Wound biofilm

Biofilms are communities of microbes that attach to and grow on surfaces (tooth plaque is the best-known example).

Biofilms also grow in chronic wounds and in some cases delay healing.

Biofilms are formed by microbes; mainly bacteria that are firmly embedded in the wound and encapsulated in a matrix which contains host material which makes treatment and dispersal problematic.

The microbes in a biofilm are protected from the patient’s immune system and antimicrobial agents such as antiseptics and antibiotics in 2 ways:

  • By the barrier formed by the protective coating
  • By becoming inactive or going to sleep (bacteria need to be active or awake to be susceptible to antibiotics)

Signs and symptoms of wound biofilm:

  • The absence of healing progression, even though all obvious comorbidities and wound management issues have been addressed
  • Visible, slimy gel-like shiny material on the surface of the wound bed which detaches easily and atraumatically from the wound bed
  • Re-forming of slough quickly, despite debridement
  • Poor quality granulation tissue – possibly fragile and hyper granulation
  • Signs of local infection
  • Failure to respond to antibiotic therapy
  • Increased exudate/ moisture level
  • Failure to respond to antiseptic treatment
  • Inconclusive or negative wound culture
  • It is reasonable to suspect a biofilm is causing a problem in chronic wounds that have not reduced in area by 40% after 4 weeks optimal standard care for the wound type that includes management of comorbidities or other relevant factors
  • Biofilms cannot be seen with the naked eye

Currently, there are no easy tests to detect biofilm in a wound and no tests to show when a wound biofilm is causing a problem. If the patient has received appropriate management for a chronic wound but the wound is slow to heal, it is logical to suspect that a biofilm is causing healing problems.

Reducing biofilm in chronic wounds

  • Repeatedly breaking up and removing the biofilm through vigorous/ active cleansing and or debridement
  • Reducing biofilm formation by decreasing the number of bacteria left in the wound through the use of an antimicrobial dressing or topical antiseptic preparation between each session of biofilm removal