The microbial flora in venous leg ulcers without clinical signs of infection. Repeated culture using a validated standardised microbiological technique

Electrical stimulation: a novel therapeutic strategy to heal biological wounds

Electrical stimulation (ES) has emerged as a powerful therapeutic modality for enhancing biological wound healing. This non-invasive technique utilizes low-level electrical currents to promote tissue regeneration and expedite the wound healing process. ES has been shown to accelerate wound closure, reduce inflammation, enhance angiogenesis, and modulate cell migration and proliferation through various mechanisms. The principle goal of wound management is the rapid recovery of the anatomical continuity of the skin, to prevent infections from the external environment and maintain homeostasis conditions inside. ES at the wound site is a compelling strategy for skin wound repair. Several ES applications are described in medical literature like AC, DC, and PC to improve cutaneous perfusion and accelerate wound healing. This review aimed to evaluate the primary factors and provides an overview of the potential benefits and mechanisms of ES in wound healing, and its ability to stimulate cellular responses, promote tissue regeneration, and improve overall healing outcomes. We also shed light on the application of ES which holds excellent promise as an adjunct therapy for various types of wounds, including chronic wounds, diabetic ulcers, and surgical incisions.

Evaluation of factors affecting the healing process of venous ulcers: A 12-week longitudinal study

The process of healing venous ulcers is complex and influenced by many factors. By identifying the risk factors that influence a slower healing process, it is possible to predict impending delays and plan an individualised care plan. We analysed our database of patients with venous ulcers and identified clinical and demographic factors that delay the healing process. The research analysed the medical records of 754 patients with VLUs at Chronic Wound Treatment Unit of the University Hospital treated between 2001 and 2019. In study, the majority (64.3%) were women, the mean age was 65.7 years. The median duration of Chronic Venous Insufficiency was 24 years, 52% patients had had the disease >20 years, and 296 (39.3%) had experienced ulceration >12 months. Most of the patients (85.8%) had comorbidities, 84% were obese. At 12-week follow-up, 432 of the 754 ulcers had healed. Identified independent predictors of slower ulcer healing rates: wound area greater than 8.25 cm2 , location of the ulceration other than the medial ankle area, underlying disease >20 years, the presence of multiple comorbidities, depth of the ulcer, the presence of an unpleasant smell and alert pathogens. The presence of redness resulted in faster healing of VLUc. Many factors influence the healing process of venous ulceration. The results of the study can help in planning patient care and implementing appropriate early strategies to promote healing.

Microbiological Status of Venous Leg Ulcers and Its Predictors: A Single-Center Cross-Sectional Study

Venous leg ulcers are frequently colonized by microbes. This can be particularly devastating if the ulcer is infected with alert pathogens, i.e., highly virulent microorganisms with well-developed mechanisms of antibiotic resistance. We analyzed the microbiological status of venous leg ulcers and identified the clinicodemographic predictors of culture-positive ulcers, especially in ulcers with colonization by alert pathogens.

METHODS

This study included 754 patients with chronic venous leg ulcers. Material for microbiological analysis was collected by swabbing only from patients who did not receive any antibiotic treatment.

RESULTS

A total of 636 (84.3%) patients presented with culture-positive ulcers. Alert pathogens, primarily Pseudomonas aeruginosa, were detected in 28.6% of the positive cultures. In a logistic regression model, culture-positive ulcers were predicted independently by age > 65 years, current ulcer duration > 12 months, and ulceration area greater than 8.25 cm². Two of these factors, duration of current ulcer > 12 months and ulceration area > 8.25 cm², were also identified as the independent predictors of colonization by alert pathogens.

CONCLUSIONS

Colonization/infection is particularly likely in older persons with chronic and/or large ulcers. Concomitant atherosclerosis was an independent predictor of culture-negative ulcers.

Integrated Multiplex Sensing Bandage for In Situ Monitoring of Early Infected Wounds

Infection, the most common complication of chronic wounds, has placed tremendous burden on patients and society. Existing care strategies could hardly reflect in situ wound status, resulting in overly aggressive or conservative therapeutic options. Multiplexed tracking of wound markers to obtain diagnostic information in a more accurate way is highly promising and in great demand for the emerging development of personalized medicine. Here, an integrated multiplex sensing bandage (MSB) system, including a multiplex sensor array (MSA), a corresponding flexible circuit, and a mobile application, was developed for real-time monitoring of sodium, potassium, calcium, pH, uric acid, and temperature indicators in the wound site to provide a quantitative diagnostic basis. The MSB was optimized for wound-oriented management applications, which exhibits a broad linear response, excellent selectivity, temporal stability, mechanical stability, reproducibility, and reliable signal transmission performance on the aforementioned physiological indicators. The results of in vivo experiments demonstrate that the MSA is capable of real-time monitoring of actual wounds as well as early prediction of infection. The results ultimately point to the potential clinical applicability of the MSB, which might benefit the quantifications of the complexity and diversity of the wound healing process. This work provides a unique strategy that holds promise for broad application in optimizing wound management and even coping with other diseases.

Bacteriophages for Chronic Wound Treatment: from Traditional to Novel Delivery Systems

The treatment and management of chronic wounds presents a massive financial burden for global health care systems, with significant and disturbing consequences for the patients affected. These wounds remain challenging to treat, reduce the patients' life quality, and are responsible for a high percentage of limb amputations and many premature deaths. The presence of bacterial biofilms hampers chronic wound therapy due to the high tolerance of biofilm cells to many first- and second-line antibiotics. Due to the appearance of antibiotic-resistant and multidrug-resistant pathogens in these types of wounds, the research for alternative and complementary therapeutic approaches has increased. Bacteriophage (phage) therapy, discovered in the early 1900s, has been revived in the last few decades due to its antibacterial efficacy against antibiotic-resistant clinical isolates. Its use in the treatment of non-healing wounds has shown promising outcomes. In this review, we focus on the societal problems of chronic wounds, describe both the history and ongoing clinical trials of chronic wound-related treatments, and also outline experiments carried out for efficacy evaluation with different phage-host systems using in vitro, ex vivo, and in vivo animal models. We also describe the modern and most recent delivery systems developed for the incorporation of phages for species-targeted antibacterial control while protecting them upon exposure to harsh conditions, increasing the shelf life and facilitating storage of phage-based products. In this review, we also highlight the advances in phage therapy regulation.

Finegoldia magna, an Anaerobic Gram-Positive Bacterium of the Normal Human Microbiota, Induces Inflammation by Activating Neutrophils

The Gram-positive anaerobic commensal Finegoldia magna colonizes the skin and other non-sterile body surfaces, and is an important opportunistic pathogen. Here we analyzed the effect of F. magna on human primary neutrophils. F. magna strains ALB8 (expressing protein FAF), 312 (expressing protein L) and 505 (naturally lacking both protein FAF and L) as well as their associated proteins activate neutrophils to release reactive oxygen species, an indication for neutrophil oxidative burst. Co-incubation of neutrophils with the bacteria leads to a strong increase of CD66b surface expression, another indicator for neutrophil activation. Furthermore, all tested stimuli triggered the release of NETs from the activated neutrophils, pointing to a host defense mechanism in response to the tested stimuli. This phenotype is dependent on actin rearrangement, NADPH oxidases and the ERK1/2 pathway. Proteins FAF and L also induced the secretion of several pro-inflammatory neutrophil proteins; HBP, IL-8 and INFγ. This study shows for the first time a direct interaction of F. magna with human neutrophils and suggests that the activation of neutrophils plays a role in F. magna pathogenesis.

Staphylococcal Biofilms

Staphylococci, with the leading species Staphylococcus aureus and Staphylococcus epidermidis, are the most frequent causes of infections on indwelling medical devices. The biofilm phenotype that those bacteria adopt during device-associated infection facilitates increased resistance to antibiotics and host immune defenses. This review presents and discusses the molecular mechanisms contributing to staphylococcal biofilm development and their in-vivo importance. Furthermore, it summarizes current strategies for the development of therapeutics against staphylococcal biofilm-associated infection.

Controlling Streptococcus mutans and Staphylococcus aureus biofilms with direct current and chlorhexidine

Microbial biofilms formed on biomaterials are major causes of chronic infections. Among them, Gram-positive bacteria Streptococcus mutans and Staphylococcus aureus are important pathogens causing infections associated with dental caries (tooth-decay) and other medical implants. Unfortunately, current antimicrobial approaches are ineffective in disrupting established biofilms and new methods are needed to improve the efficacy. In this study, we report that the biofilm cells of S. mutans and S. aureus can be effectively killed by low-level direct current (DC) and through synergy in concurrent treatment with DC and chlorhexidine (CHX) at low concentrations. For example, after treatment with 28 µA/cm² DC and 50 µg/mL CHX for 1 h, the viability of biofilm cells was reduced by approximately 4 and 5 logs for S. mutans and S. aureus, respectively. These results are useful for developing more effective approaches to control pathogenic biofilms.

The detrimental impact of extracellular bacterial proteases on wound healing

In addition to clinical signs of infection (e.g. inflammation, purulence and pain), a microbial count of ≥10⁵ colony-forming units/g has historically been used to define wound infection. However, it is increasingly recognised that, rather than a high bioburden level alone being detrimental to wound healing, it is the virulence of the invading microorganism and the host's immune status that can affect clinical outcomes. Bacteria, such as Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis, have developed a range of virulence factors to help them overcome host defences and proliferate within the underlying soft tissue. More specifically, bacterial proteases are one such virulence factor that has been implicated in promoting the invasion and destruction of the host tissue. Because of the complexities of microorganisms, the proteases can negatively impact the wound environment, leading to delayed wound healing. The aim of the present paper is to describe various extracellular bacterial proteases; review the impact they have on the wound environment, the host immune response and biofilms; and discuss potential wound management strategies against them. The evidence discussed suggests that proteases may play a profound role in wound infections, contribute to the development of an inflammatory response and impede wound healing.

Infection in Venous Leg Ulcers: Considerations for Optimal Management in the Elderly

Venous leg ulcers are the most common cause of chronic leg wounds, accounting for up to 70 % of all chronic leg ulcers and carrying with them a significant morbidity, especially for elderly patients. Among people aged 65 years and older, the annual prevalence is 1.7 %. Billions of dollars per year are spent caring for patients with these often difficult-to-heal and sometimes recurrent chronic wounds. Chronic non-healing wounds of the lower extremities are susceptible to microbial invasion and can lead to serious complications, such as delayed healing, cellulitis, enlargement of wound size, debilitating pain, and deeper wound infections causing systemic illness. Recognition and treatment of the infected venous leg ulcer is an essential skill set for any physician caring for geriatric patients. Most physicians rely on subjective clinical signs and patient-reported symptoms in the evaluation of infected chronic wounds. The conventional bacterial culture is a widely available tool for the diagnosis of bacterial infection but can have limitations. Systemic antibiotics, as well as topical antiseptics and antibiotics, can be employed to treat and control infection and critical colonization. Better understanding of microbial biofilms in the wound environment have caused them to emerge as an important reason for non-healing and infection due to their increased resistance to antimicrobial, immunological, and chemical attack. A sound understanding of the microbial-host environment and its complexities, as well as the pathophysiology of venous hypertension, must be appreciated to understand the need for a multimodality approach to treating an infected venous leg ulcer. Other treatment measures are often required, in addition to systemic and topical antibiotics, such as the application of wound bandages, compression therapy, and wound debridement, which can hasten clearance of the infection and help to promote healing.

Usability and effectiveness of Suprathel® in partial thickness burns in children

Purpose

Evaluation of usability and effectiveness of Suprathel^® in the treatment of partial thickness burns in children.

Methods

A prospective, observational study to evaluate adherence of Suprathel^® to the wound bed, reepithelialization time, grafting, wound colonization and infection, pain, dressing changes, length of hospital stay (LOS) and scar formation.

Results

Twenty-one children (median age 2.4 years, range 5 months–14 years) with a median total body surface area (TBSA) of 4 % (range 1–18) were included. Median LOS was 10 days (range 3–20). Median outer layer dressing changes was 3 (range 1–14). Suprathel^® was only adherent in wounds debrided with Versajet^®. Median reepithelialization time was 13 days (range 7–29). Three patients needed a split skin graft. There were 7 (33 %) patients with wound colonization before application of Suprathel^®. This increased to 12 (57 %) patients during treatment. One patient developed a wound infection. Median visual analog scale (VAS) scores for background and procedural pain in patients >7 years were 3.2 (range 2–5) and 3.5 (range 2–5), respectively. In younger patients, median background and procedural COMFORT-B scores were 13.8 (range 10–23) and 14.8 (range 13–23, p = 0.03), respectively. Patient and Observer Scar Assessment Scale (POSAS) scores were favorable after 3 and 6 months post burn.

Conclusions

Suprathel^® provides potential advantages regarding pain and scar formation, but extensive wound debridement is needed to achieve adequate adherence.

Antibiotics and antiseptics for pressure ulcers

BACKGROUND

Pressure ulcers, also known as bedsores, decubitus ulcers and pressure injuries, are localised areas of injury to the skin or the underlying tissue, or both. A range of treatments with antimicrobial properties, including impregnated dressings, are widely used in the treatment of pressure ulcers. A clear and current overview is required to facilitate decision making regarding use of antiseptic or antibiotic therapies in the treatment of pressure ulcers. This review is one of a suite of Cochrane reviews investigating the use of antiseptics and antibiotics in different types of wounds. It also forms part of a suite of reviews investigating the use of different types of dressings and topical treatments in the treatment of pressure ulcers.

OBJECTIVES

To assess the effects of systemic and topical antibiotics, and topical antiseptics on the healing of infected and uninfected pressure ulcers being treated in any clinical setting.

SEARCH METHODS

In October 2015 we searched: the Cochrane Wounds Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations), Ovid EMBASE, and EBSCO CINAHL Plus. We also searched three clinical trials registries and the references of included studies and relevant systematic reviews. There were no restrictions based on language or date of publication or study setting.

SELECTION CRITERIA

Randomised controlled trials which enrolled adults with pressure ulcers of stage II or above were included in the review.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, risk of bias assessment and data extraction.

MAIN RESULTS

We included 12 trials (576 participants); 11 had two arms and one had three arms. All assessed topical agents, none looked at systemic antibiotics. The included trials assessed the following antimicrobial agents: povidone iodine, cadexomer iodine, gentian violet, lysozyme, silver dressings, honey, pine resin, polyhexanide, silver sulfadiazine, and nitrofurazone with ethoxy-diaminoacridine. Comparators included a range of other dressings and ointments without antimicrobial properties and alternative antimicrobials. Each comparison had only one trial, participant numbers were low and follow-up times short. The evidence varied from moderate to very low quality.Six trials reported the primary outcome of wound healing. All except one compared an antiseptic with a non-antimicrobial comparator. There was some moderate and low quality evidence that fewer ulcers may heal in the short term when treated with povidone iodine compared with non-antimicrobial alternatives (protease-modulating dressings (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.62 to 0.98) and hydrogel (RR 0.64, 95% CI 0.43 to 0.97)); and no clear difference between povidone iodine and a third non-antimicrobial treatment (hydrocolloid) (low quality evidence). Pine resin salve may heal more pressure ulcers than hydrocolloid (RR 2.83, 95% CI 1.14 to 7.05) (low quality evidence). There is no clear difference between cadexomer iodine and standard care, and between honey a combined antiseptic and antibiotic treatment (very low quality evidence).Six trials reported adverse events (primary safety outcome). Four reported no adverse events; there was very low quality evidence from one showing no clear evidence of a difference between cadexomer iodine and standard care; in one trial it was not clear whether data were appropriately reported.There was limited reporting of secondary outcomes. The five trials that reported change in wound size as a continuous outcome did not report any clear evidence favouring any particular antiseptic/anti-microbial treatments. For bacterial resistance, one trial found some evidence of more MRSA eradication in participants with ulcer treated with a polyhexanide dressing compared with a polyhexanide swab (RR 1.48, 95% CI 1.02 to 2.13); patients in the dressing group also reported less pain (MD -2.03, 95% CI -2.66 to -1.40). There was no clear evidence of a difference between interventions in infection resolution in three other comparisons. Evidence for secondary outcomes varied from moderate to very low quality; where no GRADE assessment was possible we identified substantial limitations which an assessment would have taken into account.

AUTHORS' CONCLUSIONS

The relative effects of systemic and topical antimicrobial treatments on pressure ulcers are not clear. Where differences in wound healing were found, these sometimes favoured the comparator treatment without antimicrobial properties. The trials are small, clinically heterogenous, generally of short duration, and at high or unclear risk of bias. The quality of the evidence ranges from moderate to very low; evidence on all comparisons was subject to some limitations.

Wound samples: moving towards a standardised method of collection and analysis

Chronic wounds, including diabetic foot ulcers, pressure ulcers and venous leg ulcers, impact the lives of millions of people worldwide. These types of wounds represent a significant physical, social and financial burden to both patients and health care systems. Wound care has made great progress in recent years as a result of the critical research performed in academic, clinical and industrial settings. However, there has been relatively little translation of basic research discoveries into novel and effective treatments. One underlying reason for this paucity may be inconsistency in the methods of wound analysis and sample collection, resulting in the inability of researchers to accurately characterise the healing process and compare results from different studies. This review examines the various types of analytical methods being used in wound research today with emphasis on sampling techniques, processing and storage, and the findings call forth the wound care research community to standardise its approach to wound analysis in order to yield more robust and comparable data sets.

Association Between Microbial Bioburden and Healing Outcomes in Venous Leg Ulcers: A Review of the Evidence

Significance: Venous leg ulcers (VLUs) are susceptible to microbial invasion, and serious complications can result without the timely control of infection. Diagnosis of wound infection is primarily based on subjective clinical characteristics and patient-reported symptoms, and the treatment with antimicrobials has not consistently shown improvement in healing outcomes. This is a review of studies using bacterial cultures and/or new molecular-based methods associating microbial bioburden with healing outcomes in VLU patients, with the goal of guiding future studies to better determine significant patterns of microbial involvement in chronic wounds. Recent Advances: Studies reviewed here use cultivation-based identification of bacteria and next-generation sequencing of the bacterial 16S rRNA gene to gain insight into microbial bioburden in VLUs. Further application of sophisticated DNA sequencing and bioinformatic analyses has the potential to revolutionize our ability to further discern, with high resolution, complex microbial communities in chronic wounds. Critical Issues: Few previous studies of microbial bioburden in VLUs have incorporated the knowledge of clinical treatments, which includes close monitoring of patients' symptoms and responses to therapy. Thus, wound care practitioners are currently without evidence-based guidance for the diagnosis and treatment of wound infections. Future Directions: Clinically relevant breakthroughs are possible by combining advanced microbial detection techniques with improved study designs that reflect clinical practices. Well-designed longitudinal studies have great potential to lead to better evidence-based diagnosis of chronic wounds. A greater understanding of microbial bioburden in chronic wounds is likely to lead to better therapies that speed healing and prevent wound infection without risking the development of antimicrobial resistance.

A novel model of chronic wounds: importance of redox imbalance and biofilm-forming bacteria for establishment of chronicity

Chronic wounds have a large impact on health, affecting ∼6.5 M people and costing ∼$25B/year in the US alone. We previously discovered that a genetically modified mouse model displays impaired healing similar to problematic wounds in humans and that sometimes the wounds become chronic. Here we show how and why these impaired wounds become chronic, describe a way whereby we can drive impaired wounds to chronicity at will and propose that the same processes are involved in chronic wound development in humans. We hypothesize that exacerbated levels of oxidative stress are critical for initiation of chronicity. We show that, very early after injury, wounds with impaired healing contain elevated levels of reactive oxygen and nitrogen species and, much like in humans, these levels increase with age. Moreover, the activity of anti-oxidant enzymes is not elevated, leading to buildup of oxidative stress in the wound environment. To induce chronicity, we exacerbated the redox imbalance by further inhibiting the antioxidant enzymes and by infecting the wounds with biofilm-forming bacteria isolated from the chronic wounds that developed naturally in these mice. These wounds do not re-epithelialize, the granulation tissue lacks vascularization and interstitial collagen fibers, they contain an antibiotic-resistant mixed bioflora with biofilm-forming capacity, and they stay open for several weeks. These findings are highly significant because they show for the first time that chronic wounds can be generated in an animal model effectively and consistently. The availability of such a model will significantly propel the field forward because it can be used to develop strategies to regain redox balance that may result in inhibition of biofilm formation and result in restoration of healthy wound tissue. Furthermore, the model can lead to the understanding of other fundamental mechanisms of chronic wound development that can potentially lead to novel therapies.

Identification of molecular mechanisms used by Finegoldia magna to penetrate and colonize human skin

Finegoldia magna is a Gram-positive anaerobic commensal of the human skin microbiota, but also known to act as an opportunistic pathogen. Two primary virulence factors of F. magna are the subtilisin-like extracellular serine protease SufA and the adhesive protein FAF. This study examines the molecular mechanisms F. magna uses when colonizing or establishing an infection in the skin. FAF was found to be essential in the initial adherence of F. magna to human skin biopsies. In the upper layers of the epidermis FAF mediates adhesion through binding to galectin-7 - a keratinocyte cell marker. Once the bacteria moved deeper into the skin to the basement membrane layer, SufA was found to degrade collagen IV which forms the backbone structure of the basement membrane. It also degraded collagen V, whereby F. magna could reach deeper dermal tissue sites. In the dermis, FAF interacts with collagen V and fibrillin, which presumably helps the bacteria to establish infection in this area. The findings of this study paint a clear picture of how F. magna interacts with human skin and explain how it is such a successful opportunistic pathogen in chronic wounds and ulcers.

A prospective, open, multicentre study to evaluate a new gelling fibre dressing containing silver in the management of venous leg ulcers

This study investigated the performance of a new gelling fibre dressing containing silver (DURAFIBER™ Ag; Smith & Nephew, Hull, UK) in moderate to highly exuding venous leg ulcers with one or more clinical signs of infection. Fourteen patients with venous leg ulceration of median ulcer duration 12·5 weeks, recruited from three centres in South Africa, received treatment with the new dressing for a maximum of 8 weeks. Multilayer compression bandaging was used for all patients, at the majority of assessments. The objectives of this study were to assess the clinical acceptability of the dressing in terms of the following characteristics: antimicrobial properties, the progress of the wound towards healing, wear time, exudate management, conformability, patient comfort, pain on application, pain on removal and dressing integrity. The new dressing was rated as clinically acceptable for all characteristics, for all 14 patients (100%). It was easy to apply and remove; in 96·8% of removals, the dressing stayed intact on removal and could be removed in one piece. Fifty per cent of the wounds healed within the 8-week study duration; between baseline and final assessment, the median percentage reduction in wound area was 98·2% and the median percentage reduction in devitalised tissue was 78%. Exudate levels and wound pain were significantly improved at final assessment compared to baseline assessment, and an increase in the number of patients with healthy peri-wound skin between baseline and final assessment was observed. A reduction in bioburden and signs of clinical infection and an improvement in quality of life were observed over the 8-week period. The average wear time was 6·4 days. This study supports the use of new dressing in the management of moderately to highly exuding venous leg ulcers with clinical signs of infection.

Antimicrobial and antiseptic strategies in wound management

Wounds, especially chronic wounds, represent a global problem costing millions of dollars per year in developed countries and are characterised by microbial complications including local or overt infection, delayed healing and spread of multiresistant germs. Therefore, antimicrobial wound management is a major challenge that continues to require new solutions against microbes and their biofilms. As systemic antibiotics can barely penetrate into wound biofilms and topically applied ones can easily lead to sensitisation, antisepsis is the method of choice to treat germs in wounds. This brief review discusses the role of antiseptics in reducing bioburden in chronic wounds. Balancing antimicrobial potency and tolerability of antiseptic procedures is critical in wound therapy. However, antiseptics alone may not be able to achieve wound healing without addressing other factors regarding the patient's general health or the wound's physical environment. Although the precise role of bioburden in chronic wounds remains to be evaluated, planktonic as well as biofilm-bound microbes are indications for antiseptic intervention. Octenidine dihydrochloride and polyhexanide are the most effective, as well as best tolerated, antiseptics in wound management today, and new strategies to reduce bacterial wound burden and support the body's immune response are being developed.

[Microbial stress of skin and wounds in clinical aspects and practice. Between search and destroy and monitor and relax]

The antibiotic treatment of microbial pathogens of the skin and wounds could so far not fulfil the expectations of an effective and permanent elimination of pathogens so that local treatment with antiseptic agents as a flanking measure to wound cleansing and debridement has become increasingly more established. Because an antiseptic treatment does not actually represent a treatment of infections, the current antimicrobial treatment strategy for infections in skin and wound areas consists of combined antibiotic and flanking antiseptic administration following debridement. However, the combined therapy is not always successful. There is an urgent need for new forms of therapy particularly to combat multiresistant pathogens in biofilms in infections of chronic and other complicated wounds.

Generating and reversing chronic wounds in diabetic mice by manipulating wound redox parameters

By 2025, more than 500 M people worldwide will suffer from diabetes; 125 M will develop foot ulcer(s) and 20 M will undergo an amputation, creating a major health problem. Understanding how these wounds become chronic will provide insights to reverse chronicity. We hypothesized that oxidative stress (OS) in wounds is a critical component for generation of chronicity. We used the db/db mouse model of impaired healing and inhibited, at time of injury, two major antioxidant enzymes, catalase and glutathione peroxidase, creating high OS in the wounds. This was necessary and sufficient to trigger wounds to become chronic. The wounds initially contained a polymicrobial community that with time selected for specific biofilm-forming bacteria. To reverse chronicity we treated the wounds with the antioxidants α-tocopherol and N-acetylcysteine and found that OS was highly reduced, biofilms had increased sensitivity to antibiotics, and granulation tissue was formed with proper collagen deposition and remodeling. We show for the first time generation of chronic wounds in which biofilm develops spontaneously, illustrating importance of early and continued redox imbalance coupled with the presence of biofilm in development of wound chronicity. This model will help decipher additional mechanisms and potentially better diagnosis of chronicity and treatment of human chronic wounds.

FAF and SufA: proteins of Finegoldia magna that modulate the antibacterial activity of histones

Many bacterial pathogens have developed methods to overcome the defences of the host innate immune system. One such defence is the release of antimicrobial peptides (AMPs). Histones have been found to function as AMPs, in addition to their main biological function of packaging and organising DNA into nucleosomes. In this study, the Gram-positive anaerobic coccus Finegoldia magna was found to bind histones by Western blot and immunoprecipitation analysis. F. magna, which is normally a commensal of the skin and mucous membranes, is also known to act as an opportunistic pathogen and has been isolated from various clinical infection sites. It was found to bind to histones extracted from human skin epidermis through its surface and extracellular adhesion protein FAF. Through FAF binding, F. magna was protected from histone bactericidal activity. Furthermore, the histones were found to be degraded by SufA, a subtilisin-like extracellular serine protease of F. magna. Hence, the results of the present study will give more insight into how F. magna persists both as a commensal organism at the basement membrane of the skin and as an opportunistic pathogen during infection.

Biofilms and Inflammation in Chronic Wounds

SIGNIFICANCE

The incidence, cost, morbidity, and mortality associated with non-healing of chronic skin wounds are dramatic. With the increasing numbers of people with obesity, chronic medical conditions, and an increasing life expectancy, the healthcare cost of non-healing ulcers has recently been estimated at $25 billion annually in the United States. The role played by bacterial biofilm in chronic wounds has been emphasized in recent years, particularly in the context of the prolongation of the inflammatory phase of repair.

RECENT ADVANCES

Rapid high-throughput genomic approaches have revolutionized the ability to identify and quantify microbial organisms from wounds. Defining bacterial genomes and using genetic approaches to knock out specific bacterial functions, then studying bacterial survival on cutaneous wounds is a promising strategy for understanding which genes are essential for pathogenicity.

CRITICAL ISSUES

When an animal sustains a cutaneous wound, understanding mechanisms involved in adaptations by bacteria and adaptations by the host in the struggle for survival is central to development of interventions that favor the host.

FUTURE DIRECTIONS

Characterization of microbiomes of clinically well characterized chronic human wounds is now under way. The use of in vivo models of biofilm-infected cutaneous wounds will permit the study of the mechanisms needed for biofilm formation, persistence, and potential synergistic interactions among bacteria. A more complete understanding of bacterial survival mechanisms and how microbes influence host repair mechanisms are likely to provide targets for chronic wound therapy.

Bacterial cultures, rapid strep test, and antibiotic treatment in infected hard-to-heal ulcers in primary care

OBJECTIVE

In-depth studies on antibiotic treatment for patients with hard-to-heal ulcers in primary care are lacking. The present study was undertaken to update the bacteriological spectrum for this patient group and to investigate antibiotic treatment. A further aim was to investigate the potential of a rapid strep test to find group A streptococci (GAS) causing ulcer infection.

DESIGN

A prospective study from August 2009 to August 2010.

SETTING

Blekinge Wound Healing Center.

SUBJECTS

Patients with clinical signs of infected hard-to-heal ulcers of any etiology.

MAIN OUTCOME MEASURES

A bacterial culture and a rapid strep test were taken from every ulcer to capture the bacteriological spectrum. Antibiotic treatment before and during the study period was measured.

RESULTS

Forty-one patients with 49 infected ulcers were recruited. Staphylococcus aureus, found in 68.8% of all cultures, was the most observed species. Group G streptococci (GGS) were found in 12.5%. GAS was found in one case where the rapid strep test was positive. Staphylococcus aureus was found in three patients out of four with clinical signs of erysipelas. Some 59% of the patients were treated with antibiotics before the study period compared with 44% during the study period.

CONCLUSION

Antibiotic treatment was largely reduced because of structured wound management. The current bacteriological spectrum showed high rates of GGS and erysipelas caused by Staphylococcus aureus. The rapid strep test was found useful in identifying GAS but we would not recommend its use in the clinical setting due to the low rate of GAS in this patient group.

Time course study of delayed wound healing in a biofilm-challenged diabetic mouse model

Bacterial biofilm has been shown to play a role in delaying wound healing of chronic wounds, a major medical problem that results in significant health care burden. A reproducible animal model could be very valuable for studying the mechanism and management of chronic wounds. Our previous work showed that Pseudomonas aeruginosa (PAO1) biofilm challenge on wounds in diabetic (db/db) mice significantly delayed wound healing. In this wound time course study, we further characterize the bacterial burden, delayed wound healing, and certain aspects of the host inflammatory response in the PAO1 biofilm-challenged db/db mouse model. PAO1 biofilms were transferred onto 2-day-old wounds created on the dorsal surface of db/db mice. Control wounds without biofilm challenge healed by 4 weeks, consistent with previous studies; none of the biofilm-challenged wounds healed by 4 weeks. Of the biofilm-challenged wounds, 64% healed by 6 weeks, and all of the biofilm-challenged wounds healed by 8 weeks. During the wound-healing process, P. aeruginosa was gradually cleared from the wounds while the presence of Staphylococcus aureus (part of the normal mouse skin flora) increased. Scabs from all unhealed wounds contained 10(7) P. aeruginosa, which was 100-fold higher than the counts isolated from wound beds (i.e., 99% of the P. aeruginosa was in the scab). Histology and genetic analysis showed proliferative epidermis, deficient vascularization, and increased inflammatory cytokines. Hypoxia inducible factor expression increased threefold in 4-week wounds. In summary, our study shows that biofilm-challenged wounds typically heal in approximately 6 weeks, at least 2 weeks longer than nonbiofilm-challenged normal wounds. These data suggest that this delayed wound healing model enables the in vivo study of bacterial biofilm responses to host defenses and the effects of biofilms on host wound healing pathways. It may also be used to test antibiofilm strategies for treating chronic wounds.

Microbiology of the skin and the role of biofilms in infection

The integrity of human skin is central to the prevention of infection. Acute and chronic wounds can develop when the integrity of skin as a barrier to infection is disrupted. As a multi-functional organ, skin possesses important biochemical and physical properties that influence its microbiology. These properties include a slightly acidic pH, a low moisture content, a high lipid content (which results in increased hydrophobicity) and the presence of antimicrobial peptides. Such factors have a role to play in preventing exogenous microbial colonisation and subsequent infection. In addition, the properties of skin both select for and enhance colonisation and biofilm formation by certain 'beneficial' micro-organisms. These beneficial micro-organisms can provide further protection against colonisation by potential pathogens, a process known as colonisation resistance. The aim of this paper is to summarise the microflora of skin and wounds, highlighting the role of certain micro-organisms and biofilms in associated infections.

Staphylococcus aureus biofilms: properties, regulation, and roles in human disease

Increasing attention has been focused on understanding bacterial biofilms and this growth modality's relation to human disease. In this review we explore the genetic regulation and molecular components involved in biofilm formation and maturation in the context of the Gram-positive cocci, Staphylococcus aureus. In addition, we discuss diseases and host immune responses, along with current therapies associated with S. aureus biofilm infections and prevention strategies.

Biofilms and bacterial imbalances in chronic wounds: anti-Koch

Microbial imbalances and synergistic relationships between bacteria in medically important biofilms are poorly researched. Consequently, little is known about how synergy between bacteria may increase the net pathogenic effect of a biofilm in many diseases and infections, including chronic wounds. Microbial synergy in chronic wounds may increase virulence and pathogenicity, leading to enhanced tissue degradation, malodour and in some cases, an impairment of the host immune response. Microbial synergy and growth within a biofilm provide a competitive advantage to the microorganisms cohabiting in a wound, thereby promoting their survival and tolerance and resistance to antimicrobial agents. The aim of this article was to provide greater insight into microbial imbalances found within wound biofilms and the significance they may have on non healing and infected wounds. We also present two possible hypotheses which could explain the role microorganisms play in non healing chronic wounds and offer possible strategies for combating harmful and detrimental biofilms.

A clinical investigation into the microbiological status of 'locally infected' leg ulcers

The complex interactions between patients and the microbial species that reside in their wounds are not yet fully characterised. Investigations to date have dealt with either those organisms that cause infections or those that establish long-term colonisations. The objective of this open, prospective pilot study was to quantitatively and qualitatively assess the microbiological status of 'locally infected' venous leg ulcers. Three different sampling techniques were used to recover organisms from 20 venous leg ulcers that had failed to progress towards healing and comparisons made to explore the distribution of colonised flora within the wound. In total, 116 isolates were recovered (mean of 5.8 per ulcer) with highest recovery rates seen with swabs. Greatest agreement of colonisation and counts was found between swabs and absorbent polyvinyl acetate (PVA) foam disc, and also between PVA discs and biopsies. Lowest agreement was between the distribution of anaerobes and coryneforms in swabs and biopsies, suggesting uneven vertical distribution within ulcers. No justification for using routine biopsies in locally infected venous leg ulcers was found.

A comparison of bacterial composition in diabetic ulcers and contralateral intact skin

An extensive portion of the healthcare budget is allocated to chronic human infection. Chronic wounds in particular are a major contributor to this financial burden. Little is known about the types of bacteria which may contribute to the chronicity, biofilm and overall bioburden of the wound itself. In this study we compare the bacteriology of wounds and associated intact skin. Wound and paired intact skin swabs (from a contralateral location) were collected. The bacterial diversity was determined using bacterial Tag-encoded FLX amplicon pyrosequencing (bTEFAP). Diversity analysis showed intact skin to be significantly more diverse than wounds on both the species and genus levels (3% and 5% divergence). Furthermore, wounds show heightened levels of anaerobic bacteria, like Peptoniphilus, Finegoldia, and Anaerococcus, and other detrimental genera such as Corynebacterium and Staphylococcus. Although some of these and other bacterial genera were found to be common between intact skin and wounds, notable opportunistic wound pathogens were found at lower levels in intact skin. Principal Component Analysis demonstrated a clear separability of the two groups. The findings of the study not only greatly support the hypothesis of differing bacterial composition of intact skin and wounds, but also contribute additional insight into the ecology of skin and wound microflora. The increased diversity and lowered levels of opportunistic pathogens found in skin make the system highly distinguishable from wounds.

Evaluation of the quality and cost-effectiveness of Versajet hydrosurgery

Judicious resource allocation to maximise benefits is essential to health care decision-making, particularly with increasingly expensive treatments and rising populations. Accurate wound debridement is important, and while many methods exist, surgical debridement is currently the gold standard with material costs at approximately pound 140. Versajet, a hydrosurgical device, is suggested by some to have facilitated a paradigm shift in wound management by allowing debridement of undesirable tissue while accurately preserving viable structures. Its proponents claim that it minimises surgical duration, length of hospital admission, improves wound healing and may be deployed at the bedside or in the community. Consoles and single-use hand-units cost pound 6000- pound 7000 and pound 220- pound 240, respectively. Some propose that hydrosurgery may provide an efficacious, efficient and cost-effective alterative to surgical debridement. However, the evidence available is largely based on expert opinion. Methodological flaws of such descriptive studies include the lack of control groups, selection bias and lack of blinding. Hence, these claims need to be interpreted cautiously. This opinion review examines the available evidence as to whether Versajet hydrosurgery provides quality and cost-effective care.

SufA - a bacterial enzyme that cleaves fibrinogen and blocks fibrin network formation

Finegoldia magna is a member of the normal human bacterial flora on the skin and other non-sterile body surfaces, but this anaerobic coccus is also an important opportunistic pathogen. SufA was the first F. magna proteinase to be isolated and characterized. Many bacterial pathogens interfere with different steps of blood coagulation, and here we describe how purified SufA efficiently and specifically cleaves fibrinogen in human plasma. SufA is both secreted by F. magna and associated with the bacterial surface. Successful gene targeting has previously not been performed in anaerobic cocci, but in order to study the role of the SufA that is present at the bacterial surface, we constructed an F. magna mutant that expresses a truncated SufA lacking proteolytic activity. In contrast to wild-type bacteria that delayed the coagulation of human plasma, mutant bacteria had no such effect. Wild-type and mutant bacteria adhered to keratinocytes equally well, but in a plasma environment only wild-type bacteria blocked the formation of fibrin networks surrounding adherent bacteria. The effective cleavage of fibrinogen by SufA suggests that the interference with fibrin network formation represents an adaptive mechanism of F. magna with potential implications also for pathogenicity.

Polymicrobial nature of chronic diabetic foot ulcer biofilm infections determined using bacterial tag encoded FLX amplicon pyrosequencing (bTEFAP)

BACKGROUND

Diabetic extremity ulcers are associated with chronic infections. Such ulcer infections are too often followed by amputation because there is little or no understanding of the ecology of such infections or how to control or eliminate this type of chronic infection. A primary impediment to the healing of chronic wounds is biofilm phenotype infections. Diabetic foot ulcers are the most common, disabling, and costly complications of diabetes. Here we seek to derive a better understanding of the polymicrobial nature of chronic diabetic extremity ulcer infections.

METHODS AND FINDINGS

Using a new bacterial tag encoded FLX amplicon pyrosequencing (bTEFAP) approach we have evaluated the bacterial diversity of 40 chronic diabetic foot ulcers from different patients. The most prevalent bacterial genus associated with diabetic chronic wounds was Corynebacterium spp. Findings also show that obligate anaerobes including Bacteroides, Peptoniphilus, Fingoldia, Anaerococcus, and Peptostreptococcus spp. are ubiquitous in diabetic ulcers, comprising a significant portion of the wound biofilm communities. Other major components of the bacterial communities included commonly cultured genera such as Streptococcus, Serratia, Staphylococcus and Enterococcus spp.

CONCLUSIONS

In this article, we highlight the patterns of population diversity observed in the samples and introduce preliminary evidence to support the concept of functional equivalent pathogroups (FEP). Here we introduce FEP as consortia of genotypically distinct bacteria that symbiotically produce a pathogenic community. According to this hypothesis, individual members of these communities when they occur alone may not cause disease but when they coaggregate or consort together into a FEP the synergistic effect provides the functional equivalence of well-known pathogens, such as Staphylococcus aureus, giving the biofilm community the factors necessary to maintain chronic biofilm infections. Further work is definitely warranted and needed in order to prove whether the FEPs concept is a viable hypothesis. The findings here also suggest that traditional culturing methods may be extremely biased as a diagnostic tool as they select for easily cultured organisms such as Staphylococcus aureus and against difficult to culture bacteria such as anaerobes. While PCR methods also have bias, further work is now needed in comparing traditional culture results to high-resolution molecular diagnostic methods such as bTEFAP.

Survey of bacterial diversity in chronic wounds using pyrosequencing, DGGE, and full ribosome shotgun sequencing

BACKGROUND

Chronic wound pathogenic biofilms are host-pathogen environments that colonize and exist as a cohabitation of many bacterial species. These bacterial populations cooperate to promote their own survival and the chronic nature of the infection. Few studies have performed extensive surveys of the bacterial populations that occur within different types of chronic wound biofilms. The use of 3 separate16S-based molecular amplifications followed by pyrosequencing, shotgun Sanger sequencing, and denaturing gradient gel electrophoresis were utilized to survey the major populations of bacteria that occur in the pathogenic biofilms of three types of chronic wound types: diabetic foot ulcers (D), venous leg ulcers (V), and pressure ulcers (P).

RESULTS

There are specific major populations of bacteria that were evident in the biofilms of all chronic wound types, including Staphylococcus, Pseudomonas, Peptoniphilus, Enterobacter, Stenotrophomonas, Finegoldia, and Serratia spp. Each of the wound types reveals marked differences in bacterial populations, such as pressure ulcers in which 62% of the populations were identified as obligate anaerobes. There were also populations of bacteria that were identified but not recognized as wound pathogens, such as Abiotrophia para-adiacens and Rhodopseudomonas spp. Results of molecular analyses were also compared to those obtained using traditional culture-based diagnostics. Only in one wound type did culture methods correctly identify the primary bacterial population indicating the need for improved diagnostic methods.

CONCLUSION

If clinicians can gain a better understanding of the wound's microbiota, it will give them a greater understanding of the wound's ecology and will allow them to better manage healing of the wound improving the prognosis of patients. This research highlights the necessity to begin evaluating, studying, and treating chronic wound pathogenic biofilms as multi-species entities in order to improve the outcomes of patients. This survey will also foster the pioneering and development of new molecular diagnostic tools, which can be used to identify the community compositions of chronic wound pathogenic biofilms and other medical biofilm infections.

Interleukin-6 concentrations in wound fluids rather than serological markers are useful in assessing bacterial triggers of ulcer inflammation

Bacterial pathogenicity, microbial load and diversity are decisive for outcome and therapy of non healing ulcers. However, until now, no routine laboratory parameter is available to assess the inflammatory level caused by chronic wound infections. We thus investigated the usefulness of levels of interleukin (IL)-6 and tumour necrosis factor alpha (TNFalpha) in wound fluids for assessing ulcer inflammation in the presence or absence of microbial triggers. In addition, the predictive values of local cytokine analyses were compared with those of C-reactive protein (CRP) and lipopolysaccharide-binding protein (LBP) because serological markers are normally used to underline the suspicion of wound infections. The present data from chronic arterial and venous ulcers (n = 45) clearly show that mixed bacterial infections increased IL-6 and TNFalpha concentrations in wound fluids when compared with ulcers with a monomicrobial infection (P < 0.01 and P < 0.05, respectively). IL-6 was also significantly elevated when a high bacterial load [versus <10(5) colony-forming units (cfu)/ml: P = 0.04] or an infection with Pseudomonas was observed (versus isolation of non Pseudomonas strains: P = 0.05). Although distinct proinflammatory triggers may interfere with regard to cytokine levels, sensitivity and specificity were significant in predicting bacterial risk factors, particularly for IL-6 at a designated cut-off of 125 pg/ml (sensitivity and specificity for predicting a mixed infection: 70% and 64%, for predicting a bacterial load of >10(5) cfu/ml: 62% and 57% and for predicting an infection with Pseudomonas: 90% and 57%). In contrast to local cytokine levels, the serological markers CRP and LBP were not associated with the presence of any of the investigated bacterial triggers. Focusing on the aim of the study, IL-6 analysed in wound washouts seems to be a useful diagnostic marker for a sensitive and specific assessment of ulcers inflammation with regard to bacterial triggers.

Venous leg ulcers - the search for a prognostic indicator

Disordered cell function within chronic wounds generates many parameters that can be measured to differentiate between healing and non healing status. Theoretically, these may form the basis of a wound assessment system to define disease severity and response to treatment. In a review of tissue, wound exudate and microbiology studies of venous leg ulcers, we identify many such parameters that are associated with healing status. These include cytokines, proteases and their inhibitors, senescence markers, oxidative stress markers and microbiological status defined by culture. Some of these, such as protease level in wound exudate, have been proposed as prognostic indicators of healing status and many more could be considered potential markers to incorporate into a wound assessment system. However, no published data are available that validate known wound components to accurately reflect wound progression on a single patient basis. Rather than further characterisation of the expression of known wound biomarkers, the development of an accurate and objective test for prediction of chronic wound outcome requires identification of an appropriate combination of novel molecules that vary coordinately with healing status.

Multiple bacterial species reside in chronic wounds: a longitudinal study

The aim of the study was to investigate the bacterial profile of chronic venous leg ulcers and the importance of the profile to ulcer development. Patients with persisting venous leg ulcers were included and followed for 8 weeks. Every second week, ulcer samples were collected and the bacterial species present were identified. More than one bacterial species were detected in all the ulcers. The most common bacteria found were Staphylococcus aureus (found in 93.5% of the ulcers), Enterococcus faecalis (71.7%), Pseudomonas aeruginosa (52.2%), coagulase-negative staphylococci (45.7%), Proteus species (41.3%) and anaerobic bacteria (39.1%). Resident bacterial species were present in all the ulcers. In 76% of the ulcers, two or more (up to five) resident bacterial species were found. The most common resident bacterial species were S. aureus and P. aeruginosa. Furthermore, ulcers with P. aeruginosa were found to be significantly larger than ulcers without the presence of P. aeruginosa (P < 0.005). Our study demonstrated that the chronic wound is colonised by multiple bacterial species and that once they are established many of them persist in the wound. Our results suggest that the presence of P. aeruginosa in venous leg ulcers can induce ulcer enlargement and/or cause delayed healing.

Wound microbiology and associated approaches to wound management

The majority of dermal wounds are colonized with aerobic and anaerobic microorganisms that originate predominantly from mucosal surfaces such as those of the oral cavity and gut. The role and significance of microorganisms in wound healing has been debated for many years. While some experts consider the microbial density to be critical in predicting wound healing and infection, others consider the types of microorganisms to be of greater importance. However, these and other factors such as microbial synergy, the host immune response, and the quality of tissue must be considered collectively in assessing the probability of infection. Debate also exists regarding the value of wound sampling, the types of wounds that should be sampled, and the sampling technique required to generate the most meaningful data. In the laboratory, consideration must be given to the relevance of culturing polymicrobial specimens, the value in identifying one or more microorganisms, and the microorganisms that should be assayed for antibiotic susceptibility. Although appropriate systemic antibiotics are essential for the treatment of deteriorating, clinically infected wounds, debate exists regarding the relevance and use of antibiotics (systemic or topical) and antiseptics (topical) in the treatment of nonhealing wounds that have no clinical signs of infection. In providing a detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, this review has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.

Interactive wound dressings. A practical guide to their use in older patients

The properties of an ideal wound dressing do not change with the introduction of new types of wound dressing, but the range of effects on wound healing increases. The number of dressings available is enormous, and the choice between them is often bewildering. Because there is still no ideal dressing for all wound types, it is necessary to get to know a few well, and to avoid switching to new therapies solely on the basis of anecdotal reports. The adoption of novel dressings should be based on scientific evidence. At present, dressings are still chosen on the basis of local traditions and personal empirical experience, together with evidence from the few double-blind, placebo-controlled trials that have been performed. In the management of ulcers, a particular wound management plan should not be changed if the ulcer being treated is decreasing in size and the patient is comfortable. The dressing should be chosen with care. The type of chronic ulcer and its appearance, the amount of exudate and the presence or absence of pain all assist in the selection of an appropriate wound dressing product. Quality-of-life aspects are important. In the elderly, good quality of life may not necessarily require complete ulcer healing, although this is naturally desirable. Dressing changes should be minimised and the ulcer should be kept moist and the surrounding skin dry. The high cost of interactive dressings is a potential disadvantage of their use. However, if the wound can be re-dressed at longer intervals and if healing occurs more quickly, their use may be cost effective and associated with less pain and a better quality of life.