Understanding Real-Time Fluorescence Signals from Bacteria and Wound Tissues Observed with the MolecuLight i:XTM

Effect of ceramic dressings and silver-impregnated dressings on bacterial load and wound closure: a comparative study

Wound healing is a series of complex and dynamic processes which occur in several stages. Optimal wound healing is essential for restoring the integrity and function of the affected area. Although medicated wound dressings have been extensively employed to control wound infection, the risks associated with antimicrobials make the use of non-medicated alternatives necessary. Nevertheless, the relationship between the concentrations of medicated wound dressings and their antimicrobial activities, along with their wound healing efficacies, still remains unclear. Non-medicated wound dressings are an alternative to dressings that contain active ingredients acting as antimicrobials or antiseptics. In the present study, the researchers examined the reduction of bacterial load as the primary endpoint and the healing rate as the secondary endpoint, comparing microporous ceramic dressings to silver-impregnated dressings in participants from two outpatient wound management clinics. The study included 25 participants in the silver-impregnated dressing (control) group and 28 participants in the ceramic dressing (study) group. The participants' wounds were assessed through MolecuLight i:X (MolecuLight Inc., Canada) wound tracing and MolecuLight i:X fluorescence imaging to measure the wound size, as well as presence of a bacterial load of >104 colony forming units/g at weeks 1, 2, 3 and 4. The results indicated that there was a significant difference in the distribution over the categories of bacterial load cleared after weeks 1, 2, 3 or 4 in the two groups. Moreover, the bacterial load cleared significantly faster in the study group (p=0.001). Mean wound size was 10.93cm2 (range: 0.10-37.95cm2) in the control group and 11.48cm2 (range: 0.80-60cm2) in the study group. In the maximum likelihood regression analysis, the mean reduction in wound area for the study group was greater than that for the control group. The study concluded that the ceramic dressings could be an effective alternative to silver-impregnated dressings when treating infected wounds.

Audit of Antimicrobial Prescribing Trends in 1447 Outpatient Wound Assessments: Baseline Rates and Impact of Bacterial Fluorescence Imaging

Background/Objectives: In the field of wound care, the prescription of antibiotics and antimicrobials is haphazard and irrational, which has led to unchecked overprescribing. Recent Joint Commission guidelines mandate that hospital outpatient clinics develop and implement antimicrobial stewardship programs (ASPs). Yet few ASPs exist in wound clinics across the United States (US). Understanding baseline prescribing practices and rates in the US is a critical first step toward rational antimicrobial use and effective ASPs. Methods: This prospective study was conducted across eight outpatient wound clinics from January-December 2022. Data from consecutive patients attending single-time-point initial visits were recorded, including clinical findings, antimicrobial prescribing trends, and sampling practices. Results: A total of 1438 wounds were included; 964 were assessed by clinical examination (standard of care, SoC), and 474 by clinical examination plus fluorescence imaging. SoC patients were prescribed more concurrent medications on average than fluorescence patients (1.4 vs. 1 per patient). Prescriptions were preferentially topical in the fluorescence group (92% vs. 64%, p > 0.0001), and systemic antibiotics represented 36% of the single items prescribed under SoC (vs. 8% in fluorescence group p < 0.0001). Conclusions: Fluorescence imaging provided objective and actionable information at the bedside, which led to a decrease in the use of antibiotics. Real-time diagnostic technologies are essential in establishing a meaningful ASP.

Systematic review and meta-analysis of diagnostic test accuracy in chronic wound's microbiology

PURPOSE

This study aims to assess the diagnostic accuracy of non-culture-based methodologies for detecting microorganisms in chronic wounds.

METHODS

We systematically reviewed studies that evaluated the diagnostic accuracy of alternative tests in chronic wound samples, excluding studies focused on animal samples or unrelated conditions. The search encompassed PubMed, CINAHL, Scopus and Web of Science databases, employing the QUADAS-2 tool for risk of bias assessment. Our search included the PubMed, CINAHL, Scopus and Web of Science databases, and we assessed the risk of bias using the QUADAS-2 tool. A meta-analysis was conducted on polymerase chain reaction (PCR) and colorimetric methods to determine sensitivity, specificity, diagnostic odds ratio, and summary receiver-operating characteristic (sROC) curves using a random-effects model. For methods not suitable for quantitative synthesis, a narrative synthesis was performed.

RESULTS

Nineteen studies involving various types of chronic wounds were analysed, revealing diverse diagnostic methods including fluorescence, PCR, colorimetry, voltammetry, electronic nose, biosensors, enzymatic methods, staining and microscopy. Combining fluorescence with clinical signs and symptoms (CSS) versus culture showed significant accuracy. Colorimetry demonstrated low sensitivity but high specificity, with a diagnostic odds ratio of 6.3. PCR generally exhibited good accuracy, although significant heterogeneity was noted, even in subgroup analyses.

CONCLUSIONS

This study identified a broad spectrum of diagnostic approaches, highlighting the superior diagnostic accuracy achieved when microbiological analysis is combined with clinical assessments. However, the heterogeneity and methodological variations across studies present challenges in meta-analysis. Future research should aim for standardized and homogeneous study designs to enhance the assessment of diagnostic accuracy for alternative methods.

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.

Treatment of bacterially contaminated lower extremity ulcers with a fatty acid-containing wound matrix: a case series

OBJECTIVE

The aim was to evaluate the effectiveness of a marine omega fatty acid-containing multimodal wound matrix (MWM) in reducing bacterial contamination and supporting wound area reduction (WAR) in patients with hard-to-heal wounds of varying aetiologies.

METHOD

A prospective, single-site, pilot case series of patients with hard-to-heal wounds. All wounds were considered non-healing prior to inclusion as they had failed to achieve at least 50% WAR after at least four weeks of standard of care (SoC) treatments. Patients were seen once weekly for wound assessments, matrix application and dressing changes. Baseline and weekly fluorescence images, standard wound images and wound measurements were obtained.

RESULTS

A total of three patients, two with venous leg ulcers (VLUs) and one with a diabetic foot ulcer (DFU) were enrolled in this pilot study. The mean baseline wound age prior to study enrolment was 24 weeks, with a mean baseline wound size of 8.61cm2. The two VLUs went on to complete closure. The DFU displayed a total WAR of 53% by six weeks, when the patient was lost to follow-up due to a geographical relocation. The mean percentage area reduction of all wounds combined was 82% upon study completion.

CONCLUSION

The use of MWM proved to be effective and safe in this patient cohort. The wounds included in this case series failed to enter a healing trajectory with SoC wound therapies. The MWM supported wound closure and reduced bacterial loads in this patient cohort.

Incisional Negative Pressure Wound Therapy After Revascularisation Surgery in Patients with Peripheral Arterial Disease: A Randomised Trial (PICO-Vasc Study)

OBJECTIVE

This study assessed the potential benefits of using incisional negative pressure wound therapy (iNPWT) for patients undergoing revascularisation due to peripheral arterial disease.

METHODS

A prospective randomised controlled trial was conducted to compare the inguinal application of iNPWT vs. standard surgical dressings. Patients were enrolled from February 2021 to November 2022. A total of 133 groin incisions were randomised (66 intervention group, 67 control group). The randomisation sequence was carried out by permuted blocks and allocation assigned by opening opaque envelopes once the revascularisation procedure had finished. Wound healing and complication rates were assessed at post-operative days 5, 14, and 30. Primary and secondary endpoints were: 30 day post-operative surgical site infection (SSI) and surgical site occurrence (SSO) rates, defined as a surgical wound complication other than a SSI. Post-operative SSI was defined according to the US Centers for Disease Control and Prevention criteria. SSO included: wound dehiscence, seroma or lymphocele, haematoma, and lymphorrhagia. The study was registered at ClinicalTrials.gov database (NCT04840576) and reported according to the CONSORT guidelines.

RESULTS

iNPWT did not modify the 30 day inguinal SSI and SSO rates (16.7% vs. 20.9% and 37.9% vs. 44.8%; p = .53, relative risk [RR] 0.999, 95% confidence interval [CI] 0.52 - 1.88 and p = .42, RR 1.29, 95% CI 0.89 - 1.86, respectively). It reduced the early SSO rate (19.7% vs. 35.8%; p = .044, RR 1.45, 95% CI 1.047 - 2.013) and post-operative seroma rate (4.6% vs. 19.4%; p = .014, RR 1.73, 95% CI 1.296 - 2.397).

CONCLUSION

There were no differences in SSI and SSO rates, although statistically significant reductions in early SSO rates and seroma were found in the intervention group.

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.

Photonics-powered augmented reality skin electronics for proactive healthcare: multifaceted opportunities

Rapid technological advancements have created opportunities for new solutions in various industries, including healthcare. One exciting new direction in this field of innovation is the combination of skin-based technologies and augmented reality (AR). These dermatological devices allow for the continuous and non-invasive measurement of vital signs and biomarkers, enabling the real-time diagnosis of anomalies, which have applications in telemedicine, oncology, dermatology, and early diagnostics. Despite its many potential benefits, there is a substantial information vacuum regarding using flexible photonics in conjunction with augmented reality for medical purposes. This review explores the current state of dermal augmented reality and flexible optics in skin-conforming sensing platforms by examining the obstacles faced thus far, including technical hurdles, demanding clinical validation standards, and problems with user acceptance. Our main areas of interest are skills, chiroptical properties, and health platform applications, such as optogenetic pixels, spectroscopic imagers, and optical biosensors. My skin-enhanced spherical dichroism and powerful spherically polarized light enable thorough physical inspection with these augmented reality devices: diabetic tracking, skin cancer diagnosis, and cardiovascular illness: preventative medicine, namely blood pressure screening. We demonstrate how to accomplish early prevention using case studies and emergency detection. Finally, it addresses real-world obstacles that hinder fully realizing these materials' extraordinary potential in advancing proactive and preventative personalized medicine, including technical constraints, clinical validation gaps, and barriers to widespread adoption.

The use of fluorescence lifetime imaging (FLIM) for in situ microbial detection in complex mineral substrates

The utility of fluorescence lifetime imaging microscopy (FLIM) for identifying bacteria in complex mineral matrices was investigated. Baseline signals from unlabelled Bacillus subtilis and Euglena gracilis, and Bacillus subtilis labelled with SYTO 9 were obtained using two-photon excitation at 730, 750 and 800 nm, identifying characteristic lifetimes of photosynthetic pigments, unpigmented cellular autofluorescence, and SYTO 9. Labelled and unlabelled B. subtilis were seeded onto marble and gypsum samples containing endolithic photosynthetic cyanobacteria and the ability to distinguish cells from mineral autofluorescence and nonspecific dye staining was examined in parallel with ordinary multichannel confocal imaging. It was found that FLIM enabled discrimination of SYTO 9 labelled cells from background, but that the lifetime of SYTO 9 was shorter in cells on minerals than in pure culture under our conditions. Photosynthetic microorganisms were easily observed using both FLIM and confocal. Unlabelled, nonpigmented bacteria showed weak signals that were difficult to distinguish from background when minerals were present, though cellular autofluorescence consistent with NAD(P)H could be seen in pure cultures, and phasor analysis permitted detection on rocks. Gypsum and marble samples showed similar autofluorescence profiles, with little autofluorescence in the yellow-to-red range. Lifetime or time-gated imaging may prove a useful tool for environmental microbiology. LAY DESCRIPTION: The standard method of bacterial enumeration is to label the cells with a fluorescent dye and count them under high-power fluorescence microscopy. However, this can be difficult when the cells are embedded in soil and rock due to fluorescence from the surrounding minerals and dye binding to ambiguous features of the substrate. The use of fluorescence lifetime imaging (FLIM) can disambiguate these signals and allow for improved detection of bacteria in environmental samples.

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.

A multimodal nonlinear optical microscopy study of the responses of Pseudomonas aeruginosa to blue light and antibiotic treatment

Pseudomonas aeruginosa (P. aeruginosa) is a multidrug-resistant human pathogen involved in numerous infections. Understanding the response of P. aeruginosa to various treatments is critical to developing new ways for the antimicrobial susceptibly test and more effective treatment methods. Conventional antimicrobial susceptibility tests lack molecular information at the single bacterium level. In this study, we used label-free multimodal nonlinear optical microscopy to identify an autofluorescence signal from pyoverdine, a siderophore of the bacteria, for quantification of P. aeruginosa responses to antibiotics and blue light treatment. We also discovered that the bleaching of the pyoverdine autofluorescence signals is correlated with the inactivation of P. aeruginosa and is perhaps one of the mechanisms involved in the blue light inactivation of P. aeruginosa.

A Clinical Study to Evaluate Autofluorescence Imaging of Diabetic Foot Ulcers Using a Novel Artificial Intelligence Enabled Noninvasive Device

Diabetic foot ulcers, with worldwide prevalence ranging from 12%-25%, are an important cause of nontraumatic lower limb amputation. Evidence-based assessment of early infection can help the clinician provide the right first line treatment thus helping improve the wound closure rate. Illuminate®, a novel point of care device working on multispectral autofluorescence imaging, helps in the rapid identification and classification of bacteria. This study was aimed to evaluate the diagnostic accuracy of the device in detecting bacterial gram type against standard culture methods. A total of 178 patients from a tertiary care center for diabetes was recruited and 203 tissue samples were obtained from the wound base by the plastic surgeon. The device was handled by the trained investigator to take wound images. The tissue samples were taken from the color-coded infected region as indicated by the device's Artificial Intelligence algorithm and sent for microbial assessment. The results were compared against the Gram type inferred by the device and the device was found to have an accuracy of 89.54%, a positive predictive value of 86.27% for detecting Gram-positive bacteria, 80.77% for Gram-negative bacteria, and 91.67% for no infection. The negative predictive value corresponded to 87.25% for Gram-positive, 92% for Gram-negative, and 96.12% for no infection. The Results exhibited the accuracy of this novel autofluorescence device in identifying and classifying the gram type of bacteria and its potential in significantly aiding clinicians towards early infection assessment and treatment.

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.

Treatment of severe pressure ulcers with protein-enriched filtered platelet-rich plasma (PEFPRP): a possible management

Background: Biological dressings with non-transfusion blood components are among the treatments available for pressure ulcers (PUs). Biological dressings contain active concentrated pro-regenerative molecules that can modify and switch off local inflammatory pathways. This re-establishes the physiological homing, which results in healing. In our study, we used a biological component obtained by ultrafiltration of plasma-platelet concentrate: protein-enriched filtered platelet-rich plasma (PEFPRP) with a higher platelet and higher plasma protein concentration. We tested whether treatment with PEFPRP could improve healing in advanced-stage pressure ulcers with a large surface area. All the patients in this study had a surgical indication but were not able to undergo surgery for various reasons. Materials and methods: Ten patients with severe neurological disability and advanced-stage sacral pressure ulcers were treated with allogenic PEFPRP. The mean lesion surface area at T0 was 13.4 cm2 ( ± 9.8 SD). PEFPRP was derived from allogenic plasma-platelet apheresis that had been pre-ultrafiltered with a ProSmart™ filter (Medica, Italy) to obtain a concentration after filtration of the plasma protein (12-16 g/dL) and platelet (1-1.2 x 106 microL). Results and Conclusion: All cases showed a reduction in the surface area of the pressure ulcer and in the Pressure Ulcer Scale for Healing (PUSH) score. The mean reduction values at week 6 were as follows: -52% for surface area and -21% for PUSH. Rapid wound healing is fundamental to avoid infections and improve patients' quality of life. This blood component builds new tissue by creating a new extracellular matrix. This, in turn, promotes rapid restoration of the three-dimensional structure of the tissue necessary for healing deeper wounds. PEFPRP shrinks the PU and improves its morphological features (reducing undermining and boosting granulation tissue). PEFPRP also promotes tissue restoration, obtaining an optimal scar. It is a safe and feasible treatment, and these preliminary results support the use of PEFPRP in the treatment of pressure ulcers. PEFPRP dressings could be integrated in the standard treatment of advanced-stage PU.

Identifying infection in chronic wounds in a community setting: A systematic review of diagnostic test accuracy studies

AIM

To determine the diagnostic accuracy of different methods currently available to identify infection in chronic wounds applicable to adult patients in a community setting.

DESIGN

Systematic review of diagnostic test accuracy studies.

REVIEW METHODS

Two authors independently completed screening, data extraction and quality and bias assessments (QUADAS2). Eligible studies compared a method (index test) for detecting infection (diagnosis of interest) with microscopy and culture of either deep tissue biopsy or wound swab (reference test) in adult patients with wounds of >4 weeks duration (participants). The results were synthesized narratively.

DATA SOURCES

We systematically searched CINAHL, Embase and Medline from 2011 to April 2022.

RESULTS

Four studies were included, all recruiting from secondary care wound clinics. Two studies assessed the diagnostic accuracy of Moleculight i:X, a bacterial fluorescence imaging device against deep tissue biopsy culture. One study assessed the diagnostic accuracy of the elevation of various enzymes detected in wound fluid against wound swab microscopy of culture. One study assessed the diagnostic accuracy of bacterial protease activity against wound swab microscopy and culture. Sensitivities of these methods ranged from 50 to 75% and specificities from 47 to 100%.

CONCLUSION

Only a small number of studies were included in this systematic review due to our strict inclusion criteria. We have not identified any methods for diagnosing infection in chronic wounds with either a sufficient quality of evidence to recommend their use in community settings at present. Further research is needed to develop and evaluate appropriate diagnostics for this purpose.

IMPACT

This study highlights the paucity of research into wound diagnostics in a community setting and should prompt further research in this area. Accurate diagnostic tests have the potential to improve community-based wound care by optimizing antibiotic use and potentially improving healing time.

REPORTING METHOD

PRISMA-DTA checklist.

PATIENT OR PUBLIC CONTRIBUTION

The PPI group for the NIHR Community Healthcare MIC were supportive of this topic of work.

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.

Fluorescent bioinspired albumin/polydopamine nanoparticles and their interactions with Escherichia coli cells

Inspired by the eumelanin aggregates in human skin, polydopamine nanoparticles (PDA NPs) are promising nanovectors for biomedical applications, especially because of their biocompatibility. We synthesized and characterized fluorescent PDA NPs of 10-25 nm diameter based on a protein containing a lysine-glutamate diad (bovine serum albumin, BSA) and determined whether they can penetrate and accumulate in bacterial cells to serve as a marker or drug nanocarrier. Three fluorescent PDA NPs were designed to allow for tracking in three different wavelength ranges by oxidizing BSA/PDA NPs (Ox-BSA/PDA NPs) or labelling with fluorescein 5-isothiocyanate (FITC-BSA/PDA NPs) or rhodamine B isothiocyanate (RhBITC-BSA/PDA NPs). FITC-BSA/PDA NPs and RhBITC-BSA/PDA NPs penetrated and accumulated in both cell wall and inner compartments of Escherichia coli (E. coli) cells. The fluorescence signals were diffuse or displayed aggregate-like patterns with both labelled NPs and free dyes. RhBITC-BSA/PDA NPs led to the most intense fluorescence in cells. Penetration and accumulation of NPs was not accompanied by a bactericidal or inhibitory effect of growth as demonstrated with the Gram-negative E. coli species and confirmed with a Gram-positive bacterial species (Staphylococcus aureus). Altogether, these results allow us to envisage the use of labelled BSA/PDA NPs to track bacteria and carry drugs in the core of bacterial cells.

Integrating Point-of-Care Bacterial Fluorescence Imaging-Guided Care with Continued Wound Measurement for Enhanced Wound Area Reduction Monitoring

AIM

This prospective observational study investigated wound area reduction (WAR) outcomes in a complex wound population composed of non-healing acute and chronic wounds. The relationship between bacterial autofluorescence signals and WAR was investigated. Area measurements were collected both manually and digitally, and both methods were compared for accuracy.

METHODS

Twenty-six participants with 27 wounds of varying etiologies were observed twice weekly for two weeks. Digital wound measurement, wound bacterial status assessment, and targeted debridement were performed through a point-of-care fluorescence imaging device (MolecuLight® i: X, MolecuLight Inc, Toronto, Canada). The wound area reduction (WAR) rate was calculated using baseline and last visit measurements. Statistical analyses, including t-tests, Fisher exact tests, the Wilcoxon signed rank test for method comparison, and ANOVA for bacterial subgroups, were applied as pertinent.

RESULTS

The overall average WAR was -3.80 cm2, or a decrease of 46.88% (manual measurement), and -2.62 cm2, or a 46.05% decrease (digital measurement via MolecuLight® device). There were no statistically significant differences between the WAR of acute and chronic wounds (p = 0.7877). A stepwise correlation between the WAR and bacterial status classification per fluorescence findings was observed, where persistent bacteria resulted in worse WAR outcomes. An overestimation of wound area by manual measurement was 23% on average.

CONCLUSION

Fluorescence imaging signals were linked to WAR outcome and could be considered predictive. Wounds exhibiting bacterial loads that persisted at the end of the study period had worse WAR outcomes, while those for which management was able to effectively remove them demonstrated greater WAR. Manual measurement of the wound area consistently overestimated wound size when compared to digital measurement. However, if performed by the same operator, the overestimation was uniform enough that the WAR was calculated to be close to accurate. Notwithstanding, single wound measurements are likely to result in overestimation.

Development and use of a porcine model with clinically relevant chronic infected wounds

Chronic ischemic wounds affect millions of people causing significant pain and disability. They can be considered to be stalled in the inflammatory stage and cannot heal without additional measures. A valid animal model is necessary to evaluate the efficacy of topical wound healing therapies and wearable technologies. A porcine model, although higher in cost, maintenance, and space requirements, is superior to the commonly used rodent or rabbit model for wound healing. Previous studies have shown that pig wounds have greater similarity to human wounds in responses to a variety of treatments, including wound dressings and antibiotics. The current study created a porcine model of large chronic wounds to assess a wearable electroceutical technology, with monitoring of healing variables and infection. Electroceutical therapy is the only adjunctive treatment recommended for chronic wound therapy. A porcine model of large chronic wounds of clinically realistic size was created and utilized to evaluate a wearable electroceutical biotechnology. Multivariate non-invasive assessment was used to monitor wound progression over multiple timepoints. Outcomes suggest that a wearable electrostimulation bandage, has the potential to offer therapeutic benefit in human wounds. The tested wearable device provides the same proven effectiveness of traditional electroceutical therapy while mitigating commonly cited barriers, including substantial time requirements, and availability and complexity of currently available equipment, preventing its implementation in routine wound care. The model is also appropriate for evaluation of other wearables or topical therapeutics.

Diabetic Foot Ulcer Imaging: An Overview and Future Directions

Diabetic foot ulcers (DFUs) affect one in every three people with diabetes. Imaging plays a vital role in objectively complementing the gold-standard visual yet subjective clinical assessments of DFUs during the wound treatment process. Herein, an overview of the various imaging techniques used to image DFUs is summarized. Conventional imaging modalities (e.g., computed tomography, magnetic resonance imaging, positron emission tomography, single-photon emitted computed tomography, and ultrasound) are used to diagnose infections, impact on the bones, foot deformities, and blood flow in patients with DFUs. Transcutaneous oximetry is a gold standard to assess perfusion in DFU cases with vascular issues. For a wound to heal, an adequate oxygen supply is needed to facilitate reparative processes. Several optical imaging modalities can assess tissue oxygenation changes in and around the wounds apart from perfusion measurements. These include hyperspectral imaging, multispectral imaging, diffuse reflectance spectroscopy, near-infrared (NIR) spectroscopy, laser Doppler flowmetry or imaging, and spatial frequency domain imaging. While perfusion measurements are dynamically monitored at point locations, tissue oxygenation measurements are static two-dimensional spatial maps. Recently, we developed a spatio-temporal NIR-based tissue oxygenation imaging approach to map for the extent of asynchrony in the oxygenation flow patterns in and around DFUs. Researchers also measure other parameters such as thermal maps, bacterial infections (from fluorescence maps), pH, collagen, and trans-epidermal water loss to assess DFUs. A future direction for DFU imaging would ideally be a low-cost, portable, multi-modal imaging platform that can provide a visual and physiological assessment of wounds for comprehensive wound care intervention and management.

Rapid identification of bacteria by the pattern of redox reactions rate using 2',7'-dichlorodihydrofluorescein diacetate

Bacterial infection is a life-threatening situation, and its rapid diagnosis is essential for treatment. Apart from medical applications, rapid identification of bacteria is vital in the food industry or the public health system. There are various bacterial identification techniques, including molecular-based methods, immunological approaches, and biosensor-based procedures. The most commonly used methods are culture-based methods, which are time-consuming. The objective of this study is to find a fingerprint of bacteria to identify them. Three strains of bacteria were selected, and seven different concentrations of each bacterium were prepared. The bacteria were then treated with two different molar concentrations of the fluorescent fluorophore, dichlorodihydrofluorescein diacetate for 30 minutes. Then, using the fluorescence mode of a multimode reader, the fluorescence emission of each bacterium is scanned twice during 60 minutes. Plotting the difference between two scans versus the bacteria concentration results in a unique fluorescence pattern for each bacterium. Observation of the redox state of bacteria, during 90 minutes, results in a fluorescence pattern that is clearly a fingerprint of different bacteria. This pattern is independent of fluorophore concentration. Mean Squares Errors (MSE) between the fluorescence patterns of similar bacteria is less than that of different bacteria, which shows the method can properly identify the bacteria. In this study, a new label-free method is developed to detect and identify different species of bacteria by measuring the redox activity and using the fluorescence fluorophore, dichlorodihydrofluorescein diacetate. This robust and low-cost method can properly identify the bacteria, uses only one excitation and emission wavelength, and can be simply implemented with current multimode plate readers.

Fluorescence-Based Evaluation of Bacterial Load in Perilesional Skin: A Comparison Between Short Stretch Bandage and Zinc Oxide Bandage

Bacterial proliferation plays a well-known role in delayed tissue healing. To date, the presence of microorganisms on the wound bed can be detected by skin swabs or skin biopsies. A novel noninvasive fluorescence imaging device has recently allowed real-time detection of bacteria in different types of wounds through endogenous autofluorescence. The fluorescence signals detected by the device provide health workers with a visual indication of the presence, load, and distribution of bacteria. The aim of our study was to evaluate the level of bacterial colonization in perilesional skin of patients affected by venous leg ulcers treated with 2 different types of bandages: short stretch bandage and zinc oxide bandage. We conducted a monocentric prospective study, enrolling 30 patients with venous leg ulcers, divided into 2 groups: group A was treated with short stretch bandage and group B with zinc oxide bandage. A complete patient's assessment was performed once a week for 3 weeks. Levels of potentially harmful bacteria in perilesional skin were detected using a fluorescent device by 2 experienced operators on the frames taken at individual injuries, while pain was evaluated with the Numerical Rating Scale. After 3 weeks, we observed a reduction in the bacterial colonization levels of the perilesional skin by 68.67% for group A and 85.54% for group B. All the patients had a statistically significant reduction in bacterial load (P < .001), and a statistically significant difference was identified between the 2 groups (P = .043). No statistically significant differences were found between the 2 groups in terms of pain relief (P = .114). Our study demonstrated that the application of zinc oxide bandage provides a higher reduction in bacterial load perilesional skin. On the other hand, we found no difference between the 2 bandages in terms of pain symptom reduction.

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.

Quantitative Insights and Visualization of Antimicrobial Tolerance in Mixed-Species Biofilms

Biofilms are a major problem in hard-to-heal wounds. Moreover, they are composed of different species and are often tolerant to antimicrobial agents. At the same time, interspecific synergy and/or competition occurs when some bacterial species clash. For this reason, the tolerance of two dual-species wound biofilm models of Pseudomonas aeruginosa and Staphylococcus aureus or Enterococcus faecium against antimicrobials and antimicrobial dressings were analyzed quantitatively and by confocal laser scanning microscopy (CLSM). The results were compared to findings with planktonic bacteria. Octenidine-dihydrochloride/phenoxyethanol and polyhexamethylene biguanide (PHMB) irrigation solutions showed a significant, albeit delayed reduction in biofilm bacteria, while the PHMB dressing was not able to induce this effect. However, the cadexomer-iodine dressing caused a sustained reduction in and killed almost all bacteria down to 102 cfu/mL within 6 days compared to the control (1010 cfu/mL). By means of CLSM in untreated human biofilm models, it became evident that P. aeruginosa dominates over E. faecium and S. aureus. Additionally, P. aeruginosa appeared as a vast layer at the bottom of the samples, while S. aureus formed grape-like clusters. In the second model, the distribution was even clearer. Only a few E. faecium were visible, in contrast to the vast layer of P. aeruginosa. It seems that the different species avoid each other and seek their respective niches. These mixed-species biofilm models showed that efficacy and tolerance to antimicrobial substances are nearly species-independent. Their frequent application appears to be important. The bacterial wound biofilm remains a challenge in treatment and requires new, combined therapy options.

Is my wound infected? A study on the use of hyperspectral imaging to assess wound infection

Introduction

Clinical signs and symptoms (CSS) of infection are a standard part of wound care, yet they can have low specificity and sensitivity, which can further vary due to clinician knowledge, experience, and education. Wound photography is becoming more widely adopted to support wound care. Thermography has been studied in the medical literature to assess signs of perfusion and inflammation for decades. Bacterial fluorescence has recently emerged as a valuable tool to detect a high bacterial load within wounds. Combining these modalities offers a potential objective screening tool for wound infection.

Methods

A multi-center prospective study of 66 outpatient wound care patients used hyperspectral imaging to collect visible light, thermography, and bacterial fluorescence images. Wounds were assessed and screened using the International Wound Infection Institute (IWII) checklist for CSS of infection. Principal component analysis was performed on the images to identify wounds presenting as infected, inflamed, or non-infected.

Results

The model could accurately predict all three wound classes (infected, inflamed, and non-infected) with an accuracy of 74%. They performed best on infected wounds (100% sensitivity and 91% specificity) compared to non-inflamed (sensitivity 94%, specificity 70%) and inflamed wounds (85% sensitivity, 77% specificity).

Discussion

Combining multiple imaging modalities enables the application of models to improve wound assessment. Infection detection by CSS is vulnerable to subjective interpretation and variability based on clinicians' education and skills. Enabling clinicians to use point-of-care hyperspectral imaging may allow earlier infection detection and intervention, possibly preventing delays in wound healing and minimizing adverse events.

Selective Optical Imaging for Detection of Bacterial Biofilms in Tissues

SIGNIFICANCE

The development of an imaging technique to accurately identify biofilm regions on tissues and in wounds is crucial for the implementation of precise surface-based treatments, leading to better patient outcomes and reduced chances of infection.

AIM

The goal of this study was to develop an imaging technique that relies on selective trypan blue (TB) staining of dead cells, necrotic tissues, and bacterial biofilms, to identify biofilm regions on tissues and wounds.

APPROACH

The study explored combinations of ambient multi-colored LED lights to obtain maximum differentiation between stained biofilm regions and the underlying chicken tissue or glass substrate during image acquisition. The TB imaging results were then visually and statistically compared to fluorescence images using a shape similarity measure.

RESULTS

The comparisons between the proposed TB staining method and the fluorescence standard used to detect biofilms on tissues and glass substrates showed up to 97 percent similarity, suggesting that the TB staining method is a promising technique for identifying biofilm regions.

CONCLUSIONS

The TB staining method demonstrates significant potential as an effective imaging technique for the identification of fluorescing and non-fluorescing biofilms on tissues and in wounds. This approach could lead to improved precision in surface-based treatments and better patient outcomes.

The effect of inflammation management on pH, temperature, and bacterial burden

The aim of this feasibility study was to investigate the impact of inflammation management on wound pH, temperature, and bacterial burden, using the principles of TIME and Wound Bed Preparation. A quantitative non-comparative, prospective, descriptive observational design. Following ethical approval, 26 participants with 27 wounds of varying aetiologies were observed twice weekly for 2 weeks. Wounds were treated with cleansing, repeated sharp debridement, and topical cadexomer iodine. Wound pH (pH indicator strips), temperature (infrared camera), bacterial burden (fluorescence imaging) and size (ruler method) was monitored at each visit. The mean age of all participants was 47 years (SD: 20.3 years), and 79% (n = 19) were male, and most wounds were acute (70%; n = 19) and included surgical and trauma wounds, the remaining (30%; n = 8) were chronic and included vascular ulcers and non-healing surgical wounds. Mean wound duration was 53.88 days (SD: 64.49 days). Over the follow up period, pH values ranged from 6 to 8.7, temperature (centre spot) ranged from 28.4°C to 36.4°C and there was an average 39% reduction in wound size. Inflammation management had a positive effect on pH, temperature, bacterial burden, and wound size. This study demonstrated that it was feasible to practice inflammation management using a structured approach to enhance wound outcomes.

Fluorescence Methods for the Detection of Bioaerosols in Their Civil and Military Applications

The article presents the history of the development and the current state of the apparatus for the detection of interferents and biological warfare simulants in the air with the laser-induced fluorescence (LIF) method. The LIF method is the most sensitive spectroscopic method and also enables the measurement of single particles of biological aerosols and their concentration in the air. The overview covers both the on-site measuring instruments and remote methods. The spectral characteristics of the biological agents, steady-state spectra, excitation-emission matrices, and their fluorescence lifetimes are presented. In addition to the literature, we also present our own detection systems for military applications.

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.

Fluorescence - modern method of the diagnosis of chronic wounds on the example of venous leg ulcer

Introduction

Fluorescence imaging has become a method for bacterial visualisation in chronic wounds for the last few years. MolecuLight i:X (MolecuLight, Inc, ON, Canada) is a handheld device, which enables quick diagnostics to determine both the type and location of pathogens present in the wound and on the skin. By means of fluorescent light illumination the tissues populated by pathogenic bacteria emit red or cyan fluorescent signatures, depending on the type of the pathogen: red fluorescence signal is emitted by Staphylococcus and Escherichia coli among others, while Pseudomonas aeruginosa produce cyan fluorescence. The fluorescence image also presents the spatial pattern of bacterial load, which creates bacterial mapping of the wound and may be used by a clinician for targeted sampling or debridement, among others.

Aim

This study presents the method of microbiological fluorescent imaging and two case studies of patients with venous leg ulcers.

Material and methods

In both cases, the sample for microbiological testing was obtained by means of a swab stick.

Results

The results obtained from fluorescent imaging showed moderate-to-heavy bacterial load, which corresponded with the results from microbiology laboratory. Thanks to quick diagnostics with the use of MolecuLight i:X device, instant implementation of targeted topical actions such as wound hygiene, skin disinfection, appropriate dressing choice and curative treatment among others was possible.

Conclusions

Our observations are consistent with the reports from other facilities.

3D-Bioprinted Phantom with Human Skin Phototypes for Biomedical Optics

3D-bioprinted skin-mimicking phantoms with skin colors ranging across the Fitzpatrick scale are reported. These tools can help understand the impact of skin phototypes on biomedical optics. Synthetic melanin nanoparticles of different sizes (70-500 nm) and clusters are fabricated to mimic the optical behavior of melanosome. The absorption coefficient and reduced scattering coefficient of the phantoms are comparable to real human skin. Further the melanin content and distribution in the phantoms versus real human skins are validated via photoacoustic (PA) imaging. The PA signal of the phantom can be improved by: 1) increasing melanin size (3-450-fold), 2) increasing clustering (2-10.5-fold), and 3) increasing concentration (1.3-8-fold). Then, multiple biomedical optics tools (e.g., PA, fluorescence imaging, and photothermal therapy) are used to understand the impact of skin tone on these modalities. These well-defined 3D-bioprinted phantoms may have value in translating biomedical optics and reducing racial bias.

Antibiotic Misuse in Wound Care: Can Bacterial Localization through Fluorescence Imaging Help?

(1) Background: Systemic antibiotic use in chronic wounds is alarmingly high worldwide. Between 53% to 71% of patients are prescribed at least one course per chronic wound. Systemic antibiotic use should follow antibiotic stewardship guidelines and ought to be reserved for situations where their use is deemed supported by clinical indications. Unfortunately, in the field of wound care, indiscriminate and often inadequate use of systemic antibiotics is leading to both patient complications and worsening antibiotic resistance rates. Implementing novel tools that help clinicians prevent misuse or objectively determine the true need for systemic antibiotics is essential to reduce prescribing rates. (2) Methods: We present a compendium of available systemic antibiotic prescription rates in chronic wounds. The impact of various strategies used to improve these rates, as well as preliminary data on the impact of implementing fluorescence imaging technology to finesse wound status diagnosis, are presented. (3) Results: Interventions including feedback from wound care surveillance and treatment data registries as well as better diagnostic strategies can ameliorate antibiotic misuse. (4) Conclusions: Interventions that mitigate unnecessary antibiotic use are needed. Effective strategies include those that raise awareness of antibiotic overprescribing and those that enhance diagnosis of infection, such as fluorescence imaging.

Challenges and innovations in treating chronic and acute wound infections: from basic science to clinical practice

Acute and chronic wound infection has become a major worldwide healthcare burden leading to significantly high morbidity and mortality. The underlying mechanism of infections has been widely investigated by scientist, while standard wound management is routinely been used in general practice. However, strategies for the diagnosis and treatment of wound infections remain a great challenge due to the occurrence of biofilm colonization, delayed healing and drug resistance. In the present review, we summarize the common microorganisms found in acute and chronic wound infections and discuss the challenges from the aspects of clinical diagnosis, non-surgical methods and surgical methods. Moreover, we highlight emerging innovations in the development of antimicrobial peptides, phages, controlled drug delivery, wound dressing materials and herbal medicine, and find that sensitive diagnostics, combined treatment and skin microbiome regulation could be future directions in the treatment of wound infection.

Challenges in the diagnosis and management of wound infection

Human epithelia are constantly exposed to microorganisms present in the environment or residing as part of commensal flora. Despite this exposure, infections involving the skin and subcutaneous tissue in healthy individuals are, fortunately, quite rare. Many of the wounds that afflict the human body occur in individuals of ill health and/or where the mechanism of wounding is impeded by host immunological, physiological or regenerative dysfunction. The interplay between microorganisms and host immunity is complex and remains ill defined; however, the interpretation of downstream manifestations of the host response to invading microorganisms is still based largely on the clinical signs and symptoms of an active infectious process. In this review article we will provide a brief overview of the current challenges clinicians face in diagnosing wound infections, how chronic infections caused by biofilms are a major challenge, and how there have been minimal advancements in developing new diagnostics or therapeutics in the identification and management of wound infections.

Acute and chronic wound infections: microbiological, immunological, clinical and therapeutic distinctions

Wound infection is a complex pathology that may manifest either as a rapid onset acute condition, or as a prolonged chronic condition. Although systemic antibiotic therapy is often appropriate and necessary for acute wound infections, it is often used inappropriately, excessively and unsuccessfully in chronic wound infections. Overuse of antibiotics in chronic (hard-to-heal) wound management contributes to antibiotic resistance. This literature review confirms that acute and chronic wound infections are significantly differentiated by their cause (microbial phenotype), the subsequent host immune response and by the resulting clinical manifestations. Consequently, recognition of the type of wound infection followed by appropriate and timely therapy is required to improve wound healing outcomes while encouraging more judicious and responsible use of antibiotics.

[Modern concept about trophic venous ulcers]

Venous trophic ulcer is a common complication of chronic venous diseases that have a negative impact on the quality of life and result negative socio-economic consequences. There are three main theories of development of venous trophic ulcers. The criterion is visible trophic changes of skin (CEAP class C4). If correction of etiological factor of ulcer is impossible, local management is preferred. There are various wound coverings which can be used for the treatment of trophic ulcers. However, data on their effectiveness are sometimes unavailable. Therefore, it is necessary to systematize knowledge about modern measures and methods of exposure to trophic ulcers. The authors also discuss current understanding of pathophysiology, symptoms and diagnosis of venous trophic ulcers.

Optical clearing of tissues: Issues of antimicrobial phototherapy and drug delivery

This review presents principles and novelties in the field of tissue optical clearing (TOC) technology, as well as application for optical monitoring of drug delivery and effective antimicrobial phototherapy. TOC is based on altering the optical properties of tissue through the introduction of immersion optical cleaning agents (OCA), which impregnate the tissue of interest. We also analyze various methods and kinetics of delivery of photodynamic agents, nanoantibiotics and their mixtures with OCAs into the tissue depth in the context of antimicrobial and antifungal phototherapy. In vitro and in vivo studies of antimicrobial phototherapies, such as photodynamic, photothermal plasmonic and photocatalytic, are summarized, and the prospects of a new TOC technology for effective killing of pathogens are discussed.

Depth distributions of bacteria for the Pseudomonas aeruginosa-infected burn wounds treated by methylene blue-mediated photodynamic therapy in rats: effects of additives to photosensitizer

SIGNIFICANCE

Pseudomonas(P.) aeruginosa, a common cause of infection in burns, acquires antibiotic resistance easily and forms biofilms efficiently. Thus, it is difficult to control P. aeruginosa infection in burn wounds, which causes lethal septicemia. Antimicrobial photodynamic therapy (aPDT) is attractive as a new strategy to treat burn wound infections with drug-resistant bacteria.

AIM

We examined the efficacy of methylene blue (MB)-mediated aPDT with various additives in a tissue depth-resolved manner to find conditions that minimize the bacterial invasion.

APPROACH

We applied MB-mediated aPDT with LED array illumination to an extensive, full-thickness burn infected with P. aeruginosa in rats for three consecutive days (days 0, 1, and 2). On day 2, the depth distributions of bacteria were assessed based on the histological analysis using Gram staining. We examined how the addition of ethylenediaminetetraacetic acid (EDTA), ethanol, and dimethyl sulfoxide (DMSO) affected the efficacy of aPDT.

RESULTS

Pure MB-mediated aPDT significantly reduced the numbers of bacteria with biofilms on the wound surface and in the epidermis compared with those for the control tissue (saline only). However, there were many bacteria in the deeper region of the tissue. In contrast, MB/EDTA/ethanol/DMSO-mediated aPDT minimized the numbers of bacteria in the broad depth region of the tissue. Still, a limited number of bacteria was observed in the subcutaneous tissue.

CONCLUSIONS

The depthwise analysis of bacteria demonstrated the efficacy of the MB-mediated aPDT with the addition of EDTA, ethanol, and DMSO in controlling burn wound infections. However, further improvement of the therapy is needed to suppress bacterial migration into the deep tissue completely.

Smartphone-based autofluorescence imaging to detect bacterial species on laboratory surfaces

This work demonstrated instantaneous, reagent- and staining-free, smartphone-based autofluorescence detection of bacterial contamination on typical laboratory desk surfaces. Detection was successfully distinguished from protein, salt, and tap water.

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.

Portable point-of-care diagnostic devices: an updated review

The global pandemic caused by the SARS-CoV-2 (COVID) virus indiscriminately impacted people worldwide with unquantifiable and severe impacts on all aspects of our lives, regardless of socioeconomic status. The pandemic brought to light the very real possibility of pathogens changing and shaping the way we live, and our lack of preparedness to deal with viral/bacterial outbreaks. Importantly, the quick detection of pathogens can help prevent and control the spread of disease, making the importance of diagnostic techniques undeniable. Point-of-care diagnostics started as a supplement to standard lab-based diagnostics, and are gradually becoming mainstream. Because of this, and their importance in detecting pathogens (especially in the developing world), their development has accelerated at an unprecedented rate. In this review, we highlight some important and recent examples of point-of-care diagnostics for detecting nucleic acids, proteins, bacteria, and other biomarkers, with the intent of making apparent their positive impact on society and human health.

Healing of disrupted perineal wounds after vaginal delivery: a poorly understood condition

Perineal injury following childbirth can result in complications such as wound infection and dehiscence. The reported incidence of these complications in the literature range between 0.1-23.6% and 0.2-24.6%, respectively. However, the healing of disrupted perineal wounds is poorly understood. In addition, it is a neglected area in maternity services. In this review, the authors explore the process of wound healing in the context of infected perineal wounds following childbirth. In addition, the authors describe the management of complications including hypergranulation, perineal pain and dyspareunia.

Fluorescence Lifetime Imaging Microscopy of Porphyrins in Helicobacter pylori Biofilms

Bacterial biofilm constitutes a strong barrier against the penetration of drugs and against the action of the host immune system causing persistent infections hardly treatable by antibiotic therapy. Helicobacter pylori (Hp), the main causative agent for gastritis, peptic ulcer and gastric adenocarcinoma, can form a biofilm composed by an exopolysaccharide matrix layer covering the gastric surface where the bacterial cells become resistant and tolerant to the commonly used antibiotics clarithromycin, amoxicillin and metronidazole. Antimicrobial PhotoDynamic Therapy (aPDT) was proposed as an alternative treatment strategy for eradicating bacterial infections, particularly effective for Hp since this microorganism produces and stores up photosensitizing porphyrins. The knowledge of the photophysical characteristics of Hp porphyrins in their physiological biofilm microenvironment is crucial to implement and optimize the photodynamic treatment. Fluorescence lifetime imaging microscopy (FLIM) of intrinsic bacterial porphyrins was performed and data were analyzed by the 'fit-free' phasor approach in order to map the distribution of the different fluorescent species within Hp biofilm. Porphyrins inside bacteria were easily distinguished from those dispersed in the matrix suggesting FLIM-phasor technique as a sensitive and rapid tool to monitor the photosensitizer distribution inside bacterial biofilms and to better orientate the phototherapeutic strategy.

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.