What You Should Know About Biofilms And Chronic Wounds

Guy Pupp, DPM, FACFAS, and Channa Williams, DPM

Biofilms reportedly cause an estimated 1 million nosocomial infections each year in the United States.1 Surgically, these microorganisms may cause abscesses, prosthetic failure and osteomyelitis. These complications may require surgical excision of the infected prosthesis and underlying soft tissue along with reconstruction of the affected part.
Understanding the nature of biofilms through research and clinical experience is key to providing the appropriate treatment. Moreover, such treatment and prevention may even lead to the eradication of serious, chronic illnesses and surgical complications.1
Biofilm may not be a familiar term but you have encountered it on a regular basis. The plaque that forms on teeth and causes decay is one type of biofilm. The “gunk” that clogs the drain is also biofilm. Biofilm forms when bacteria adhere to surfaces in moist environments by excreting a slimy, glue-like substance. Whenever you find a combination of moisture, nutrients and a surface, you are likely to find biofilms. Biofilms are held together by sugary molecular strands, collectively termed extracellular polymeric substances (EPS).
In order to understand the impact of chronic bacterial infection and host response, one must understand the nature of biofilms (see “A Closer Look At The Formation Of Biofilm” on page 50). These bacteria can be the source of various chronic diseases and increased mor- bidity. In surgical patients, they may cause latent infections that physicians see many weeks to months following a surgical procedure.1,2 Upon the initial treatment with antibiotics, the infection may respond. However, it may return at a later time despite a full course of antibiotic therapy. This is partly due to the natural composition of these bacteria, which allow them to develop drug resistance.1,2

Currently, there are no definitive methods for the diagnosis of a biofilm infection, except clinical suspicion and clinical presentation. Due to the lack of sound diagnostic technique, prevention of the infection is crucial.
Prophylactic prevention of biofilms is an important consideration for major podiatric surgical procedures. Advanced podiatric procedures, which require the use of prosthetic implants and biomaterials, such as stainless-steel pins used in external fixation frames, require judicious attention for the prevention of infection.These implants can be a source of biofilm infection. In fact, “pin tract infections in external fixation frames have been shown to occur in as much as 71 percent of patients.”1
Such complications often lead to osteomyelitis and possibly amputation of the affected part. Biofilm infection rates for orthopedic procedures, such as hip and knee replacements,“remain between 1 and 2 percent, and even higher for revisional surgical procedures.”1 These rates may or may not result from breaches in surgical aseptic technique.
Newer studies have indicated that treatment for these infections may involve local antibiotic therapy in addition to intravenous therapy. Current studies have also investigated natural treatments such as tea tree oil for biofilm infections involving the skin.1
Future treatment of biofilm infections may combine the use of prophylactic antibiotics and natural medications with surgical intervention.

What The Literature Reveals About Common Bacterial Biofilms
While some studies have isolated the most common microorganism (Staphylococcus epidermidis) that triggers biofilm infections, many other organisms have been isolated. Common bacteria found in biofilms include grampositive Enterococcus faecalis and Staphylococcus aureus. Gram-negative bacteria include Escherichia coli, Klebsiella pneumonia, Proteus mirabilis and Pseudomonas aeruginosa.1

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