Infection fighter has global potential

Stephanie-Anne Croft is in the second year of her PhD at Auckland University of Technology (AUT). Photo / Nic Scrivin

Surgical implants can be life-changing. Millions of people across the globe have had their mobility restored due to hip or knee replacements, for example; their quality of life restored by a single operation.

But there is a darker side to implants. Studies reveal up to 5 per cent of those who receive them suffer post-operative infections, ultimately leading to long-term hospitalisation, limb loss or even death.

One Auckland PhD student and her supervisor may be on the verge of developing a solution to this pressing issue.

Stephanie-Anne Croft is in the second year of her PhD at Auckland University of Technology (AUT). Under the supervision of Professor Stephen Henry from Kode Biotech (based at the AUT campus), she is helping to develop a coating that will protect implants from bacteria and could ultimately prevent hundreds of thousands of patients from suffering the ravages of infection.

"Infections of this nature are incredibly difficult to treat," says Croft. "People who are infected need to stay in hospital for months. The infection can cause huge amounts of discomfort, not to mention the possibility of disfigurement, loss of limbs and even death."
Then there's the cost factor - treatment of a hip infection, for example, is estimated at up to $250,000 per patient, significant for any health provider. So a coating that eliminates the chance of infection is likely to have huge international potential.

As our population ages, implants will become more commonplace as will the likelihood of infection caused by bacterial contamination.

Croft, who initially trained as a medical laboratory scientist at AUT, began work on this research, funded by The William & Lois Manchester Trust, at the beginning of last year. Her work involves design experiments to prove the technology around the coating and test the hypotheses around its potential use.

While implants are sterilised before they enter the human body, they are not fully protected from the bacteria present in the air and on the human skin in the surgical theatre. Such bacteria can affix themselves to implants during surgery and multiply exponentially in the body.

This mass of bacteria then develops a self-protective film shielding it from antibiotics and natural bodily defences, resulting in severe, sometimes untreatable infection. The coating being developed by Croft and Henry would serve a dual function - preventing bacteria from adhering to the surface of the implant and killing any bacteria that comes in contact with it.

"Essentially the coating will create a surface that's self-sterilising," says Henry.
While there are some implant products that can kill bacteria, these can interfere with the cells around the implant. The Kode coating will remain on the implant only for the time needed to prevent bacteria from attaching. Once positioned within the body, the coating dissipates - allowing natural healing.

Henry started Kode Biotech in 1996. It specialises in what Henry calls "multifunctional nanotechnology paint", which mimics certain molecules' natural ability to "paint" blood cell membranes. The molecules he developed at Kode can harmlessly modify anything to which they are applied and can have almost anything attached to them.

Kode Biotech was recently awarded the Supreme New Zealand Innovator at the 2015 New Zealand Innovators Awards for their development of cell surface membrane technology that aids in the fight against tumours.

The genesis of the idea around a protective coating for implants came about after Henry gave a lecture to a group of leading New Zealand plastic surgeons: "One of the surgeons approached me after the talk and said the industry really needed a product that could prevent infection after implants."

Henry designed a Kode construct to kill bacteria, with Croft working on experiments to prove the efficacy of the technology.

While the coating is still in the early stages of development, the research has established "proof of concept", positively identifying that the coating can affix itself to implants and kill bacteria. The next six months will help determine how the molecules self-assemble on a wide range of materials.

"Stephanie will be looking at the way in which the coating works on hundreds of subtle variable surfaces," says Henry.

The formulation that best adheres to implants is expected to be identified by the end of this year; work on the development of the coating can then begin in earnest.

* This story is part of a content partnership with AUT

Read more from AUT research here