Development of an infection detecting wound dressing

Infection is the primary cause of complications following a burn injury. Even a small hot water scald can become infected, which can lead to a great increase in pain, delayed healing, increased scarring, and a greater time in treatment (including antibiotic usage and surgery). This not only undermines the outcome for patients, but also increases costs to the NHS related to treatment and for patients, in terms of days off work, travel to hospital, and related loss of income. In rare cases infection can lead to death, particularly in large and deep burns and even in children with small burns, via complications such as toxic shock syndrome.

Despite the importance of identifying infection, this currently remains a major challenge for clinicians. Much of the difficulty arises from the fact that the symptoms of infection in burn patients can be very difficult to distinguish from other symptoms arising from inflammatory response to the burn itself, as well as other illness such as cold, sore throat etc. Because of these challenges, the standard methods that clinicians use to diagnose infection under other conditions are of limited value in treating burns patients. The situation is further complicated by the fact that most wounds have normal background level of bacteria, which does not need to be treated unless bacteria reach a certain level at which they begin to cause harm. However, clinicians may wait around three days to confirm the presence of bacteria in a wound, but these tests do not distinguish between beginning background levels and those representative of infection.

Collectively, these limitations can also lead to patients being 'over treated', resulting in over and unnecessary prescription of antibiotics, dressing changes (which are often painful and may increase the risk of scarring), and extended hospital stay.

Over 140,000 people in England and Wales suffer burn injuries every year, with about 50,000 requiring treatment at specialised burn centres, and approximately 13,000 admitted to hospital. A major problem in the care of these patients is infection, to which patients with burn injuries are particularly vulnerable. An estimated 18 per cent of burn patients acquire infection-related complications – a major cause of morbidity, mortality and increased cost of care. In addition to aggressive antibiotic therapy, treatment typically necessitates the removal of dressings, and sometimes further surgery. This significantly increases the probability of scarring and undermines clinical outcomes, resulting in a subsequent life-long psychological burden to the patient.

Failure to treat patients in a timely manner also increases overall morbidity and mortality rates. Infection also greatly increases treatment costs associated with in-patient stays, dressing changes and surgical time.

The dressing being developed in this research programme indicates critical bacterial infection within a burn wound without the need to remove it. The dressing will signal infection by a simple colour change, that occurs when clinically relevant bacteria in the wound reach a level at which treatment is necessary. This can be used by clinicians directly at the patients’ bedside to provide more accurate and more effective treatment. In doing so our technology would not only improve outcomes for patients, but also reduce NHS costs and unnecessary antibiotic use.

This work was funded by the Medical Research Council through the Biomedical Catalyst stream, and was led by the University of Bath, with University of Brighton researchers as co-investigators.

The overall aim of the proposed work programme was to create a wound dressing that provides an early indication of infection at point of care (PoC) which would significantly enhance clinical decision-making - with the capability to rapidly distinguish the bacterial Clinical Colonisation Threshold (TREAT) from sub-clinical colonisation (DON'T TREAT). The major overarching outcome the team wished to deliver was to progress the dressing technology to a point suitable for large scale manufacture and first-in-human studies post DPFS.

This study included an in vitro study of burn patients with suspected infections, using a non-invasive exudate collection approach that would be subjected to the normal microbiological culture tests as well as quantitative evaluation of virulence factors expression. This work would also aid analysis and understanding of various biological mechanisms of bacterial infection related to population density (quorum sensing). For example, understanding the processes involved in wound healing or identifying early indicators of tissue damage and wound infection related to quorum sensing controlled activity could identify additional targets for intervention, and there is considerable interest in this area. Specific beneficiaries will include:

> Academics and other scientists seeking to understand the pathogenesis of wound infections, and undertaking translational research
> 'Front line' nursing and clinical care staff in secondary care settings involved in infection control and the treatment of burn patients.
> Clinical microbiologists based in secondary care settings with responsibility for infection diagnosis.
> Infection control teams responsible for monitoring and preventing hospital acquired infections.

There was also significant potential to adapt and exploit the novel technology as a platform technology for critical colonisation detection (infection) in other acute and chronic wounds.

Led by the University of Bath, researcher Dr Brian Jones joined the project from the University of Brighton.

Following the success of the research, the lead institution, the University of Bath, were able to promote the innovation through SmartWound Ltd.

"The Biophysical Chemistry group at the University of Bath, led by Professor Toby Jenkins, applies research and methods in Chemistry, Materials Science and Microbiology to improve human health. The focus is on early detection and treatment of wound, bladder and skin infection, working closely with clinical colleagues specialising in: burn care (adult and children); diabetic foot ulcer management; urology. The team is translating laboratory innovation to the clinic, to benefit for patients. The aim is to create cost-effective and clinically effective devices that help prevent the over-use of antibiotics and AMR (antimicrobial resistance)."