'Granulitis': defining a common, biofilm-induced, hyperinflammatory wound pathology.

The hard-to-heal (chronic) wound condition, now believed to be inextricably linked to the presence of microbial biofilm, has posed challenges in translating scientific understanding to clinical practice in recent decades. During this time, multiple descriptive terms of the wound pathology have been described, including critical colonisation, biofilm infection and inflammatory stasis. However, the absence of naming this disease state as a specifically identified condition that is tangible to treat has led to some confusion and delay in possible therapeutic approaches. When there is clinical uncertainty of wound status, antibiotics are too often inappropriately administered as a precaution. We therefore propose that introducing the term 'granulitis' (inflamed, unhealthy granulation tissue) could be used to identify the biofilm-induced, persistent inflammatory wound condition. This will help to raise clinician and public awareness of the condition, guide appropriate and prompt local wound hygiene, and encourage allocation of adequate resources to improve wound healing outcomes globally.

A Host-Directed Approach to the Detection of Infection in Hard-to-Heal Wounds.

Wound infection is traditionally defined primarily by visual clinical signs, and secondarily by microbiological analysis of wound samples. However, these approaches have serious limitations in determining wound infection status, particularly in early phases or complex, chronic, hard-to-heal wounds. Early or predictive patient-derived biomarkers of wound infection would enable more timely and appropriate intervention. The observation that immune activation is one of the earliest responses to pathogen activity suggests that immune markers may indicate wound infection earlier and more reliably than by investigating potential pathogens themselves. One of the earliest immune responses is that of the innate immune cells (neutrophils) that are recruited to sites of infection by signals associated with cell damage. During acute infection, the neutrophils produce oxygen radicals and enzymes that either directly or indirectly destroy invading pathogens. These granular enzymes vary with cell type but include elastase, myeloperoxidase, lysozyme, and cathepsin G. Various clinical studies have demonstrated that collectively, these enzymes, are sensitive and reliable markers of both early-onset phases and established infections. The detection of innate immune cell enzymes in hard-to-heal wounds at point of care offers a new, simple, and effective approach to determining wound infection status and may offer significant advantages over uncertainties associated with clinical judgement, and the questionable value of wound microbiology. Additionally, by facilitating the detection of early wound infection, prompt, local wound hygiene interventions will likely enhance infection resolution and wound healing, reduce the requirement for systemic antibiotic therapy, and support antimicrobial stewardship initiatives in wound care.

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.

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

Introduction: Wound microflora in hard-to-heal wounds is invariably complex and diverse. Determining the interfering organisms(s) is therefore challenging. Tissue sampling, particularly in large wounds, is subjective and, when performed, might involve swabbing or biopsy of several locations. Fluorescence (FL) imaging of bacterial loads is a rapid, non-invasive method to objectively locate microbial hotspots (loads >104 CFU/gr). When sampling is deemed clinically necessary, imaging may indicate an optimal site for tissue biopsy. This study aimed to investigate the microbiology of wound tissue incisional biopsies taken from sites identified by FL imaging compared with sites selected by clinical judgment. Methods: A post hoc analysis of the 350-patient FLAAG wound trial was conducted; 78 wounds were included in the present study. All 78 wounds were biopsied at two sites: one at the center of the wound per standard of care (SoC) and one site guided by FL-imaging findings, allowing for comparison of total bacterial load (TBL) and species present. Results: The comparison between the two biopsy sites revealed that clinical uncertainty was higher as wound surface area increased. The sensitivity of a FL-informed biopsy was 98.7% for accurately finding any bacterial loads >104 CFU/g, compared to 87.2% for SoC (p=0.0059; McNemar test). Regarding species detected, FL-informed biopsies detected an average of 3 bacterial species per biopsy versus 2.2 species with SoC (p < 0.001; t-test). Microbial hotspots with a higher number of pathogens also included the CDC's pathogens of interest. Conclusions & perspective: FL imaging provides a more accurate and relevant microbiological profile that guides optimal wound sampling compared to clinical judgment. This is particularly interesting in large, complex wounds, as evidenced in the wounds studied in this post hoc analysis. In addition, fluorescence imaging enables earlier bacterial detection and intervention, guiding early and appropriate wound hygiene and potentially reducing the need for antibiotic use. When indicated, this diagnostic partnership with antibiotic stewardship initiatives is key to ameliorating the continuing threat of antibiotic resistance.

Are Semi-Quantitative Clinical Cultures Inadequate? Comparison to Quantitative Analysis of 1053 Bacterial Isolates from 350 Wounds.

Early awareness and management of bacterial burden and biofilm is essential to wound healing. Semi-quantitative analysis of swab or biopsy samples is a relatively simple method for measuring wound microbial load. The accuracy of semi-quantitative culture analysis was compared to 'gold standard' quantitative culture analysis using 428 tissue biopsies from 350 chronic wounds. Semi-quantitative results, obtained by serial dilution of biopsy homogenates streaked onto culture plates divided into 4 quadrants representing occasional, light, moderate, and heavy growth, were compared to total bacterial load quantified as colony-forming units per gram (CFU/g). Light growth, typically considered an insignificant finding, averaged a clinically significant 2.5 × 105 CFU/g (SE = 6.3 × 104 CFU/g). Occasional growth (range: 102-106 CFU/g) and light growth (103-107 CFU/g) corresponded to quantitative values that spanned a 5-log range; moderate and heavy growth corresponded to a range of 4-log and 6-log, respectively, with a high degree of overlap in range of CFU/g per category. Since tissue biopsy and quantitative culture cannot be widely practiced and semi-quantitative analysis is unreliable, other clinically relevant approaches are required to determine wound bioburden and guide best management practices. Fluorescence imaging is a point-of-care technology that offers great potential in this field.

Biofilm exacerbates antibiotic resistance: Is this a current oversight in antimicrobial stewardship?

OBJECTIVE: To raise awareness of the role of environmental biofilm in the emergence and spread of antibiotic resistance and its consideration in antimicrobial stewardship. BACKGROUND: Antibiotic resistance is a major threat to public health. Overuse of antibiotics, increased international travel, and genetic promiscuity amongst bacteria have contributed to antibiotic resistance, and global containment efforts have so far met with limited success. Antibiotic resistance is a natural mechanism by which bacteria have adapted to environmental threats over billions of years and is caused either by genetic mutations or by horizontal gene transfer. Another ancient survival strategy involves bacteria existing within a self-produced polymeric matrix, which today is termed biofilm. Biofilm similarly enables bacterial tolerance to environmental threats, and also encourages the transfer of antibiotic resistance genes between bacterial species. This natural and ubiquitous mode of bacterial life has not been considered amongst strategies to tackle antibiotic resistance in healthcare facilities, despite its ability to significantly enhance bacterial survival and persistence, and to encourage antibiotic resistance. CONCLUSION: Biofilm must be considered synonymously with antibiotic resistance because of its proficiency in transferring resistance genes as well as its innate phenotypic tolerance to antibiotics. Although biofilm falls outside of the current definition of antimicrobial stewardship, greater awareness of the existence, ubiquity, and consequences of environmental biofilm amongst healthcare practitioners is crucial to improving hygiene practices and controlling the emergence and spread of antibiotic resistance in healthcare facilities.

Clinical impact of an anti-biofilm Hydrofiber dressing in hard-to-heal wounds previously managed with traditional antimicrobial products and systemic antibiotics.

BACKGROUND: Hard-to-heal wounds are often compromised by the presence of biofilm. This presents an infection risk, yet traditional antimicrobial wound care products and systemic antibiotics are often used despite the uncertainty of therapeutic success and wound progression. The aim of this study was to investigate the clinical impact of a next-generation anti-biofilm Hydrofiber wound dressing (AQUACEL Ag+ Extra[AQAg+ E]) in hard-to-heal wounds that had previously been treated unsuccessfully with traditional silver-, iodine- or polyhexamethylene biguanide (PHMB)-containing dressings and products and/or systemic antibiotics. METHODS: Clinical case study evaluations of the anti-biofilm dressing were conducted, where deteriorating or stagnant wounds were selected by clinicians and primary dressings were replaced by the anti-biofilm dressing for up to 4 weeks, or as deemed clinically appropriate, with monitoring via case report forms. The data was stratified for cases where traditional silver-, iodine- or PHMB-containing products, or systemic antibiotics, had been used prior to the introduction of the anti-biofilm dressing. RESULTS: Sixty-five cases were identified for inclusion, wounds ranging in duration from 1 week to 20 years (median: 12 months). In 47 (72%) cases the wounds were stagnant, while 15 (23%) were deteriorating; 3 wounds were not recorded. After an average of 4.2 weeks of management with the anti-biofilm dressing (range: 1-11 weeks), in 11 (17%) cases the wounds had healed (i.e. complete wound closure), 40 (62%) wounds improved, 9 (14%) wounds remained the same and 5 (8%) wounds deteriorated. CONCLUSIONS: The introduction of this anti-biofilm dressing into protocols of care that had previously involved wound management with traditional antimicrobial products and/or antibiotics was shown to facilitate improvements in the healing status of most of these hard-to-heal wounds. Dressings containing proven anti-biofilm technology, in combination with antimicrobial silver and exudate management technology, appear to be an effective alternative to traditional antimicrobial products and antibiotics in the cases presented here. The use of antimicrobial wound dressings that contain anti-biofilm technology may have a key role to play in more effective wound management and antibiotic stewardship.

Contamination Risk During Fecal Management Device Removal: An In vitro, Simulated Clinical Use Study.

Fecal management devices (FMDs) are used to drain and contain fecal matter in incontinent, often acutely or critically ill patients to protect their skin as well as the environment from contamination. However, there is potential for contamination and resultant infection at various stages of FMD use. PURPOSE: This in vitro study was conducted to compare device removal factors and subsequent splash of simulated fecal matter of 3 different designs of FMDs using a simulated rectum. METHODS: A Universal Test Machine was used to automatically measure removal forces (in newtons [N]) and tube extensions as the FMDs were pulled from the simulated rectum by the machine. Splash distance and quantity were measured using a splash-capture cylinder and image analysis software. Each device was tested 3 times. Two-sample t tests were conducted to examine statistical differences in removal forces, removal extensions, and splash areas. RESULTS: The forces required to remove the FMDs from the simulated rectum were significantly lower for the device with a collapsible, donut-shaped retention balloon compared with the devices with a green, foldable, trumpet-shaped retention cuff and a foldable, spherical-shaped retention balloon (12.0 ± 0.3 N vs. 32.6 ± 4.3 N and 34.8 ± 3.1 N, respectively; P <.05). The extensions of the catheter tubing were significantly lower for the device with a collapsible, donut-shaped retention balloon compared with the devices with a green, foldable, trumpet-shaped retention cuff and a foldable, spherical-shaped retention balloon (32.0 ± 7.5 mm vs. 81.3 ± 9.1 mm and 105.2 ± 10.6 mm, respectively; P <.05). Simulated fecal matter was splashed over mean areas of 25.5 ± 16.1 cm2 and 27.3 ± 13.5 cm2 for the devices with a green, foldable, trumpet-shaped retention cuff and a foldable, spherical-shaped retention balloon, respectively; no splash was observed for the device with a collapsible, donut-shaped retention balloon. CONCLUSION: In vitro observations suggest contamination and potential infection risk during FMD removal from the patient are influenced by FMD design. Future in vitro and clinical studies assessing the infectious nature of effluent and methods for containment are warranted.

Perceptions of Wound Biofilm by Wound Care Clinicians.

OBJECTIVE: The aim of this study was to gain a greater understanding of the perceptions of wound biofilm held by wound care clinicians. METHODS: Independent market research was conducted in the United States and Europe via an online questionnaire to understand the knowledge levels of wound biofilm among clinicians. RESULTS: Clinicians from the United States appeared most knowledgeable on the subject of wound biofilm, though there was a wider consensus that biofilm contributes to delayed wound healing. A number of visual and indirect clinical signs for the presence of wound biofilm were commonly listed by all clinicians. In this study, and others, widespread calls for further education on wound biofilm, in addition to anti-biofilm and diagnostic technologies, were made. CONCLUSIONS: This study has contributed to the global call to focus on tackling biofilm for the benefit of wound care patients, caregivers, and health care systems.

Clinical and in vitro performance of an antibiofilm Hydrofiber wound dressing.

OBJECTIVE: To compare the clinical and in vitro performance of a next-generation antibiofilm silver dressing (NGAD) with an established antimicrobial dressing technology that was developed before the recognition of wound biofilm as a clinical challenge. METHOD: Real-life evaluations of challenging wounds managed previously with cadexomer iodine (CI) dressings followed by switching to NGAD were evaluated alongside electron, confocal and light microscopy images from a challenging, in vitro, exuding chronic wound model. Clinical case studies on the use of CI and NGAD dressings are presented to further explore the real-life evidence and in vitro findings. RESULTS: We assessed 13 non-healing wounds that had been managed with protocols including CI dressings. After a median of four weeks, switching to the NGAD as primary dressing resulted in improvements in nine wounds and healing in two wounds, with associated improvements in wound bed appearance, while dressing usage was the same as or lower than before. The NGAD was observed to prevent the development of Staphylococcus aureus- Pseudomonas aeruginosa biofilm over three days, in contrast to the CI dressing, which appeared to support biofilm development once the active antimicrobial was exhausted from its carrier material. Clinical case studies exhibited this exhaustion as 'whiting out' of the dressing, with wound biofilm observed from samples taken following dressing use. Positive wound and patient outcomes were observed in two cases following the switch from a CI primary dressing to the NGAD, in highly exuding and infected wounds. CONCLUSION: Antimicrobial dressings may be effective against biofilm in some laboratory models, but their effectiveness as a wound dressings in protocols of care must be verified clinically.

The wound-healing effects of a next-generation anti-biofilm silver Hydrofiber wound dressing on deep partial-thickness wounds using a porcine model.

Topical antimicrobials are widely used to control wound bioburden and facilitate wound healing; however, the fine balance between antimicrobial efficacy and non-toxicity must be achieved. This study evaluated whether an anti-biofilm silver-containing wound dressing interfered with the normal healing process in non-contaminated deep partial thickness wounds. In an in-vivo porcine wound model using 2 pigs, 96 wounds were randomly assigned to 1 of 3 dressing groups: anti-biofilm silver Hydrofiber dressing (test), silver Hydrofiber dressing (control), or polyurethane film dressing (control). Wounds were investigated for 8 days, and wound biopsies (n = 4) were taken from each dressing group, per animal, on days 2, 4, 6, and 8 after wounding and evaluated using light microscopy. No statistically significant differences were observed in the rate of reepithelialisation, white blood cell infiltration, angiogenesis, or granulation tissue formation following application of the anti-biofilm silver Hydrofiber dressing versus the 2 control dressings. Overall, epithelial thickness was similar between groups. Some differences in infiltration of specific cell types were observed between groups. There were no signs of tissue necrosis, fibrosis, or fatty infiltration in any group. An anti-biofilm silver Hydrofiber wound dressing did not cause any notable interference with normal healing processes.

Antibiotic resistance and biofilm tolerance: a combined threat in the treatment of chronic infections.

Since the introduction of antibiotics into human medicine in the 1940's, antibiotic resistance has emerged at an alarming rate and is now a major threat to public health. This problem is amplified by pathogenic bacteria existing most commonly in biofilm form, creating additional bacterial tolerance to antimicrobial agents. Biofilm is now considered to be a primary cause of chronic infection, and antibiotic-resistant bacteria are prevalent in biofilm form. In particular, chronic non-healing wounds commonly harbour complex polymicrobial, pathogenic biofilm that is tolerant to systemic and topical antimicrobial therapy. Antibiotic stewardship programmes have emerged globally to improve antibiotic prescribing practices, and to curb the emergence and spread of bacterial resistance. In this regard, new antimicrobial strategies must be considered, one of which is to use antibiofilm/antimicrobial combinations to disrupt biofilm, thereby facilitating effectiveness of antimicrobial agents, and reducing the opportunity for antibiotic resistance gene transfer within biofilm. This strategy is being considered in several clinical conditions, one of which is chronic non-healing wounds, where antibiotics are used excessively and often indiscriminately. A combination antibiofilm/antimicrobial wound dressing has been shown to facilitate healing in previously biofilm-impaired non-healing wounds. This approach must be considered as part of antibiotic stewardship programmes to reduce the usage and implications of antibiotic therapy, and improve outcomes associated with chronic infections.

Clinical safety and effectiveness evaluation of a new antimicrobial wound dressing designed to manage exudate, infection and biofilm.

The objective of this work was to evaluate the safety and effectiveness of a next-generation antimicrobial wound dressing (NGAD; AQUACEL® Ag+ Extra™ dressing) designed to manage exudate, infection and biofilm. Clinicians were requested to evaluate the NGAD within their standard protocol of care for up to 4 weeks, or as long as deemed clinically appropriate, in challenging wounds that were considered to be impeded by suspected biofilm or infection. Baseline information and post-evaluation dressing safety and effectiveness data were recorded using standardised evaluation forms. This data included wound exudate levels, wound bed appearance including suspected biofilm, wound progression, skin health and dressing usage. A total of 112 wounds from 111 patients were included in the evaluations, with a median duration of 12 months, and biofilm was suspected in over half of all wounds (54%). After the introduction of the NGAD, exudate levels had shifted from predominantly high or moderate to low or moderate levels, while biofilm suspicion fell from 54% to 27% of wounds. Wound bed coverage by tissue type was generally shifted from sloughy or suspected biofilm towards predominantly granulation tissue after the inclusion of the NGAD. Stagnant (65%) and deteriorating wounds (27%) were shifted to improved (65%) or healed wounds (13%), while skin health was also reported to have improved in 63% of wounds. High levels of clinician satisfaction with the dressing effectiveness and change frequency were accompanied by a low number of dressing-related adverse events (n = 3; 2·7%) and other negative observations or comments. This clinical user evaluation supports the growing body of evidence that the anti-biofilm technology in the NGAD results in a safe and effective dressing for the management of a variety of challenging wound types.

Enhanced Performance and Mode of Action of a Novel Antibiofilm Hydrofiber® Wound Dressing.

Biofilm development in wounds is now acknowledged to be a precursor to infection and a cause of delayed healing. A next-generation antibiofilm carboxymethylcellulose silver-containing wound dressing (NGAD) has been developed to disrupt and kill biofilm microorganisms. This in vitro study aimed to compare its effectiveness against various existing wound dressings and examine its mode of action. A number of biofilm models of increasing complexity were used to culture biofilms of wound-relevant pathogens, before exposure to test dressings. Confocal microscopy, staining, and imaging of biofilm constituents, total viable counting, and elemental analysis were conducted to assess dressing antibiofilm performance. Live/dead staining and viable counting of biofilms demonstrated that the NGAD was more effective at killing biofilm bacteria than two other standard silver dressings. Staining of biofilm polysaccharides showed that the NGAD was also more effective at reducing this protective biofilm component than standard silver dressings, and image analyses confirmed the superior biofilm killing and removal performance of the NGAD. The biofilm-disruptive and silver-enhancing modes of action of the NGAD were supported by significant differences (p < 0.05) in biofilm elemental markers and silver donation. This in vitro study improves our understanding of how antibiofilm dressing technology can be effective against the challenge of biofilm.

Management of diabetic foot ulcers: evaluation of case studies.

This article explores local barriers to diabetic foot ulcer healing, and describes the use of a dressing designed to manage exudate, infection and biofilm (AQUACEL® Ag+ dressing (AQAg+)) on recalcitrant diabetic foot ulcers. The authors consider four case studies that demonstrate how managing local barriers to wound healing with antimicrobial and anti-biofilm dressings in protocols of care can improve outcomes for patients.

Clinician perceptions of wound biofilm.

In wound care today, biofilm is a subject area of great interest and debate. There is an increasing awareness that biofilm exists in the majority of non-healing wounds, and that it is implicated in both recalcitrance and infection. Together with the presence of devitalised host tissue, biofilm is recognised as a component of the wound environment that requires removal to enable wound progression. However, uncertainty exists among wound care practitioners regarding confirmation of the presence of biofilm, and how best to remove biofilm from a non-healing wound. While recent efforts have been taken to assist practitioners in signs and symptoms of wound biofilm, continuing research is required to characterise and confirm wound biofilm. This research was conducted as part of a market research process to better understand the knowledge levels, experiences, clinical awareness and impact of biofilm in wound care, which was undertaken across the USA and Europe. While knowledge levels and experiences vary from country to country, certain wound characteristics were consistently associated with the presence of biofilm.

Safety and performance evaluation of a next-generation antimicrobial dressing in patients with chronic venous leg ulcers.

The objective of this study was to investigate the safety and performance of AQUACEL™ Ag+ dressing, a wound dressing containing a combination of anti-biofilm and antimicrobial agents, in the management of chronic wounds. Patients (n = 42) with venous leg ulcers exhibiting signs of clinical infection were treated for 4 weeks with AQUACEL™ Ag+ dressing, followed by management with AQUACEL™ wound dressings for 4 weeks. Wound progression, wound size, ulcer pain and clinical evolution of the wound were assessed for up to 8 weeks. Adverse events were recorded throughout the study. AQUACEL™ Ag+ dressing had an acceptable safety profile, with only one patient discontinuing from the study, because of a non-treatment-related adverse event. After 8 weeks, substantial wound improvements were observed: 5 patients (11·9%) had healed ulcers and 32 patients (76·2%) showed improvement in ulcer condition. The mean ulcer size had reduced by 54·5%. Patients reported less pain as the study progressed. Notable improvements were observed in patients with ulcers that were considered to require treatment with systemic antibiotics or topical antimicrobials at baseline (n = 10), with a mean 70·2% reduction in wound area. These data indicate that AQUACEL™ Ag+ dressing has an acceptable safety profile in the management of venous leg ulcers that may be impeded by biofilm.

Enzyme-responsive polymers for microbial infection detection.

There is a pressing need for point-of-care diagnostics indicating early stages of infection. Polymers can respond to enzymes secreted by microorganisms or released by the human immune system. This provokes either a direct color reaction or release of dyes, allowing early-stage detection of wound infections and contamination of medical devices. Conventional methods for the detection of infection indicators are based on slow, laboratory-based procedures and, consequently, do not allow a timely assessment. In contrast, polymer-based materials offer real-time responses in point-of-care devices that, in turn, allow therapists to amend treatment before the infection has become firmly established. The use of protein, polysaccharide and mixed polymer systems provides a sensitive means to detect the low levels of proteases and glycosyl hydrolases produced on initiation of infection in the clinical setting. These polymers can be easily fabricated into various forms that can be directly applied in diagnostic devices.

The visualization of biofilms in chronic diabetic foot wounds using routine diagnostic microscopy methods.

Diabetic foot wounds are commonly colonised by taxonomically diverse microbial communities and may additionally be infected with specific pathogens. Since biofilms are demonstrably less susceptible to antimicrobial agents than are planktonic bacteria, and may be present in chronic wounds, there is increasing interest in their aetiological role. In the current investigation, the presence of structured microbial assemblages in chronic diabetic foot wounds is demonstrated using several visualization methods. Debridement samples, collected from the foot wounds of diabetic patients, were histologically sectioned and examined using bright-field, fluorescence, and environmental scanning electron microscopy and assessed by quantitative differential viable counting. All samples (n = 26) harboured bioburdens in excess of 5 log10 CFU/g. Microcolonies were identified in 4/4 samples by all three microscopy methods, although bright-field and fluorescence microscopy were more effective at highlighting putative biofilm morphology than ESEM. Results in this pilot study indicate that bacterial microcolonies and putative biofilm matrix can be visualized in chronic wounds using fluorescence microscopy and ESEM, but also using the simple Gram stain.