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.     

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.     

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.     

Handheld fluorescence imaging device detects subclinical wound infection in an asymptomatic patient with chronic diabetic foot ulcer: a case report

Chronic wounds are a significant burden to global patient and health care infrastructures, and there is a need for better methods of early wound diagnosis and treatment. Traditional diagnosis of chronic wound infection by pathogenic bacteria, using clinical signs and symptoms, is based on visual inspection under white light and microbiological sampling (e.g. swabbing and/or biopsy) of the wound, which are subjective and suboptimal. Diagnosing microbial infection based on traditional clinical signs and symptoms in wounds of asymptomatic patients is especially challenging at the bedside. Bacteria are invisible to the unaided eye and wound sampling for diagnostic testing can cause unacceptable delays in diagnosis and treatment. To address this problem, we developed a new prototype handheld, portable fluorescence imaging device that enables non‐contact, real‐time, high‐resolution visualisation of pathogenic bacteria and tissues in wounds. Herein, we report the clinical use of this imaging device in detecting subsurface heavy bacterial load and subclinical local infection in an asymptomatic 50‐year‐old patient with a non‐healing diabetic foot ulcer.     

Clinical validation of a machine‐learning‐based handheld 3‐dimensional infrared wound imaging device in venous leg ulcers

Chronic venous insufficiency is a chronic disease of the venous system with a prevalence of 25% to 40% in females and 10% to 20% in males. Venous leg ulcers (VLUs) result from venous insufficiency. VLUs have a prevalence of 0.18% to 1% with a 1‐year recurrence of 25% to 50%, bearing significant socioeconomic burden. It is therefore important for regular assessment and monitoring of VLUs to prevent worsening. Our study aims to assess the intra‐ and inter‐rater reliability of a machine learning‐based handheld 3‐dimensional infrared wound imaging device (WoundAide [WA] imaging system, Konica Minolta Inc, Tokyo, Japan) compared with traditional measurements by trained wound nurse. This is a prospective cross‐sectional study on 52 patients with VLUs from September 2019 to January 2021 using three WA imaging systems. Baseline patient profile and clinical demographics were collected. Basic wound parameters (length, width and area) were collected for both traditional measurements and measurements taken by the WA imaging systems. Intra‐ and inter‐rater reliability was analysed using intra‐class correlation statistics. A total of 222 wound images from 52 patients were assessed. There is excellent intra‐rater reliability of the WA imaging system on three different image captures of the same wound (intra‐rater reliability ranging 0.978‐0.992). In addition, there is excellent inter‐rater reliability between the three WA imaging systems for length (0.987), width (0.990) and area (0.995). Good inter‐rater reliability for length and width (range 0.875‐0.900) and excellent inter‐rater reliability (range 0.932‐0.950) were obtained between wound nurse measurement and each of the WA imaging system. In conclusion, high intra‐ and inter‐rater reliability was obtained for the WA imaging systems. We also obtained high inter‐rater reliability of WA measurements against traditional wound measurement. The WA imaging system is a useful clinical adjunct in the monitoring of VLU wound documentation.     

Impact of COVID‐19 on wound care in Germany

Recent studies showed that the COVID‐19 pandemic caused collateral damage in health care in terms of reduced hospital submissions or postponed treatment of other acute or chronic ill patients. An anonymous survey was sent out by mail to patients with chronic wounds in order to evaluate the impact of the pandemic on wound care. Sixty‐three patients returned the survey. In 14%, diagnostic workup or hospitalisation was cancelled or postponed. Thirty‐six percent could not seek consultation by their primary care physician as usual. The use of public transport or long travel time was not related to limited access to medical service (P = .583). In ambulatory care, there was neither a significant difference in the frequency of changing wound dressings (P = .67), nor in the person, who performed wound care (P = .39). There were no significant changes in wound‐specific quality of life (P = .505). No patient used telemedicine in order to avoid face‐to‐face contact or anticipate to pandemic‐related restrictions. The COVID‐19 pandemic impaired access to clinical management of chronic wounds in Germany. It had no significant impact on ambulatory care or wound‐related quality of life. Telemedicine still plays a negligible role in wound care.     

Evaluation of near point‐of‐care viral load implementation in public health facilities across seven countries in sub‐Saharan Africa

IntroductionIn many low‐ and middle‐income countries, HIV viral load (VL) testing occurs at centralized laboratories and time‐to‐result‐delivery is lengthy, preventing timely monitoring of HIV treatment adherence. Near point‐of‐care (POC) devices, which are placed within health facility laboratories rather than clinics themselves (i.e. “true” POC), can offer VL in conjunction with centralized laboratories to expedite clinical decision making and improve outcomes, especially for patients at high risk of treatment failure. We assessed impacts of near‐POC VL testing on result receipt and clinical action in public sector programmes in Cameroon, Democratic Republic of Congo, Kenya, Malawi, Senegal, Tanzania and Zimbabwe.MethodsRoutine health data were collected retrospectively after introducing near‐POC VL testing at 57 public sector health facilities (2017 to 2019, country‐dependent). Where possible, key indicators were compared to data from patients receiving centralized laboratory testing using hazard ratios and the Somers’ D test.ResultsData were collected from 6795 tests conducted on near‐POC and 17614 tests on centralized laboratory‐based platforms. Thirty‐one percent (2062/6694) of near‐POC tests were conducted for high‐risk populations: pregnant and breastfeeding women, children and those with suspected failure. Compared to conventional testing, near‐POC improved the median time from sample collection to return of results to patient [six vs. sixty‐eight days, effect size: −32.2%; 95% CI: −41.0% to −23.4%] and to clinical action for individuals with an elevated HIV VL [three vs. fourty‐nine days, effect size: −35.4%; 95% CI: −46.0% to −24.8%]. Near‐POC VL results were two times more likely to be returned to the patient within 90 days compared to centralized tests [50% (1781/3594) vs. 27% (4172/15271); aHR: 2.22, 95% CI: 2.05 to 2.39]. Thirty‐seven percent (340/925) of patients with an elevated near‐POC HIV VL result had documented clinical follow‐up actions within 30 days compared to 7% (167/2276) for centralized testing.ConclusionsNear‐POC VL testing enabled rapid test result delivery for high‐risk populations and led to significant improvements in the timeliness of patient result receipt compared to centralized testing. While there was some improvement in time‐to‐clinical action with near‐POC VL testing, major gaps remained. Strengthening of systems supporting the utilization of results for patient management are needed to truly capitalize on the benefits of decentralized testing.     

Mode of action of poloxamer‐based surfactants in wound care and efficacy on biofilms

Surfactants are widely used as detergents, emulsifiers, wetting agents, foaming agents, and dispersants in both the food and oil industry. Their use in a clinical setting is also common, particularly in wound care. Complicated or chronic wounds show clinical signs of delayed healing, persistent inflammation, and the production of non‐viable tissue. These types of wounds also present challenges such as infection and potentially house antimicrobial‐tolerant biofilms. The use of wound cleansers to aid cleaning and debridement of the wound is essential. A large proportion of skin and wound cleansers contain surfactants but there is only a small amount of data that shows the effectiveness of them in the enhancement of wound closure. This review paper aims to explore the available literature surrounding the use and mode of action of surfactants in wound healing, in particular Poloxamer 188 (Pluronic F‐68) and Poloxamer 407 (Pluronic F‐127), and also uncover the potential mechanisms behind the enhancement of wound healing and comparison to other surfactants used in wound care. Furthermore, the presence of a microbial biofilm in the wound is a significant factor in delayed wound healing. Therefore, the effect of clinically used surfactants on biofilms will be discussed, with emphasis on poloxamer‐based surfactants.     

Diagnostic point‐of‐care ultrasound: applications in obstetric anaesthetic management

Complications during pregnancy are not frequent, but may occur abruptly. Point‐of‐care ultrasound is a non‐invasive, non‐ionising diagnostic tool that is available at the bed‐side when complications occur. This review covers the use of ultrasound in various clinical situations. Gastric ultrasound can identify stomach contents that put the woman at risk for pulmonary aspiration. In the future, this tool will probably be used routinely before induction of anaesthesia to determine the presence of stomach contents above a particular risk threshold. Difficult tracheal intubation, and the potential for ‘can't intubate, can't oxygenate’, is more frequent in pregnant women. Point‐of‐care ultrasound of the airway allows accurate identification of the cricothyroid membrane, permitting rapid and safer establishment of front‐of‐neck airway access. Combined cardiac and lung ultrasound can determine the potential risk:benefit of fluid administration in the pregnant patient. Such prediction is of critical importance, given the tendency of pregnant women to develop pulmonary oedema. Combined echocardiography and lung ultrasound can be combined with ultrasound of the leg veins to differentiate between the various causes of acute respiratory failure, and guide treatment in this situation. Finally, as shown in the general population, multi‐organ point‐of‐care ultrasound allows early diagnosis of the main causes of circulatory failure and cardiac arrest at the bed‐side. As the importance of point‐of‐care ultrasound in critical patients is increasingly recognised, it is emerging as an important tool in the therapeutic armoury of obstetric anaesthetists.     

Evaluating the impact of using a wound‐specific oral nutritional supplement to support wound healing in a rehabilitation setting

Chronic wounds adversely affect patient quality of life, increase the risk of mortality, and impose high costs on healthcare systems. Since protein‐energy malnutrition or specific nutrient deficiencies can delay wound healing, nutritionally focused care is a key strategy to help prevent or treat the occurrence of non‐healing wounds. The objective of our study of inpatients in a rehabilitation hospital was to quantify the effect of daily wound‐specific oral nutritional supplementation (WS‐ONS) on healing chronic wounds. Using electronic medical records, we conducted a retrospective analysis of patients with chronic wounds. We identified records for (a) a treatment group who received standard wound care + usual hospital diet + daily WS‐ONS for ≥14 days, and (b) a control group who received standard wound care + a usual hospital diet. We collected data for demographics, nutritional status, and wound‐relevant health characteristics. We examined weekly measurements of wound number and sizes (surface area for superficial wounds or volume for non‐superficial wounds). There were 341 patients identified, 114 with 322 wounds in the treatment group and 227 patients with 420 wounds in the control group. We found that rehabilitation inpatients who were given nutritional support had larger wounds and lower functional independence on admission. At discharge, wound area reduction (percent) was nearly two‐fold better in patients who were given daily WS‐ONS + usual hospital diet compared to those who consumed usual diet only (61.1% vs 34.5%). Overall, weekly wound improvement (lowered wound area or wound volume) was more likely in the WS‐ONS group than in the Control group, particularly from the start of care to week 2. Inpatients with largest wounds and lowest functional independence on admission were most likely to be given WS‐ONS, an indication that caregivers recognised the need for supplementation. Week‐to‐week improvement in wound size was more likely in patients who received WS‐ONS than in those who did not. Specifically, wound areas and wound volumes were significantly lower at discharge among patients who were given specialised nutritional support. More research in this field is needed to improve care and reduce healthcare costs.     

Negative pressure wound treatment with computer‐controlled irrigation/instillation decreases bacterial load in contaminated wounds and facilitates wound closure

Microbial wound contamination is known to be a hindrance to wound healing. Negative pressure wound therapy (NPWT) with or without irrigation is known to optimise conditions in problem wounds. The aim of this study was to investigate the influence of computer‐controlled wound irrigation with NPWT on the bacterial load in contaminated wounds. A total of 267 patients were treated with NPWT with automated instillation because of problematic wounds using an antiseptic instillation solution. In 111 patients, a minimum of 4 operative procedures were necessary, and swabs were taken at least at the first and at the fourth operation in a standardised procedure. The number of different bacteria and the amount of bacteria were analysed during the course. In a subgroup of 51 patients, swabs were taken at all 4 operative procedures and analysed separately. In an overall analysis, the number of different bacteria and the amount of bacteria significantly decreased independent of wound localisation and diagnosis. NPWT with automated instillation demonstrates a positive influence in the reduction of bacterial load in problem wounds. Thus, it may help to optimise wound conditions before definite wound closure.     

In situ analysis of breast cancer progression in murine models using a macroscopic fluorescence imaging system

BACKGROUND AND OBJECTIVE: The goal of this study was to use an inexpensive macroscopic imaging system to monitor tumor progression in mouse models in real-time with minimal intervention. STUDY DESIGN/MATERIALS AND METHODS: Illumination is provided via a xenon arc lamp and a fiber optic probe which delivers white light or quasi-monochromatic excitation via specific bandpass filters. Fluorescence emission from SCID and nude mice following mammary fat pad injection of red fluorescence protein (RFP)-expressing human breast cancer cell lines was recorded and quantified using a single lens reflex (SLR) digital camera. RESULTS: This simple system enabled the verification of successful tumor take and temporal quantification of tumor progression in mouse models. CONCLUSION: The macroscopic fluorescence imaging system represents an inexpensive and portable tool to facilitate non-invasive in situ cancer detection with the potential to monitor fluorescent tumor formation and investigation of the efficacy of potential cancer therapeutics.     

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.     

一种可用活体荧光成像技术检测的前列腺原位肿瘤模型的建立

目的建立可用活体荧光成像技术动态观察前列腺原位肿瘤发生及生长的裸鼠模型。方法 10只BALB/c裸鼠前列腺背侧包膜内注入携带红色荧光蛋白（RFP）的前列腺癌PC-3细胞（PR7细胞）悬液20μL,第2、4、6、8周分别用非侵入式活体分子影像系统观察前列腺原位肿瘤发生及其转移情况。尸检取前列腺原位肿瘤、肺、肝、肾、股骨、盆腔淋巴结等组织,制成冰冻切片,通过荧光显微镜下观察及HE染色等方法分别检测肿瘤发生及有无转移等情况。结果第2周开始可用非侵入式活体分子影像系统检测到前列腺原位肿瘤形成,第4周开始可于裸鼠下腹部触及原位肿瘤,第6～8周裸鼠逐渐出现恶液质。荧光信号随原位肿瘤长大而增强,但并未见明显转移灶。尸检也未发现转移灶。结论前列腺包膜内注入携带RFP的前列腺癌PR7细胞可成功建立可用活体荧光成像技术监测的前列腺原位肿瘤模型,该模型可作为研究前列腺肿瘤发生发展及治疗方式的较理想的动物模型。     

A proof‐of‐concept study of the removal of early and late phase biofilm from skin wound models using a liquid acoustic stream

Chronic wounds fail to progress through the normal stages of healing, with the largest remediable cause of chronicity being presence of a multi‐species biofilm. Removal of biofilm from the wound environment is central to wound care. A device for mechanically removing biofilms from wounds has been devised. The removal is caused by small‐scale liquid currents and shear, generated by acoustically activated microscopic air bubbles. These bubbles and acoustic waves are delivered onto the wound by a gentle liquid stream, allowing cleaning in situ and removal of debris in the run‐off liquid. We have investigated if this liquid acoustic wound stream (LAWS) can remove bacterial biofilm from soft biological wound models and studied the effect of LAWS on the cellular tissues of the substrate. LAWS will efficiently remove early Pseudomonas aeruginosa biofilm from an artificial wound in a pig''s trotter, 24 hours‐mature biofilm of P. aeruginosa from a pre‐wounded human full thickness skin model (EpiDerm FT), and 3‐day mature biofilm of P. aeruginosa or Staphylococcus aureus from a porcine skin explant. Histological examinations of uninfected EpiDerm models that had been treated by LAWS and then stained with Haematoxylin and Eosin, demonstrated no damage to the human tissue, and wound diameter was smaller in the treated skin models compared with untreated samples. Immunofluorescence staining for cytokeratin 14 showed that keratinocytes had migrated further across the wound in the uninfected samples treated by LAWS. We discuss the implications for wound healing and propose further laboratory and clinical studies to demonstrate the removal of biofilm from patients with chronic leg ulcers and the impact on healing.     

Cellular interactions with bacterial cellulose: Polycaprolactone nanofibrous scaffolds produced by a portable electrohydrodynamic gun for point‐of‐need wound dressing

Electrospun nanofibrous scaffolds are promising regenerative wound dressing options but have yet to be widely used in practice. The challenge is that nanofibre productions rely on bench‐top apparatuses, and the delicate product integrity is hard to preserve before reaching the point of need. Timing is critically important to wound healing. The purpose of this investigation is to produce novel nanofibrous scaffolds using a portable, hand‐held “gun”, which enables production at the wound site in a time‐dependent fashion, thereby preserving product integrity. We select bacterial cellulose, a natural hydrophilic biopolymer, and polycaprolactone, a synthetic hydrophobic polymer, to generate composite nanofibres that can tune the scaffold hydrophilicity, which strongly affects cell proliferation. Composite scaffolds made of 8 different ratios of bacterial cellulose and polycaprolactone were successfully electrospun. The morphological features and cell–scaffold interactions were analysed using scanning electron microscopy. The biocompatibility was studied using Saos‐2 cell viability test. The scaffolds were found to show good biocompatibility and allow different proliferation rates that varied with the composition of the scaffolds. A nanofibrous dressing that can be accurately moulded and standardised via the portable technique is advantageous for wound healing in practicality and in its consistency through mass production.     

Challenges around quantifying uncertainty in a holistic approach to hard‐to‐heal wound management: Health economic perspective

Treatment of hard‐to‐heal wounds involves a holistic approach for choosing between available treatment options. However, evidence for informing these choices is sparse, introducing uncertainty into decisions about the optimum treatment pathways that reflect the vast heterogeneity in this patient population. This paper discusses the existing clinical and health economic literature in order to provide insight into sources of uncertainty in the evaluation of the holistic approach to management of the hard‐to‐heal wounds, and how this uncertainty can be appropriately reflected in research. We identified three key sources of uncertainty in the evaluation of chronic wound treatments, namely heterogeneity in aetiology and patient populations, heterogeneity in treatment pathways, and challenges around capturing all relevant outcomes. Reflecting these complexities requires sophisticated modelling of treatment sequencing and long‐term outcomes. The paper discusses how the scope specification, scenario analyses, and sensitivity analyses can be used to fully characterise analytical uncertainty.     

The role of near‐infrared fluorescence imaging with indocyanine green dye in pedicle division with the paramedian forehead flap

The paramedian forehead flap is considered the gold standard for nasal reconstruction following oncologic surgery. During the 21‐day delay in two‐stage surgery protocols, many patients report considerably reduced quality of life because of the pedicle. This prospective case series study examined the usefulness of near‐infrared (NIR) fluorescence with indocyanine green (ICG) for flap perfusion assessment and identified variables associated with time to flap perfusion. Ten patients (mean age 75.3 ± 11.6 years) with diagnosis of basal cell carcinoma (n = 9) or squamous cell carcinoma (n = 1) underwent intravenous indocyanine injection and NIR fluorescence imaging for assessment of flap vascularisation 2 to 3 weeks after stage 1 surgery. NIR fluorescence imaging showed 90% to 100% perfusion areas in all patients after 14 to 21 days. Early pedicle division occurred in two patients on postoperative days 14 and 16. One minor complication (wound healing disorder) was seen following flap takedown after 14 days. There were no associations between time to flap perfusion and defect size or flap area. NIR fluorescence imaging with ICG dye is a useful method for non‐invasive perfusion assessment when used in conjunction with clinical assessment criteria. However, a decision for early pedicle division may raise risk of complications in specific patient groups and must therefore be made with great care.