(CS-075) Fifty Shades of Red Fluorescence: What Bacterial Imaging of Subsurface and Periwound Tissues Can Tell Us

Carolina Wuesthoff, MD – Moleculight; Raymond Abdo, DPM – Geistler Family Foot Care Inc.; Misael Alonso, MD, FACP, CWSP, FAPWCA; Charles A. Andersen, MD, FACS, MAPWCA – Madigan Army Medical Center; Nathan Krehbiel, BNS, RN – Clinical Specialist, Moleculight Inc

Introduction: Red and cyan signals on fluorescence (FL) imaging* accurately detect and locate bacterial hotspots in and around the wound, regardless of clinical expression^1–4. The present study examines the color shades and nuances of FL-imaging that, once understood, reveal actionable information. Image interpretation is influenced by bacterial location which varies in depth (within the skin layers), and its distribution within tissue/wound types. This case series explores varying shades of red fluorescence and the impact of targeted treatments on the shades observed.

Methods:

In this multi-center, pre-and post-interventional, 20-wound case series, images were examined for change(s) in fluorescence shades pre-intervention (prior to alteration of wound’s components and/or tissue removal) and then after the intervention (cleansing, mechanical/sharp debridement, antibiotics). Images from the wound bed and periphery were included. Changes in locational and color tonality were recorded and noted for analysis.

Results:

Pre/post interventional image analysis revealed significant changes in bacterial burden, indicated by variable FL shades. Shades corresponded to varying depths at which bacterial loads were located within the wounds, e.g. callus tissue around DFUs appeared blush red or yellow pre-debridement (a mix of red and green [tissue] fluorescence signals), increasing in redness as layers of tissue were removed. Regarding bacterial spread, in some cases, +FL findings in the periwound and beyond were noted/treated for intact skin that was clinically inapparent (e.g. wound associated cellulitis⁵). Also, the ability to objectively assure complete bacterial removal through negative FL signals post-debridement contributed to the preservation of healthy tissue.

Discussion:

Accurate image interpretation is key to any diagnostic and its accuracy. Actionable bedside information results in targeted and timely treatment decisions. This study enlightens FL users on image interpretation nuances and approaches to FL-guided treatment which supports adequate and effective bacterial removal. Frequent and thorough treatments to reduce bacterial loads are needed to prevent/disrupt biofilm formation and improve healing rates^6–9. Herein, FL imaging detected bacterial hotspots in the peri-wound region and deeper within the tissues post-debridement, that would have been otherwise overlooked. Where aggressive debridement was not possible, other measures such as antimicrobial dressings and/or systemic antibiotics were incorporated. 

Trademarked Items: *Moleculight i:X, DX

References: Le L Briggs P Bullock N Cole W DiMarco D Hamil R Harrell K Jensen J Kasper M Li W Patel K Sabo M Thibodeaux K Serena T.E. BM. Diagnostic Accuracy of Point- of- Care Fluorescence Imaging for the Detection of Bacterial Burden in Wounds: Results from the 350-Patient FLAAG Trial. Adv Wound Care (New Rochelle). 2021;10(3):123-136.
2. Rennie MY, Lindvere-Teene L, Tapang K, Linden R. Point-of-care fluorescence imaging predicts the presence of pathogenic bacteria in wounds: a clinical study. J Wound Care. 2017;26(8):452-460. doi:10.12968/jowc.2017.26.8.452
3. Raizman R, Little W, Smith AC. Rapid Diagnosis of Pseudomonas aeruginosa in Wounds with Point-Of-Care Fluorescence Imaing. Diagnostics. 2021;11(2). doi:10.3390/DIAGNOSTICS11020280
4. Jones LM, Dunham D, Rennie MY, et al. In vitro detection of porphyrin-producing wound bacteria with real-time fluorescence imaging. Future Microbiol. 2020;15(5):319-332. doi:10.2217/fmb-2019-0279
5. Andersen CA, McLeod K, Steffan R. Diagnosis and treatment of the invasive extension of bacteria (cellulitis) from chronic wounds utilising point-of-care fluorescence imaging. Int Wound J. 2022;19(5):996-1008. doi:10.1111/IWJ.13696
6. Rahma S Brown S Nixon J Russell D WJ. The Use of Point-of-Care Bacterial Autofluorescence Imaging in the Management of Diabetic Foot Ulcers: A Pilot Randomized Controlled Trial. Diabetes Care. 2022;7(45):1601-1609. doi:doi: 10.2337/dc21-2218.
7. Moelleken M, Jockenhofer F, Benson S, Dissemond J. Prospective clinical study on the efficacy of bacterial removal with mechanical debridement in and around chronic leg ulcers assessed with fluorescence imaging. Int Wound J. Published online 2020. doi:10.1111/iwj.13345
8. Wilcox JR, Carter MJ, Covington S. Frequency of debridements and time to heal: a retrospective cohort study of 312 744 wounds. JAMA Dermatol. 2013;149(9):1050-1058. doi:10.1001/jamadermatol.2013.4960
9. Cole W, Coe S. Use of a bacterial fluorescence imaging system to target wound debridement and accelerate healing: a pilot study. J Wound Care. 2020;29(Sup7):S44-s52. doi:10.12968/jowc.2020.29.Sup7.S44