Dr. Brian Kunimoto (biography and disclosures)
What I did before
I direct an outpatient clinic that treats patients with chronic leg ulcers. The majority of these wounds are venous in origin with some diabetic foot ulcers and pressure sores. The vast majority of patients do well with so-called ‘Best Clinical Practice’; however, it is not unusual for some ulcers to be very stubborn. In many cases, this failure to heal is characterized by the lack of development of healthy granulation tissue. The majority of these ulcers lacking granulation tissue have, instead, yellow/green, slimy, odourous material on the base. Despite this, we would try to facilitate proper moisture balance by applying modern wound dressings. Unfortunately, when this slimy material is prevalent, healing is impaired.
What changed my practice
I have always wondered just what that yellow slimy material was in the wound base. Yellow in the wound can signify different things. Fibrin presents as a gel usually on the base of venous leg ulcers. Yellow slough represents hydrated necrotic tissue and has the consistency of leather. We observed that when this yellow/green coloured slimy material persists, the wound does not heal and granulation tissue either does not develop or disappears.
One day, while flying to Toronto, I read an article in the Scientific American magazine I purchased at the airport. It was a review article by William Costerton, the man who coined the term, ‘Biofilm’, in 1979. He described the structure, formation, and the polymicrobial nature of biofilms in nature. In nature, biofilms often have the consistency of slime and it made sense that they could develop in a chronic wound. Furthermore, it seemed perfectly reasonable that this complex matrix of multiple species of bacteria could successfully compete with host immune defense and prevent healing. It also seemed logical that this material should be removed regularly in order to enhance healing. After all, if plaque, a prototypical biofilm of teeth, needs to be removed daily in order to avoid tooth decay and periodontal disease, wound biofilms would need to be regularly debrided to promote healing.
What I do now
The concept of biofilm in chronic wounds is in its infancy at the present time. It is just now being proposed that they play an important role in the pathogenesis of non-healing. It is also known that they are very resistant to treatment by systemic or topical antibiotics. Antimicrobial dressings, often consisting of sliver derivatives, are also unable to significantly impede biofilms. At the Wound Healing Clinic, we believe that almost every one of our poorly-healing leg ulcers possesses a healthy thriving biofilm. We now, routinely, debride biofilms using a disposable curette after providing topical local anesthesia (2% xylocaine gel applied under gauze for 10 minutes). I use the dull side of the curette to avoid cutting. Since the synonym for biofilm is ‘slime’, cutting and aggressive scraping are not required. Biofilms are extremely tenacious and so debridement must be relentless and repeated weekly at least. Although the biofilm usually returns quite quickly, eventually it ‘gives up’ and does not return. This is followed by rapid healing. Since we, at the Wound Healing Clinic, have instituted this form of debridement as part of wound bed preparation, better clinical outcomes have been realized.
References: (Note: Article requests might require a login ID with the BC College of Physicians website or UBC)
- Costerton, W. Battling Biofilms. Scientific American July 2001. (View article with CPSBC or UBC)
- James GA, et al. Biofilms in chronic wounds. Wound Rep Reg 16,37-44,2008. (View article with CPSBC or UBC)
- Bjarnsholt T, et al. Why chronic wounds will not heal: a novel hypothesis. Wound Rep Reg 16,2-10,2008. (View article with CPSBC or UBC)
- Cardinal M, et al. Serial surgical debridement: A retrospective study on clinical outcomes in chronic lower extremity wounds. Wound Rep Reg 17,306-311,2009. (View article with CPSBC or UBC)
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I have found this information very useful.
So is the biofilm usually contamibnated as well, i.e. the ocassional positive, deep wound culture(and I ussually do not culture wounds routinely) that is obtained, is that not the reason for the biofilm occurring?
Interesting article. I like it. How often do you have to debride before the biofilm gives up?
I have often wondered about this situation before and appreciate this help.
Interesting makes me think back to the use of ELase[hyluronidase] or maggots to clean up sloughy wounds i will try it
Useful info and worth a try.
Makes sense
I have often been tempted to debride this more aggressively. Now I have more reason to do so.
Very good article
I remember this talk at the last derm conference as it had some nasty photos.
good reminder -problem getting equipment at nursing homes
What dressing after the curetting?
Does hyperbaric oxygen treatment slow or prevent the formation of the biofilm?
Good article. I’ll give it a try.
Very basic but clever.
Interesting. I previously was familiar with biofilms that occur in water distribution systems and are suspected when non-coliform bacteria counts are elevated. They cause comsumption of the chlorine or bromine disinfectants. This is the slime that you might find in your charcoal filters when you replace them. Chemicals don’t remove them, you must physically do so.
Good comparison to plaque formation.
Does the 2% xyloc. gel penetrate the biofilm to be truly efficacious? Otherwise an interesting approach worth trying.
Fantastic information. I am part owner of a Personal Care Home and we deal with this issue occasionally.
Great to see this – now I can debride properly and enhance wound healing
I can concur with the rationale of debridgement in treating chronic ulcer,but wonder how practical it is in a busy family practice.
This is what I normally do, but I also do biopsies of non healing ulcers to understand nature of ulcer and rule out wound cancers.
Curreting as suggested is tedious and too time consuming for the busy office. Is there still something in the pharmaceutical market (like ? “Debrisand” beads) that the patient can do/apply/assist in debridement at home ?
1. To Leslie Sank:
Biofilm is actually a structure that is composed of the multiple species of bacteria housed in an exo-polysaccharide matrix. It occurs whenever there is a solid-fluid interface (ie your mouth, the bathroom sink, the toilet, and even stainless steel sinks). Biofilm is bacteria!
2. To William Wu:
I usually debride BF with a curette or the blunt end of a cotton tip applicator once a week. Studies have shown that more often is better (but less practical!)
3. To John Taylor:
I am glad you found this interesting. BF represents about 90% of the biomass of bacteria on this planet. It is about time we humans began to understand them. I believe they are the biggest reason for multi-drug resistant bacteria. We docs just can’t seem to stop prescribing antibiotics for non-infections resulting in toys for these bugs to play with.
4. To all who found this interesting: Go forth and DEBRIDE!!!
5. To Dr. Surkan:
An absorbent dressing such as Allevyn or Mepilex or ETE could be used because these wounds are usually quite exudative
6. To T. Pickett:
There is no evidence that Hyperbaric Oxygen inhibits biofilms.
After debridement what kind of dressing is best
very good article. I will try it
thank you, I see chronic wounds all the time in the hospital
Very interesting post i liked it a lot. Great work.
I am studying Podiatry at the moment and have an assignment on wound healing. I was going to do diabetic ulcers using biofilm. Is there any other healing treatment that can be used to heal diabetic ulcers? and what other healing methods are good for treating diabetic ulcers? thankyou.