Wound Center Research Articles

Community Analysis of Chronic Wound Bacteria Using 16S rRNA Gene-Based Pyrosequencing: Impact of Diabetes and Antibiotics on Chronic Wound Microbiota

BackgroundBacterial colonization is hypothesized to play a pathogenic role in the non-healing state of chronic wounds. We characterized wound bacteria from a cohort of chronic wound patients using a 16S rRNA gene-based pyrosequencing approach and assessed the impact of diabetes and antibiotics on chronic wound microbiota.Methodology/Principal FindingsWe prospectively enrolled 24 patients at a referral wound center in Baltimore, MD; sampled patients' wounds by curette; cultured samples under aerobic and anaerobic conditions; and pyrosequenced the 16S rRNA V3 hypervariable region. The 16S rRNA gene-based analyses revealed an average of 10 different bacterial families in wounds—approximately 4 times more than estimated by culture-based analyses. Fastidious anaerobic bacteria belonging to the Clostridiales family XI were among the most prevalent bacteria identified exclusively by 16S rRNA gene-based analyses. Community-scale analyses showed that wound microbiota from antibiotic treated patients were significantly different from untreated patients (p = 0.007) and were characterized by increased Pseudomonadaceae abundance. These analyses also revealed that antibiotic use was associated with decreased Streptococcaceae among diabetics and that Streptococcaceae was more abundant among diabetics as compared to non-diabetics.Conclusions/SignificanceThe 16S rRNA gene-based analyses revealed complex bacterial communities including anaerobic bacteria that may play causative roles in the non-healing state of some chronic wounds. Our data suggest that antimicrobial therapy alters community structure—reducing some bacteria while selecting for others.

Inflammatory cytokine levels in chronic venous insufficiency ulcer tissue before and after compression therapy

Elevated inflammatory cytokine levels have been implicated in the pathogenesis of non-healing chronic venous insufficiency (CVI) ulcers. The goal of this study was to determine the protein levels of a wide range of inflammatory cytokines in untreated CVI ulcer tissue before and after 4 weeks of high-strength compression therapy. These levels were compared to cytokines present in healthy tissue. Thirty limbs with untreated CVI and leg ulceration received therapy for 4 weeks with sustained high-compression bandaging at an ambulatory wound center. Biopsies were obtained from healthy and ulcerated tissue before and after therapy. A multiplexed protein assay was used to measure multiple cytokines in a single sample. Patients were designated as rapid or delayed healers based on ulcer surface area change. The majority of pro-inflammatory cytokine protein levels were elevated in ulcer tissue compared to healthy tissue, and compression therapy significantly reduced these cytokines. TGF-beta1 was upregulated in ulcer tissue following compression therapy. Rapid healing ulcers had significantly higher levels of IL-1alpha, IL-1beta, IFN-gamma, IL-12p40, and granulocyte macrophage colony stimulating factor (GM-CSF) before compression therapy, and IL-1 Ra after therapy. IFN-gamma levels significantly decreased following therapy in the rapidly healing patients. CVI ulcer healing is associated with a pro-inflammatory environment prior to treatment that reflects metabolically active peri-wound tissue that has the potential to heal. Treatment with compression therapy results in healing that is coupled with reduced pro-inflammatory cytokine levels and higher levels of the anti-inflammatory cytokine IL-1 Ra.

Combined Use of Acid Fibroblast Growth Factor, Granulocyte Colony-stimulating Factor and Zinc Sulphate Accelerates Diabetic Ulcer Healing

Our previous studies demonstrated that topic application of recombinant human acid fibroblast growth factor (aFGF) significantly, but still not completely, improved in diabetic ulcer healing. To obtain a maximal therapy for diabetic ulcer healing, a combined protocol containing aFGF, anti-oxidative reagent zinc (Zn) and stem cell stimulator granulocyte colony-stimulating factor (G-CSF), i.e.: aFGF/G-CSF/zinc sulphate (ZnSO4), was explored in the present study. Diabetes was induced by a single dose of streptozotocin (STZ, 55 mg/kg) in Sprague Dawley rats, and full thickness skin wound was made in diabetic rats at 2 months after diabetes onset. Diabetic ulcer rats were treated with aFGF, G-CSF, ZnSO4, aFGF/G-CSF/ZnSO4 or vehicle control, respectively and 3, 6, 9, 12, 15, 18, 21 and 28 days later, therapeutic effects were evaluated by calculating ulcer area. On day 7, 14, 21 after treatment, rats were sacrificed to collect 2 pieces of dorsal skin from 3 different sites (wound center, edge and healed area) to perform histopathological examination. Results showed that treatment with aFGF/G-CSF/ZnSO4 significantly enhanced ulcer healing compared with single drug treatment groups at different time points. Healing times for 100% of the wound in the aFGF/G-CSF/ZnSO4 group was 20.00 ± 1.15 days, and significantly shorter than those in single treatment groups (p < 0.05). Histopathological and immunohistochemical analysis disclosed significant increases in capillary density, proliferating cells, the expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) and the ratios of TIMP-1 to matrix metalloproteinase 1 (MMP-1) in aFGF/G-CSF/ZnSO4 group as compared to other single treatments. Collectively, the combinative protocol of aFGF/G-CSF/ZnSO4 significantly enhanced the therapeutic effect on diabetic ulcer wound, probably through the promotion of fibroblast proliferation and differentiation, enhancement of blood vessel regeneration, and up-regulation of TIMP-1 and down-regulation of MMP-1 expression in diabetic ulcer healing process.

How to make a hospital-based wound center financially viable: The Georgetown University Hospital model

As the medical need and expenditure for chronic wound care have increased markedly over the past decade, wound centers have grown exponentially throughout the country. They can be community-based or hospital-based, and in either case, can be run by the facility or by a national chain. The wound center's viability is dependent on generated revenue, and its clinical effectiveness is based on a multidisciplinary approach to wound care. By incorporating the wound center into an existing hospital system, one can take advantage of the hospital's resources to effectively treat the more complex patients. Additionally, by focusing on limb salvage, the hospital attracts the critical limb ischemia and other complex patients that often require inpatient admission. We examined the Georgetown University Hospital Center for Wound Healing performance over the first 6 years of operation. Since opening the wound center in 1999, the number of outpatient visits has doubled, the wound care inpatient census has doubled, and the operative cases have increased 3-fold. Because the outpatient segment of the wound center can at best cover its direct cost, it cannot financially justify its existence. Hyperbaric oxygen (HBO) can increase the revenue to the point where the indirect costs are covered as well and the wound center can be revenue neutral. Due to the medical complexity of limb salvage patients, the inpatient collections are much higher than those of the outpatient wound center and therefore can serve as justification for the latter's financial viability. More importantly, with the wound center in place, the hospital can provide the local/regional community with a comprehensive service that can effectively treat the most challenging wounds. The success is built on a multidisciplinary team approach, use of evidence-based treatment protocols, efficient clinical structure, and a supportive hospital system. The beneficiaries include the patient with a healed wound, the physician with a gratifying practice, the health care system with lower costs, and the hospital with a steady influx of complex patients.

169 Pressure Ulcer Prevention: An Aggressive Quality Improvement Initiative Centered on a Hospital-Wide Bed Replacement Program-

Advocate Christ hospital is a 650-bed, level-one tertiary-care center that created a comprehensive wound care program in November 1998. Over the first 3 years of the program there were over 140 admissions per year directly from the wound center along with numerous hospital to hospital transfers for complex wound management. Prevalence rates therefore increased linearly over this time frame. The wound team calculated a system-wide (eight hospitals) spend of $2.1 million per year for specialty rental beds. Incidence rates for the system were at, but not lower than, national levels despite the high cost incurred. A $1.3 million capital purchase for KCI atmos-air 9000† mattresses resulted in the complete replacement of all medical surgical beds in all eight hospitals. An internal prevalence and incidence team was created and data were collected both at the hospital and system-wide level on a quarterly basis. Hospital and system incidence rates fell to or below 7%(targeted goal) and the entire project will achieve a return on investment in 18 months. Data to be presented include prevalence and incidence results, rental bed costs pre- and postbed purchase, and a detailed review of the process of creating an electronic prevalence and incidence tracking system. Acknowledgments: This study was not supported by any outside grants.

The safety of negative pressure wound therapy using vacuum‐assisted closure in diabetic foot ulcers treated in the outpatient setting

The purpose of this project was to evaluate the safety of negative pressure wound therapy using the vacuum-assisted closure (V.A.C.) Therapy System (KCI, San Antonio, TX) in diabetic foot ulcers (DFUs) among wound centre outpatients. We defined events that could represent complications or adverse events (AEs) as a result of treatment with the V.A.C., including symptoms of infection, pain, bleeding and periwound skin breakdown. The frequency of these AEs among V.A.C. patients with DFUs was compared with those among similar non V.A.C. patients. This project prospectively queried data collected during routine clinical care from 16 outpatient wound centres using the Intellicure electronic medical record system. The electronic records were de-identified according to HIPAA requirements and pooled to create a data repository dedicated to research (the Intellicure Research Consortium). Analysis was performed on 1331 DFUs representing 16,438 outpatient visits. A total of 1299 non V.A.C. and 72 V.A.C. DFUs were available for analysis. There was either no statistical difference between the AEs of V.A.C. versus non V.A.C. patients or the V.A.C. exerted a protective effect. We conclude that the V.A.C. is safe in outpatient use.

Traumatic resin ducts in Larix decidua stems impacted by debris flows

Following mechanical injury, stems of many conifers produce tangential rows of traumatic resin ducts (TRDs), the distribution of which has been used to date geomorphic events. However, little is known about how far TRD formation extends tangentially and axially from the point of injury or what the time course of TRD appearance is. We analyzed 28 injuries in eight Larix decidua Mill. tree stems resulting from debris flows in October 2000 and November 2004. Injuries occurred outside the period of cambial activity, and TRD formation occurred in the first layers of the growth ring formed in the year following that of injury. The axial extent of TRD formation averaged 74 cm and was greater above the injury than below it. At the height of the wound center, TRDs extended horizontally to a mean of 18% of the stem circumference excluding that portion where the cambium had been destroyed. In subsequent growth rings, TRDs, if present, were confined mainly to the height of the center of injury. Both the vertical and horizontal extent of TRD formation was related to the injury size. Within growth rings, the position of TRD formation changed with increasing distance from the wound progressing from early earlywood to later portions of the growth ring.

Digital Imaging of Wounds: Are Measurements Reproducible Among Observers?

Advances in digital imaging and archiving have made the measurement and documentation of wound areas possible over time. To assess the reproducibility and precision of digital image measurements, we used WoundMatrix Web (http://www.woundmatrix.com/) and recruited a group of caregivers from the Johns Hopkins Wound Center to measure the size of wounds on digital images by measuring length and width and tracing the circumference of the same wounds. One set of images was provided by WoundMatrix (WoundMatrix Inc, Chadds Ford, PA) and a second set used our own photographs taken at the Johns Hopkins Wound Center. Our results demonstrate that digital analysis with WoundMatrix Web is reproducible and precise with acceptable variation among readers. This supports the use of digital images of wounds to follow clinical progress as well as analyze the effects of new clinical interventions in clinical trials.

Education and Credentialing for Non-Baccalaureate Nurses

Dorothy Doughty, MN, RN, CWOCN, FAAN, Director, Emory University Wound, Ostomy, and Continence Nursing Education Center, Emory Clinic, Atlanta, Georgia ([email protected]).

The Specialized Wound Care Center

Multidisciplinary wound care centers have proliferated as a result of an increasing need for care of nonhealing wounds. Information regarding types of wounds treated, length of treatment, compliance with treatment, and rates of healing was collected from a tertiary care hospital-based wound center over a 7-year period. Venous stasis ulcers were the most common type of wound treated (21%) and were also the most likely to heal. Pressure ulcers (20%), diabetic neuropathic ulcers (14%), ischemic ulcers (6%), and postsurgical wounds (6%) comprised the remainder of wounds treated. The success of treating wounds varied greatly with the wound's etiology. Despite the chronic nature of these wounds, most patients did not become long-term patients of the wound center. This study provides baseline outcome measures, which can serve as the basis for the comparison of treatment protocols and the development of prospective clinical trials.

Outcomes of Conventional Wound Treatment in a Comprehensive Wound Center

Outcomes of Conventional Wound Treatment in a Comprehensive Wound Center

Treatment of toxic epidermal necrolysis in a pediatric patient with a nanocrystalline silver dressing

Background/Purpose To report a case of toxic epidermal necrolysis (TEN) involving 90% body surface area, successfully treated with a nanocrystalline silver dressing (Acticoat, Smith & Nephew, Largo, FL). Methods A review of the hospital and acute wound center patient records and the recent English medical literature regarding TEN and nanocrystalline silver dressing. Results We found only 1 report of TEN treated with a nanocrystalline silver dressing. The nanocrystalline silver dressing was both effective in preventing wound infection and convenient for treating our patient with TEN. Conclusion The use of nanocrystalline silver dressing should be considered for the treatment of TEN.

Natural history of limbs with arterial insufficiency and chronic ulceration treated without revascularization

The natural history of limbs affected by ischemic ulceration is poorly understood. In this report, we describe the outcome of limbs with stable chronic leg ulcers and arterial insufficiency that were treated with wound-healing techniques in patients who were not candidates for revascularization. A prospectively maintained database of limb ulcers treated at a comprehensive wound center was used to identify patients with arterial insufficiency, defined as an ankle-brachial index (ABI) <0.7 or a toe pressure <50 mm Hg. Patients were treated without revascularization when medical comorbidity or anatomic considerations did not allow revascularization with acceptable risk. Ulcers were treated with a protocol emphasizing pressure relief, débridement, infection control, and moist wound healing. Risk factors analyzed for their affect on healing and amputation risk included age, gender, diabetes mellitus, chronic renal insufficiency (serum creatinine > 2.5 mg/dL), severity of ischemia measured by ABI or toe pressure, wound grade, wound size, and wound location. Between January 1999 and March 2005, 142 patients with 169 limbs having arterial insufficiency and full-thickness ulceration were treated without revascularization. Mean patient age was 70.8 +/- 4.5. Diabetes mellitus was present in 70.4% of limbs and chronic renal insufficiency in 27.8%. Toe amputations or other foot-sparing procedures were performed in 28% of limbs. Overall, limb loss occurred in 37 patients. By life-table analysis, 19% of limbs required amputation < or =6 months of initial treatment and 23% at 12 months. Complete wound closure was achieved in 25% by 6 months and in 52% by 12 months. Statistical analysis showed a correlation between ABI and the risk of limb loss. In patients with an ABI <0.5, 28% and 34% of limbs experienced limb loss at 6 and 12 months, respectively, compared with 10% and 15% of limbs in patients with an ABI >0.5 (P = .01). The only risk factor associated with wound closure was initial wound size (P < .005). Limb salvage can be achieved in most patients with arterial insufficiency and uncomplicated chronic nonhealing limb ulcers using a program of wound management without revascularization. Healing proceeds slowly, however, requiring more than a year in many cases. Patients with an ABI <0.5 are more likely to require amputation. Interventions designed to improve outcomes in critical limb ischemia should stratify outcomes based on hemodynamic data and should include a comparative control group given the natural history of ischemic ulcers treated in a dedicated wound program.

Outcomes of Conventional Wound Treatment in a Comprehensive Wound Center

Conventional wound care is the elementary treatment modality for treating chronic wounds. However, early treatment with topical growth factors may be needed for a subset of chronic wounds that fail to heal with good wound care alone. A prospective nonrandomized case series from a single-community outpatient wound care clinic is presented here in an effort to identify the subset of chronic wounds that may require early adjuvant intervention. There were 378 consecutive patients with 774 chronic wounds of varying etiology. All patients received 4 weeks of conventional wound care, including weekly debridement and twice-daily dressing changes. Wounds not reduced by 50 per cent volume at 4 weeks were nonrandomly treated with human skin equivalent (Apligraf), platelet-derived wound healing factor, or platelet-derived growth factor isoform BB (becaplermin gel, Regranex). A total of 601 of 774 (78%) wounds healed regardless of treatment type. The median time to heal for all wounds was 49 days (interquartile range = 26-93). More women than men healed (85% vs 71%, respectively, P < 0.0001). Diabetic wounds were as likely to heal as nondiabetic wounds (78% vs 80%, P = 0.5675). Wounds that did not heal had larger volumes and higher grade compared with wounds that healed (P < 0.0001 for both variables). The data presented here show that the majority of chronic wounds will heal with conventional wound care, regardless of etiology. Large wounds with higher grades are less responsive to conventional wound care and will benefit from topical growth factor treatment early in the treatment course.

Best‐practice algorithms for the use of a bilayered living cell therapy (Apligraf®) in the treatment of lower‐extremity ulcers

Tissue-engineered skin substitutes such as Apligraf have emerged over the past 20 years as among the most carefully studied and efficacious of the advanced wound modalities. These products have been proven as effective enhancements to general wound care, promoting wound closure particularly in instances where conventional wound care fails. Marketed for hard-to-heal wounds since 1998, Apligraf has become part of standard wound care in many wound centers across the United States. Despite this situation, few general wound care guidelines incorporate advanced and active wound-healing technologies, such as tissue-engineered skin products. Because of this deficiency, appropriate patient selection and proper use of these product remain largely unaddressed within the general wound care community. Here, we describe the development of guidelines surrounding optimal use of the bilayered living cell therapy, Apligraf, in the treatment of the two types of lower extremity ulcers for which the product is FDA approved: venous leg ulcer and diabetic foot ulcer. The guidelines detailed in this article focus on the identification and selection of patients who are at risk for failure of standard wound care therapy and thus appropriate for Apligraf treatment. The intended audience for these guidelines is the general wound care practitioner, for whom the developed treatment algorithms and accompanying figure legends should provide practical, user-friendly direction simplifying both patient selection and appropriate use of Apligraf within the context of good wound-healing practice.

Numerous Keratinocyte Subtypes Involved in Wound Re-Epithelialization

The expression of different keratin intermediate filaments has been used to define keratinocyte maturation and different phenotypic subtypes involved in acute wound (AW) healing. Immunohistochemistry with specific anti-keratin monoclonal and polyclonal antibodies was used to examine AW in normal healthy volunteers (n = 16). In all wounds examined, basal keratinocytes and cells at the leading edge of the wound expressed keratins K5 and K14. However, suprabasal cells had a more complex pattern of keratin expression, which was dependent on their position relative to the wound and location within the suprabasal compartment of the epidermis. In general, K10 was expressed in suprabasal keratinocytes at the wound edge, but not in keratinocytes covering the wound center, which expressed K6, K16, and K17 in a complex fashion. Ki67 expression, a marker of cell proliferation, was restricted to basal and immediate suprabasal layers at the wound edge. Keratinocytes populated the wound bed below the scab by migration, which was supported by keratinocyte proliferation in the surrounding epidermis both at and adjacent to the wound edge.

Wound healing in rat cornea: the role of electric currents

Human corneal epithelial cells respond rapidly following injury to restore the integrity of the ocular surface. What stimulates and guides cells to move into the wound to heal? One candidate is the wound-induced electric field. Using vibrating probe techniques, we provide detailed temporal and spatial mapping of endogenous electric currents at rat corneal wounds. We find Cl- and Na+ are the major components of electric currents in rat corneal wounds. Na+ is the major component of ionic transport in the resting (nonwounded) rat cornea and of the wound center leakage current, whereas Cl- is a more important component of the endogenous electrical current at the wound edges. Enhancing or decreasing Cl- flow with clinically approved pharmacological agents such as aminophylline, ascorbic acid, or furosemide increased or decreased endogenous wound electric currents, respectively. These changes in wound currents correlated directly with the rate of wound healing in vivo. Thus, pharmacologically enhancing or decreasing wound-induced electric currents increased and decreased wound healing rate, respectively. This may have wide-reaching and novel therapeutic potential in the management of wound healing and may help explain some mechanistic aspects of the effects of some clinically used agents.

Neovascularization during healing of wounds treated with dermal substitutes and fibrin glue in nude mice

Loor, Michele M. MD; Truong, Anh-Tuan MD; Kowal-Vern, Areta MD; Latenser, Barbara MD, FACS; Wiley, Dorion MD; Walter, Robert PhD Author Information

Organization of wound healing services: the Danish experience and the importance of surgery.

Thomas K. Hunt is a general surgeon. Through his basic wound healing research and clinical work with wound patients he has been a great inspiration for my work in wound healing. In order to fulfill Dr. Hunt's vision, the clinical wound healing arena must be organized in an optimal way, and this article focuses on different options. Multidisciplinary wound care teams or centers focusing on all types of problem wounds have proved to be most effective at providing treatment and care for patients with problem wounds. The ultimate model is an outpatient clinic and an inpatient ward joined within a departmental structure, which represents an integrated part of an accepted national expert program on wound healing. Different types of center models can be established with different advantages and disadvantages. Currently, the wound care arena is being organized in Denmark and the model is described in this article. Of all specialties involved in treatment of wounds, surgery is of vital importance. "Wound healing is the keystone on which surgery is founded" (Thomas K. Hunt). This has long been understood in relation to acute wounds, while the importance of surgery in the treatment of chronic wounds has been less widely recognized. Surgical procedures directly related to the wound consist of debridement of all types of problem wounds and, in more specialized procedures such as skin transplantation, different types of flap constructions, bone surgery, and tendo-Achilles lengthening. Arterial reconstruction is a type of surgery that indirectly, through improved tissue perfusion, improves healing of problem wounds. This study concludes that multidisciplinary specialized wound healing concepts integrated into the national health care system as accepted expert functions would be the ideal way to organize wound healing to best benefit patients and society. Emphasis is on the importance of surgical procedures in wound healing and care. The models described can be applied with minor adjustments to both industrialized and developing countries.

The mesothelial cell

Mesothelial cells form a monolayer of specialised pavement-like cells that line the body’s serous cavities and internal organs. The primary function of this layer, termed the mesothelium, is to provide a slippery, non-adhesive and protective surface. However, mesothelial cells play other pivotal roles involving transport of fluid and cells across the serosal cavities, antigen presentation, inflammation and tissue repair, coagulation and fibrinolysis and tumour cell adhesion. Injury to the mesothelium triggers events leading to the migration of mesothelial cells from the edge of the lesion towards the wound centre and desquamation of cells into the serosal fluid which attach and incorporate into the regenerating mesothelium. If healing is impaired, fibrous serosal adhesions form between organs and the body wall which impede vital intrathoracic and abdominal movement. Neoplastic transformation of mesothelial cells gives rise to malignant mesothelioma, an aggressive tumour predominantly of the pleura. Although closely associated with exposure to asbestos, recent studies have implicated other factors including simian virus 40 (SV40) in its pathogenesis. Cell facts 1. Mesothelial cells are derived from the mesoderm but express both mesenchymal and epithelial cell intermediate filaments. 2. Mesothelial cells form a monolayer (mesothelium) lining the serosal cavities (pleural, pericardial and peritoneal) and the organs contained within these cavities. 3. The mesothelium is a slowly renewing tissue with 0.16–0.5% of cells undergoing mitosis at any one time. 4. The primary function of the mesothelium is as a protective non-adhesive surface but it is also involved in transport of solutes and cells across serosal cavities, antigen presentation, inflammation and tissue repair, coagulation and fibrinolysis and tumour cell adhesion. 5. Mesothelial regeneration involves migration of cells from the wound edge and attachment and incorporation of free-floating mesothelial cells from the serosal fluid onto the wound surface. 6. Impaired healing and cell transformation lead to the formation of serosal adhesions and malignant mesothelioma, respectively.