The Association of Bacterial Autofluorescence Signals with Healing Outcomes in Diabetic Foot Ulcers

Introduction: Diabetic foot ulcers (DFUs) represent a significant human and economic burden to the healthcare system. Bacterial infections amplify the cost-to-treat, and thus proactive infection management lessens this burden. However, patients with DFUs frequently fail to mount clinical signs of bacterial infection; one study found that only 12% of DFU containing bacterial loads >108 CFU/g appeared to be clinically infected1. Fluorescence imaging devices* are bedside tools that objectively detect bacterial loads >104 CFU/g with high sensitivity (93% at 108 CFU/g in DFUs1). Clinical evidence suggests that the bacterial fluorescence signals may be associated with healing outcomes in DFUs.Methods:We present a scoping review of peer-reviewed, clinical evidence reporting on the association of autofluorescence signals and DFU outcomes – specifically incidence of delayed healing, complete wound closure, and wound area reduction. Case series and studies with mixed wound types were excluded from this review. We also present herein a small case series reporting on fluorescence imaging findings in DFUs and their healing progression over time. Results:After searching the PubMed/Embase and CINAL databases, we identified only 3 prospective, peer-reviewed studies (209 DFUs total) that reported on the association of bacterial fluorescence signals and DFU outcomes. All these studies were in favor of an association between bacterial fluorescence signals and DFUs healing outcomes, however they failed to control for confounding factors. The clinical cases presented demonstrate fluorescence detection of covert chronic inhibitory bacterial load (CIBL) in DFUs that enabled proactive infection management for positive healing outcomes.Discussion: We identified some clinical evidence supporting the association of bacterial fluorescence signals with DFU healing outcomes, however several limitations were identified in the studies’ design/analysis. Given the ability of objective, predictive diagnostics to support proactive DFU infection management, there is a need for additional well-designed, prospective studies aimed at exploring this association specifically.References:1 Armstrong DG, Edmonds ME, Serena TE. Point-of-care fluorescence imaging reveals extent of bacterial load in diabetic foot ulcers. Int Wound J. 2023 Feb;20(2):554-566. doi: 10.1111/iwj.14080.