Real-time bacterial fluorescence imaging accurately identifies wounds with moderate-to-heavy bacterial burden

Abstract

Objective: Clinical evaluation of signs and symptoms (CSS) of infection is imperative to the diagnostic process. However, patients with heavily colonised and infected wounds are often asymptomatic, leading to poor diagnostic accuracy. Point-of-care fluorescence imaging rapidly provides information on the presence and location of bacteria. This clinical trial (#NCT03540004) aimed to evaluate diagnostic accuracy when bacterial fluorescence imaging was used in combination with CSS for identifying wounds with moderate-to-heavy bacterial loads. Methods: Wounds were assessed by study clinicians using NERDS and STONEES CSS criteria to determine the presence or absence of moderate-to-heavy bacterial loads, after which the clinician prescribed and reported a detailed treatment plan. Only then were fluorescence images of the wound acquired, bacterial fluorescence determined to be present or absent and treatment plan adjusted if necessary. Results: We examined 17 VLUs/2 DFUs. Compared with CSS alone, use of bacterial fluorescence imaging in combination with CSS significantly improved sensitivity (22% versus 72%) and accuracy (26% versus 74%) for identifying wounds with moderate-to-heavy bacterial loads (≥104 CFU/g, p=0.002). Clinicians reported added value of fluorescence images in >90% of study wounds, including identification of wounds incorrectly diagnosed by CSS (47% of study wounds) and treatment plan modifications guided by fluorescence (73% of study wounds). Modifications included image-guided cleaning, treatment selection, debridement and antimicrobial stewardship. Conclusion: Findings from this pilot study suggest that when used in combination with CSS, bacterial fluorescence may: (1) improve the diagnostic accuracy of identifying patients with wounds containing moderate-to-heavy bacterial loads and (2) guide more timely and appropriate treatment decisions at the point-of-care.

Use of a bacterial fluorescence imaging device: wound measurement, bacterial detection and targeted debridement

“…The current standard of care for bacterial assessment of a wound is made from subjective assessment metrics, for example swelling, odour, redness, heat, pain, all of which are host responses to high bacterial loads that vary from patient to patient. These clinical signs and symptoms have a poor predictive value 20, 21 and poor sensitivity 15,20,21 for the detection of high levels of bacteria and infection, yet they are relied upon routinely to guide decisions on where to sample, antimicrobial/antibiotic usage and the level and location of debridement. This problem is compounded in centres where patient wounds are treated by staff inexperienced with wound assessment and with little or insufficient training in complex wound care.…”

“…Diagnostic tools can standardise care by providing objective assessment information between centres and between care providers. Multisite clinical trials with the bacterial-fluorescence imaging device, in combination with clinical signs and symptoms assessment, have increased the sensitivity for detection of moderate-to-heavy bacterial loads by three to fourfold, across multiple wound types, 15,27 facilitating evidence-based treatment decisions.…”

“…The MolecuLight i:X imaging device is a novel, handheld, point-of-care diagnostic imaging tool designed to accurately and digitally measure wound areas and to provide objective, real-time evidence on the presence and location of high bacterial loads (both planktonic and in biofilm. [11][12][13][14][15][16] This provides objective documentation, performed at the bedside, during which the device captures an image in a format compatible with most electronic medical records (EMR) systems. The device contains built-in digital wound measurement software and emits a safe violet light which is used for non-invasive, contrast agent free fluorescence imaging to identify regions with concerning levels of bacteria in real-time.…”

“…This trial further documented the high prevalence of bacterial fluorescence in the general wound population, which is vastly underestimated by standard of care clinical signs and symptoms assessment. 15,20,21 Lastly, bacterial fluorescence imaging was used to assess pre-and post-debridement bioburden, and to inform and document when there is a need for additional and more targeted debridement to remove bacteria-burdened tissues. This compilation of work demonstrates that the bacterial fluorescence imaging device can be readily and reproducibly implemented for real-time, point-of-care wound assessment to improve wound documentation and targeted treatment in the clinical setting.…”

Incorporating Point-of-Care Bacterial Fluorescence into a Wound Clinic Antimicrobial Stewardship Program

“…There is a robust body of evidence suggesting that bacterial loads at this level or greater inhibit wound healing 19 . Studies have reported high sensitivity and specificity of MLiX in detecting bacterial fluorescence in a variety of wounds including diabetic foot ulcers, venous leg ulcers, pressure ulcers, burns and surgical and trauma wounds 13,14,[18][19][20][21][22] . Information provided by fluorescence imaging on the presence and location of bacteria at loads >10 4 CFU/g is used to target cleaning, debridement, and appropriate deployment of antimicrobials 14,18 .…”