Point-of-care fluorescence imaging predicts the presence of pathogenic bacteria in wounds: a clinical study

Diagnostic value of a point of care bacterial fluorescence imaging device for detecting wound infections in dogs and cats

OBJECTIVE

To determine if a hand-held point of care imaging device would improve the detection of bacteria on the surface of wounds in dogs and cats in postoperative and traumatic wounds.

STUDY DESIGN

Clinical prospective study.

SAMPLE POPULATION

Three cats and 15 dogs.

METHODS

Wounds were swabbed without and with the point of care wound imaging device (WID). Quantitative bacterial culture (QBC), polymerase chain reaction (PCR) and microbiome analysis were performed to assess for any significant difference in the findings of image-guided and non-guided sampling methods.

RESULTS

A total of four feline and 17 canine wounds were evaluated. Bacterial fluorescence was detected in all wounds using the point of care WID. Bacterial infections of wounds in dogs and cats was detected by the fluorescent imaging device. No significant difference was identified between the results of QBC and PCR for image-guided and non-guided wound swabs (p > .05).

CONCLUSION

The WID was able to detect bacteria on the surface of wounds in dogs and cats, accurately confirming the presence of a clinically relevant wound infection at the time of wound evaluation in all wounds but there was no significant difference in the bacterial yield with guided and non-guided swabs.

CLINICAL SIGNIFICANCE

The WID device was able to confirm the presence of a clinically relevant wound infection in real-time, enabling the clinician to initiate appropriate systemic and/or topical antibacterial treatment immediately. This study provides proof of concept of the point of care WID in dogs and cats upon which further studies can be based.

Modelling the effects of temperature, pH and osmotic shifts on the autofluorescence of Staphylococcus aureus in vitro

AIMS

This study aims to investigate how different wound microenvironmental factors (temperature, pH, and osmotic pressure) influence the autofluorescence of Staphylococcus aureus (S. aureus) and its underlying molecular mechanisms, specifically focusing on the porphobilinogen synthase gene (hemB) gene expression.

METHODS

We measured the average fluorescence intensity of S. aureus colonies under varying conditions of pH (3, 5, 7, 9, 11), temperature (25°C, 31°C, 37°C, 43°C), and osmotic pressure (0.9%, 1.8%, 2.7%, 3.6%) over time. Fluorescence intensity was quantified using ImageJ software. Additionally, RT-qPCR was used to analyze the expression levels of the hemB under these conditions.

RESULTS

Bacterial fluorescence intensity increased as the temperature ranged from 25°C to 43°C, with corresponding upregulation of hemB expression. At pH values between 3 and 11, fluorescence intensity decreased as pH increased, reflecting a similar trend in hemB expression. Fluorescence also diminished with higher osmotic pressures (0.9% to 3.6%), mirroring the downregulation of hemB.

CONCLUSIONS

Our findings indicate that temperature, pH, and osmotic pressure significantly affect the autofluorescence of S. aureus by modulating porphyrin accumulation through hemB gene expression. These environmental factors should be considered when using bacterial fluorescence for wound infection assessment.

Prospective evaluation of the Moleculight i:X™ in the early detection of driveline infections

OBJECTIVES

Driveline infection (DLI) is a common complication in patients with left ventricular assist devices. This complication can seriously undermine quality of life while on left ventricular assist devices. Current diagnosis of a DLI in the outpatient setting is based on clinical examination and later bacteria isolation. The Moleculight i:XTM is a handheld fluorescence imaging device capable to visualize bacterial colonization in real-time. We here evaluated the performance of the Moleculight i:XTM for diagnosis of DLIs as this device may have the potential advantage to rapidly identify infection and therefore promptly influence therapy.

METHODS

A total of 107 examinations in patients with suspected DLIs were prospectively included in this study. All examinations took place in the outpatient setting. In addition to the standard treatment, Moleculight fluorescence images were captured and swabs were taken at the area of maximal luminosity. Wounds and pictures were reviewed and classified as positive or negative by a wound specialist and two heart surgeons independently from microbiological results.

RESULTS

The Moleculight i:XTM showed positive results (red fluorescence) in 19 cases (17.76%), whereas microbiological examination was positive for microorganisms in 74 cases (69.16%). The most common bacteria was Staphylococcus aureus. The findings resulted in a sensitivity of 13.51% and a specificity of 72.73%. The positive predictive value was 52.63% and the negative predictive value was 27.27%. Sub-analyses of different wound dressings or previous antibiotic treatment did not show any relevant difference.

CONCLUSIONS

The results of the Moleculight i:X show a low sensitivity and specificity when being used to detect DLIs in the outpatient setting. Clinical examination and swabs should remain the gold standard despite the delay for bacteria isolation and consequent antibiotic treatment. Sensitivity and specificity of the Moleculight i:X in open wounds after surgical revision of the driveline remain to be clarified.

Development of an experimental heterogeneous burn wound model

BACKGROUND

Many research-based burn models rely on creating homogenous burns that are subsequently studied and treated. However, the majority of burn wounds sustained - and in particular those that are combat-related - are heterogeneous in nature, with varying degrees of severity intermixed throughout the entire wound, creating a complex debridement and overall treatment plan. The purpose of this study was to develop a clinically relevant heterogeneous porcine burn wound model.

MATERIALS AND METHODS

This study consisted of 3 anesthetized pigs with up to 6 heterogeneous 10 cm x 10 cm burn wounds. The burns were created using a thermocouple device with a square plate (5 cm x 5 cm) heated to 100 °C applied to the skin at constant pressure. The device was applied for a duration between 2-20 s for each burn segment to create burns of varying severity (superficial, partial-thickness, and full-thickness). Each heterogeneous burn wound consisted of 4 separate 5 cm x 5 cm burns, each with different and randomized burn times. Macroscopic images of the burns were obtained on days 0, 1, and 3. A punch biopsy was collected from each burn segment (1 of each depth) to determine the burn depth on day 0. On day 3, after euthanasia, all of the burns were harvested to give a cross-sectional view of the burn.

RESULTS

Histology demonstrated that heterogeneous burns were created and burn progression was evident during the 3-day follow-up time. The depth of the burn wound significantly correlated with the burn time. By day 3, the 20-second burn wound had the deepest depth at 1003 ± 67 µm while the 2-second burn wound had the shallowest depth of burn at 258 ± 19 µm. Burn heterogeneity was also demonstrated with laser speckle image analysis. By day 3, the superficial blood flow for 20, 15, 12, 9, and 6 s burn times was below 85 AU. The 2 s burn mean flux (138 ± 48 AU) was noticeably different from other groups and well above the intact skin values (102 ± 4 AU). It was also shown that on day 3, at least 1 burn for each burn time resulted in identifiable infection via macroscopic imaging.

CONCLUSIONS

The heterogeneity of burn wounds creates a clinical challenge. This model will help to create burns that are more similar to the heterogeneous burn wounds that are seen in clinical practice and will help further research efforts in treating burns.

Effects of adjuvant hyperbaric oxygen therapy and real-time fluorescent imaging on deep sternal wound infection: a retrospective study

OBJECTIVE

Deep sternal wound infection (DSWI) is a rare but devastating complication that is estimated to occur in 1-2% of patients after median sternotomy. Current standard of care (SoC) comprises antibiotics, debridement and negative pressure wound therapy (NPWT). Hyperbaric oxygen therapy (HBOT) appears to be an effective adjuvant therapy for osteomyelitis. The aim of this study was to determine the effectiveness of HBOT and real-time fluorescence imaging (RTFI) in a DSWI treatment protocol and their benefits on infection control.

METHOD

A retrospective analysis of DSWI management was performed. Enrolled patients were divided into two groups: HBOT group and RTFI group. Patients in the HBOT group received SoC, HBOT, NPWT and reconstructive flap surgery. Patients in the RTFI group received the same therapeutic plan as well as treatment with a RTFI device (MolecuLight i:X (MolecuLight, Inc., Canada) to achieve high-quality debridement. Infection status and short-term outcomes within three months were measured. Long-term outcomes were analysed at a 12-month follow-up.

RESULTS

Of the 55 patients enrolled: 22 in the HBOT group and 33 in the RTFI group. Infection control status, evaluated in terms of white blood cell counts and C-reactive protein levels, antibiotic use duration, antibiotic costs, reinfection rate and osteomyelitis recurrence rate, were statistically significantly improved in the RTFI group (<0.001, <0.001, 0.042, 0.022, 0.049 and 0.022, respectively). Length of total intensive care unit stay and duration of complete healing were statistically significantly decreased in the RTFI group (<0.001 and 0.046, respectively).

CONCLUSION

Patients with DSWI can benefit from HBOT, especially in terms of in-hospital mortality. RTFI can be used to eliminate bacterial burden and achieve high-quality debridement, which considerably improves infection control and clinical outcomes.

Assessing Biofilm at the Bedside: Exploring Reliable Accessible Biofilm Detection Methods

INTRODUCTION

Biofilm is linked through a variety of mechanisms to the pathogenesis of chronic wounds. However, accurate biofilm detection is challenging, demanding highly specialized and technically complex methods rendering it unapplicable for most clinical settings. This study evaluated promising methods of bedside biofilm localization, fluorescence imaging of wound bacterial loads, and biofilm blotting by comparing their performance against validation scanning electron microscopy (SEM).

METHODS

In this clinical trial, 40 chronic hard-to-heal wounds underwent the following assessments: (1) clinical signs of biofilm (CSB), (2) biofilm blotting, (3) fluorescence imaging for localizing bacterial loads, wound scraping taken for (4) SEM to confirm matrix encased bacteria (biofilm), and (5) PCR (Polymerase Chain Reaction) and NGS (Next Generation Sequencing) to determine absolute bacterial load and species present. We used a combination of SEM and PCR microbiology to calculate the diagnostic accuracy measures of the CSB, biofilm blotting assay, and fluorescence imaging.

RESULTS

Study data demonstrate that 62.5% of wounds were identified as biofilm-positive based on SEM and microbiological assessment. By employing this method to determine the gold truth, and thus calculate accuracy measures for all methods, fluorescence imaging demonstrated superior sensitivity (84%) and accuracy (63%) compared to CSB (sensitivity 44% and accuracy 43%) and biofilm blotting (sensitivity 24% and accuracy 40%). Biofilm blotting exhibited the highest specificity (64%), albeit with lower sensitivity and accuracy. Using SEM alone as the validation method slightly altered the results, but all trends held constant.

DISCUSSION

This trial provides the first comparative assessment of bedside methods for wound biofilm detection. We report the diagnostic accuracy measures of these more feasibly implementable methods versus laboratory-based SEM. Fluorescence imaging showed the greatest number of true positives (highest sensitivity), which is clinically relevant and provides assurance that no pathogenic bacteria will be missed. It effectively alerted regions of biofilm at the point-of-care with greater accuracy than standard clinical assessment (CSB) or biofilm blotting paper, providing actionable information that will likely translate into enhanced therapeutic approaches and better patient outcomes.

Bacterial fluorescence imaging as a predictor of skin graft integration in burn wounds

BACKGROUND

Split-thickness skin graft (STSG)1 integration rates are susceptible to improvement. Infection and/or biofilm should be appropriately addressed prior to grafting to improve the likelihood of graft-take. Incorporating technological aids such as fluorescence (FL)2 imaging (MolecuLight®), which accurately locates areas of bacterial loads above 104 CFU/gr, for graft site assessment and preparation could yield better outcomes.

METHODS

This single-center, prospective observational study included adult burn patients with previously infected wounds that had been deemed clinically and microbiologically clean and were therefore candidates for grafting. Prior to grafting, a FL imaging assessment (blinded to the surgical team) localized areas positive for moderate-high bacterial loads (>104 CFU/gr). Intra-operatively, a standard swab sample from the recipient site was collected by the surgical team. Postoperatively, areas positive/negative for FL and areas of graft take and failure were overlapped and measured (cm2) over a 2D schematic. The performance and accuracy of FL imaging and swab sampling in relation to graft outcomes were assessed.

RESULTS

38 patients were enrolled in the study. The mean total body surface area (TBSA)3 involvement was 14.5 ± 12.4 % [range 0.8 - 40.2 %]. 25/38 of the subjects enrolled had complete graft take while 13 had partial graft losses. There were no total losses. FL-imaging was positive in 100 % of losses versus 31 % (4/13) of the swab microbiology. FL-imaging was found to have a sensitivity of 86 %, specificity of 98 %, PPV of 72 %, NPV of 99 %, and an accuracy of 94 % for predicting any type or range of graft loss in the entire cohort. Meanwhile, the sensitivity of microbiology from swab samples was 30 %, with a specificity of 76 %.

CONCLUSIONS

FL imaging is an accurate method for assessing recipient sites and predicting the outcome of a skin graft among burn patients. These findings suggest that FL imaging can inform better decision-making surrounding grafts that may lead to better outcomes.

LEVEL OF EVIDENCE

Level IIA, Therapeutic study.

Assessing Pediatric Burn Wound Infection Using a Point-of-Care Fluorescence Imaging Device

Wound infection is the most common complication among pediatric burn patients. When not treated promptly, burn wound infection may lead to delayed healing, failure of skin grafts, or death. Standard burn wound assessment includes inspection for visual signs and symptoms of infection (VSSI) and microbial sampling. To aid in the assessment of burn wound infection, the MolecuLight, a point-of-care autofluorescence imaging device, was introduced at our pediatric burn program in 2020. The MolecuLight uses violet light to illuminate the wound bed, causing clinically relevant quantities of 29 different species of bacteria (>104 CFU/g) to fluoresce in real time. The objectives of this study were to evaluate the role of the MolecuLight in the management of pediatric burn wounds and determine if the findings from the MolecuLight corresponded to VSSI and/or microbial sampling. A retrospective review of patients 0-18 years who had burn wounds assessed with the MolecuLight between November 1, 2020 and June 8, 2023 was conducted. Data were extracted from the medical records of 178 eligible patients with 218 wounds imaged with the device. Fluorescence corresponded with VSSI in 81% of wounds and microbial findings in 82% of wounds. MolecuLight fluorescence, in combination with VSSI, improved sensitivity for detecting wound infections by 39% and decreased specificity by 19% compared to visual signs and symptoms in isolation. Incorporation of the MolecuLight in standard burn wound assessments can improve the detection of infections, which may promote improved wound healing outcomes and antimicrobial stewardship.

Determination of the Course of Cyan Fluorescence of Pseudomonas aeruginosa with a Handheld Bacterial Imaging Device

Chronic wound infections are of clinical concern as they often lead to high rates of mortality and morbidity. A point-of-care handheld bacterial fluorescence imaging has been designed to detect the auto-fluorescent characteristics of most clinically relevant species of bacteria. This device causes most species of bacteria to exhibit red fluorescence due to the production of exoproduct porphyrins. One of the most significant contributors to the pathogenicity of chronic wounds is the pathogen Pseudomonas aeruginosa, and interestingly, this organism exhibits an additional unique cyan fluorescence signature. There is an over 90% positive predictive value that, when a chronic wound exhibits cyan fluorescence with the bacterial fluorescence imaging device, the wound will harbor P. aeruginosa. This project seeks to understand what genetic factor(s) contribute to the cyan phenotype observed.

How effective is simple mechanical wound debridement in reducing bacterial colonisation? Results of a prospective clinical study

BACKGROUND AND AIMS

Bacteria in wounds can lead to stagnation of wound healing as well as to local or even systemic wound infections up to potentially lethal sepsis. Consequently, the bacterial load should be reduced as part of wound treatment. Therefore, the efficacy of simple mechanical wound debridement should be investigated in terms of reducing bacterial colonisation.

PATIENTS AND METHODS

Patients with acute or chronic wounds were assessed for bacterial colonisation with a fluorescence camera before and after mechanical wound debridement with sterile cotton pads. If bacterial colonisation persisted, a second, targeted wound debridement was performed.

RESULTS

A total of 151 patients, 68 (45.0%) men and 83 (55.0%) women were included in this study. The male mean age was 71.0 years and the female 65.1 years. By establishing a new analysis method for the image files, we could document that the bacterial colonised areas were distributed 21.9% on the wound surfaces, 60.5% on the wound edges (up to 0.5 cm) and 17.6% on the wound surroundings (up to 1.5 cm). One mechanical debridement achieved a significant reduction of bacterial colonised areas by an average of 29.6% in the wounds, 18.9% in the wound edges and 11.8% in the wound surroundings and was increased by performing it a second time.

CONCLUSIONS

It has been shown that even a simple mechanical debridement with cotton pads can significantly reduce bacterial colonisation without relevant side effects. In particular, the wound edges were the areas that were often most contaminated with bacteria and should be included in the debridement with special attention. Since bacteria remain in wounds after mechanical debridement, it cannot replace antimicrobial therapy strategies, but offer a complementary strategy to improve wound care. Thus, it could be shown that simple mechanical debridement is effective in reducing bacterial load and should be integrated into a therapeutic approach to wounds whenever appropriate.

A Rapid Point-of-care Fluorescence Imaging Device Helps Prevent Graft Rejection Post Modified Radical Mastectomy

Pathogenic bacteria in wounds impede successful skin grafting. However, their detection relies on culture methods, which delay confirmation by several days. Real-time fluorescence imaging detects bacteria, allowing for rapid assessment and documentation. We herein report a post modified radical mastectomy, surgical site infection with multidrug-resistant Pseudomonas spp. that underwent repeated antibiotic therapy and debridement and eventually grafting. In this case, a real-time fluorescence imaging device helped prevent graft rejection.

Skin Pigmentation Impacts the Clinical Diagnosis of Wound Infection: Imaging of Bacterial Burden to Overcome Diagnostic Limitations

Underrepresentation of diverse skin tones in medical education and providers' implicit racial bias drives inequities in wound care, such as disproportionally poor outcomes for Black patients. Diagnostic indicators (e.g., erythema) can present differently depending on skin pigmentation. This post hoc analysis of 350 chronic wounds from a prospective 14-site clinical trial aimed to determine how the perception of clinical signs and symptoms of infection (CSS) differs by patient skin tone and if fluorescence-imaging can offer a more objective diagnostic solution. Participants were grouped by skin tone (low, medium, high) as measured by the Fitzpatrick Skin Phototype Classification (FSPC) scale. CSS and total bacterial load (TBL) were compared across FSPC groups, along with sensitivity to detect TBL >104 CFU/g using CSS alone and combined with fluorescence-imaging. Erythema was reported less often with increasing FSPC score (p = 0.05), from 13.4% (low), to 7.2% (medium), to 2.3% (high), despite comparable bacterial loads (median = 1.8 × 106 CFU/g). CSS sensitivity in the high group (2.9%) was 4.8-fold to 8.4-fold lower than the low (p = 0.003) and medium groups (p = 0.04). Fluorescence-imaging significantly improved the detection of high bacterial load in each group, peaking in the high group at 12-fold over CSS alone. These findings underscore the threat of pervasive racialized health inequities in wound care, where missed diagnosis of pathogenic bacteria and infection could delay treatment, increasing the risk of complications and poor outcomes. Fluorescence-imaging is poised to fill this gap, at least in part, serving as a more objective and equitable indicator of wound bacteria. Clinicaltrials.gov #NCT03540004 registered 16-05-2018.

A standardized wound infection model for antimicrobial testing of wound dressings in vitro

To investigate the effectiveness of antimicrobial agents against wound infections, experiments using either 2D cultures with planktonic microorganisms or animal infection models are frequently carried out. However, the transferability of the results to human skin is limited by the lack of complexity of the 2D models or by the poor translation of the results from animal models. Hence, there is a need for wound infection models capable of assessing antimicrobial agents. In this study, an easily standardized wound infection model was established. This model consists of a mechanically wounded human skin model on a collagen matrix infected with various clinically relevant bacteria. Infection of the model led to recognition of the pathogens and induction of an inflammatory response. The untreated infection spread over time, causing significant tissue damage. By applying an antimicrobial-releasing wound dressing, the bacterial load could be reduced and the success of the treatment could be further measured by a decrease in the inflammatory reaction. In conclusion, this wound infection model can be used to evaluate new antimicrobial therapeutics as well as to study host-pathogen interactions.

Red/Orange Autofluorescence in Selected Candida Strains Exposed to 405 nm Laser Light

BACKGROUND

Candida albicans and similar species are significant pathogens in immunocompromised and hospitalized individuals, known for mucosal colonization and bloodstream/organ invasion. Many pathogenic fungi, including these species, exhibit autofluorescence (R/OF) under specific light conditions, a feature crucial for their detection.

AIM

We investigated the use of a 405 nm diode laser for the direct observation of red/orange autofluorescence of Candida spp., common in the oral cavity, exploring its potential in health screenings.

METHODS

This study utilized cultures of Candida spp. on Sabouraud dextrose agar with Qdot 655 and 685 for fluorescence benchmarking, illuminated using a 405 nm diode laser (continuous wave, power 250 mW, 0.0425 J/cm² fluence, 0.0014 W/cm² power density). Images were captured using a yellow-filter camera at set intervals (48 to 144 h). Visual and computational analyses evaluated the R/OF in terms of presence, intensity, coloration, and intra-colony variation.

RESULTS

Most Candida strains displayed red/orange autofluorescence at all observation times, characterized by varied coloration and intra-colony distribution. Initially, there was an increase in R/OF intensity, which then stabilized in the later stages of observation.

CONCLUSIONS

The majority of the Candida strains tested are capable of emitting R/OF under 405 nm laser light. This finding opens up new possibilities for integrating R/OF detection into routine dental screenings for Candida spp.

An objective comparative study of non-surgical cleansing techniques and cleanser types in bacterial burden management

Cleansing is a vital component of effective wound hygiene and biofilm management, often accomplished through vigorous mechanical action or through soaking with moistened gauze. In the present study, a quantitative comparison of the effectiveness of different cleansing techniques and solutions in removing bacteria was conducted on 71 chronic wounds using bacterial fluorescence imaging as a real-time diagnostic for moderate to high bacterial loads. Vigorous gauze cleansing for 30 s proved most effective by reducing bacterial fluorescence by 33.99%, surpassing 10-min soaking in bacterial reduction (13.24%). Among different cleansers, no statistically significant differences in effectiveness were observed, but povidone-iodine showed the strongest trend towards bacterial reduction. Sub-analysis highlighted the superiority of antiseptic cleansers over saline and gentle soap (-33.30% vs. -1.80% bacterial reduction respectively). Five percent acetic acid was also shown to be more effective in removing specific bacterial strains (Pseudomonas aeruginosa). Findings from studies like this contribute to refining wound hygiene guidelines and clinical algorithms for bacterial and biofilm management.

Narrative Review: Pyoderma Gangrenosum

Pyoderma gangrenosum (PG) is a skin lesion, characteristically a neutrophilic dermatosis, that can be complicated by rapid progression, necrosis, and ulceration. This is an important pathology to be discussed given that there are no established criteria for diagnosis or treatment. This review aims to elucidate characteristics and variations of PG that distinguish it from other ulcerative skin lesions. Variability in presentation can lead to missed or incorrect diagnosis, and some of the currently proposed criteria for categorizing and diagnosing PG have been included here. These criteria distinguish PG in terms of the nature of the lesion, the location, etiology, responsiveness to immunosuppressive therapy, and patient history. The etiology and pathogenesis of PG remain unknown, but we summarize prominent theories and explanations. Furthermore, recent research indicates that the incidence of PG has a strong correlation with autoimmune conditions, particularly inflammatory bowel disease. Major treatments for PG coincide with these findings, as the majority involve targeted anti-inflammatories, immunosuppressants, and surgical interventions. These treatments are addressed in this review, with added context for local versus systemic disease.

New Medical Device and Therapeutic Approvals in Otolaryngology: State of the Art Review of 2022

Objective

To review new drugs and devices relevant to otolaryngology approved by the Food and Drug Administration (FDA) in 2022.

Data Sources

Publicly available FDA data on drugs and devices approved in 2022.

Review Methods

A preliminary screen was conducted to identify drugs and devices relevant to otolaryngology. A secondary screen by members of the American Academy of Otolaryngology-Head and Neck Surgery's (AAO-HNS) Medical Devices and Drugs Committee differentiated between minor updates and new approvals. The final list of drugs and devices was sent to members of each subspecialty for review and analysis.

Conclusion

A total of 1251 devices and 37 drugs were identified on preliminary screening. Of these, 329 devices and 5 drugs were sent to subspecialists for further review, from which 37 devices and 2 novel drugs were selected for further analysis. The newly approved devices spanned all subspecialties within otolaryngology. Many of the newly approved devices aimed to enhance patient experience, including over-the-counter hearing aids, sleep monitoring devices, and refined CPAP devices. Other advances aimed to improve surgical access, convenience, or comfort in the operating room and clinic.

Implications for Practice

Many new devices and drugs are approved each year to improve patient care and care delivery. By staying up to date with these advances, otolaryngologists can leverage new innovations to improve the safety and quality of care. Given the recent approval of these devices, further studies are needed to assess long-term impact within the field of otolaryngology.

Bacterial metabolism-triggered-chemiluminescence-based point-of-care testing platform for sensitive detection and photothermal inactivation of Staphylococcus aureus

Post-operative pathogenic infections in liver transplantation seriously threaten human health. It is essential to develop novel methods for the highly sensitive and rapid detection of Staphylococcus aureus (S. aureus). Interestingly, the combination of the property of bacteria to secrete hydrogen peroxidase, bacterial metabolism-triggered-chemiluminescence (CL)-based bioassays can be as a candidate point-of-care testing (POCT) for the detection of S. aureus against the CL substrate Luminol and hydrogen peroxide without excitation light sources. Here, a CL-based strategy with stable and visualized CL intensity was fabricated according to a hybrid biomimetic enzyme of copper-Hemin metal-organic framework, which enhances the biological enzyme activity while improving the stability and sensitivity of the assay. By further integrating S. aureus-specific capture and one-step separation of the antibody-modified Fe3O4 NPs (Fe3O4 NPs@Ab), the portable device integrated smartphone enables CL-based POCT for specific detection of S. aureus in the range of 101-106 CFU/mL with a limit of detection as low as 1 CFU/mL. Specifically, S. aureus can be eliminated after detection with high antibacterial efficiency due to the excellent photothermal properties of Fe3O4 NPs@Ab. The developed multifunctional platform has the advantages of simplicity of operation and low cost, indicating great potential in clinical applications.

Lights, fluorescence, action-Influencing wound treatment plans including debridement of bacteria and biofilms

High bacterial loads within chronic wounds increase the risk of infection and complication. Detection and localization of bacterial loads through point-of-care fluorescence (FL) imaging can objectively inform and support bacterial treatment decisions. This single time-point, retrospective analysis describes the treatment decisions made on 1000 chronic wounds (DFUs, VLUs, PIs, surgical wounds, burns, and others) at 211 wound-care facilities across 36 US states. Clinical assessment findings and treatment plans derived from them, as well as subsequent FL-imaging (MolecuLight®) findings and any associated treatment plan changes, were recorded for analysis. FL signals indicating elevated bacterial loads were observed in 701 wounds (70.8%), while only 293 (29.6%) showed signs/symptoms of infection. After FL-imaging, treatment plans changed in 528 wounds as follows: more extensive debridement (18.7%), more extensive hygiene (17.2%), FL-targeted debridement (17.2%), new topical therapies (10.1%), new systemic antibiotic prescriptions (9.0%), FL-guided sampling for microbiological analysis (6.2%), and changes in dressing selection (3.2%). These real-world findings of asymptomatic bacterial load/biofilm incidence, and of the frequent treatment plan changes post-imaging, are in accordance with clinical trial findings using this technology. These data, from a range of wound types, facilities, and clinician skill sets, suggest that point-of-care FL-imaging information improves bacterial infection management.

A Clinical Trial Design for Evaluating Topical Antimicrobials in Chronic Wounds: The BLEU Trial

Chronic wound management is a global challenge. Millions of patients suffer from nonhealing ulcers and health systems are overwhelmed by the growing demand for treatment. Despite the prevalence of chronic wounds, the emergence of wound centers and specialized physicians is a recent phenomenon. Likewise, clinical research in wound healing is in its infancy. To date, many of the products in wound care have little or no clinical evidence. The field needs standardized clinical trial design, endpoints recognized by clinicians and payers, and improved overall clinical evidence. Wound healing is impeded by the presence of bacterial biofilms, which exist in most chronic wounds. It is not surprising that biofilm disruption is the focus of wound management and essential to the healing process. Multiple laboratory and preclinical studies demonstrate promising efficacy of several antimicrobials in treating biofilms; however, the field lacks in vivo clinical studies. In addition, a standardized trial design to evaluate efficacy of antimicrobials in chronic wounds does not exist. The advent of new diagnostic technologies, such as fluorescence imaging, has led to clinical trial designs that are reliable, easier to conduct, and cost efficient. The protocol presented here describes a randomized controlled double-blind trial designed to evaluate antiseptics in chronic wounds.

Jet Lavage Irrigation Resolves Stage 4 Pelvic Pressure Injury Undermining

OBJECTIVE

Patients with stage 4 pelvic pressure injuries that have large, undermined cavities are at high risk for treatment failure and often fall into the category of palliative care. This case series identified five cases where treatment had stalled, and surgical reconstructive options were limited. Jet lavage irrigation in the outpatient setting was assessed as a treatment alternative.

METHODS

From an investigational review board study assessing the use of low-pressure jet lavage irrigation in the outpatient setting for chronic wounds, five patients were identified where the wound dimension increased at least 50% resulting from undermined cavities. All were considered high risk with Charlson Comorbidity Index scores of 5 or greater, and their wound healing had stalled with extended treatments of topicals and medicated dressings. A team of physical therapists irrigated these patients' wounds at the bedside with 3 L of saline 3 to 5 days per week using a special long irrigation tip to reach the depth of the undermined cavity. Digital planimetry was used to assess healing with wound size as the outcome.

RESULTS

Reduction of the undermined cavities was seen early within the first 3 weeks. No patient developed wound sepsis, and bacterial contamination was determined by use of autofluorescence digital imaging. Undermining resolution occurred in four patients, and one patient with an improving wound died of COVID-19.

CONCLUSIONS

This simple method offered clear benefits in each patient, but only one patient survived to complete wound healing. Patient and family satisfaction were high regarding the treatment, which created a painless, odor-free wound.

Postpartum perineal wound infection and its effect on anal sphincter integrity: Results of a prospective observational study

INTRODUCTION

Perineal wound infection can affect tissues at superficial, deep, and organ space levels. Women with obstetric anal sphincter injuries (OASIS) are at risk of infection; however, no study to date has investigated if infection can extend to affect the anal sphincter integrity. The aim of this study was to evaluate the clinical progression of perineal wound infection and its effect on the anal sphincter in women with or without OASIS using three-dimensional endoanal ultrasound (3D-EAUS).

MATERIAL AND METHODS

Women were recruited into the Prospective Observational Study Evaluating the Sonographic Appearance of the Anal Sphincter in Women With Perineal Wound Infection Following Vaginal Delivery (PERINEAL Study) between August 2020 and August 2021 (NCT04480684). 3D-EAUS was performed weekly until complete wound healing. Significant bacterial colonization was diagnosed using the MolecuLight i:X camera. The primary study outcome was a change in a sphincter defect angle from baseline (wound infection) until wound healing. A robust Poisson regression model was used to analyze the effect of significant bacterial loads on the anal sphincter.

RESULTS

Seventy-three women were included. A median of two ultrasound scans were performed in each patient (range 1-16). Five women (6.8%) had an OASI clinically diagnosed at delivery. In total, 250 EAUS were performed. An external anal sphincter defect was found on EAUS in 55 (22.0%) scans (n = 10 women). An external anal sphincter and internal anal sphincter defect was found in 26 scans (10.4%) (n = 3 women). During the course of the wound healing process, there was no significant change in defect size in wounds with or without significant bacterial colonization. In cases of an intact anal sphincter, wound infection did not disrupt its integrity.

CONCLUSIONS

We found that perineal wound infection does not disrupt an intact anal sphincter or OASIS. This new information can provide important information for clinicians and patients. As there are myths frequently encountered in cases of litigation when disruption of sphincter integrity is attributed to perineal infection, the findings of this study should be tested in larger studies in the future.

Point-of-care fluorescence imaging reveals extent of bacterial load in diabetic foot ulcers

Elevated levels of bacteria, including biofilm, increase the risk of chronic wound infection and inhibit healing. Addressing asymptomatic high bacterial loads is challenged by a lack of clinical terminology and diagnostic tools. This post-hoc multicenter clinical trial analysis of 138 diabetic foot ulcers investigates fluorescence (FL)-imaging role in detecting biofilm-encased and planktonic bacteria in wounds at high loads. The sensitivity and specificity of clinical assessment and FL-imaging were compared across bacterial loads of concern (104 -109  CFU/g). Quantitative tissue culture confirmed the total loads. Bacterial presence was confirmed in 131/138 ulcers. Of these, 93.9% had loads >104  CFU/g. In those wounds, symptoms of infection were largely absent and did not correlate with, or increase proportionately with, bacterial loads at any threshold. FL-imaging increased sensitivity for the detection of bacteria across loads 104 -109 (P < .0001), peaking at 92.6% for >108  CFU/g. Imaging further showed that 84.2% of ulcers contained high loads in the periwound region. New terminology, chronic inhibitory bacterial load (CIBL), describes frequently asymptomatic, high bacterial loads in diabetic ulcers and periwound tissues, which require clinical intervention to prevent sequelae of infection. We anticipate this will spark a paradigm shift in assessment and management, enabling earlier intervention along the bacterial-infection continuum and supporting improved wound outcomes.

Use of fluorescence imaging to optimize location of tissue sampling in hard-to-heal wounds

Introduction

Wound microflora in hard-to-heal wounds is invariably complex and diverse. Determining the interfering organisms(s) is therefore challenging. Tissue sampling, particularly in large wounds, is subjective and, when performed, might involve swabbing or biopsy of several locations. Fluorescence (FL) imaging of bacterial loads is a rapid, non-invasive method to objectively locate microbial hotspots (loads >104 CFU/gr). When sampling is deemed clinically necessary, imaging may indicate an optimal site for tissue biopsy. This study aimed to investigate the microbiology of wound tissue incisional biopsies taken from sites identified by FL imaging compared with sites selected by clinical judgment.

Methods

A post hoc analysis of the 350-patient FLAAG wound trial was conducted; 78 wounds were included in the present study. All 78 wounds were biopsied at two sites: one at the center of the wound per standard of care (SoC) and one site guided by FL-imaging findings, allowing for comparison of total bacterial load (TBL) and species present.

Results

The comparison between the two biopsy sites revealed that clinical uncertainty was higher as wound surface area increased. The sensitivity of a FL-informed biopsy was 98.7% for accurately finding any bacterial loads >104 CFU/g, compared to 87.2% for SoC (p=0.0059; McNemar test). Regarding species detected, FL-informed biopsies detected an average of 3 bacterial species per biopsy versus 2.2 species with SoC (p < 0.001; t-test). Microbial hotspots with a higher number of pathogens also included the CDC's pathogens of interest.

Conclusions & perspective

FL imaging provides a more accurate and relevant microbiological profile that guides optimal wound sampling compared to clinical judgment. This is particularly interesting in large, complex wounds, as evidenced in the wounds studied in this post hoc analysis. In addition, fluorescence imaging enables earlier bacterial detection and intervention, guiding early and appropriate wound hygiene and potentially reducing the need for antibiotic use. When indicated, this diagnostic partnership with antibiotic stewardship initiatives is key to ameliorating the continuing threat of antibiotic resistance.

What COVID-19 taught us: New opportunities and pathways from telemedicine and novel antiseptics in wound healing

The COVID-19 pandemic deeply impacted the capacity of the health systems to maintain preventive and curative services, especially for the most vulnerable populations. During the pandemic, the wound healing centres in Italy assisted a significant reduction of the frequency of their hospital admission, since only urgencies, such as severe infections or wound haemorrhagic complications, were allowed to the hospital. The aim of this multidisciplinary work is to highlight the importance of a new pathway of wound care with patient-based therapeutic approach, tailored treatments based on the characteristics of the wound and fast tracks focused on the outpatient management, reserving hospital assessment only for patients with complicated or complex wounds. This analysis highlights the point that patients with chronic wounds need to be critically evaluated in order to find the best and most appropriate care pathway, which should vary according to the patient and, especially, to the characteristics of the wound. Moreover, the most adequate topic antiseptic should be started as soon as possible. An appropriate and correct management of the wound care will allow to link the knowledge based on years of clinical practice with the new challenges and the need to visit patients remotely, when possible.

The Use of Point-of-Care Bacterial Autofluorescence Imaging in the Management of Diabetic Foot Ulcers: A Pilot Randomized Controlled Trial

OBJECTIVE

To estimate comparative healing rates and decision-making associated with the use of bacterial autofluorescence imaging in the management of diabetic foot ulcers (DFUs).

RESEARCH DESIGN AND METHODS

This is a single-center (multidisciplinary outpatient clinic), prospective pilot, randomized controlled trial (RCT) in patients with an active DFU and no suspected clinical infection. Consenting patients were randomly assigned 1:1 to either treatment as usual informed by autofluorescence imaging (intervention), or treatment as usual alone (control). The primary outcome was the proportion of ulcers healed at 12 weeks by blinded assessment. Secondary outcomes included wound area reduction at 4 and 12 weeks, patient quality of life, and change in management decisions after autofluorescence imaging.

RESULTS

Between November 2017 and November 2019, 56 patients were randomly assigned to the control or intervention group. The proportion of ulcers healed at 12 weeks in the autofluorescence arm was 45% (n = 13 of 29) vs. 22% (n = 6 of 27) in the control arm. Wound area reduction was 40.4% (autofluorescence) vs. 38.6% (control) at 4 weeks and 91.3% (autofluorescence) vs. 72.8% (control) at 12 weeks. Wound debridement was the most common intervention in wounds with positive autofluorescence imaging. There was a stepwise trend in healing favoring those with negative autofluorescence imaging, followed by those with positive autofluorescence who had intervention, and finally those with positive autofluorescence with no intervention.

CONCLUSIONS

In the first RCT, to our knowledge, assessing the use of autofluorescence imaging in DFU management, our results suggest that a powered RCT is feasible and justified. Autofluorescence may be valuable in addition to standard care in the management of DFU.

The clinical progression and wound healing rate of dehisced perineal tears healing by secondary intention: A prospective observational study

OBJECTIVES

To establish the clinical progression of dehisced perineal wounds healing by secondary intention and to investigate the incidence and factors associated with delayed healing.

METHODS

Secondary analysis of women with perineal wound dehiscence recruited into the PERINEAL study between August 2020- August 2021 (NCT04480684). Three-dimensional wound measurements were taken with the Silhouette® camera. Significant bacterial colonisation was diagnosed using the MolecuLight i:X camera. As it is agreed that acute wounds should heal sufficiently within four weeks, diagnosis of delayed wound healing was made if a wound took longer than four weeks to heal. A wound was deemed to have healed if there was complete wound closure, with no evidence of granulation tissue or signs of infection on clinical examination.

RESULTS

55 women with perineal wound dehiscence participated. Wounds took an average of 3 weeks to heal (range 1-16) and 38 (69.1%) wounds healed in ≤ 4 weeks from the first clinical review. 17 (30.9%) wounds had significant bacterial colonisation, identified on bacterial fluorescence imaging. Women with a wound area of < 1.60 cm² or wound perimeter of < 5.57 cm had a 70% probability of wound healing in ≤ 4 weeks. 47.1% of wounds with significant bacteria colonisation healed within 4 weeks, in comparison to 78.9% of wounds not colonised (p = 0.03). 25.0 % (n = 2) of wounds with OASI healed within 4 weeks, in comparison to 76.5% (n = 36) of wounds with no OASI (p = 0.02). Bacterial fluorescence (OR 0.21 (0.05-0.87)) and OASIs (OR 0.09 (0.01-0.66)) were independent risk factors associated with delayed wound healing. The model including wound area, fluorescence and OASIs had the greatest AUC (0.81, 95% CI 0.67-0.94) indicating the best predictive model.

CONCLUSIONS

This is the first study to describe healing outcomes of dehisced perineal wounds and factors associated with delayed healing. The study findings will help clinicians counsel women effectively and tailor follow-up care at the first assessment, based on individual risk factors.

Advanced Wound Diagnostics: Toward Transforming Wound Care into Precision Medicine

Significance: Nonhealing wounds are an ever-growing global pandemic, with mortality rates and management costs exceeding many common cancers. Although our understanding of the molecular and cellular factors driving wound healing continues to grow, standards for diagnosing and evaluating wounds remain largely subjective and experiential, whereas therapeutic strategies fail to consistently achieve closure and clinicians are challenged to deliver individualized care protocols. There is a need to apply precision medicine practices to wound care by developing evidence-based approaches, which are predictive, prescriptive, and personalized. Recent Advances: Recent developments in "advanced" wound diagnostics, namely biomarkers (proteases, acute phase reactants, volatile emissions, and more) and imaging systems (ultrasound, autofluorescence, spectral imaging, and optical coherence tomography), have begun to revolutionize our understanding of the molecular wound landscape and usher in a modern age of therapeutic strategies. Herein, biomarkers and imaging systems with the greatest evidence to support their potential clinical utility are reviewed. Critical Issues: Although many potential biomarkers have been identified and several imaging systems have been or are being developed, more high-quality randomized controlled trials are necessary to elucidate the currently questionable role that these tools are playing in altering healing dynamics or predicting wound closure within the clinical setting. Future Directions: The literature supports the need for the development of effective point-of-care wound assessment tools, such as a platform diagnostic array that is capable of measuring multiple biomarkers at once. These, along with advances in telemedicine, synthetic biology, and "smart" wearables, will pave the way for the transformation of wound care into a precision medicine. Clinical Trial Registration number: NCT03148977.

Point-of-Care Wound Blotting with Alcian Blue Grading versus Fluorescence Imaging for Biofilm Detection and Predicting 90-Day Healing Outcomes

Biofilm infection has been identified as a crucial factor of the pathogenesis of chronic wound, but wound biofilm diagnosis remains as an unmet clinical need. We previously proposed a modified wound blotting technique using Alcian blue staining for biofilm detection that was characterized as being non-invasive, time-saving, non-expansive, and informative for biofilm distribution. In this study, we adapted a novel Alcian blue grading method as the severity of biofilm infection for the wound blotting technique and compared its biofilm detection efficacy with MolecuLight i:X- a point-of-care florescence imaging device to detect bacteria and biofilm in wounds. Moreover, their predictive value of complete wound healing at 90 days was analyzed. When validated with wound culture results in the 53 enrolled subjects with chronic wounds, the modified wound blotting method showed a strong association with wound culture, while MolecuLight i:X only exhibited a weak association. In predicting 90-day wound outcomes, the modified wound blotting method showed a strong association (Kendall’s tau value = 0.563, p < 0.001), and the wound culture showed a moderate association (Spearman’s rho = 0.535, p < 0.001), but MolecuLight i:X exhibited no significant association (p = 0.184). In this study, modified wound blotting with the Alcian blue grading method showed superior value to MolecuLight i:X both in biofilm detection and predictive validity in 90-day wound-healing outcomes.

The Role of Autoflorescence Imaging Device in the Evaluation of Bacteria Burden Control

MolecuLight i:X is a autofluorescence, portable device that allows an assessment of wound area, perimeter, width and length and an evaluation in real time of wound surface bacteria (>104 CFU/g). Primary objective of our study was to evaluate the reduction of bacterial load associated to 3 different therapeutic approaches: dressings and multicomponent bandages (Group1), sharp debridement, dressings and multicomponent bandages (Group 2), and 10 patients treated with zinc oxide bandage (Group 3). Secondary objective was NRS pain scale, Wound Bed Score (WBS) and Quality of Life (QoL) assessment. Despite the improvement of bacterial load, WBS, Qol and NRS was evident in all 3 groups, the analysis of our results demonstrates that the application of zinc oxide bandage, directly in contact with the wound bed and/or the perilesional skin, resulted in a higher improvement and a significant reduction of WBS and bacterial load. Fluorescence imaging can help the specialist in a more targeted assessment and management of infection. Sharp debridement and antiseptic dressings are classically used to reduced bacteria burden. Zinc oxide directly on the wound is an interesting cost-effective option to control different types of bacteria.

Novel Diagnostic Technologies and Therapeutic Approaches Targeting Chronic Wound Biofilms and Microbiota

Purpose of Review

To provide an up-to-date overview of recent developments in diagnostic methods and therapeutic approaches for chronic wound biofilms and pathogenic microbiota.

Recent Findings

Biofilm infections are one of the major contributors to impaired wound healing in chronic wounds, including diabetic foot ulcers, venous leg ulcers, pressure ulcers, and nonhealing surgical wounds. As an organized microenvironment commonly including multiple microbial species, biofilms develop and persist through methods that allow evasion from host immune response and antimicrobial treatments. Suppression and reduction of biofilm infection have been demonstrated to improve wound healing outcomes. However, chronic wound biofilms are a challenge to treat due to limited methods for accurate, accessible clinical identification and the biofilm's protective properties against therapeutic agents. Here we review recent approaches towards visual markers for less invasive, enhanced biofilm detection in the clinical setting. We outline progress in wound care treatments including investigation of their antibiofilm effects, such as with hydrosurgical and ultrasound debridement, negative pressure wound therapy with instillation, antimicrobial peptides, nanoparticles and nanocarriers, electroceutical dressings, and phage therapy.

Summary

Current evidence for biofilm-targeted treatments has been primarily conducted in preclinical studies, with limited clinical investigation for many therapies. Improved identification, monitoring, and treatment of biofilms require expansion of point-of-care visualization methods and increased evaluation of antibiofilm therapies in robust clinical trials.

Uncovering the high prevalence of bacterial burden in surgical site wounds with point-of-care fluorescence imaging

Detection of bacterial burden within or near surgical wounds is critical to reducing the occurrence of surgical site infection (SSI). A distinct lack of reliable methods to identify postoperative bioburden has forced reliance on clinical signs and symptoms of infection (CSS). As a result, infection management has been reactive, rather than proactive. Fluorescence imaging of bacterial burden (FL) is positioned to potentially flip that paradigm. This post hoc analysis evaluated 58 imaged and biopsied surgical site wounds from the multi‐centre fluorescence imaging assessment and guidance clinical trial. Diagnostic accuracy measures of CSS and FL were evaluated. A reader study investigated the impact of advanced image interpretation experience on imaging sensitivity. Forty‐four of fifty‐eight surgical site wounds (75.8%) had bacterial loads >10⁴ CFU/g (median = 3.11 × 10⁵ CFU/g); however, only 3 of 44 were CSS positive (sensitivity of 6.8%). FL improved sensitivity of bacterial detection by 5.7‐fold compared with CSS alone (P = .0005). Sensitivity improved by 11.3‐fold over CSS among clinicians highly experienced with FL interpretation (P < .0001). Surgical sites that reach the stage of referral to a wound specialist frequently harbour asymptomatic high bacterial loads that delay healing and increase infection risk. Advanced imaging of pathological bacterial burden improves surgical site monitoring and may reduce the rate of SSIs.

Diagnosis and treatment of the invasive extension of bacteria (cellulitis) from chronic wounds utilising point-of-care fluorescence imaging

Early diagnosis of wound‐related cellulitis is challenging as many classical signs and symptoms of infection (erythema, pain, tenderness, or fever) may be absent. In addition, other conditions (ie, chronic stasis dermatitis) may present with similar clinical findings. Point‐of‐care fluorescence imaging detects elevated bacterial burden in and around wounds with high sensitivity. This prospective observational study examined the impact of incorporating fluorescence imaging into standard care for diagnosis and management of wound‐related cellulitis. Two hundred thirty‐six patients visiting an outpatient wound care centre between January 2020 and April 2021 were included in this study. Patients underwent routine fluorescence scans for bacteria (range: 1‐48 scans/patient). Wound‐related cellulitis was diagnosed in 6.4% (15/236) of patients. In these patients, fluorescence scans showed an irregular pattern of red (bacterial) fluorescence extending beyond the wound bed and periwound that could not be removed through cleansing or debridement, indicating the invasive extension of bacteria (wound‐related cellulitis). Point‐of‐care identification facilitated rapid initiation of treatments (source control and antibiotics, when warranted) that resolved the fluorescence. No patients had worsening of cellulitis requiring intravenous antibiotics and/or hospitalisation. These findings demonstrate the utility of point‐of‐care fluorescence imaging for efficient detection and proactive, targeted management of wound‐related cellulitis.

Detection of bacterial fluorescence from in vivo wound biofilms using a point-of-care fluorescence imaging device

Wound biofilms must be identified to target disruption and bacterial eradication but are challenging to detect with standard clinical assessment. This study tested whether bacterial fluorescence imaging could detect porphyrin-producing bacteria within a biofilm using well-established in vivo models. Mouse wounds were inoculated on Day 0 with planktonic bacteria (n = 39, porphyrin-producing and non-porphyrin-producing species, 107  colony forming units (CFU)/wound) or with polymicrobial biofilms (n = 16, 3 biofilms per mouse, each with 1:1:1 parts Staphylococcus aureus/Escherichia coli/Enterobacter cloacae, 107  CFU/biofilm) that were grown in vitro. Mouse wounds inoculated with biofilm underwent fluorescence imaging up to Day 4 or 5. Wounds were then excised and sent for microbiological analysis. Bacteria-matrix interaction was assessed with scanning electron microscopy (SEM) and histopathology. A total of 48 hours after inoculation with planktonic bacteria or biofilm, red fluorescence was readily detected in wounds; red fluorescence intensified up to Day 4. Red fluorescence from biofilms persisted in excised wound tissue post-wash. SEM and histopathology confirmed bacteria-matrix interaction. This pre-clinical study is the first to demonstrate the fluorescence detection of bacterial biofilm in vivo using a point-of-care wound imaging device. These findings have implications for clinicians targeting biofilm and may facilitate improved visualisation and removal of biofilms.

Point-of-Care Ultrasound as a Tool to Assess Wound Size and Tissue Regeneration after Skin Grafting

Chronic wounds can be difficult to heal and are often accompanied by pain and discomfort. Multiple skin substitutes or cellularized/tissue-based skin products have been used in an attempt to facilitate closure of complex wounds. Allografts from cadaveric sources have been a viable option in achieving such closure. However, early assessment of graft incorporation has been difficult clinically, often with delayed evidence of failure. Visual cues to assess graft integrity have been limited and remain largely superficial at the skin surface. Furthermore, currently used optical imaging techniques can penetrate only a few millimeters deep into tissue. Ultrasound (US) imaging offers a potential solution to address this limitation. This work evaluates the use of US to monitor wound healing and allograft integration. We used a commercially available dual-mode (US and photoacoustic) scanner operating only in US mode. We compared the reported wound size from the clinic with the size measured using US in 45 patients. Two patients from this cohort received an allogenic skin graft and underwent multiple US scans over a 110-d period. All data were processed by two independent analysts; one of them was blinded to the study. We measured change in US intensity and wound contraction as a function of time. Our results revealed a strong correlation (R² = 0.81, p < 0.0001) between clinically and US-measured wound sizes. Wound contraction >91% was seen in both patients after skin grafting. An inverse relationship between wound size and US intensity (R² = 0.77, p < 0 .0001) indicated that the echogenicity of the wound bed increases as healthy cells infiltrate the allograft matrix, regenerating and leading to healthy tissue and re-epithelization. This work indicates that US can be used to measure wound size and visualize tissue regeneration during the healing process.

Utility of MolecuLight i:X for Managing Bacterial Burden in Pediatric Burns

Pediatric burn injuries are vulnerable to severe complications, most often infection, making prompt and precise diagnosis of bacterial bioburden vital to preventing detrimental consequences and optimizing patients' outcomes. Currently, burn wounds are assessed for infection via examining the clinical signs and symptoms of infection, which can be confirmed by swab culture analysis. While the former approach is subjective and experience-dependant, the latter technique is susceptible to missing subsurface, biofilm-associated colonization, and any peripheral bacterial burden, and also delays confirmation by up to 5 days. The MolecuLight i:X is a handheld, noncontact fluorescence imaging device, which can reveal real-time information about clinically significant levels of bacteria and their biodistribution in surface and subsurface burn wound tissues. We conducted a single-center observational study to assess the device efficacy in identifying critical bacterial levels in pediatric burn wounds and to test the children's compliance and the overall feasibility of the device integration into the current diagnostic practice. Ten patients with 16 wounds were recruited and assessed for the presence or absence of clinical signs and symptoms of infection and the presence or absence of bacterial fluorescence on images, with swabs taken to confirm findings. Results demonstrate the device's ability to visualize clinically significant bacterial burden and to localize distribution of pathogens. All clinicians agreed on the high compliance with the device and high feasibility of incorporating the device into routine wound assessments. The results of this study may pave the way toward including bacterial fluorescence imaging into the standard diagnostic algorithm for pediatric burn population.

Guidelines for Point-of-Care Fluorescence Imaging for Detection of Wound Bacterial Burden Based on Delphi Consensus

Excessive levels of bacteria impede wound healing and can lead to infectious complications. Unfortunately, clinical signs and symptoms of elevated bacterial burden are often unreliable. As a result, point--of--care fluorescence imaging, used to detect critical bacterial burden in wounds, is becoming widely recognized and adopted by clinicians across the globe as an accepted and added component of wound assessment protocol. A Delphi method was employed to establish consensus guidelines describing fluorescence imaging use. A multidisciplinary panel of 32 wound experts (56% MD, 22% podiatrist, 12.5% nurses/nurse practitioners) representing multiple sites of service (e.g., hospital outpatient, inpatient, private office, long-term care) completed two rounds of online questionnaires. The Delphi included key topics, including competencies required to perform imaging, clinical indications for imaging (e.g., signs/symptoms present, procedures warranting imaging), frequency of imaging, and a clinical workflow algorithm. Describing their clinical experiences of imaging impact, >80% reported changes in treatment plans, 96% reported that imaging-informed treatment plans led to improved wound healing, 78% reported reduced rates of amputations, and 83% reported reduced rates of microbiological sampling. The guidelines provided here will help to standardize use of fluorescence imaging among wound care providers and enhance the quality of patient care.

Efficacy and safety of a porcine peritoneum-derived matrix in diabetic foot ulcer treatment: a pilot study

OBJECTIVE

A third of people with diabetes will develop a foot ulcer during their lifetime. The absence of pain secondary to neuropathy often leads to a delay in diagnosis and treatment. Diabetic foot ulcer (DFU) complications, such as infection and amputation, increase mortality and strain the financial resources of health systems across the world. Cellular and/or tissue products (CTPs) have played an important role in the closure of DFUs. Investigators continue to search for new CTPs that facilitate healing. The aim of this study was to assess the efficacy and safety of a porcine peritoneum-derived matrix in DFU treatment.

METHOD

Patients with longstanding DFUs participated in this institutional review board-approved, multicentre, prospective pilot study evaluating the time to healing over 12 weeks. In addition to weekly assessments for wound size, investigators analysed bacterial burden using the MolecuLight procedure (MLiX) and bacterial protease (BPA) testing. Participants received a weekly application of Meso Wound Matrix Scaffold (MWM), a lyophilised porcine peritoneum-derived matrix (DSM Biomedical Inc., Exton, PA, US) for up to eight weeks. Descriptive statistics were chosen for this analysis.

RESULTS

A total of 12 male patients and three female patients with an average age of 57 years were enrolled over a two-month period. The average wound duration was 30 weeks. Due to unrelated health issues, four participants were withdrawn. For the study endpoint of complete wound closure at 12 weeks, six (55%) of the remaining 11 patients achieved complete closure, and four (36%) patients healed during the 8-week treatment period. The average number of CTP applications was six. Patients who healed all had negative BPA by nine weeks and no fluorescence on MLiX, indicating low bacterial load.

CONCLUSION

This small pilot study indicates that patients with longstanding DFUs may respond to a porcine peritoneal-derived CTP. In this study, the CTP appears to have inhibited bacterial growth in the wound; however, further research is needed.

Functional Imaging in Wounds: Imaging Modalities of Today and Tomorrow

Wound care is a multidisciplinary field with significant economic burden to our healthcare system. Not only does wound care cost the US healthcare system $20 billion annually, but wounds also remarkably impact the quality of life of patients; wounds pose significant risk of mortality, as the five-year mortality rate for diabetic foot ulcers (DFUs) and ischemic ulcers is notably higher compared to commonly encountered cancers such as breast and prostate. Although it is important to measure how wounds may or may not be improving over time, the only relative "marker" for this is wound area measurement-area measurements can help providers determine if a wound is on a healing or non-healing trajectory. Because wound area measurements are currently the only readily available "gold standard" for predicting healing outcomes, there is a pressing need to understand how other relative biomarkers may play a role in wound healing. Currently, wound care centers across the nation employ various techniques to obtain wound area measurements; length and width of a wound can be measured with a ruler, but this carries a high amount of inter- and intrapersonal error as well as uncertainty. Acetate tracings could be used to limit the amount of error but do not account for depth, thereby making them inaccurate. Here, we discuss current imaging modalities and how they can serve to accurately measure wound size and serve as useful adjuncts in wound assessment. Moreover, new imaging modalities are also discussed and how up-and-coming technologies can provide important information on "biomarkers" for wound healing.

The Association Between pH and Fluorescence as Noninvasive Diagnostic Tools in Chronic Wounds

MolecuLight i:X is a noninvasive, portable device that captures images, measures wound areas, and allows the evaluation of the bacterial environment in real time. The aim of the study was to correlate the different fluorescence (light green, red, cyan) and dark red-purple-black color areas with average pH values in these areas and with average wound bed score (WBS). During a 4-week period, we enrolled 43 adult patients (23 females and 20 males) with clinically infected and uninfected chronic ulcers. In our study, the mean age was 68 years old. The etiologies were 21 venous ulcers, 3 arterial ulcers, 4 vasculitis, 7 pyoderma gangrenosum, 7 traumatic ulcers, and 1 neoplastic ulcer. The average area was 16.92 cm² and the average WBS was 9.17. A total of 16 ulcers (37%) were positive for clinical signs and symptoms of infection and 27 ulcers were negative (63%). Thirty-six ulcers emitted a single fluorescence: cyan (n = 13), red (n = 1), light green (n = 14), and dark red-purple-black (n = 8). Six wounds showed a double fluorescence area: red and cyan (n = 1) and cyan and light green (n = 5). One ulcer emitted a triple fluorescence area: red, cyan, and light green. Overall in 43 ulcers, we found 43 fluorescence and 8 dark red-purple-black color. We found significant data between pH and fluorescence. pH values on wound bed confirm in a noninvasive way the correlation between fluorescence and bacterial burden. Moreover, MolecuLight i:X is able to detect objectively the bacterial proliferation, in contrast with pH which cannot distinguish different types of bacteria.

Bacterial Autofluorescence Digital Imaging Guides Treatment in Stage 4 Pelvic Pressure Injuries: A Preliminary Case Series

Pelvic pressure injuries in long-term care facilities are at high risk for undetected infection and complications from bacterial contamination and stalling of wound healing. Contemporary wound healing methods must address this problem with mechanical debridement, wound irrigation, and balanced dressings that reduce bacterial burden to enable the normal healing process. This study evaluated the impact of bacterial autofluorescence imaging to indicate wound bacterial contamination and guide treatment for severe stage 4 pelvic pressure injuries. A handheld digital imaging system was used to perform bacterial autofluorescence imaging in darkness on five elderly, high-risk, long-term care patients with advanced stage 4 pelvic pressure injuries who were being treated for significant bacterial contamination. The prescient findings of bacterial autofluorescence imaging instigated treatment strategies and enabled close monitoring of the treatment efficacy to ameliorate the bacterial contamination. Wound sepsis recurrence, adequate wound cleansing, and diagnosis of underlying periprosthetic total joint infection were confirmed with autofluorescence imaging showing regions of high bacterial load. By providing objective information at the point of care, imaging improved understanding of the bacterial infections and guided treatment strategies.

Use of a bacterial fluorescence imaging system to target wound debridement and accelerate healing: a pilot study

OBJECTIVE

Optimal wound-bed preparation consists of regular debridement to remove devitalised tissues, reduce bacterial load, and to establish an environment that promotes healing. However, lack of diagnostic information at point-of-care limits effectiveness of debridement.

METHOD

This observational case series investigated use of point-of-care fluorescence imaging to detect bacteria (loads >10⁴CFU/g) and guide wound bed preparation. Lower extremity hard-to-heal wounds were imaged over a 12-week period for bacterial fluorescence and wound area.

RESULTS

A total of 11 wounds were included in the study. Bacterial fluorescence was present in 10 wounds and persisted, on average, for 3.7 weeks over the course of the study. The presence of red or cyan fluorescent signatures from bacteria correlated with an average increase in wound area of 6.5% per week, indicating stalled or delayed wound healing. Fluorescence imaging information assisted in determining the location and extent of wound debridement, and the selection of dressings and/or antimicrobials. Elimination of bacterial fluorescence signature with targeted debridement and other treatments correlated with an average reduction in wound area of 27.7% per week (p<0.05), indicative of a healing trajectory.

CONCLUSION

These results demonstrate that use of fluorescence imaging as part of routine wound care enhances assessment and treatment selection, thus facilitating improved wound healing.

Diagnostic Accuracy of Point-of-Care Fluorescence Imaging for the Detection of Bacterial Burden in Wounds: Results from the 350-Patient Fluorescence Imaging Assessment and Guidance Trial

Objective: High bacterial load contributes to chronicity of wounds and is diagnosed based on assessment of clinical signs and symptoms (CSS) of infection, but these characteristics are poor predictors of bacterial burden. Point-of-care fluorescence imaging (FL) MolecuLight i:X can improve identification of wounds with high bacterial burden (>10⁴ colony-forming unit [CFU]/g). FL detects bacteria, whether planktonic or in biofilm, but does not distinguish between the two. In this study, diagnostic accuracy of FL was compared to CSS during routine wound assessment. Postassessment, clinicians were surveyed to assess impact of FL on treatment plan. Approach: A prospective multicenter controlled study was conducted by 20 study clinicians from 14 outpatient advanced wound care centers across the United States. Wounds underwent assessment for CSS followed by FL. Biopsies were collected to confirm total bacterial load. Three hundred fifty patients completed the study (138 diabetic foot ulcers, 106 venous leg ulcers, 60 surgical sites, 22 pressure ulcers, and 24 others). Results: Around 287/350 wounds (82%) had bacterial loads >10⁴ CFU/g, and CSS missed detection of 85% of these wounds. FL significantly increased detection of bacteria (>10⁴ CFU/g) by fourfold, and this was consistent across wound types (p < 0.001). Specificity of CSS+FL remained comparably high to CSS (p = 1.0). FL information modified treatment plans (69% of wounds), influenced wound bed preparation (85%), and improved overall patient care (90%) as reported by study clinicians. Innovation: This novel noncontact, handheld FL device provides immediate, objective information on presence, location, and load of bacteria at point of care. Conclusion: Use of FL facilitates adherence to clinical guidelines recommending prompt detection and removal of bacterial burden to reduce wound infection and facilitate healing.

Rapid Diagnosis of Pseudomonas aeruginosa in Wounds with Point-Of-Care Fluorescence Imaing

Pseudomonas aeruginosa (PA) is a common bacterial pathogen in chronic wounds known for its propensity to form biofilms and evade conventional treatment methods. Early detection of PA in wounds is critical to the mitigation of more severe wound outcomes. Point-of-care bacterial fluorescence imaging illuminates wounds with safe, violet light, triggering the production of cyan fluorescence from PA. A prospective single blind clinical study was conducted to determine the positive predictive value (PPV) of cyan fluorescence for the detection of PA in wounds. Bacterial fluorescence using the MolecuLight i:X imaging device revealed cyan fluorescence signal in 28 chronic wounds, including venous leg ulcers, surgical wounds, diabetic foot ulcers and other wound types. To correlate the cyan signal to the presence of PA, wound regions positive for cyan fluorescence were sampled via curettage. A semi-quantitative culture analysis of curettage samples confirmed the presence of PA in 26/28 wounds, resulting in a PPV of 92.9%. The bacterial load of PA from cyan-positive regions ranged from light to heavy. Less than 20% of wounds that were positive for PA exhibited the classic symptoms of PA infection. These findings suggest that cyan detected on fluorescence images can be used to reliably predict bacteria, specifically PA at the point-of-care.

Diagnosing Burn Wounds Infection: The Practice Gap & Advances with MolecuLight Bacterial Imaging

Burn injuries constitute a critical economic burden on healthcare infrastructures worldwide. They are often associated with high mortality rates due to severe complications. Infection is the most common complication, highlighting the importance of prompt and precise diagnosis in order to prevent detrimental consequences and to optimize patient outcomes. Here we examine the current standard of care for diagnosing infection in both burn and chronic wounds followed by an investigation into the research surrounding a relatively new technique for bacterial detection, fluorescence imaging. With five years of published research on bacterial fluorescence imaging (MolecuLight i:X device), we have summarized and analysed the validity of the procedure and compared it to the current standard of care; clinical assessment and microbiological analysis. We highlight the benefits that could be obtained through the use of this technology as well as the limitations and the feasibility of incorporating this novel procedure into the standard of care.