Microscopy visualisation confirms multi-species biofilms are ubiquitous in diabetic foot ulcers

Increasing evidence within the literature has identified the presence of biofilms in chronic wounds and proposed that they contribute to delayed wound healing. Malone and colleagues aimed to investigate the presence of biofilm in diabetic foot ulcers (DFUs) using microscopy and molecular approaches and define if biofilms were present in both infected DFUs and chronic non-healing DFUs.

Sixty-five consecutive patients were enrolled in the study making it the largest single source of evidence within the literature. The results identified that 65 DFU specimens evaluated by microscopy, were all characterised as containing biofilm (100%, P < 0·001), but this is no surprise as the authors enrolled diabetic foot ulcers that were problematic (i.e infected or non-healing). Clinical cues to aid clinicians in detecting wound biofilm were also not accurate for use in DFUs suggesting clinicians should not rely on clinical cues such as the presence of slough or gelatin material covering a wound.

The paper does raise an important question, whether or not biofilms serve as a nidus of infection for seeding planktonic bacteria which are responsible for causing acute infection. If there is a causal link between biofilms acting as a nidus, it may explain in some circumstances why chronic diabetic foot infections often require prolonged antimicrobial therapy. Further work continues on this interesting area.