Burns,biofilm and a new appraisal of burn wound sepsis

Purpose

Following a burn, the wound may become colonized and septic complications may ensue. Many organisms, commonly isolated from burn wounds produce biofilms, which are defined as a collection of organisms on a surface surrounded by a matrix. Biofilms are associated with development of antibiotic resistant organisms and are refractory to the immune system. The presence of biofilm in the burn wound has not been documented.

Methods

A study was undertaken using light and electron microscopy to determine the presence of biofilm in the burn wound. Specific stains were used to detect the presence of micro-organisms and associated carbohydrate, a major constituent of the biofilm matrix. A concurrent microbiological study of the burn wound was also carried out.

Results

Biofilm was detected in ulcerated areas of the burn wound. Bacterial wound invasion with mixed organisms was also commonly detected.

Conclusions

The finding of biofilm in the burn wound has significance in our understanding of burn wound sepsis and supports the evidence for early excision and closure of the burn wound. Due to the recalcitrant nature of biofilm associated sepsis and the difficulty in disrupting biofilm it has implications for the future development of wound care dressings.     

The antimicrobial efficacy of a silver alginate dressing against a broad spectrum of clinically relevant wound isolates

Wound dressings impregnated with silver have a role to play in aiding to reduce both the dressing and wound microbial bioburden. It is therefore imperative that antimicrobial wound dressings have efficacy on a broad range of clinical significant microorganisms. Accordingly, this study aimed to determine the antimicrobial efficacy of a silver alginate dressing against 115 wound isolates that had been isolated routinely from patients at West Virginia University Hospital. Standardised corrected zones of inhibition (CZOIs) were performed on all clinical isolates. It was found that the silver alginate dressing was able to inhibit the growth of all microorganisms tested. In particular, the silver alginate dressing inhibited the growth of Candida albicans and yeasts with CZOI of 3-11·5 mm. All meticillin-resistant Staphylococcus aureus (MRSA) strains were found to be sensitive to the silver alginate dressing with a CZOI range calculated at 3-7·8 mm. Sensitivity to the silver alginate dressing was also evident for S. aureus and vancomycin-resistant Enterococci. CZOIs of 4·25 mm were calculated for Enterococcus faecium and 9·8 mm for viridans streptococcus. The bacteria which demonstrated the highest tolerance to ionic silver included Enterobacter cloacae and Acinetobacter baumannii. Contrary to this the most responsive microorganisms to ionic silver included strains of staphylococci, viridans streptococcus and Candida albicans. No antibiotic-resistant isolates, as identified by Kirby Bauer Clinical Laboratory Standards Institute classification system, were found to be resistant to ionic silver. When a selected number of microorganisms were grown in the biofilm phenotypic state enhanced tolerance to silver was observed, compared to their non biofilm counterparts. Overall, this study has demonstrated the broad antimicrobial activity of a silver alginate dressing on wound isolates grown in the non biofilm and biofilm state. This finding is clinically relevant as both the non biofilm and biofilm phenotypic states of microorganisms are evident in wounds and therefore significant to delayed healing. Consequently, it is imperative that antimicrobial wound dressings demonstrate antimicrobial activity against microorganisms in both phenotypic states.     

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.     

A prospective randomised open label study to evaluate the potential of a new silver alginate/carboxymethylcellulose antimicrobial wound dressing to promote wound healing

The aim of this study was to observe both the clinical signs and symptoms of wounds at risk of infection, that is critically colonised (biofilm infected) and antimicrobial‐performance of an ionic silver alginate/carboxymethylcellulose (SACMC) dressing, in comparison with a non silver calcium alginate fibre (AF) dressing, on chronic venous leg and pressure ulcers. Thirty‐six patients with venous or pressure ulcers, considered clinically to be critically colonised (biofilm infected), were randomly chosen to receive either an SACMC dressing or a non silver calcium AF dressing. The efficacy of each wound dressing was evaluated over a 4‐week period. The primary study endpoints were prevention of infection and progression to wound healing. The SACMC group showed a statistically significant (P = 0·017) improvement to healing as indicated by a reduction in the surface area of the wound, over the 4‐week study period, compared with AF controls. In conclusion, the SACMC dressing showed a greater ability to prevent wounds progressing to infection when compared with the AF control dressing. In addition, the results of this study also showed an improvement in wound healing for SACMC when compared with a non silver dressing.     

The effect of a new wound dressing on wound healing: Biochemical and histopathological evaluation

Electrospinning process has gained importance in the production of wound dressings in recent years. The wound dressings prepared by electrospinning method provide many advantages over conventional wound dressings. The aim of this study was to assess the histological, biochemical, and immunohistochemical evaluation of collagen/doxycycline loaded nanofiber wound dressing in both acute and chronic wound healing. Full-thickness wound model was created on rats and rats were divided in two main groups: normoglycemic (acute) and hyperglycemic (chronic) groups. Each group was divided into three sub groups: not treated (control) group, treated with nanofiber wound dressing group and treated with commercial product group. Wound closure rates were measured. Oxidative events were investigated by biochemical analyses. In addition to histological studies, matrix metalloproteinase, tissue inhibitor of metalloproteinase, vascular endothelial growth factor, basic-fibroblast growth factor, and von Willebrand factor levels were investigated with immunohistochemical studies. According to the biochemical analyses, it was concluded that the nanofiber wound dressing helps to increase antioxidant capacity and decrease lipid peroxidation. Immunohistochemical studies showed that nanofiber wound dressing enhanced angiogenesis and shortened the inflammatory phase. It was concluded that an effective and safe prototype nanofiber wound dressing, which has similar wound healing effect to the commercial product, has been developed to be used in acute or chronic wound treatment.     

A prospective,randomized, multicenter clinical trial to evaluate the safety and effectiveness of a new lesion localization device

BACKGROUND: The objective was to compare the safety and effectiveness of a new localization device to traditional flexible wires. Safety variables included blood loss, procedure time, pain and complications. Effectiveness variables included placement accuracy, lesion retrieval, histological diagnosis, procedural enhancements, and margin status. METHODS: Twelve sites enrolled 120 patients between June 2000 and June 2001, with 58 randomized to treatment and 62 to control. RESULTS: The two groups were equivalent in device placement accuracy, lesion retrieval, histological diagnosis, blood loss, pain, and complications. There was a significant difference favoring the treatment group for procedural enhancements, (ie, use as a palpable guide and retractor) and operating time. There were significantly fewer positive margins in the treatment group. CONCLUSIONS: This multicenter trial demonstrated equivalent safety and improved effectiveness for the treatment group. The new device demonstrated greater surgeon utility, reduced operative time, and fewer positive margins than the current wires.