported in acute care hospitals.
Centers for Disease Control and Prevention
Another PhD student is working on a bone culture cell model, which would enable orthopaedics researchers to investigate infections without needing to perform tests on animals. At the same time, microbiology lecturer Dr Keith Miller is investigating new antimicrobial agents derived from snake and scorpion venom. “He’s identified a number of different peptides,” says Nichol, “and he’s altered versions of those peptides. We’ve looked at putting those peptides into the coating as well.”
Addressing antimicrobial resistance An especially promising avenue for the researchers is their collaboration with MetalloBio, a spin-out company from the University of Sheffield. MetalloBio is developing two new antimicrobial compounds – the first to emerge in nearly 40 years – while the Sheffield Hallam team are looking to integrate these compounds into their sol-gel coating. “MetalloBio has a ruthenium-based antimicrobial that has shown some really promising results,” Nichol explains. “They’re interested in using it in a whole host of different applications, including a coating for catheters. So we applied for a grant together through the Medical Research Council, and we managed to get a postdoc doing the initial work.” This research was put on hiatus for a while, owing to the sudden passing of Dr Kirsty Smitten, CEO and co-founder of MetalloBio, at the age of just 29. Nonetheless, the two groups are planning on continuing their collaboration, and are now looking for their next round of funding. “I can’t say too much about it,” says Nichol, “but essentially we’ve got a coating that shows a very good activity against a broad range of bacterial species. It shows favourable, sustained protection of the coating, and it’s not toxic to the cells of the body. We’re interested in carrying that on.” While clearly excited about future developments – he describes their initial work as “very, very promising” – Nichol adds the caveat that this was just a proof-of-concept, and further research is needed. The path from idea to clinic is rarely straightforward, and there are more steps to be taken before the work can enter clinical trials. “Hopefully, we’ll be able to secure some more funding in order to develop that to a point where we can approach potential commercial partners,” the lecturer says. “They will be able to take that through the relevant legislation and the relevant testing technologies.” Despite the challenges ahead, Nichol is optimistic about the long-term prospects. He hopes that, over time, his team’s product could lead to a reduction in catheter-associated urinary tract infections – as well as healthcare-associated infections more generally. “The main aim is to improve the quality of life of patients,” he says. “That’s the best thing about my research – you have that goal of helping people, as well as significantly reducing the economic burden on the healthcare system.”
As antimicrobial resistance becomes more widespread, infections such as CAUTI could start to become more prevalent, not to mention harder to treat. New strategies will therefore be urgently needed. A new kind of catheter coating, impregnated with a new class of antimicrobial, could be exactly what makes the difference further down the line. ●
Medical Device Developments /
www.nsmedicaldevices.com
Kateryna Kon/
Shutterstock.com
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