Wound care
The healing process is a complex molecular choreography danced by immune cells and proteins. It can be broadly broken down into four distinct phases: haemostasis, inflammation, proliferation and maturation. Chronic wounds tend to get stuck at the second stage, when bacteria and fungi invade the wound bed and create infection, forcing the body to dial up its inflammatory response. Unfortunately, many bugs have developed a way of getting around the body’s defences. The microbes can band together in a sticky goo called a biofilm, which makes it much harder for the immune system to eradicate the infection. As a result, biofilms, which affect around 60% of chronic wounds, represent a significant challenge in wound healing, according to Karen Ousey, professor of skin integrity at the University of Huddersfield.
Biofilms are not unique to chronic wounds, though. We encounter one every day. “You have a biofilm every morning on your teeth,” she explains. We get rid of this sticky plaque by practising good oral hygiene and brushing it away in the bathroom, but it’s not so simple for open wounds that can be colonised by nasty bacteria such as Pseudomonas aeruginosa and Staphylococcus aureus.
Biofilm trifecta
There are three stages to biofilm formation. First, free-floating bacteria or other microorganisms attach themselves to the wound. Then they colonise it. The bugs group up in a diverse community, learning from each other about how to evade antibiotics and antiseptics. Critical colonisation is the final stage, where the grouped bacteria exude a sticky covering called an extracellular polymeric substance (EPS). This provides a barrier against the patient’s immune system. Once the three-step process is complete, free- floating bacteria can detach from the structure and form new colonies, forcing the patient’s immune system to go into attack mode again, and producing even more inflammatory cells and proteins. This leads to a chronic relapsing infection where the inflammation phase of wound-healing is never complete. “Ultimately, this creates a situation where the body is ineffectively fighting the organisms involved in the biofilm while also damaging healing tissue – causing a delay in the wound healing,” Ousey explains. “This is why it is imperative for clinicians to have the ability to diagnose them early.” As well as affecting the body’s natural healing process, biofilms can blunt the standard tools healthcare professionals use for dealing with a chronic wound, such as hygiene, medication and dressings. “Biofilms cover the wound bed, and mean we can’t get the healing process to initiate in a timely fashion,” reveals Ousey. “When we try to clean the wound, we’re cleaning the biofilm rather than the wound itself. And if we apply antibiotics or use antimicrobial wound
Practical Patient Care /
www.practical-patient-care.com Biofilm indicators
Signs that a wound is likely to be hard to heal because of the presence of biofilm include: ■history of or current recalcitrance to antibiotic or antimicrobial treatment ■treatment failure, even with appropriate antibiotic or antimicrobial treatment ■delayed healing ■cycles of recurrent infection/exacerbation ■excessive moisture and wound exudate ■low-level chronic inflammation
■low-level erythema. Source: International Consensus Document, Journal of Wound Care
dressings, they won’t reach the wound bed because the biofilm stops it.”
A major issue with biofilms is that they can’t be seen with the human eye. That means many healthcare professionals are not able to identify their presence in time for patients to receive the most effective treatments. Even routine hospital tests can’t distinguish between floating bacteria that can be targeted with antibiotics and an attached biofilm that will not respond to them.
Although there are limited ways of detecting biofilms in a clinical setting, laboratory studies have revealed a few promising diagnostic tools, from those that track and identify biofilm-associated biomarkers to advanced microscopy. Genetic-sequencing technologies may also be employed to determine proteins associated with biofilm formation, while techniques involving electric currents and surface acoustic waves have shown promise in detecting biofilms in the laboratory. Ousey’s team at the University of Huddersfield has joined forces with testing laboratory Perfectus Biomed to investigate more practical ways for wound care clinicians to accurately identify and manage the presence of biofilms. The Huddersfield researchers will explore whether the highly-sensitive assays developed by the contract research organisation’s microbiologists will be suitable for detecting biofilms in real-life chronic wound patients.
“The body is ineffectively fighting the organisms involved in the biofilm while also damaging healing tissue – causing a delay in the wound healing.”
For any hard-to-heal wound, the current standard of care involves cleaning and applying topical or systemic antimicrobials and dressings, explains Ousey. But if a biofilm is suspected, the main weapon healthcare professionals have against it is a process called debridement. This involves scraping away at poor- healing tissues in the wound with a sharp instrument such as a scalpel. While it’s a helpful tool, debridement can be a painful procedure that may affect patient adherence. And even after debriding a well-established biofilm, it can form again in as little as 24 hours.
39
Opposite page: A microscopic view of biofilm formation – grouped bacteria exude a sticky extracellular polymeric substance, providing a barrier against patients’ immune system.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59
