3D Biofilm Models Containing Multiple Species for Antimicrobial Testing of Wound Dressings

The treatment of chronic wounds presents a major challenge in medical care. In particular, the effective treatment of bacterial infections that occur in the form of biofilms is of crucial importance. To develop successful antibiofilm strategies for chronic wound treatment, biofilm models are needed that resemble the in vivo situation, are easy to handle, standardizable, and where results are readily transferable to the clinical situation. We established two 3D biofilm models to distinguish the effectiveness of wound dressings on important microorganisms present in chronic wounds. The first 3D biofilm model contains Staphylococcus aureus, Escherichia coli, and Acinetobacter baumannii, while the second is based on Pseudomonas aeruginosa. Bacteria are cultivated in a nutrient-rich agar/gelatin mix, into which air bubbles are incorporated. This results in a mature biofilm growing in clusters similar to its organization in chronic wounds. The models are convenient to use, have low variability and are easy to establish in the laboratory. Treatment with polihexanide and silver-containing wound dressings showed that the models are very well suited for antimicrobial testing and that they can detect differences in the efficacy of antimicrobial substances. Therefore, these models present valuable tools in the development of effective antibiofilm strategies in chronic wounds.

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.

A desiccation compound as a biofilm- and necrosis-removing agent: a case series

Objective:

A new compound, Debrichem (DEBx Medical BV, the Netherlands), a topical desiccation agent (TDA), is an active gel that contains an acidic species with a potent hygroscopic action. When in contact with microorganisms and necrosis, rapid desiccation and carbonisation of the proteins in these microorganisms, as well as of the extracellular matrix of biofilms and necrosis, occurs. The resulting ‘precipitate’ rapidly dislodges from the wound bed, resulting in a clean wound which granulates, which is a prerequisite for healing by secondary intention.

Method:

In a retrospective study, a series of mostly large and hard-to-heal lesions of different aetiologies were treated with a one-time application of the TDA, followed by weekly dressing changes.

Results:

Of the total of 54 lesions included in this case series, 22 were diagnosed as venous leg ulcers (VLUs), 20 as diabetic foot ulcers (DFUs), nine as post-traumatic, hard-to-heal lesions, two as vascular ulcers and one as an ischaemic ulcer. All of the VLUs, 75% of the DFUs and all of the other lesions reached complete granulation.

Conclusion:

The use of a TDA may contribute to the consistent, fast and easy removal of both biofilms and necrosis, and hence to wound healing.

Degradable microneedle patches loaded with antibacterial gelatin nanoparticles to treat staphylococcal infection-induced chronic wounds

Infection-induced chronic wounds cause prolonged pains, a high risk of amputation, and even increased mortality in immunocompromised patients. Here we report an antibacterial microneedle (MN) patch, which features high degradability in biological fluids and gelatinase-responsive release of an antibacterial photothermal peptide AMP-Cypate. We first synthesize gelatin nanoparticles (GNPs) and then conjugate the AMP-Cypate to afford composite AMP-Cypate@GNPs. The proteinaceous nanoparticles can responsively release AMP-Cypate in the presence of gelatinase, an enzyme secreted specifically by Staphylococcus aureus (S. aureus). AMP-Cypate@GNPs were then deposited in the tips of MNs fabricated by PVP and recombinant human type III collagen (Col III) to devise the antibacterial MN/AMP-Cypate@GNP patches. When applied to the infection site, MNs break through the epidermis and the stratum corneum, dissolve in the infected dermis, reach the bacterial colony or biofilm, release AMP-Cypate@GNPs, and exert a gelatinase-responsive photothermal therapy under near-infrared (NIR) irradiation to kill the pathogen S. aureus. In a rat model of staphylococcal infection-induced chronic wounds mimicking the condition of diabetic foot ulcer, the antibacterial MN/AMP-Cypate@GNP patches eradiated the bacterial infection and resulted in complete healing of the wounds, proving its potential application in the treatment of chronic wound infections and diabetic foot ulcers.

Antibiofilm Properties of Antiseptic Agents Used on Pseudomonas aeruginosa Isolated from Diabetic Foot Ulcers

In diabetic foot ulcers (DFUs), biofilm formation is a major challenge that promotes wound chronicity and delays healing. Antiseptics have been proposed to combat biofilms in the management of DFUs. However, there is limited evidence on the activity of these agents against biofilms, and there are questions as to which agents have the best efficiency. Here, we evaluated the antibiofilm activity of sodium hypochlorite, polyvinylpyrrolidoneIodine (PVPI), polyhexamethylenebiguanide (PHMB) and octenidine against Pseudomonas aeruginosa strains using static and dynamic systems in a chronic-wound-like medium (CWM) that mimics the chronic wound environment. Using Antibiofilmogram®, a technology assessing the ability of antiseptics to reduce the initial phase of biofilm formation, we observed the significant activity of antiseptics against biofilm formation by P. aeruginosa (at 1:40 to 1:8 dilutions). Moreover, 1:100 to 1:3 dilutions of the different antiseptics reduced mature biofilms formed after 72 h by 10-log, although higher concentrations were needed in CWM (1:40 to 1:2). Finally, in the BioFlux200TM model, after biofilm debridement, sodium hypochlorite and PHMB were the most effective antiseptics. In conclusion, our study showed that among the four antiseptics tested, sodium hypochlorite demonstrated the best antibiofilm activity against P. aeruginosa biofilms and represents an alternative in the management of DFUs.

Homocysteine and Inflammatory Cytokines in the Clinical Assessment of Infection in Venous Leg Ulcers

Inflammation and biofilm-associated infection are common in chronic venous leg ulcers (VU), causing deep pain and delayed healing. Albeit important, clinical markers and laboratory parameters for identifying and monitoring persistent VU infections are limited. This study analyzed 101 patients with infected (IVU) and noninfected VUs (NVU). Clinical data were collected in both groups. The serum homocysteine (Hcys) and inflammatory cytokines from the wound fluid were measured. In addition, microbial identification, antibiotic susceptibility, and biofilm production were examined. IVU were 56 (55.4%) while NVU were 45 (44.5%). IVUs showed a significant increase in the wound's size and depth compared to NVUs. In addition, significantly higher levels of interleukin (IL)-6, IL-10, IL17A, and tumor necrosis factor-alpha (TNF-α) were found in patients with IVUs compared to those with NVUs. Notably, hyperhomocysteinemia (HHcy) was significantly more common in patients with IVUs than NVUs. A total of 89 different pathogens were identified from 56 IVUs. Gram-negative bacteria were 51.7%, while the Gram-positives were 48.3%. At the species level, Staphylococcus aureus was the most common isolate (43.8%), followed by Pseudomonas aeruginosa (18.0%). Multidrug-resistant organisms (MDROs) accounted for 25.8% of the total isolates. Strong biofilm producers (SBPs) (70.8%) were significantly more abundant than weak biofilm producers (WBP) (29.2%) in IVUs. SBPs were present in 97.7% of the IVUs as single or multispecies infections. Specifically, SBPs were 94.9% for S. aureus, 87.5% for P. aeruginosa, and 28.6% for Escherichia coli. In IVU, the tissue microenvironment and biofilm production can support chronic microbial persistence and a most severe clinical outcome even in the presence of an intense immune response, as shown by the high levels of inflammatory molecules. The measurement of local cytokines in combination with systemic homocysteine may offer a novel set of biomarkers for the clinical assessment of IVUs caused by biofilm-producing bacteria.

Polymicrobial Biofilm Organization of Staphylococcus aureus and Pseudomonas aeruginosa in a Chronic Wound Environment

Biofilm on the skin surface of chronic wounds is an important step that involves difficulties in wound healing. The polymicrobial nature inside this pathogenic biofilm is key to understanding the chronicity of the lesion. Few in vitro models have been developed to study bacterial interactions inside this chronic wound. We evaluated the biofilm formation and the evolution of bacteria released from this biofilm on the two main bacteria isolated in this condition, Staphylococcus aureus and Pseudomonas aeruginosa, using a dynamic system (BioFlux™ 200) and a chronic wound-like medium (CWM) that mimics the chronic wound environment. We observed that all species constituted a faster biofilm in the CWM compared to a traditional culture medium (p < 0.01). The percentages of biofilm formation were significantly higher in the mixed biofilm compared to those determined for the bacterial species alone (p < 0.01). Biofilm organization was a non-random structure where S. aureus aggregates were located close to the wound surface, whereas P. aeruginosa was located deeper in the wound bed. Planktonic biofilm-detached bacteria showed decreased growth, overexpression of genes encoding biofilm formation, and an increase in the mature biofilm biomass formed. Our data confirmed the impact of the chronic wound environment on biofilm formation and on bacterial lifecycle inside the biofilm.

Bacteriophage as a potential therapy to control antibiotic-resistant Pseudomonas aeruginosa infection through topical application onto a full-thickness wound in a rat model

Background

Antibiotic-resistant Pseudomonas aeruginosa (P. aeruginosa) is one of the most critical pathogens in wound infections, causing high mortality and morbidity in severe cases. However, bacteriophage therapy is a potential alternative to antibiotics against P. aeruginosa. Therefore, this study aimed to isolate a novel phage targeting P. aeruginosa and examine its efficacy in vitro and in vivo.

Results

The morphometric and genomic analyses revealed that ZCPA1 belongs to the Siphoviridae family and could infect 58% of the tested antibiotic-resistant P. aeruginosa clinical isolates. The phage ZCPA1 exhibited thermal stability at 37 °C, and then, it decreased gradually at 50 °C and 60 °C. At the same time, it dropped significantly at 70 °C, and the phage was undetectable at 80 °C. Moreover, the phage ZCPA1 exhibited no significant titer reduction at a wide range of pH values (4–10) with maximum activity at pH 7. In addition, it was stable for 45 min under UV light with one log reduction after 1 h. Also, it displayed significant lytic activity and biofilm elimination against P. aeruginosa by inhibiting bacterial growth in vitro in a dose-dependent pattern with a complete reduction of the bacterial growth at a multiplicity of infection (MOI) of 100. In addition, P. aeruginosa-infected wounds treated with phages displayed 100% wound closure with a high quality of regenerated skin compared to the untreated and gentamicin-treated groups due to the complete elimination of bacterial infection.

Conclusion

The phage ZCPA1 exhibited high lytic activity against MDR P. aeruginosa planktonic and biofilms. In addition, phage ZCPA1 showed complete wound healing in the rat model. Hence, this research demonstrates the potential of phage therapy as a promising alternative in treating MDR P. aeruginosa.

Effects of boric acid and potassium metaborate on cytokine levels and redox stress parameters in a wound model infected with methicillin‑resistant Staphylococcus aureus

Methicillin‑resistant Staphylococcus aureus (MRSA) infections are usually found in hospital settings and, frequently, in patients with open wounds. One of the most critical virulence factors affecting the severity and recurrence of infections is the biofilm; increasing antibiotic resistance due to biofilm formation has led to the search for alternative compounds to antibiotics. The present study aimed to use boric acid and potassium metaborate against MRSA infection in a fibroblast wound model. For this purpose, a two‑part experiment was designed: First, MRSA strains were used for the test, and both boric acid and potassium metaborate were prepared in microdilution. In the second step, an MRSA wound model was prepared using a fibroblast culture, and treatments with boric acid and potassium metaborate were applied for 24 h. For the evaluation of the effects of treatment, cell viability assay (MTT assay), analysis of redox stress parameters, including total oxidant status and total antioxidant capacity analyses, lactate dehydrogenase analysis and immunohistochemical staining were performed. In addition, IL‑1β and IL‑10 gene expression levels were assayed. According to the results, potassium metaborate was more effective and exhibited a lower toxicity to fibroblast cells compared to boric acid; moreover, potassium metaborate decreased the level of prooxidant species and increased the antioxidant status more effectively than boric acid. The IL‑1β level in the bacteria group was high; however, boric acid and potassium metaborate significantly decreased the expression levels of inflammatory markers, exhibiting the potential to improve the resolution of the lesion. On the whole, the findings of the present study suggest that boric acid and potassium metaborate may be effective on the tested microorganisms.

A lipophilic chitosan-modified self-nanoemulsifying system influencing cellular membrane metabolism enhances antibacterial and anti-biofilm efficacy for multi-drug resistant Pseudomonas aeruginosa wound infection

Wound infections, especially infections with multidrug-resistant bacteria, are a serious public health issue worldwide. In addition, the accumulation microbial biofilm of multidrug-resistant Pseudomonas aeruginosa increases the risk and physically obstruct its healing activity at the wound site. Therefore, the development of an eminent agent to control wound infection is urgently needed. Here, we report a novel chitosan (a natural biological macromolecule)-modified self-nanoemulsifying system (CSN) with lipophilic chlorhexidine acetate (CAA, a poorly water-soluble agent) that was designed and prepared using low-energy emulsification methods. We found that CSN displays better antibacterial efficacy, which occurs more quickly than its aqueous solution, in destroying the structure of the bacterial cell membrane and promoting the leakage of nucleic acids, proteins, K⁺, and Mg²⁺ from Pseudomonas aeruginosa cells. Importantly, CSN also accelerates skin wound healing after Pseudomonas aeruginosa infection by inhibiting biofilm formation and eradicating mature biofilms. Moreover, the proteomic results suggested that CSN altered membrane permeability and cellular membrane metabolism, allowing more drug molecules to enter the cytosol. Based on these results, this lipophilic self-nanoemulsifying system may be applied in the treatment of skin wounds caused by multidrug-resistant bacteria, especially Pseudomonas aeruginosa.

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Hard-to-heal wounds are a problem for both patients and caregivers. The biofi lm is one of the local factors of delayed healing. Wound hygiene carried out in 4 steps (cleansing, debridement, refashion - care of the edges, and dressing) constitutes the basis of proactive and curative anti-biofi lm strategies.

An overview of the prevention and management of wound infection

A wound can be defined as infected when the presence and subsequent proliferation of microorganisms leads to a local or systemic response in an individual. Wound infection is associated with delayed healing, wound chronicity, increased risk of hospital admission, loss of limb or digit and increased healthcare costs. The presence of biofilm is also recognised as a challenge in infected wounds and is associated with chronicity and delays in healing. Identifying and managing wound infection early can contribute to faster wound healing, thus reducing the risk of negative outcomes. This article details the pathophysiology, risk factors and signs and symptoms of wound infection. It also outlines various prevention and management options for wound infection.

Translational challenges and opportunities in biofilm science: a BRIEF for the future

Biofilms are increasingly recognised as a critical global issue in a multitude of industries impacting health, food and water security, marine sector, and industrial processes resulting in estimated economic cost of $5 trillion USD annually. A major barrier to the translation of biofilm science is the gap between industrial practices and academic research across the biofilms field. Therefore, there is an urgent need for biofilm research to notice and react to industrially relevant issues to achieve transferable outputs. Regulatory frameworks necessarily bridge gaps between different players, but require a clear, science-driven non-biased underpinning to successfully translate research. Here we introduce a 2-dimensional framework, termed the Biofilm Research-Industrial Engagement Framework (BRIEF) for classifying existing biofilm technologies according to their level of scientific insight, including the understanding of the underlying biofilm system, and their industrial utility accounting for current industrial practices. We evidence the BRIEF with three case studies of biofilm science across healthcare, food & agriculture, and wastewater sectors highlighting the multifaceted issues around the effective translation of biofilm research. Based on these studies, we introduce some advisory guidelines to enhance the translational impact of future research.

Bactericidal and anti-biofilm effects of uncharged and cationic ultrasound-responsive nitric oxide microbubbles on Pseudomonas aeruginosa biofilms

Bacterial biofilms are a major and ongoing concern for public health, featuring both inherited genetic resistance traits and a conferred innate tolerance to traditional antibiotic therapies. Consequently, there is a growing need for novel methods of drug delivery, to increase the efficacy of antimicrobial agents. This research evaluated the anti-biofilm and bactericidal effects of ultrasound responsive gas-microbubbles (MBs) of either air or nitric oxide, using an in vitro Pseudomonas aeruginosa biofilm model grown in artificial wound medium. The four lipid-based MB formulations evaluated were room-air MBs (RAMBs) and nitric oxide MBs (NOMBs) with no electrical charge, as well as cationic (+) RAMBs⁺ and NOMBs⁺. Two principal treatment conditions were used: i) ultrasound stimulated MBs only, and ii) ultrasound stimulated MBs with a sub-inhibitory concentration (4 µg/mL) of the antibiotic gentamicin. The total treatment time was divided into a 60 second passive MB interaction period prior to 40 second ultrasound exposure; each MB formulation was tested in triplicate. Ultrasound stimulated RAMBs and NOMBs without antibiotic achieved reductions in biofilm biomass of 93.3% and 94.0%, respectively. Their bactericidal efficacy however was limited, with a reduction in culturable cells of 26.9% and 65.3%, respectively. NOMBs with sub-inhibitory antibiotic produced the most significant reduction in biofilm biomass, corresponding to a 99.9% (SD ± 5.21%); and a 99.9% (SD ± 0.07%) (3-log) reduction in culturable bacterial cells. Cationic MBs were initially manufactured to promote binding of MBs to negatively charged biofilms, but these formulations also demonstrated intrinsic bactericidal properties. In the absence of antibiotic, the bactericidal efficacy of RAMB⁺ and NOMB⁺ was greater that of uncharged counterparts, reducing culturable cells by 84.7% and 86.1% respectively; increasing to 99.8% when combined with antibiotic. This study thus demonstrates the anti-biofilm and bactericidal utility of ultrasound stimulated MBs, and specifically is the first to demonstrate the efficacy of a NOMB for the dispersal and potentiation of antibiotics against bacterial biofilms in vitro. Importantly the biofilm system and complex growth-medium were selected to recapitulate key morphological features of in vivo biofilms. The results us offer new insight for the development of new clinical treatments, for example, in chronic wounds.

Introducing a new approach to debridement and wound bed preparation

Debridement of devitalised tissue and wound biofilm is vital to promote healing. This article introduces an innovative debridement product, ChloraSolv Wound Debridement Gel, which is as effective as a blade but also selective, atraumatic and fast-acting and does not require specialist training. Its ease of use makes it suitable for all settings and staff.

Local wound management: A review of modern techniques and products

Management of wounds is a commonly performed and essential aspect of small animal veterinary medicine. Appropriate wound management is a difficult art to master, due to the inherent complexity of the clinical scenario, as well as the ever-evolving nature of the field with the constant addition of new products and techniques. This article reviews key concepts that may help the practitioner better understand the natural process of wound healing, factors that delay healing and strategies to help improve the local wound environment to make it more conducive to healing during open wound management. The concept of wound bed preparation is defined before common local wound management strategies, such as wound lavage and debridement, are discussed in more detail. Key aspects of the management of biofilms and appropriate use of antimicrobial agents are also reviewed. Finally, the concept of moist wound healing and its impact in modern wound management is explained before a broad variety of types of wound dressings are reviewed, with a particular focus on active dressings.

Biofabrication of ZnO/Malachite nanocomposite and its coating with chitosan to heal infectious wounds

Recently, nanocomposites produced from clays and metals coated with chitosan have shown wound healing activity. This study aimed to synthesize the zinc oxide/malachite nanocomposite (ZnO/Mlt-NC) and its coating form with chitosan (ZnO/Mlt/Chsn-NC). Physicochemical characterization of the produced nanocomposites was investigated. Biomedical effects of nanocomposites, such as in vivo and in vitro antibacterial activity, antioxidant properties, cytotoxicity, and modulation in the gene expressions of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), and transforming growth factor-β (TGF-β) and histopathological parameters, were also investigated. Expression intensities of basic fibroblast growth factor (bFGF) and tumor necrosis factor alpha (TNF-α) were also investigated by immunofluorescence staining. To investigate biomedical effects under in vivo conditions, infected wounds were induced and inoculated with Staphylococcus aureus (ATCC 25923), and Pseudomonas aeruginosa (ATCC 27853). The results indicated spherical ZnO nanoparticles on the surface of malachite and strong antibacterial activity and antioxidant properties. The ointments produced from the nanocomposites also exhibited wound healing activity. The administration of the ointments prepared from ZnO/Mlt, and ZnO/Mlt/Chsn NCs decreased the expressions of IL-1β, IL-6, and TNF-α, while it increased the expressions of IL-10, TGF-β and bFGF. In sum, the nanocomposites produced from ZnO, malachite, and chitosan had better biological activity than ZnO/Malachite nanocomposites. We suggest applying ZnO/Mlt/Chsn nanocomposites in the structure of ointments to treat infected wounds after future clinical studies.

Murine burn lesion model for studying acute and chronic wound infections

Acute wounds, such as thermal injury, and chronic wounds are challenging for patients and the healthcare system around the world. Thermal injury of considerable size induces immunosuppression, which renders the patient susceptible to wound infections, but also in other foci like the airways and urinary tract. Infected thermal lesions can progress to chronic wounds with biofilm making them more difficult to treat. While animal models have their limitations, murine wound models are still the best tool at the moment to identify strategies to overcome these challenges. Here, we present a murine burn model, which has been developed to study biofilm formation, the significance of wound healing, and for identifying novel treatment candidates. Investigating the effect of a thermal injury in mice, we observed that 48 h after introduction of the injury, the mice showed a reduction in polymorphonuclear neutrophil granulocytes (PMNs) and a reduced capacity for phagocytosis and oxidative burst. Regarding the chronic wound, Pseudomonas aeruginosa biofilm arrested wound healing and kept the wound in an inflammatory state, but suppressing PMN function by means of the PMN factor S100A8/A9, corresponding to observations in human venous leg ulcers. Monotherapy and dual treatment with S100A8/A9 and ciprofloxacin on P. aeruginosa biofilm-infected murine wounds have been investigated. In combination, S100A8/A9 and ciprofloxacin reduced the bacterial quantity, lowered the proinflammatory response, and increased anti-inflammatory cytokines after 4 days of treatment. When the treatment was prolonged, an additional prevention of resistance development was detected in all the dual-treated mice. In the present review, we provide data on using the murine model for research with the aim of better understanding pathophysiology of wounds and for identifying novel treatments for humans suffering from these lesions.

Functional amyloids from bacterial biofilms - structural properties and interaction partners

Protein aggregation and amyloid formation have historically been linked with various diseases such as Alzheimer's and Parkinson's disease, but recently functional amyloids have gained a great deal of interest in not causing a disease and having a distinct function in vivo. Functional bacterial amyloids form the structural scaffold in bacterial biofilms and provide a survival strategy for the bacteria along with antibiotic resistance. The formation of functional amyloids happens extracellularly which differs from most disease related amyloids. Studies of functional amyloids have revealed several distinctions compared to disease related amyloids including primary structures designed to optimize amyloid formation while still retaining a controlled assembly of the individual subunits into classical cross-β-sheet structures, along with a unique cross-α-sheet amyloid fold. Studies have revealed that functional amyloids interact with components found in the extracellular matrix space such as lipids from membranes and polymers from the biofilm. Intriguingly, a level of complexity is added as functional amyloids also interact with several disease related amyloids and a causative link has even been established between functional amyloids and neurodegenerative diseases. It is hence becoming increasingly clear that functional amyloids are not inert protein structures found in bacterial biofilms but interact with many different components including human proteins related to pathology. Gaining a clear understanding of the factors governing the interactions will lead to improved strategies to combat biofilm associated infections and the correlated antibiotic resistance. In the current review we summarize the current state of the art knowledge on this exciting and fast growing research field of biofilm forming bacterial functional amyloids, their structural features and interaction partners.

Biofilm Formation of Staphylococcus aureus from Pets, Livestock, and Wild Animals: Relationship with Clonal Lineages and Antimicrobial Resistance

This study aimed to compare the biofilm formation ability of Staphylococcus aureus isolated from a wide range of animals and study the association between biofilm formation and antimicrobial resistance and genetic lineages. A total of 214 S. aureus strains isolated from pets, livestock, and wild animals were evaluated regarding their ability to form biofilms by the microtiter biofilm assay and their structure via confocal scanning laser microscopy. Statistical analysis was used to find an association between biofilm formation and antimicrobial resistance, multidrug resistance, sequence types (STs), spa and agr-types of the isolates. The antimicrobial susceptibility of 24 h-old biofilms was assessed against minimum inhibitory concentrations (MIC) and 10× MIC of amikacin and tetracycline, and the biomass reduction was measured. The metabolic activity of biofilms after antimicrobial treatment was evaluated by the XTT assay. All isolates were had the ability to form biofilms. Yet, significant differences in biofilm biomass production were detected among animal species. Multidrug resistance had a positive association with biofilm formation as well as methicillin-resistance. Significant differences were also detected among the clonal lineages of the isolates. Both tetracycline and amikacin were able to significantly reduce the biofilm mass. However, none of the antimicrobials were able to eradicate the biofilm at the maximum concentration used. Our results provide important information on the biofilm-forming capacity of animal-adapted S. aureus isolates, which may have potential implications for the development of new biofilm-targeted therapeutics.

Cost-effectiveness of Debrichem in managing hard-to-heal venous leg ulcers in the UK

OBJECTIVE

To estimate whether the topical debriding agent, Debrichem, could potentially afford the UK's National Health Service (NHS) a cost-effective intervention for the management of hard-to-heal venous leg ulcers (VLUs).

METHOD

A Markov model was constructed depicting the management of hard-to-heal VLUs with Debrichem plus standard care (SC) or SC alone over a period of 12 months. The model was populated with inputs from an indirect comparison of two propensity score-matched cohorts. The model estimated the cost-effectiveness of the two interventions in terms of the incremental cost per quality-adjusted life year (QALY) gained at 2019/20 prices.

RESULTS

Addition of Debrichem to a SC protocol to treat hard-to-heal VLUs was found to increase the probability of healing by 75% (from 0.35 to 0.61) by 12 months, and to increase health-related quality of life over 12 months from 0.74 to 0.84 QALYs per patient. The 12-month cost of treatment with Debrichem plus SC (£3128 per patient) instead of SC alone (£7195 per patient) has the potential to reduce the total NHS cost of wound management by up to 57%. Hence, Debrichem was estimated to improve health outcomes for less cost. Sensitivity analysis showed that Debrichem plus SC remained a cost-effective (dominant) treatment with plausible variations in costs and effectiveness.

CONCLUSION

Within the limitations of the study, the addition of Debrichem to a SC protocol potentially affords a cost-effective treatment to the NHS for managing hard-to-heal VLUs.

Biofilm model on mice skin wounds

PURPOSE

To evaluate a biofilm model of Pseudomonas aeruginosa in excisional cutaneous wound in mice.

METHODS

Preclinical, translational study conducted with 64 C57BL/6 mice randomly assigned to control and intervention groups. Evaluation was on days D0, D3, D5, D7 and D10 of wound making. The profile of biofilm formation and induction was evaluated using wound closure kinetics, quantitative culture, and evaluation of wounds using transmission electron microscopy (TEM). Clinical evaluation was performed by liver tissue culture, weight variation, and quantification of leukocytes in peripheral blood. Analyses were performed with GraphPad Prism software.

RESULTS

Bacterial load for induction of infection with P. aeruginosa and survival of animals was 104 UFC·mL-1. In D5 (p < 0.0001) and D7 (p < 0.01), animals in the intervention group showed a delay in the healing process and had their wounds covered by necrotic tissue until D10. Statistical differences were observed in wound cultures and weight at D5 and D7 (p < 0.01). Liver cultures and leukocyte quantification showed no statistical differences. No bacteria in planktonic or biofilm form were identified by TEM.

CONCLUSIONS

The findings raise questions about the understanding of the ease of formation and high occurrence of biofilm in chronic wounds.

The c-di-GMP Phosphodiesterase PipA (PA0285) Regulates Autoaggregation and Pf4 Bacteriophage Production in Pseudomonas aeruginosa PAO1

In Pseudomonas aeruginosa PAO1, 41 genes encode proteins predicted to be involved in the production or degradation of c-di-GMP, a ubiquitous secondary messenger that regulates a variety of physiological behaviors closely related to biofilm and aggregate formation. Despite extensive effort, the entire picture of this important signaling network is still unclear, with one-third of these proteins remaining uncharacterized. Here, we show that the deletion of pipA, which produces a protein containing two PAS domains upstream of a GGDEF-EAL tandem, significantly increased the intracellular c-di-GMP level and promoted the formation of aggregates both on surfaces and in planktonic cultures. However, this regulatory effect was not contributed by either of the two classic pathways modulating biofilm formation, exopolysaccharide (EPS) overproduction or motility inhibition. Transcriptome sequencing (RNA-Seq) data revealed that the expression levels of 361 genes were significantly altered in a ΔpipA mutant strain compared to the wild type (WT), indicating the critical role of PipA in PAO1. The most remarkably downregulated genes were located on the Pf4 bacteriophage gene cluster, which corresponded to a 2-log reduction in the Pf4 phage production in the ΔpipA mutant. The sizes of aggregates in ΔpipA cultures were affected by exogenously added Pf4 phage in a concentration-dependent manner, suggesting the quantity of phage plays a part in regulating the formation of aggregates. Further analysis demonstrated that PipA is highly conserved across 83 P. aeruginosa strains. Our work therefore for the first time showed that a c-di-GMP phosphodiesterase can regulate bacteriophage production and provided new insights into the relationship between bacteriophage and bacterial aggregation. IMPORTANCE The c-di-GMP signaling pathways in P. aeruginosa are highly organized and well coordinated, with different diguanylate cyclases and phosphodiesterases playing distinct roles in a complex network. Understanding the function of each enzyme and the underlying regulatory mechanisms not only is crucial for revealing how bacteria decide the transition between motile and sessile lifestyles, but also greatly facilitates the development of new antibiofilm strategies. This work identified bacteriophage production as a novel phenotypic output controlled transcriptionally by a phosphodiesterase, PipA. Further analysis suggested that the quantity of phage may be important in regulating autoaggregation, as either a lack of phage or overproduction was associated with higher levels of aggregation. Our study therefore extended the scope of c-di-GMP-controlled phenotypes and discovered a potential signaling circuit that can be target for biofilm treatment.

Economic significance of biofilms: a multidisciplinary and cross-sectoral challenge

The increasing awareness of the significance of microbial biofilms across different sectors is continuously revealing new areas of opportunity in the development of innovative technologies in translational research, which can address their detrimental effects, as well as exploit their benefits. Due to the extent of sectors affected by microbial biofilms, capturing their real financial impact has been difficult. This perspective highlights this impact globally, based on figures identified in a recent in-depth market analysis commissioned by the UK’s National Biofilms Innovation Centre (NBIC). The outputs from this analysis and the workshops organised by NBIC on its research strategic themes have revealed the breath of opportunities for translational research in microbial biofilms. However, there are still many outstanding scientific and technological challenges which must be addressed in order to catalyse these opportunities. This perspective discusses some of these challenges.

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

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

Paving the way for phage therapy using novel drug delivery approaches

Bacterial resistance against antibiotics is an emergent medical issue. The development of novel therapeutic approaches is urgently needed and, in this context, bacteriophages represent a promising strategy to fight multi resistant bacteria. However, for some applications, bacteriophages cannot be used without an appropriate drug delivery system which increases their stability or provides an adequate targeting to the site of infection. This review summarizes the main application routes for bacteriophages and presents the new delivery approaches designed to increase phage's activity. Clinical successes of these formulations are also highlighted. Globally, this work paves the way for the design and optimization of nano and micro delivery systems for phage therapy.

Use of Phage Cocktail BFC 1.10 in Combination With Ceftazidime-Avibactam in the Treatment of Multidrug-Resistant Pseudomonas aeruginosa Femur Osteomyelitis-A Case Report

High-energy trauma with severe bone fractures can be complicated by infection, leading to the development of osteomyelitis. Pseudomonas aeruginosa is an important causative agent of such infections because of its high virulence profile and ability to develop resistance against a wide range of antimicrobials quickly. P. aeruginosa biofilms cause treatment failure and relapsing infections. Bacteriophages are viruses that can be used to treat biofilm-associated infections. Moreover, the combination of phages with certain antimicrobials have demonstrated synergistic and additive effects. We present a case of a 21-year-old patient with relapsing multidrug-resistant (MDR) P. aeruginosa femur osteomyelitis that developed after a road accident, with a proximal right femoral Grade III B open fracture and severe soft tissue damage. Despite extensive antimicrobial treatment and multiple surgical interventions with wound debridement, the infection persisted, with subsequent development of femoral osteomyelitis with a fistula. Patient care management included femoral head excision with wound debridement, intravenous (IV) ceftazidime-avibactam, and the local application of the lytic Pseudomonas bacteriophage cocktail BFC 1.10. Nine months after the intervention, the patient did not show any clinical, radiological, or laboratory signs of inflammation; therefore, hip replacement was performed. Nevertheless, recurrent P. aeruginosa infection evolved at the distal side of the femur and was successfully treated with conventional antimicrobials. In this case, wound debridement combined with antibiotics and bacteriophages resulted in bacterial eradication of proximal femoral segment, avoiding leg amputation, but failed to treat osteomyelitis in distal bone segment. An in vitro assessment of the isolated MDR P. aeruginosa strain for biofilm formation and phage susceptibility was performed. Additionally, the antimicrobial effects of ceftazidime-avibactam and BFC 1.10 were determined on planktonic cell growth and bacterial biofilm prevention was evaluated. The isolated bacterial strains were susceptible to the bacteriophage cocktail. Strong biofilm formation was detected 6 h after inoculation. Ceftazidime-avibactam combined with BFC 1.10 was most effective in preventing planktonic cell growth and biofilm formation. In both cases, the required concentration of ceftazidime-avibactam decreased two-fold. This study demonstrates the possible use of bacteriophages and antibiotics in difficult-to-treat bone and soft tissue infections, where the additive effects of phages and antibiotics were observed.

Antibiotics-Free Compounds for Chronic Wound Healing

The rapid rise in the health burden associated with chronic wounds is of great concern to policymakers, academia, and industry. This could be attributed to the devastating implications of this condition, and specifically, chronic wounds which have been linked to invasive microbial infections affecting patients' quality of life. Unfortunately, antibiotics are not always helpful due to their poor penetration of bacterial biofilms and the emergence of antimicrobial resistance. Hence, there is an urgent need to explore antibiotics-free compounds/formulations with proven or potential antimicrobial, anti-inflammatory, antioxidant, and wound healing efficacy. The mechanism of antibiotics-free compounds is thought to include the disruption of the bacteria cell structure, preventing cell division, membrane porins, motility, and the formation of a biofilm. Furthermore, some of these compounds foster tissue regeneration by modulating growth factor expression. In this review article, the focus is placed on a number of non-antibiotic compounds possessing some of the aforementioned pharmacological and physiological activities. Specific interest is given to Aloevera, curcumin, cinnamaldehyde, polyhexanide, retinoids, ascorbate, tocochromanols, and chitosan. These compounds (when alone or in formulation with other biologically active molecules) could be a dependable alternative in the management or prevention of chronic wounds.

Effectiveness of testing hard-to-heal wounds for bacterial protease activity: a randomised clinical trial

OBJECTIVE

The study aimed to evaluate whether using a point-of-care test for bacterial protease activity (BPA) to target antimicrobial dressing use can improve outcomes for hard-to-heal wounds and reduce cost.

METHOD

Wounds asymptomatic for infection and testing positive for BPA were randomly assigned to two weeks' treatment with a silver antimicrobial dressing in addition to standard of care (SoC) (intervention group) or to SoC only (control group). The patient's outcomes were monitored for 12 weeks.

RESULTS

The study included 100 wounds. A reduction in annualised nursing resource of 29.0% (95% confidence interval (CI): 1.9-34.1) for hard-to-heal wounds was predicted for the intervention versus control group (44±25.10 intervention group nurse/clinic visits versus 62±31.23 control group nurse/clinic visits; p=0.034). The percentage of patients reporting problems reduced for all EQ5D-3L dimensions for the intervention group, with the largest reductions in 'pain/discomfort' (-36.2%) and 'anxiety/depression' (-19.1%). Prescription of antibiotics fell by 45% for wound-related infections in the intervention group compared with the control group. In the intervention group the number of patients who did not receive a prescription was 37/50 (74%), nine (18%) patients received one prescription and four (8%) patients received two or more prescriptions. In the control group 29/50 (58%) patients did not receive a prescription, 12 (24%) received one prescription and nine (18%) patients received two or more prescriptions; p=0.068.

CONCLUSION

The utility of the BPA test to reduce predicted annualised nursing time was demonstrated. The strong trend towards reduced antibiotic prescribing and improved quality of life for patients with wounds treated for BPA deserves further study.

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.

An Overview on the Recent Advances in the Treatment of Infected Wounds: Antibacterial Wound Dressings

A wound can be surgical, cuts from an operation or due to accident and trauma. The infected wound, as a result of bacteria growth within the damaged skin, interrupts the natural wound healing process and significantly impacts the quality of life. Wound dressing is an important segment of the skincare industry with its economic burden estimated at $ 20.4 billion (in 2021) in the global market. The results of recent clinical trials suggest that the use of modern dressings can be the easiest, most accessible, and most cost-effective way to treat chronic wounds and, hence, holds significant promise. With the sheer number of dressings in the market, the selection of correct dressing is confusing for clinicians and healthcare workers. The aim of this research was to review widely used types of antibacterial wound dressings, as well as emerging products, for their efficiency and mode of action. In this review, we focus on introducing antibiotics and antibacterial nanoparticles as two important and clinically widely used categories of antibacterial agents. The perspectives and challenges for paving the way for future research in this field are also discussed. This article is protected by copyright. All rights reserved.

Evidenz in der lokalen Therapie chronischer Wunden: Was ist gesichert?

Chronische Wunden sind ein komplexes Symptom verschiedener Grunderkrankungen. Sie können bspw. vaskulärer, metabolischer oder immunologischer Genese sein. Auch wenn die Therapie dieser Grunderkrankungen im Vordergrund steht und zielführend ist, so beeinflussen diese Wunden die Lebensqualität der einzelnen Patienten oder Patientinnen stark. Zur Lokaltherapie chronischer Wunden steht ein breites Portfolio an Möglichkeiten zur Verfügung. Anders als in anderen Bereichen der Medizin ist die Evidenz für die verschiedenen Lokaltherapeutika meist gering. Deshalb rücken Experten-Empfehlungen und Leitlinien an ihre Stelle, die sinnvolle Behandlungspfade aufzeigen. Die wichtigsten Fragestellungen in der täglichen Praxis betreffen die Wahl und Effektivität der Wundspülung und des Wunddebridements, das Exsudatmanagement, den Einsatz von antimikrobiellen Wirkstoffen in Lösungen und Wundauflagen, die Unterdruck-Wundtherapie (NPWT) und die Indikationsstellung zur Kompressionstherapie. Trotz des Mangels an Evidenz folgt die Behandlung chronischer Wunde einigen grundlegenden Prinzipien, die im folgenden Artikel inklusive der dazugehörigen Behandlungsempfehlungen dargestellt werden.

Assessing the inflammatory response to in vitro polymicrobial wound biofilms in a skin epidermis model

Wounds can commonly become infected with polymicrobial biofilms containing bacterial and fungal microorganisms. Microbial colonization of the wound can interfere with sufficient healing and repair, leading to high rates of chronicity in certain individuals, which can have a huge socioeconomic burden worldwide. One route for alleviating biofilm formation in chronic wounds is sufficient treatment of the infected area with topical wound washes and ointments. Thus, the primary aim here was to create a complex in vitro biofilm model containing a range of microorganisms commonly isolated from the infected wound milieu. These polymicrobial biofilms were treated with three conventional anti-biofilm wound washes, chlorhexidine (CHX), povidone-iodine (PVP-I), and hydrogen peroxide (H₂O₂), and efficacy against the microorganisms assessed using live/dead qPCR. All treatments reduced the viability of the biofilms, although H₂O₂ was found to be the most effective treatment modality. These biofilms were then co-cultured with 3D skin epidermis to assess the inflammatory profile within the tissue. A detailed transcriptional and proteomic profile of the epidermis was gathered following biofilm stimulation. At the transcriptional level, all treatments reduced the expression of inflammatory markers back to baseline (untreated tissue controls). Olink technology revealed a unique proteomic response in the tissue following stimulation with untreated and CHX-treated biofilms. This highlights treatment choice for clinicians could be dictated by how the tissue responds to such biofilm treatment, and not merely how effective the treatment is in killing the biofilm.

Biofilm Survival Strategies in Chronic Wounds

Bacterial biofilms residing in chronic wounds are thought to have numerous survival strategies, making them extremely difficult to eradicate and resulting in long-term infections. However, much of our knowledge regarding biofilm persistence stems from in vitro models and experiments performed in vivo in animal models. While the knowledge obtained from such experiments is highly valuable, its direct translation to the human clinical setting should be undertaken with caution. In this review, we highlight knowledge obtained from human clinical samples in different aspects of biofilm survival strategies. These strategies have been divided into segments of the following attributes: altered transcriptomic profiles, spatial distribution, the production of extracellular polymeric substances, an altered microenvironment, inter-and intra-species interactions, and heterogeneity in the bacterial population. While all these attributes are speculated to contribute to the enhanced persistence of biofilms in chronic wounds, only some of them have been demonstrated to exist in human wounds. Some of the attributes have been observed in other clinical diseases while others have only been observed in vitro. Here, we have strived to clarify the limitations of the current knowledge in regard to this specific topic, without ignoring important in vitro and in vivo observations.

Embedding Wound Hygiene into a proactive wound healing strategy

Foreword. Wound Hygiene: the next stage

Since a panel published the first consensus document on Wound Hygiene in March 2020, there has been a flurry of activity in support of this newly established concept in proactive wound healing. 1 The document concluded that all wounds, particularly hard-to-heal ones, will benefit from Wound Hygiene, which should be initiated at the first referral, following a full holistic assessment to identify the wound aetiology and comorbidities, and then implemented at every dressing change until full healing occurs. 1 The consensus has since been bolstered by educational webinars; competency-based skills training and support; development of international Wound Hygiene ambassadors; a survey of 1478 respondents, published in July 2021; 2 and a case study supplement, published in January 2022, featuring a range of wound types, anatomies and underlying conditions on the improvements in wound-healing progress that can be achieved. 3 Wound Hygiene has gained its own identity and is now a term in and of itself, that encompasses a 4-step protocol of care. It is an antibiofilm approach that is increasingly being used across wound care. The results of the survey 2 were particularly encouraging for seeing how far Wound Hygiene has come, and how quickly: More than half (57.4%) had heard of the concept of Wound Hygiene Of those, 75.3% have implemented Wound Hygiene Overall, following implementation of Wound Hygiene, 80.3% of respondents reported improved healing rates. 2 However, the top three barriers identified by the survey—lack of confidence, competence and research data—show that there is more to be done to support Wound Hygiene in practice. 2 As a result, a consensus panel of international key opinion leaders convened virtually in the summer of 2021 to discuss what has been done so far, the outputs of the survey, and ideas for addressing the unmet needs identified by the results. The result is this publication, which represents an addendum to the initial consensus document, broadening support for implementation of Wound Hygiene. This document will reflect on the reasons Wound Hygiene has been successful in its first two years of implementation, reiterating its DNA: Do not wait to treat hard-to-heal wounds Use a simple 4-step approach Enable all healthcare professionals to implement and use Wound Hygiene. The document will also discuss the evolution of the Wound Hygiene concept, focusing on how and when to implement Wound Hygiene on all tissue types of hard-to-heal wounds, and proposing what these are. The panel has expanded the framework in which Wound Hygiene is used, with the ultimate objective of introducing the concept of ‘embedding Wound Hygiene intro a proactive wound healing strategy.’ Key inefficiencies are often observed along the journeys of people living with hard-to-heal wounds. The limited number of specialised healthcare professionals and the resulting delays in reaching them may increase the likelihood of a hard-to-heal wound developing. In a world where so much is happening so quickly that we may, at times, feel powerless to drive change, the panel wants to provide further guidance to propel the use of Wound Hygiene. The concept of Wound Hygiene is resonating, and the panel wants you to know that in whatever region you work, in whatever area of clinical practice, you are enabled to make this change. Wielding the 4-step Wound Hygiene protocol consistently is a key action every healthcare professional in every care setting can take to tackle the global wound care crisis. Wound Hygiene has taken off—now, where do we want to land? In a place where Wound Hygiene is practised on all wounds, at every stage, until healing. The panel once again recognises that the community of global healthcare providers should consider their local standards and guidelines when applying the recommendations of this document. To this end, the panel has created a flexible 3-phase framework that situates Wound Hygiene as integral to proactive wound healing. The panel hopes you will continue to implement Wound Hygiene and see the benefits it can bring to people living with wounds, as well as those who care for them.

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

Purpose of Review

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

Recent Findings

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

Summary

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

Perception and Readiness to Undertake Maggot Debridement Therapy with the Use of Lucilia sericata Larvae in the Group of Nurses

The sight and smell of larvae in the wound may cause negative visual and olfactory impressions in sensitive individuals because of decaying body parts, carrion, and suffering. However, Maggot Debridement Therapy (MDT) is highly effective, safe, and cheap in wound healing and tissue revitalization for both the patient and health systems. The aim of the study was to assess the readiness to undertake MDT in a group of qualified nurses who perform therapeutic procedures in patients treated for chronic wounds. A diagnostic survey was used. The research tool was a scientific research protocol consisting of three questionnaires (sociodemographics, MDT perception questionnaire, pictures of wounds for visual assessment). The study included 290 nurses; the mean age was over 42.6 ± 9.9 years, and the median was 44 years. The perception and readiness to implement the method in the tested sample is at the average (standard) level. The image of maggots in the wound causes negative emotions among medical personnel. The higher the knowledge of the MDT method, the greater the motivation to implement it in practice.

Is ANTT Achievable in the Home Healthcare Setting?

At the heart of infection prevention in the home care setting is aseptic technique, a generic term for the clinical competency of ensuring asepsis during invasive clinical procedures and the maintenance of invasive medical devices. Variable terminology has resulted in confused education and clinical practice. Ambiguity has played out in all care environments, but especially in the home, where the challenge of providing effective aseptic technique is complicated by unique environmental and logistical factors. This has led some to conclude that aseptic technique is not possible in the home, or that it is not required at all in certain situations. This article challenges these assumptions and outlines the Aseptic Non Touch Technique (ANTT®) Clinical Practice Framework, that is used widely internationally. Through a thematic analysis of focus group discussions with home care nurses (n = 107) in the United Kingdom and the United States, opinions about aseptic practice in the home care setting were examined. Three main polarizing themes were identified and used to discuss theory and practice applications of aseptic technique for home healthcare nurses. Specific challenges in performing aseptic technique in home-based settings are exacerbated by ambiguity between what constitutes "clean," "aseptic," or so-called "sterile" technique, and are perpetuated by a lack of competency-based training that doesn't reflect the critical importance of aseptic technique to patient safety. Rather than continuing an endless debate about the definition of aseptic technique, ANTT has redefined aseptic technique education and clinical practice, with a comprehensive clinical practice framework and associated clinical governance better supporting patient safety.

Real-time detection of volatile metabolites enabling species-level discrimination of bacterial biofilms associated with wound infection

AIMS

The main aim of this study was to investigate the real-time detection of volatile metabolites for the species-level discrimination of pathogens associated with clinically relevant wound infection, when grown in a collagen wound biofilm model.

METHODS AND RESULTS

This work shows that Staphylococcus aureus, Pseudomonas aeruginosa and Streptococcus pyogenes produce a multitude of volatile compounds when grown as biofilms in a collagen-based biofilm model. The real-time detection of these complex volatile profiles using selected ion flow tube mass spectrometry and the use of multivariate statistical analysis on the resulting data can be used to successfully differentiate between the pathogens studied.

CONCLUSIONS

The range of bacterial volatile compounds detected between the species studied vary and are distinct. Discrimination between bacterial species using real-time detection of volatile metabolites and multivariate statistical analysis was successfully demonstrated.

SIGNIFICANCE AND IMPACT OF THE STUDY

Development of rapid point-of-care diagnostics for wound infection would improve diagnosis and patient care. Such technological approaches would also facilitate the appropriate use of antimicrobials, minimizing the emergence of antimicrobial resistance. This study further develops the use of volatile metabolite detection as a new diagnostic approach for wound infection.

Engineered Nanotechnology: An Effective Therapeutic Platform for the Chronic Cutaneous Wound

The healing of chronic wound infections, especially cutaneous wounds, involves a complex cascade of events demanding mutual interaction between immunity and other natural host processes. Wound infections are caused by the consortia of microbial species that keep on proliferating and produce various types of virulence factors that cause the development of chronic infections. The mono- or polymicrobial nature of surface wound infections is best characterized by its ability to form biofilm that renders antimicrobial resistance to commonly administered drugs due to poor biofilm matrix permeability. With an increasing incidence of chronic wound biofilm infections, there is an urgent need for non-conventional antimicrobial approaches, such as developing nanomaterials that have intrinsic antimicrobial-antibiofilm properties modulating the biochemical or biophysical parameters in the wound microenvironment in order to cause disruption and removal of biofilms, such as designing nanomaterials as efficient drug-delivery vehicles carrying antibiotics, bioactive compounds, growth factor antioxidants or stem cells reaching the infection sites and having a distinct mechanism of action in comparison to antibiotics-functionalized nanoparticles (NPs) for better incursion through the biofilm matrix. NPs are thought to act by modulating the microbial colonization and biofilm formation in wounds due to their differential particle size, shape, surface charge and composition through alterations in bacterial cell membrane composition, as well as their conductivity, loss of respiratory activity, generation of reactive oxygen species (ROS), nitrosation of cysteines of proteins, lipid peroxidation, DNA unwinding and modulation of metabolic pathways. For the treatment of chronic wounds, extensive research is ongoing to explore a variety of nanoplatforms, including metallic and nonmetallic NPs, nanofibers and self-accumulating nanocarriers. As the use of the magnetic nanoparticle (MNP)-entrenched pre-designed hydrogel sheet (MPS) is found to enhance wound healing, the bio-nanocomposites consisting of bacterial cellulose and magnetic nanoparticles (magnetite) are now successfully used for the healing of chronic wounds. With the objective of precise targeting, some kinds of "intelligent" nanoparticles are constructed to react according to the required environment, which are later incorporated in the dressings, so that the wound can be treated with nano-impregnated dressing material in situ. For the effective healing of skin wounds, high-expressing, transiently modified stem cells, controlled by nano 3D architectures, have been developed to encourage angiogenesis and tissue regeneration. In order to overcome the challenge of time and dose constraints during drug administration, the approach of combinatorial nano therapy is adopted, whereby AI will help to exploit the full potential of nanomedicine to treat chronic wounds.

Biofilm Formation and Antibiotic Resistance of S. aureus Strains isolated from Chronic Traumatic Wounds

Staphylococcal biofilms are the prominent cause of chronic wound infection and antibiotic resistance. It acts as a reservoir for bacteria, making wound healing difficult. Biofilm infections increase the hospital stays and cost to the patients. The current study explores the phenotypic and genotypic detection of S. aureus biofilm from chronic traumatic wounds and their association with antibiotic resistance. A prospective observational study was conducted from April 2020 to March 2021. S. aureus isolates were identified by the MALDI-TOF. Antibiotic susceptibility was determined by VITEK 2. Biofilm production detected by tissue culture plate method and associated ica genes were diagnosed through multiplex PCR. Overall, 67 isolates were investigated. The frequency of biofilm production in S. aureus was 73.1%, and most of the isolates were moderate biofilm producers (38.8%). The presence of intracellular adhesion (ica) operon among these isolates was 85.7% and also significantly associated with the strength of biofilm mass formation. Ica A was the predominant biofilm-producing gene (42.9%). Biofilm producing Methicillin-resistant S. aureus were as high as 75%, and multidrug resistant strains were significantly associated with biofilm formation. But frequency of ica genes were noted more in Methicillin sensitive S. aureus (65.2%). High frequency of biofilm in S. aureus of isolates was responsible for the development of chronic non-healing traumatic wounds. Biofilm-producing isolates showed greater multidrug-resistance. Phenotypically MRSA expressed more biofilm, but ica operon was documented in MSSA. It emphasized the further need for ica independent pathway exploration for MRSA biofilm synthesis.

Controlled-release iodine foam dressings demonstrate broad-spectrum biofilm management in several in vitro models

Multiple in vitro models were utilised to evaluate the biofilm management capabilities of seven commercially-available wound dressings, varying in composition and antibacterial ingredients, to reduce common aerobic, anaerobic, and multispecies biofilms. The Center for Disease Control bioreactor was used to evaluate single species Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) 24 and 48 hours biofilms, as well as a multispecies biofilm consisting of these two organisms in addition to Enterococcus faecalis (E. faecalis). As wound biofilms often exist in hypoxic wound environments, a direct contact anaerobic model system was used to evaluate efficacy on Bacteroides fragilis (B. fragilis). Biofilm control was evaluated against P. aeruginosa in the drip flow bioreactor model, where a constant flow of proteinaceous media is used to create a more challenging and wound-like model. The results demonstrated that biofilm management capabilities varied amongst wound dressings. Two dressings, a controlled-release iodine foam dressing and a silver nanocrystalline dressing, showed potent >4 log reductions in recovered organisms compared with untreated controls in all biofilm models evaluated. The effectiveness of other dressings to manage bioburden varied between dressing, test organism, and model system. A silver foam dressing showed moderate biofilm control in some models. However, biofilm exposure to methylene blue and gentian violet-containing foam dressings showed negligible log reductions in all in vitro biofilm methods examined. The data outlined in this in vitro study support the use of the iodine foam dressing for wounds with infection and biofilm.

Potential Advances of Adjunctive Hyperbaric Oxygen Therapy in Infective Endocarditis

Patients with infective endocarditis (IE) form a heterogeneous group by age, co-morbidities and severity ranging from stable patients to patients with life-threatening complications with need for intensive care. A large proportion need surgical intervention. In-hospital mortality is 15-20%. The concept of using hyperbaric oxygen therapy (HBOT) in other severe bacterial infections has been used for many decades supported by various preclinical and clinical studies. However, the availability and capacity of HBOT may be limited for clinical practice and we still lack well-designed studies documenting clinical efficacy. In the present review we highlight the potential beneficial aspects of adjunctive HBOT in patients with IE. Based on the pathogenesis and pathophysiological conditions of IE, we here summarize some of the important mechanisms and effects by HBOT in relation to infection and inflammation in general. In details, we elaborate on the aspects and impact of HBOT in relation to the host response, tissue hypoxia, biofilm, antibiotics and pathogens. Two preclinical (animal) studies have shown beneficial effect of HBOT in IE, but so far, no clinical study has evaluated the feasibility of HBOT in IE. New therapeutic options in IE are much needed and adjunctive HBOT might be a therapeutic option in certain IE patients to decrease morbidity and mortality and improve the long-term outcome of this severe disease.

A novel dressing with silver to treat meticillin-resistant Staphylococcus aureus biofilm infection in a pig model

OBJECTIVE

The purpose of this study was to use an in vivo biofilm porcine model to examine a new polyvinyl alcohol-based gelling fibre dressing with silver and compare it to other commercial dressings containing: polyvinyl alcohol-based gelling fibre without silver; carboxymethyl cellulose-based fibre with silver, benzethonium chloride and ethylenediaminetetraacetic acid; and untreated control.

METHODS

A total of 52 deep partial-thickness wounds (10x7x0.5mm) were created on each of three animals and inoculated with 25µl of meticillin-resistant Staphylococcus aureus (MRSA) (10⁶ colony forming units (CFU)/ml). Wounds were covered for 24 hours to allow biofilm formation and were randomly designated to one of the four treatments. Samples were recovered for microbiological and histological analysis on days 3, 5 and 7 post-treatment.

RESULTS

Polyvinyl alcohol-based gelling fibre dressing with silver was able to significantly reduce biofilm more effectively than the other treatment groups. By day 7, wounds treated with the dressing had a 2.72±0.01 log CFU/g reduction in MRSA count versus untreated control wounds and a 2.59±0.01 log CFU/g reduction versus baseline counts. For histology analysis, all wounds reached 100% re-epithelialisation by day 5.

CONCLUSION

The results of this study indicated that polyvinyl alcohol-based gelling fibre dressing with silver was effective against biofilm of antibiotic-resistant staphylococcal strains without inhibiting the wound healing process, and may have important clinical implications when treating acute and/or hard-to-heal wounds.

Effectiveness of combined modulated ultrasound and electric current stimulation to treat diabetic foot ulcers

OBJECTIVE

The use of combined ultrasound and electrostimulation (CUSECS) as an adjunct therapy for diabetic foot ulcers (DFUs) is a relatively new concept. This study aimed to investigate if combined ultrasound and electrostimulation is an effective adjunctive treatment for hard-to-heal DFUs when compared with standard wound care.

METHODS

A randomised controlled pilot study design was used. Patients with hard-to-heal DFUs from two centres were sequentially randomised. For 8 weeks, the experimental group received CUSECS and standard wound care treatment twice a week. The control group received standard wound care treatment once a week. Wound changes were documented using photography, which also facilitated wound size measurement. Self-efficacy, economic cost, quality of life and reoccurrence rates were analysed as secondary objectives.

RESULTS

The experimental group (n=6) achieved a higher rate of mean wound healing (mean difference (MD): 0.49) when compared to the control group (n=5, MD: 0.01). Two participants completed full healing in the experimental group and one in the control group. There were no statistically significant findings because of the small sample size. There were no direct adverse reactions to this therapy. Quality of life scores improved in the treatment group. There was no significant change in self-efficacy scores. Costs were higher in the experimental group; however, the healing rate was quicker, which could be extrapolated to cost reductions over time.

CONCLUSION

Results suggest that CUSECS may be a useful adjunctive therapy for treatment of hard-to-heal DFUs. Further large-scale studies are needed to ascertain the effectiveness of CUSECS. The findings here are inconclusive but indicate that CUSECS may offer promise as a treatment.