Wound infection. A failure of wound healing caused by an imbalance of bacteria

Infection in a wound, like infection elsewhere in the body, is a manifestation of a disturbed host-bacteria equilibrium in favor of the bacteria. This not only elicits a systemic septic response but actually inhibits the multiple processes involved in the wound healing scheme. Each process involved in healing is affected when bacteria proliferate in a wound. Wound infection, whether in an intentional operative incision, an acute traumatic laceration, or a chronic pressure ulcer, results when bacteria indigenous to the patient or exogenous to the wound achieve dominance over the systemic and local factors of host resistance. To be able to prevent and manage wound infections requires an understanding of how each prophylactic or therapeutic maneuver works to maintain or re-establish the bacteria-host balance. Only when this equilibrium is in balance can the normal processes of wound healing proceed to give a satisfactory healing trajectory.     

Using wound care products to promote a healing environment

Healing is characterized by the synthesis of new tissue and scar formation. Despite the complexity of healing with full-thickness injury, the repair process occurs in a predictable manner. There are four basic principles of wound care: (1) debride necrotic tissue and cleanse the wound to remove debris, (2) provide a moist wound healing environment through the use of proper dressings, (3) protect the wound from further injury, and (4) provide nutritional substrates essential to the healing process. Most importantly, any underlying pathophysiology must be treated or the wound will not heal. Products selected to create a healing environment must be chosen thoughtfully and scientific rationale must support their use. Intensive care nurses have the opportunity to get the patient off to the right start by attending to the basic principles elucidated in this article. Accurate wound assessment and appropriate product choices can promote a healing environment. Intensive care of patients includes differentiating wound types and making appropriate wound care product decisions that ultimately affect patient outcomes.     

The reversed-flow medio-distal fasciocutaneous island thigh flap: anatomic basis and clinical applications

To investigate changes in retinal pigment epithelial (RPE) cells during wound healing, we evaluated the deposition of newly synthesized extracellular matrix (ECM) over time during wound healing in rat RPE cultures. We also estimated the effect of growth factors on the healing rate and ECM synthesis. After preparing rat RPE cell sheet cultures, we made round 1-mm defects in the cultures. Fibronectin, laminin, and collagen IV synthesis were evaluated with immunocytochemistry every 12 hours after wounding. S-phase cell distribution was analyzed every 12 hours by 5-bromodeoxyuridine uptake. We added either platelet-derived growth factor (PDGF), epidermal growth factor (EGF), or transforming growth factor- beta2 (TGF-beta2) to cultures at concentrations of 1, 10, and 100 ng/mL and immunocytochemically analyzed the effects on ECM and estimated the rate of wound closure. Although approximately 50% closure was achieved 24 hours after wounding, fibronectin deposits first appeared at that time. Laminin and collagen IV were first detected at 36 hours and fibronectin staining had extended toward the wound center. S-phase cells were distributed in concentric rings that moved centripetally over time and corresponded to the leading edge of the area stained with anti-ECM antibodies. TGF-beta2 enhanced ECM deposition, but EGF and PDGF did not. TGF-beta2 decreased the healing rate in a dose-dependent manner, whereas PDGF promoted wound closure. EGF enhanced closure at the highest concentration only. In summary, wound healing in RPE may be initiated when cells at the wound edge slide or migrate toward the wound center, which is followed by cell proliferation and then ECM synthesis. ECM components may be produced in a specific sequence during healing. TGF-beta2 may promote RPE cell differentiation, and PDGF may enhance proliferation during wound healing of the RPE.     

Interobserver variation in wound assessments

Agreement in describing a chronic leg ulcer is pivotal in identifying and treating impediments to the healing process. Six nurses and one doctor without special experience with wound healing registered wound related diagnoses for a five month period. On average each patient was seen by three observers yielding 270 registrations. Agreement beyond chance (global kappa) showed poor to moderate agreement. Agreement was best for the yellow or malodorous wound and lowest for cellulitis, hypergranulation and peripheral pulses. This emphasizes the importance of allocating wound treatment to specialist departments with access to paraclinical investigations.     

Platelet-derived growth factor induces fetal wound fibrosis

The fetal response to cutaneous injury differs markedly from that of the adult, proceeding with only minimal inflammation, minimal fibroblast proliferation, and only essential collagen deposition. Although the sequence of events in adult wound healing is well defined and thought to be controlled in part by potent polypeptide cytokines, relatively sparse information exists regarding growth factor involvement in fetal wound repair. Thus, the authors sought to examine the effect of platelet-derived growth factor (PDGF), a putative adult wound healing regulator, on the cellular and extracellular matrix events at a fetal wound site. SILASTIC wound implants containing 0, 1.0, 5.0, or 10.0 ng of human PDGF were placed subcutaneously on the backs of 24-day-gestation fetal rabbits (full term, 31 days) and then harvested after either 1, 3, or 5 days in utero. The specimens underwent standard histological processing and were evaluated in a blinded fashion. Compared with controls, PDGF-treated implants had a marked increase in acute inflammation, fibroblast recruitment, and collagen and hyaluronic acid deposition; these differences appeared to be largely time- and PDGF dose-dependent. Thus, the fetal system is responsive to an adult wound healing mediator, and these data suggest that fetal repair proceeds in the absence of PDGF.     

Suicidality and aggressive behaviour

Delayed wound healing is one of the complications of diabetes mellitus, exhibited by increased wound collagenase and decreased granulation tissues. The current study compared wound healing in normal and diabetic rats, and the effects of topically applied 1% or 3% concentrations of chemically modified tetracycline-2 (CMT-2) on 6-mm circular full-thickness skin wounds healed by secondary intention. On day 7 after wounding, tissues were removed for biochemical analysis and histology. The wound granulation tissue hydroxyproline was less in the untreated diabetic rat with increased collagenase and gelatinase. Treating the diabetic rat wounds with 3% CMT-2 increased the wound hydroxyproline and decreased activities of gelatinase and collagenase. There was a delay in wound filling by granulation tissue in diabetic rats. In CMT-2-treated diabetic rats, the volume of granulation tissue was greater than that in untreated diabetic rats. CMT-2 appears to normalize wound healing in diabetic rats and may be a valuable adjunct in the treatment of chronic wounds.     

The role of selected cell growth factors in the wound healing process

Growth factors, naturally occurring proteins secreted by different cells or tissues, play very important role in accelerating the wound healing process. Growth factors are mainly released from macrophages, neutrophils, lymphocytes, platelets and fibroblasts and induce cells to migrate, divide or produce other factors required for wound healing. These factors bind to target cells via specific cell-surface receptors and may elicit inhibitory or stimulatory responses, depending on interactions with other factors and the cellular environment into which they are liberated. Systemic growth factors, such as growth hormone and local epidermal growth factor, fibroblast growth factor, platelet-derived growth factor, transforming growth factor i and insulin-like growth factor show to enhance wound healing. Growth factors stimulate fibroblasts proliferation and chemotaxis, collagen synthesis, reepithelialization and angiogenesis. Although growth factors are not widely available for clinical use, many are studied actively to determine their role in the acceleration of wound healing. Results of animal experiments and preliminary clinical trials demonstrate that specific uses growth factors may become the new mode of therapy in wound healing process.     

Retrospective evaluation of postoperative intralesional steroid injections on wound healing

Steroids have been implicated as an etiology in delayed wound healing. Although there is much documentation in the literature that steroids delay wound healing, most studies are in vitro or use high systemic doses. No studies have used a one-time, postoperative, intralesional steroid injection and evaluated wound healing. This study retrospectively reviewed 73 patients with 115 foot and ankle surgeries over 12 years. Seventy-two patients had steroid injections and 43 did not. The average healing time for the steroid group was 17.1 +/- 10.5 days, and for the non-steroid group 17.3 +/- 8.75 days. There were two infections in the non-steroid group, and one infection in the steroid group. There were five dehiscences in each group. The patients were further subdivided into groups based on age, gender, number of procedures, type of surgery, health status, steroid type, and steroid dose. The healing time increased in patients > 60 years old, and in immunocompromised patients. The patients who had more complex surgery had increased healing time. The males had a longer healing time than the females. Overall, there was not a statistically significant difference between the steroid groups and the non-steroid group. Therefore, one-time postoperative intralesional steroid injections were not found to delay wound healing.     

Basic fibroblast growth factor (b-FGF) in the perimatrix of cholesteatoma

The growth of a cholesteatoma requires angioneogenesis in the connective tissue of the perimatrix. Angioneogenesis is also needed for wound healing as a host response to tissue injury. Normal wound repair is conducted through a wide number of growth factors. Basic fibroblast growth factor (b-FGF) plays a pivotal role in wound repair. This cytokine exerts its effects through stimulation of a wide range of target cells. B-FGF is chemotactic and mitogenic for fibroblasts, endothelial cells and keratinocytes. In addition, b-FGF can stimulate the production of collagenase and plasminogen activators to enhance fibroblast proliferation and angioneogenesis. Its necessity for normal wound repair has been confirmed by several workers. METHOD: In order to demonstrate angioneogenesis in the cholesteatoma perimatrix the distribution of b-FGF as the pivotal cytokine of the process was investigated in the perimatrix of 18 cholesteatoma specimens. RESULTS: B-FGF could be observed in 12 of 18 specimens (66%) in close approximation to histological signs of inflammation and wound healing. Areas with b-FGF also exhibited proliferation of the covering squamous epithelium. Cholesteatoma matrix tissue without inflammation or any sign of wound healing did not express b-FGF (6 of 18). CONCLUSION: Histological changes and distribution pattern of b-FGF in the perimatrix of cholesteatoma in the present study indicate that the perimatrix cells and substances of the wound healing cascade may play an important role in cholesteatoma development, angiogenesis and growth.     

Wound healing and repair: a review of the art and science

This chronological review of the major biological events that occur secondary to injury of mucoperiosteal tissue from either simple surgical wounding or trauma discusses the materials used to repair the compromised tissue surgically. Suturing techniques and post-surgical wound maintenance also are reviewed. The physiological stages of wound healing, factors affecting wound healing, and wound repair techniques are discussed.     

Simplified Finite-Element Model for Tissue Regeneration with Angiogenesis

A simplified finite-element model for tissue regeneration is proposed. The model takes into account the sequential steps of angiogenesis (neo-vascularization) and wound closure (the actual healing of a wound). An innovation in the present study is the combination of both partially overlapping processes, yielding novel insights into the process of wound healing, such as geometry related influences, and could be used to investigate the influence of local injection of hormones that stimulate partial processes occurring during wound healing. These insights can be used to improve wound healing treatments. The models consist of nonlinearly coupled diffusion-reaction equations, in which transport of oxygen, growth factors, and epidermal cells and mitosis are taken into account.     

Langerhans cells may trigger the psoriatic disease process via production of nitric oxide

Psoriasis is a skin disease that appears to result from a dysfunction in the normal mechanism(s) that regulates wound healing. The Langerhans cell is a specialized epidermal macrophage that may instigate wound healing via production of nitric oxide and epidermal growth factor. Here, Vera Morhenn suggests that, whereas precise coordination of the synthesis of these two substances regulates normal wound healing, a disturbance of this regulation could lead to psoriasis.     

Metalloproteinase inhibitors and wound healing: a novel enhancer of wound strength

BACKGROUND: Wound strength is a balance between collagen synthesis and degradation. The role of collagen breakdown in wound healing is still not well understood. We investigated the role of collagenases (metalloproteinases [MMPs]) in wound healing in using GM6001, a novel inhibitor of MMPs. METHODS: We used the dorsal skin incision model with implantation of polyvinyl alcohol sponges. Twenty male Sprague-Dawley rats were randomly assigned to receive either GM6001 (10 mg/kg body weight) or 2 mL saline subcutaneously. Ten days after operation the animals were killed and fresh wound breaking strength, scar and sponge hydroxyproline content, and collagen type I gene expression in sponges were assayed. In addition, the inflammatory response and the wound fluid cytokine (tumor necrosis factor-alpha [TNF-alpha] and transforming growth factor-beta 1 [TGF-beta 1]) profile were studied. RESULTS: GM6001 significantly increased wound strength (422 +/- 59 vs 302 +/- 33 g, P < .05), whereas scar collagen content did not differ. In the sponge granulomas the inflammatory infiltrate, the collagen content, and the collagen type I gene expression were all significantly decreased by GM6001. CONCLUSIONS: Inhibition of MMP activity during acute wound healing enhances wound strength even though new collagen synthesis and the inflammatory response are significantly decreased. This could be achieved by decreasing collagen turnover or increasing collagen maturation and crosslinking, or both.     

Analysis of the tissue movements of embryonic wound healing--DiI studies in the limb bud stage mouse embryo

The tissue movements of epithelial spreading and mesenchymal contraction play key roles in many aspects of embryonic morphogenesis. One way of studying these movements in a controlled manner is to make an excisional skin wound to an embryo and watch the wound heal. In this paper we report our studies of healing of a simple excisional lesion made to the limb bud stage mouse embryo. The wounded, living embryo is cultured in a roller bottle; under such conditions the wound heals with a highly reproducible time course and is completely closed by 24 hr. During the healing period the environment bathing the wound can be simply manipulated by adding drugs or factors to the culture medium. We have used DiI to label mesenchymal cells exposed at the margin of the initial wound and, by following their fate and measuring the area of mesenchyme remaining exposed at various time points during the healing process, we have quantified both the extent of mesenchymal contraction and the extent of reepithelialisation by movement of epidermis over mesenchyme. We show that the two types of tissue movement contribute almost equally (50:50) to the total wound closure rate. We have gone on to investigate the cell machinery underlying these processes. In adult wounds the epidermis migrates by means of lamellipodial crawling, but we show that reepithelialisation in the embryo is achieved instead by purse-string contraction of a cable of filamentous actin which assembles in the basal layer of cells at the free edge of the epidermis. Addition of cytochalasin D to the culture medium blocks formation of this actin cable and leads to failure of reepithelialisation. Contraction of adult wound connective tissue appears to be driven by conversion of dermal fibroblasts into a specialist smooth muscle-like fibroblast, the myofibroblast. However, using an antibody recognising the alpha-isoform of smooth muscle actin and specific for smooth muscle cells and myofibroblasts, we show that a similar conversion into myofibroblasts does not occur at any stage during the embryonic wound healing process. These observations indicate that both of the tissue movements of embryonic wound healing utilise cell machinery fundamentally different from that driving the analogous tissue movements of adult healing.     

Wound-measuring methods

Measurement of a wound is an integral part of the overall holistic wound assessment. Wound assessment is essential for effective wound management. Wound measurement can be described as either contact or non-contact. Many measurements are subjective but remain a useful and practical indication of wound healing. For many community and hospital nurses the best method is tracing, to measure area in conjunction with a depth gauge.     

Corneal wound healing after laser in situ keratomileusis in rabbits

BACKGROUND: The aim of this study was to characterize the cell biology of wound healing in rabbit corneas subjected to laser in situ keratomileusis (LASIK). METHODS: Rabbit corneas underwent LASIK with various multizone photoablations or only a lamellar keratotomy followed by repositioning of the flap. We looked for indications for an active wound healing process. Immunohistochemistry for the extradomain A cellular fibronectin (EDA-cFn) or tenascin (Tn) and routine histology were examined. RESULTS: Four days after LASIK or lamellar keratotomy followed by repositioning of the flap, epithelial plugs and prominent keratocytes as well as Tn and EDA-cFn immunoreactions-indicative of a wound-healing process-appeared in the wound margins. Epithelial plugs were less conspicous, and prominent, presumably activated, keratocytes were no longer identified at the wound margin at 2.5 and 5 months after wounding. However, EDA-cFn and Tn immunoreactivities could still be observed. Only the stromal cells located in the periphery of the flap and in relatively close contact with the epithelium were surrounded by scar tissue expressing immunoreactivity for EDA-cFn or Tn. The central corneal stroma was devoid of scar tissue. CONCLUSION: Results indicate that the wound healing reaction after LASIK takes place only at the periphery of the microkeratome wound, leaving the central optical zone clear.     

Evaluation of increased aqueous outflow after radial keratotomy in enucleated bovine eyes

In spite of the availability of high-tech devices for wound assessment, plastic surgeons recognize that the color and confluence of granulation tissue are the most important indicators of open-wound healing. We developed a simple and inexpensive pocket-size scale--the Granulometer--to facilitate a finer assessment and to standardize the documentation of wound healing. This device overcomes limitations set by conditions such as lighting or recent exposure to other wounds that could distort the examiner's perception of the wound in question. In this study we examined the inter- and intraobserver variations in judgment, and the validity of the Granulometer. Our results demonstrate that skin graft viability can be predicted accurately by this eight-grade scale. Since graft survival depends on proper wound healing, we believe that the Granulometer can also be used for fine assessment of wound treatment. The low inter- and intraobserver variations indicate that the Granulometer measurements are both reproducible and accurate.     

Cerium ions crosslinked sodium alginate-carboxymethyl chitosan spheres with antibacterial activity for wound healing

For wound healing,wound infection caused by bacteria is one of the important reasons that delay wound healing process.Therefore,it is very meaningful to develop a multifunctional wound dressing with antibacterial capability to accelerate wound healing.Sodium alginate(SA) and carboxymethyl chitosan(CMCS) are the most commonly used compositions in wound dressing,but their poor stability inhibits the further applications.Introducing CMCS and using cerium ions(Ce³⁺) to crosslink CMCS and ...     

Will all pressure ulcers heal?

Clinicians today are faced with the need to justify their care through outcomes data. However, this is difficult with chronic, nonhealing wounds or pressure ulcers, which do not follow the expected trajectory of wound healing. Therefore, outcomes are unpredictable. This paper discusses the phases of wound healing and progress toward identifying outcomes for chronic wounds, as well as future directions in research.     

A study of perineal wound healing after abdominoperineal resection

A comparative study of 53 cases has revealed that a technique of complete primary closure of the perineal wound after abdominoperineal resection of the rectum and anal canal appears to be a superior, more rational approach than other orthodox techniques. (It is unsuitable for any case contaminated with pus or faeces during operation.) Redivac apparatus used through a separate route for continuous drainage from the sacral cavity has made the postoperative care easier for nurses and surgeons and this period more comfortable for the patient. It provides a simple method compared with other suction apparatus used for the same purpose. Of the 53 cases, 12 were operated on using a traditional technique involving the closure of the perineal wound around a tube drain connected to an underwater seal, while in the remaining 41 the approach described here was used. Primary healing of the perineal wound with the later approach was obtained in about 88 per cent. With the other technique the figures were 34 and 66 per cent respectively for early healing within 3 weeks and delayed healing between 3-8 weeks. Primary healing of the perineal wound reduces the total stay in hospital and the morbidity.