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Bacterial Fluorescence Imaging

• When excited by 405 nm violet light, tissues fluoresce green while bacteria fluoresce red (porphyrin-producers) or cyan (pyoverdine-producing Pseudomonas aeruginosa)

Patient Populations and Image Analysis

Traumatic tissue damage:• 16 consented patients with traumatic tissue damage (primarily burn

wounds) were imaged for bacterial fluorescence during routine wound care and correlative microbiology swabs obtained (Queen Elizabeth Hospital, Birmingham, UK).

Chronic Ulcers: • 41 consented patients with 63 venous/lymphedema ulcers, seen through

an ambulatory hospital and community clinic (Guelph General Hospital, Ontario, Canada), were prospectively assessed pre- and post- curettage debridement using a point of care autofluorescence imaging device to detect the presence of bacteria in the wound.

• The wounds were stratified pre- and post-debridement by the intensity of their red fluorescence: 0 (none), +1 (light blush), +2 (bright, distinct), +3 (bright, confluent).

METHODS

INTRODUCTION RESULTS: CHRONIC ULCERSRESULTS: TRAUMA CONCLUSIONS

REFERENCES

No Red (Bacterial) Fluorescence Observed

No fluorescence pre debridement (0)

Bright/confluent (3) Light blush (1)

None (0) Bright/distinct(2)

Bright/distinct (2) Bright/distinct (2)

• Bacterial colonization leading to chronic wounds continues to burden patients and healthcare systems. Real-time, point-of-care detection of critical colonization relies primarily on visual inspection of wounds and clinical signs and symptoms, which are subjective and suboptimal.

• Fluorescence imaging of wounds in this study with the MolecuLight i:X imaging device, in addition to current best clinical practices, guided sampling locations, debridement, and the timing of wound therapies.

• Fluorescence images demonstrated persistence of bacteria in chronic wound (venous leg ulcer) patients even after ‘gold standard’ sharp debridement.

• Fluorescence images of large, traumatic soft tissue wounds allowed for targeted swabbing to precise regions of red or cyan fluorescence, reducing change of false negative results, and allowed for confident deployment of appropriate therapies in real time (e.g. skin grafts, negative pressure wound therapy).

• These two patient populations demonstrate the utility of bacterial fluorescence imaging, which may be used in conjunction with current best practices to improve wound management and permit wound care patients the best chance of healing.

Fluorescence imaging targets swabbing to region of bioburden

Standard Imaging Mode Fluorescence Imaging Mode

85-year-old male suffered deep dermal and full thickness contact burns to the right axilla, forearm, and scapula. Swabs taken from exudate in

days prior to imaging were negative. Fluorescence images revealed red fluorescence on outlying tissue, not on exudate, guiding targeted

swabbing of the red region.

Swabs confirmed growth of Staphylococcus aureus and E. coli.

1. Bowler PG et al, Wound microbiology and associated approaches to wound management. Clinical Microbiology, 2001.

2. Landis SJ, Determining the effectiveness of sharp debridement using wound/periwound bacterial auto-fluorescence imaging, Symposium on Advanced Wound Care, Atlanta, Ga., USA, 2016

3. DaCosta RS et al. Point-of-Care Auto-fluorescence Imaging for Real-Time Sampling and Treatment Guidance of Bioburden in Chronic Wounds: First-in-Human Results, PLoS ONE 10(3): e0116623.doi:10.1371/journal.pone.0116623

• Damage to skin and soft tissue, whether by traumatic means or chronic ulceration, allows for opportunistic pathogens to complicate and impede the normal course of healing and repair [1,2].

• The diagnosis of microbial infection in a wound, based on common clinical signs and symptoms is difficult, as there is no gold standard to predict bacterial activity in tissue and bacteria are invisible to the unaided eye.

• Fluorescence imaging has recently been used to visualize clinically significant levels of pathogenic bacteria in real-time at the bedside using a non-contact hand held device [3].

• We report the use a fluorescence imaging device, MolecuLight i:X, in detecting the presence or absence of bacteria in two patient populations.

The MolecuLight i:X™ Imaging Device is approved by Health Canada (Medical License #95784) and has CE marking (Certificate #G1160292355002) for sale in the European Union. US FDA De Novo approval pending - the MolecuLight i:X™ Imaging Device is not available in the US.

Use of Fluorescence Imaging in Visualizing Bacteria in Chronic Ulcers & Traumatic Soft Tissue Damage

Stephan Landis, MD, FRCP(C) 1, Monique Y. Rennie, PhD2, Emily Blumenthal, RN3, Lt Col SLA Jeffrey, RAMC3,4

1Guelph General Hospital (Ontario, Canada), 2MolecuLight Inc, 3Queen Elizabeth Hospital (Birmingham, UK), and 4The Royal Centre for Defence Medicine (UK)

• Of the 20 patients imaged, 4 did not have bacterial contamination based on fluorescent images and confirmed via swabs. 16 patients exhibited fluorescence indicative of pathogenic bacteria. Details of three cases are discussed here.

exudate

exudate

Red fluorescence

Fluorescence allows for confidence when skin grafting

Standard Imaging Mode Fluorescence Imaging Mode

Bacterial Fluorescence Detection of Pseudomonas aeruginosa

Standard Imaging Mode Fluorescence Imaging Mode

32-year-old male suffered purpura fulminans following streptococcal septicaemia, affecting 50% of his total body surface area. Fluorescence

images revealed small pockets of P. aeruginosa colonization (cyan, arrows), enabling swabs to be taken from these specific regions.

Swabs confirmed heavy growth of Pseudomonas aeruginosa.

58 year old man suffered deep burns down to the bone on right leg. Fluorescence images were acquired to determine whether region was a

candidate for skin grafting (contraindicated when bioburden present). No fluorescence signals that would suggest bacterial presence were found.

Swabs confirmed no growth of bacteria.

• 63 VLU/lymphedema wounds were stratified based on the change in their bacterial fluorescence from pre to post debridement. Four categories emerged.

No fluorescence post debridement (0)

30/63 wounds (48%) had no bacterial fluorescence both prior to and post debridement.

Red Fluorescence Reduced Post Debridement

Surprisingly, only 12/63 (19%) of wounds exhibited pre-debridement red fluorescence and had reduced red fluorescence after

debridement..

Persistent/Unchanged Red Fluorescence Post Debridement

15/63(23%) of wounds exhibited persistence or unchanged red fluorescence after debridement..

Red Fluorescence Increased Post Debridement

6/63 (10%) of wounds exhibited increased red fluorescence after debridement. This was likely due to deep residing bacteria being

revealed after overlying tissue was debrided away.