News in wound healing and management

Investigation of the Mechanism and Chemistry Underlying Staphylococcus aureus' Ability to Inhibit Pseudomonas aeruginosa Growth In Vitro

Pseudomonas aeruginosa inhibits or eradicates Staphylococcus aureus in most in vitro settings. Nonetheless, P. aeruginosa and S. aureus are commonly isolated from chronically infected, nonhealing wounds and lungs of people with cystic fibrosis (CF). Therefore, we hypothesized that S. aureus could protect itself from P. aeruginosa through glucose-derived metabolites, such as small organic acids, preventing it from being eradicated. This in vitro study demonstrated that S. aureus populations, in the presence of glucose, secrete one or more substances that efficiently eradicate P. aeruginosa in a concentration-dependent manner. These substances had a molecular mass lower than three kDa, were hydrophilic, heat- and proteinase-resistant, and demonstrated a pH-dependent effect. Nuclear magnetic resonance analysis identified acetoin, acetic acid, and oligopeptides or cyclic peptides in glucose-grown S. aureus supernatants. All the tested wild-type and clinical S. aureus strain inhibited P. aeruginosa growth. Thus, we proposed a model in which a cocktail of these compounds, produced by established S. aureus populations in glucose presence, facilitated these two species' coexistence in chronic infections. IMPORTANCE Chronic infections affect a growing part of the population and are associated with high societal and personal costs. Multiple bacterial species are often present in these infections, and multispecies infections are considered more severe than single-species infections. Staphylococcus aureus and Pseudomonas aeruginosa often coexist in chronic infections. However, the interactions between these two species and their coexistence in chronic infections are not fully understood. By exploring in vitro interactions, we found a novel S. aureus-mediated inhibition of P. aeruginosa, and we suggested a model of the coexistence of the two species in chronic infections. With this study, we enhanced our understanding of the pathogenesis of chronic multispecies infections, which is crucial to paving the way for developing improved treatment strategies.

Early identification of wound infection: understanding wound odour

Malodorous wounds can be distressing for patients and their families, negatively impacting on quality-of-life outcomes. For health professionals malodorous wounds can also cause distress manifesting in feelings of disgust when faced with a wound emitting an unpleasant or repulsive odour. There has been investigation into the management of controlling odour particularly in relation to fungating wounds. However, there is limited research that explores techniques for early identification and recognition of wound odours that may be indicative of infection. Electronic nose technology has received some attention, but to date has not been integrated into either diagnostics of infection in wounds or education of health professionals to prepare them for the realities of clinical practice.

Upregulation of BAG3 with apoptotic and autophagic activities in maggot extract‑promoted rat skin wound healing

Maggot extract (ME) accelerates rat skin wound healing, however its effect on cell maintenance in wound tissues remains unclear. B‑cell lymphoma (Bcl) 2‑associated athanogene (BAG)3 inhibits apoptosis and promotes autophagy by associating with Bcl‑2 or Beclin 1. Bcl‑2, the downstream effector of signal transducer and activator of transcription 3 signaling, is enhanced in ME‑treated wound tissues, which may reinforce the Bcl‑2 anti‑apoptotic activity and/or cooperate with Beclin 1 to regulate autophagy during wound healing. The present study investigated expression levels of BAG3, Bcl‑2, Beclin 1 and light chain (LC)3 levels in rat skin wound tissues in the presence and absence of ME treatment. The results revealed frequent TUNEL‑negative cell death in the wound tissues in the early three days following injury, irrespective to ME treatment. TUNEL‑positive cells appeared in the wound tissues following 4 days of injury and 150 µg/ml ME efficiently reduced apoptotic rate and enhanced BAG3 and Bcl‑2 expression. Elevated Beclin 1 and LC3 levels and an increased LC3 II ratio were revealed in the ME‑treated tissues during the wound healing. The results of the present study demonstrate the anti‑apoptotic effects of BAG3 and Bcl‑2 in ME‑promoted wound healing. Beclin 1/LC3 mediated autophagy may be favorable in maintaining cell survival in the damaged tissues and ME‑upregulated BAG3 may enhance its activity.

Exploring nurses' and patients' feelings of disgust associated with malodorous wounds: a rapid review

OBJECTIVE

To identify primary empirical research related specifically to feelings of disgust associated with malodorous chronic cutaneous wounds.

METHOD

A rapid review of the literature using the key words disgust; wounds; malodour and psychosocial.

RESULTS

A total of 163 papers were retrieved with seven being included for the final review. Themes emanating from the review were malodour, health-care professionals coping with malodour and disgust. Malodour is a concern to patients, which can sometimes go unreported by nursing staff; although the reasons for this remain unclear. The coping mechanisms developed by nurses in response to 'disgusting' wounds requires further exploration in order for a fuller understanding of these mechanisms to be achieved. This review has identified that both health-care professionals and patients can become distressed at wound odours, yet there is little evidence that is available to guide people as to how to manage these feelings.

CONCLUSION

Hard-to-heal or chronic cutaneous wounds, such as leg ulcers and diabetic foot ulcers, are an increasing global health-care issue. While some research has been undertaken to explore the psychological impact of living with a fungating carcinoma; much less has been written about the management and mitigation of feelings of disgust for patients and families living with a malodorous wound or how health-care professionals can effectively provide psychosocial care.

Cutaneous wound healing after treatment with plant-derived human recombinant collagen flowable gel

Chronic wounds, particularly diabetic ulcers, represent a main public health concern with significant costs. Ulcers often harbor an additional obstacle in the form of tunneled or undermined wounds, requiring treatments that can reach the entire wound tunnel, because bioengineered grafts are typically available only in a sheet form. While collagen is considered a suitable biodegradable scaffold material, it is usually extracted from animal and human cadaveric sources, and accompanied by potential allergic and infectious risks. The purpose of this study was to test the performance of a flowable gel made of human recombinant type I collagen (rhCollagen) produced in transgenic tobacco plants, indicated for the treatment of acute, chronic, and tunneled wounds. The performance of the rhCollagen flowable gel was tested in an acute full-thickness cutaneous wound-healing rat model and compared to saline treatment and two commercial flowable gel control products made of bovine collagen and cadaver human skin collagen. When compared to the three control groups, the rhCollagen-based gel accelerated wound closure and triggered a significant jumpstart to the healing process, accompanied by enhanced re-epithelialization. In a cutaneous full-thickness wound pig model, the rhCollagen-based flowable gel induced accelerated wound healing compared to a commercial product made of bovine tendon collagen. By day 21 post-treatment, 95% wound closure was observed with the rhCollagen product compared to 68% closure in wounds treated with the reference product. Moreover, rhCollagen treatment induced an early angiogenic response and induced a significantly lower inflammatory response than in the control group. In summary, rhCollagen flowable gel proved to be efficacious in animal wound models and is expected to be capable of reducing the healing time of human wounds.

Biofilms in chronic infections - a matter of opportunity - monospecies biofilms in multispecies infections

It has become evident that aggregation or biofilm formation is an important survival mechanism for bacteria in almost any environment. In this review, we summarize recent visualizations of bacterial aggregates in several chronic infections (chronic otitis media, cystic fibrosis, infection due to permanent tissue fillers and chronic wounds) both as to distribution (such as where in the wound bed) and organization (monospecies or multispecies microcolonies). We correlate these biofilm observations to observations of commensal biofilms (dental and intestine) and biofilms in natural ecosystems (soil). The observations of the chronic biofilm infections point toward a trend of low bacterial diversity and sovereign monospecies biofilm aggregates even though the infection in which they reside are multispecies. In contrast to this, commensal and natural biofilm aggregates contain multiple species that are believed to coexist, interact and form biofilms with high bacterial and niche diversity. We discuss these differences from both the diagnostic and the scientific point of view.

In vitro analysis of radiation-induced dermal wounds

Objective: To investigate the pathophysiology of radiation-induced wounds of the head and neck at a molecular level.

Study Design: Basic science, prospective study.

Setting: The study was conducted at the Department of Otolaryngology–Head and Neck Surgery, Ruprecht Karls-University Heidelberg, Faculty of Medicine Mannheim, Mannheim, Germany.

Subjects and Methods: Keratinocytes from chronic nonhealing ulcers in irradiated areas as well as from healthy skin areas in the same patients (n = 3) were harvested during surgical procedures and isolated in cell culture. First, a proliferation assay was performed. Gene expression was analyzed by microarray, protein expression by immunohistochemistry.

Results: Keratinocytes from radiogenic wounds showed a shift from the high molecular keratins 1 and 10 to the low molecular keratins 5 and 14 compared to normal control skin. Keratinocytes from nonhealing wounds showed a decreased expression of transforming growth factor alpha and beta 1, fibroblast growth factor 1 and 2, keratinocyte growth factor, vascular endothelial growth factor, and hepatocyte growth factor. The matrix metalloproteinases 2, 12, and 13 showed increased expression in irradiated keratinocytes and fibroblasts.

Conclusion: Our data showed a change of keratinocytes to a less differentiated state due to radiation. Additionally, it seems that radiation-induced dermal injuries often fail to heal because of decreased proliferation, impaired angiogenesis, and persistently high concentrations of matrix metalloproteinases.