Clinical Observation Biofilm Explanations for Clinical Observation
Excessive moisture associated with wound Bacteria in biofilms secrete extracellular matrix and biofilm presence promotes inflammation, resulting in increased exudate.
Autograft or allograft fails on wounds Applying tissue grafts over biofilms provides a second growth surface and food source, leading to devitalization of graft tissue and increased exudate and inflammation.
Poor quality granulation tissue (e.g. hypergranular, friable) Biofilm presence contributes to delayed epithelialization and is frequently associated with poor quality granulation tissue.
Indications of local infection (swelling, sensitivity, redness, heat) Biofilms promote inflammation and may be a precursor to other clinical indications of infection.
History of persistent or recurrent infection despite antimicrobial therapy Biofilm bacterial phenotypes adapt rapidly and may only demonstrate 1 to 2 log reduction with antibiotic therapy at 50 to 1000x MIC. Biofilms contain persister cells that remain once antibiotic therapy is discontinued, seeding, and contributing to subsequent biofilm reformation.
Negative culture results despite clinical suspicion of infection or signs of bacterial colonization Biofilm bacteria metabolize more slowly and are phenotypically different than planktonic bacteria. Standard microbiological culture techniques are not capable of identifying all species present, making bacteria in biofilms difficult or impossible to identify by culture.
Wound remains in chronic inflammatory state and recalcitrant to therapy despite addressing comorbities Biofilms are resistant to host inflammatory responses and actually feed off exudate produced by inflammation, further promoting inflammation.