How To Assess The Bacterial Burden Of DFUs

Guy Pupp, DPM, FACFAS, and Robert Koivunen, DPM

The presence of biofilm can complicate the treatment of chronic wounds. Accordingly, these authors survey the literature for physiological insights on biofilm development, discuss diagnostic challenges and emphasize judicious use of antibiotics to help ensure optimal outcomes.

Treatment of chronic skin ulcerations can pose significant problems for the clinician. In the United States, there are millions of patients who are affected with the attendant medical, financial and psychological impact of ulcers.1

   Up to 20 percent of people with diabetes will develop a diabetic foot ulcer in their lifetime. As the incidence of diagnosed diabetes rises, the number of diabetic foot ulcers continues to increase. It is estimated that the number of patients with diabetes will double in the United States by the year 2050 to approximately 48 million people.2 This would indicate that 9.6 million diabetic foot ulcers would require treatment.

   Many of these wounds would become chronic in spite of appropriate treatment. There are many contributing factors including metabolic factors, peripheral arterial disease, venous disease, neuropathy and/or deformity and trauma. A chronic wound is any wound that fails to proceed through an orderly and timely process to produce anatomical and functional integrity.3 Difficulty in the timely treatment of these chronic wounds can lead to infections, which open the pathway for amputation and life-threatening sepsis.1,4 The prolonged healing can be a financial burden on the healthcare system with an expenditure of over $25 billion a year in the United States.5

   The long-term healing associated with a chronic diabetic ulcer certainly affects a person’s quality of life. This can result in depression, social changes and financial loss due to decreased mobility and changes in lifestyle.6

   There have been many recent advances in wound care and wound healing modalities. Numerous studies have examined the treatment of diabetic foot ulcers with advanced modalities such as cultured human dermis, skin equivalents, recombinant human platelet-derived growth factors and advanced wound dressings.4,7-11

What You Should Know About Biofilms And Bacterial Burden

Any physiologic or metabolic factor that adversely affects the normal healing pathway can lead to a delayed, non-healing chronic wound. These wounds often develop bacterial contamination, which frequently goes unrecognized due to the lack of the cardinal signs of gross infection.12 This bacterial contamination in chronic wounds can lead to biofilm structures that develop a matrix that offers protection against the host defenses.13-15 Biofilms can adhere to either living tissue or inert substances such as implants, screws or plates.

   A biofilm is a polymicrobial collection of microorganisms that develop on the surface of chronic wounds. These microorganisms produce an extra-polymeric substance that contributes to the structure of the biofilm. This matrix forms a barrier around itself, making it difficult for antimicrobial agents to penetrate.

   The study of bacterial biofilms has gained increased attention in recent years due to the implication of biofilms in delayed chronic wound healing. Numerous studies have linked biofilms with infection with one study attributing biofilms to up to 80 percent of human infections.13,16,17 The study of biofilms is a relatively new field. There is no unanimous method of diagnosis nor do we know the most effective treatment.

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