The presence of biofilm in wounds makes wound care increasingly complex, and dressings need to be designed to penetrate through biofilm.
Emerging dressings used in wound care will have to address biofilm in order to achieve effective wound healing.
"It's very hard to treat the biofilm component of a wound," says Randall Wolcott M.D., founder and medical director, Regional Wound Care Center in Lubbock, Texas. "There is no quick way to identify biofilm. Cultures are limited in how they help us in wound care. There are no hard and fast rules, but you can look for signs like exudate and odor. Acute infections usually don't give off volatile gases," he adds.
Biofilm behaves differently than planktonic bacteria, which is associated with acute infection, Dr. Wolcott explains.
"They are different phenotypes," Dr. Wolcott says. "When you treat, you should treat both (planktonic bacteria and biofilm). Biofilm attaches and inflames the tissue in the host environment, and it uses plasma to nourish itself."
Indeed, biofilm is a significant factor in the failure of a sore to heal as biofilm is highly organized and its protects bacteria from antibiotic therapy and a patient's immune response.
Addressing biofilm improves health and reduces health-care costs in medical practice, Dr. Wolcott says. In the United States, chronic wounds affect 6.5 million patients. More than US$25 billion is estimated to be dedicated to the treatment of chronic wounds, and that cost is growing with increasing health care costs, an aging population, and a steep climb in the incidence of diabetes and obesity worldwide. Wound Repair and Regeneration. 2009;17(6):763-771.
A dressing needs to contain components to allow the physical disruption of biofilm, Dr. Wolcott explains.
"There needs to be a synergy between the components in the dressing," Dr. Wolcott says. "If you use too many components, they may neutralize each other. The synergy between the components dissolves the matrix and opens up the bacteria to other components."
The formulation of wound care dressings that tackle biofilm are based on principles of allowing the antimicrobial agent to more effectively penetrate through the biofilm to kill cells, Dr. Wolcott explains, noting in some designs that includes a chelating agent.
The efficacy of a dressing can make the difference between a patient losing or salvaging a limb, according to Dr. Wolcott. "If we save a limb, we can save a life," Dr. Wolcott says.
A retrospective, cohort study that looked at mortality rate after a first lower limb amputation found nearly one quarter of people died within 30 days after a first lower limb amputation and almost half at one year. European Journal ofVascular and Endovascular Surgery. 2013 Jul;46(1):124-31.
Speaking about research into new antimicrobial dressings at the recent meeting of the Canadian Association of Wound Care here, Phil Bowler, Vice-President, Science & Technology, ConvaTec, agrees that biofilm is not going away and is a serious threat to medicine.
"It's a major problem in medicine that is not limited to wound care," says Bowler. "It is not new, but the recognition of biofilm involvement in infectious diseases is fairly new. It is involved, for example, in urinary tract infections, periodontal disease, and otitis media. Biofilm is so difficult to manage because it is tolerant to antimicrobial agents and leads to chronicity."
To address biofilm, wound bed preparation is vital to successful wound healing, says Bowler.
"Wound bed preparation is important through debridement and cleansing, giving the wound the best chance to heal," says Bowler. "That preparation can involve physical techniques like sharp debridement and appropriate antimicrobial strategies. These are wounds that are 'stuck' and are not healing."
Future strategies may involve combination technologies where anti-biofilm agents help to maximize the efficacy of antimicrobial agents such as antibiotics and antiseptics.
ConvaTec has recently developed a dressing designed to manage the local wound environment and also break down wound biofilm, which is approved for use in the European Union and in Canada. ConvaTec is seeking clearance of such a dressing by the US Food and Drug Administration for use in the United States.
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