Clinical Update TEN TOP TIPS Understanding and managing wound biofilm


“Wound care clinicians are becoming


increasingly


convinced that biofilms play a


key role in chronic nonhealing wounds.”


bacteria have been studied in vitro and in a porcine skin model. In particular, both silver and iodine releasing dressings have been shown to kill biofilm bacteria.[31–3]


One study


demonstrated a reduction in colony forming units over time with several silver dressings, however, cadexomer iodine achieved complete kill rates of Staphylococcus aureus in mature biofilms.[33] While antimicrobial dressings may have


variable effects on bacteria in mature biofilms, they are known to be widely effective against planktonic bacteria. The best strategy for biofilm based wound care is the “clean and cover” approach, which relies on adequate debridement to disrupt biofilms and the use of antimicrobial dressings between debridements to reduce the ability of planktonic bacteria to re-establish a biofilm.


as a risk factor for biofilm formation. The TIME framework[30]


7


25. Rodeheaver GT, Ratliff CR (2007) Wound cleansing, wound irrigation, wound disinfection. In: Rodeheaver GT et al (eds) Chronic Wound Care: A Clinical Source Book for Healthcare Professionals. HMP Communications, Malvern, PA: 331–42


26. World Union of Wound Healing Societies (2008) Principles Of Best Practice: Wound Infection In Clinical Practice. An International Consensus. MEP Ltd, London


27. McGuiness W et al (2004) J Wound Care 13(9): 383–5


28. Atiyeh BS et al (2009) Int Wound J 6(6): 420–30


29. Fernandez R, Griffiths R (2012) Cochrane Database Syst Rev: CD003861


30. Leaper DJ et al (2012) Int Wound J 9(Suppl 2): 1–19


31. Percival SL et al (2008) Wound Repair Regen 16(1): 52–7


32. Akiyama H et al (2004) J Dermatol 31(7): 529–34


33. Phillips PL et al (2013) Int Wound J: Sep 13 [Epub ahead of print]


34. Leaper D (2006) Int Wound J 3(4): 282–94


35. Angel DE (2011) Int Wound J 8(2): 176–85


36. Levine NS et al (1976) J Trauma 16(2): 89–94


37. Gardner SE et al (2006) Wound Repair Regen 14(5): 548–57


38. Edwards-Jones V et al (2013) The Significance of Biofilms in Wound Infections. Available at: www. woundinfection-institute.com [password protected]


outlines the need to


manage moisture levels with appropriate dressings or appliances. Excessive wound exudate may relate to underlying conditions including: inflammation/infection; venous insufficiency; poor compliance or concordance with compression therapy; development or deterioration of systemic causes of peripheral oedema (e.g. chronic heart failure, renal failure, liver failure); lymphoedema. The underlying cause of excessive


exudate must be determined and managed appropriately, with medical management or compression therapy should the cause be venous insufficiency or lymphoedema. Absorbent dressings should be used and the dressing change frequency adjusted to maintain a moisture balance and prevent maceration. If a biofilm is suspected, previously discussed strategies should be employed.


8


SWAB RESULTS ARE OFTEN INCONCLUSIVE; THE LEVINE


METHOD IS RECOMMENDED IF SWABS ARE TAKEN


While some clinicians may infer the presence of a biofilm because of presenting clinical characteristics as previously discussed, others may choose to culture the wound. However, wound swab results may be misleading as clinical microbiology laboratories use methods that select for planktonic bacteria or are not always suitable for culture of anaerobic


24


MOISTURE MANAGEMENT Malik et al[24]


identified excessive moisture


species, and the sampling technique may not capture bacteria protected within a biofilm. The result is often a negative or inconclusive culture report.[34]


presence of biofilm are required to assist the clinician in effective wound treatments. Evidence suggests the best method for obtaining a wound culture of planktonic bacteria is the Levin method.[35–7]


9


UNDERSTAND WHAT BIOFILMS REALLY MEAN FOR THE PATIENT


AND THEIR WOUND


The physical barrier of the exopolysaccharide shield protects bacteria in biofilms. Furthermore, bacteria in the biofilm – especially in the periphery – can down regulate their metabolism, making them less susceptible to antibiotics. Biofilms do release antigens that stimulate the production of antibodies, but these are incapable of killing the protected sessile bacteria and instead cause damage to surrounding tissues.[3] Thus, biofilms are highly inflammatory, constantly shedding bacteria onto the surface of the wound, exciting an immunological response, which causes tissue damage and maintains chronic inflammation; biofilms appear to “recur” despite repeated attempts at antibiotic therapy.


10


BE AWARE OF, AND KEEP UP-TO-DATE WITH THE


LATEST DEVELOPMENTS IN BIOFILM MANAGEMENT – THIS FIELD IS SET


FOR FUTURE INNOVATIONS Wound care clinicians are becoming increasingly convinced that biofilms play a key role in chronic nonhealing wounds.[38] Even when underlying causes are managed (e.g. plantar pressure redistribution in the treatment of neuropathic diabetic foot ulcers or oedema control with appropriate compression therapy in the treatment of venous disease) many wounds are difficult to heal and exhibit continuing or reoccurring signs of infection. Future developments may include: • Diagnostic tests to detect biofilm at the bedside


• A clearer understanding of strategies for debridement to disrupt biofilm


• Dressings that contain agents to disrupt biofilm


• Treatments that block biofilm formation through disruption of quorum sensing. n


Wounds International Vol 5 | Issue 2 | ©Wounds International 2014 | www.woundsinternational.com


Methods to rapidly detect the


Ten Top Tips


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