Unlocking the science behind implant infection
Prosthetic implant patients at Macquarie University Hospital are benefiting from the interface between the hospital and a robust research program in bacterial biofilm infection at the University’s medical school, which is aiming to reduce infection associated with the implant of medical devices.
Increasing evidence now points to the role of bacterial biofilms in device-associated infection as the leading cause of implant failure. Bacterial contamination in prosthetic implants is caused by free-floating bacteria that change when they come into contact with the surface of an implant.
These bacteria are able to form a three-dimensional matrix by excreting a thick polymeric slime, which eventually binds firmly to the underlying surface. Over time, biofilm – defined as bacteria encased within their own polymeric matrix – reaches a critical mass on the contaminated implant. This induces a host inflammatory reaction and can lead to ultimate failure of the implant.
The research laboratory at the Faculty of Medicine and Health Sciences (formerly the Australian School of Advanced Medicine) is currently one of the few laboratories in the world that is devoted to medically related biofilm infections.
Led by Professor Anand Deva and Associate Professor Karen Vickery, the Surgical Infection Research Group’s current laboratory work is centred around the science and clinical significance of bacterial biofilm infection using both in vitro and in vivo models.
Breast implant infection is one of several areas being investigated.
“Bacteria within biofilms are significantly less susceptible to antibiotics, host defence and antiseptics – making them difficult to treat,” said Professor Deva, who has been involved in biofilm research for more than 15 years and is also Head of the Plastic Surgery Department at Macquarie University Hospital.
“That is why it is so important for effective strategies to be used during surgery to minimise the risk of biofilm developing in the first place.”
Based on existing scientific data from best practice around the world, Professor Deva and his team have outlined strategies for prevention of device-associated infection in breast prostheses. A 14-point plan includes protocols such as specific antibiotic and irrigation regimes, particular incision and dissection techniques, minimal device handling and layered closure methods.
This work was recently published in the prestigious journal Plastic and Reconstructive Surgery, and the group’s research will, hopefully, lead to improvements in breast implant outcomes around the world, with Macquarie University Hospital planning to embark on its own clinical research in the coming years.
“The interconnection between the Faculty of Medicine and Health Sciences laboratory and the hospital is what makes us unique,” said Professor Deva. “The combination of a scientific research program and the clinical environment means that we are able to do advanced scientific research while applying that work to patient treatment.
“So the laboratory plays a role in providing optimal patient care. Because these particular bacteria are locked into the body on the surface of the device, currently the only way of confirming diagnosis is to send tissue to our biofilm laboratory for testing, using our various diagnostic testing methods. On-site testing at Macquarie University can confirm the presence of infection.
“The testing that we have developed at Macquarie University is currently only available at designated biofilm laboratories, and not yet available commercially. Macquarie University Hospital patients have direct access to specialist biofilm researchers, clinicians and laboratory services all in one location. It really is best practice in this field at the moment.”
The Surgical Infection Research Group has made significant research contributions in the field of biofilm bacterial infection, having published more than 20 papers, and secured research funding from both government and industry.
The ultimate research goal is to develop smart implant technologies that are able to combat biofilm infection at the time of insertion.
Addressing breast implant failure - Yolinda Cramm’s Story
The Faculty of Medicine and Health Sciences Surgical Infection Research Group has a particular focus on understanding the role of bacteria in the pathogenesis of breast implant failure and, ultimately, on developing technologies to prevent bacterial attachment to breast implants and other medical prostheses.
Breast implants pose a unique challenge when it comes to biofilm infection in that they are placed into a potentially contaminated pocket, with high levels of bacteria present in breast ducts and tissue. Evidence now clearly shows that biofilm is the leading cause of capsular contracture – the hardening of breast tissue that occurs as a result of infection.
Currently, about 10 per cent of women with implants present with capsular contracture, while up to 30 per cent of those who have had breast reconstruction after cancer present with the condition. Effects of subclinical infection are visibly and palpably evident as pain and distortion, which are more evident in comparison to other more deeply placed implants.
After her second set of breast implants failed, Sydney resident Yolinda Cramm suspected that simply replacing them for the third time may not be in her best interests.
Following discussions with several surgeons and completing some research of her own, Yolinda found out about Professor Anand Deva and the biofilm research program at Macquarie University’s Faculty of Medicine and Health Sciences. She presented to him with high-grade capsular contracture.
“It was a ‘light bulb’ moment when I met with Professor Deva,” said Yolinda. “He explained that the encapsulation was probably caused by infection, and that removing the implants, having the tissue laboratory tested and then giving the body a chance to heal without implants would be the best course of action.”
Laboratory tests when the implants were removed did, indeed, show bacterial biofilm infection on the surface of the implant. Breast reconstruction was performed at the time of the implant removal.
Yolinda is allowing her body to recover before making further decisions.