Comparison of bacteria-retaining ability of absorbent wound dressings

Fabrication and characterization of physically crosslinked alginate/chitosan-based hydrogel loaded with neomycin for the treatment of skin infections caused by Staphylococcus aureus

Staphylococcus aureus is a pathogen widely involved in wound infection due to its ability to release several virulence factors that impair the skin healing process, as well as its mechanism of drug resistance. Herein, sodium alginate and chitosan were combined to produce a hydrogel for topical delivery of neomycin to combat S. aureus associated with skin complications. The hydrogel was formulated by combining sodium alginate (50 mg/mL) and chitosan (50 mg/mL) solutions in a ratio of 9:1 (HBase). Neomycin was added to HBase to achieve a concentration of 0.4 mg/mL (HNeo). The incorporation of neomycin into the product was confirmed by scanning electron microscopy, FTIR and TGA analysis. The hydrogels produced are homogeneous, have a high swelling capacity, and show biocompatibility using erythrocytes and fibroblasts as models. The formulations showed physicochemical and pharmacological stability for 60 days at 4 ± 2 °C. HNeo totally inhibited the growth of S. aureus after 4 h. The antimicrobial effects were confirmed using ex vivo (porcine skin) and in vivo (murine) wound infection models. Furthermore, the HNeo-treated mice showed lower severity scores than those treated with HBase. Taken together, the obtained results present a new low-cost bioproduct with promising applications in treating infected wounds.

Multi-disciplinary management of type 1 and 2 skin tears using a silver-based hydrofiber dressing

Skin tear is a common problem encountered in the emergency department. If it is not properly managed, it can lead to wound infection, skin necrosis and a need for further surgical intervention and skin grafting. Current management is to cleanse the wound, replace the thin skin tear followed by coverage with a dressing that is inducive for wound healing. Several dressings have been suggested for the coverage of these wounds. But, up to now, there has been no mention of the use of a silver-based hydrofiber dressing in the management of this condition. The objective of this study was to explore the use of a silver-based hydrofiber dressing for the management of paper-thin skin tears. We retrospectively reviewed all patients with Type 1 or 2 skin tears that had undergone management using a silver-based hydrofiber dressing between October 2019 and October 2020. Demographic data and medical history was obtained by retrospective chart review. Data that was collected included: age, sex, comorbid illnesses, defect location, defect size, complications, number of times the silver-based hydrofiber dressing was replaced and the number of days required to achieve complete wound healing. A total of 65 patients were included in the study. There were 42 males and 23 females. There were 28 patients whose age was greater then 85 years old, of which 14 patients were over 90 years old. The mean number of outpatient visits was 2. The mean defect size was 33 cm2 (range 1 cm × 1 cm to 18 × 10 cm). The mean number of days required for total wound healing was 13 days (range 7-21). We did not encounter any patients that required further surgical debridement or split-thickness skin grafting. The use of a silver-based hydrofiber dressing was well tolerated by the elderly population as it provided an easy, efficient, economical and effective form of management of skin tears. We suggest that a silver-based hydrofiber dressing can be used as a first-line treatment method for type 1 and 2 skin tears.

Community setting survey evaluating AQUACEL dressings

OBJECTIVE

This study aimed to collect and analyse real-life data to characterise the initial use of Hydrofiber Technology dressings for the management of exuding wounds in France.

METHOD

An online survey of nurses provided data from patients managed with two dressings-AQUACEL Extra or AQUACEL Ribbon-as the primary dressing. At baseline, sociodemographic data, relevant medical histories and wound characteristics were recorded. The status of the wounds was then examined on days seven and 14 of management, together with scores of both clinician and patient satisfaction.

RESULTS

The survey included 1093 patients with a mean age of 65.9 years, comprising 53.3% women; 615 (56.3%) patients presented with acute wounds and 478 with hard-to-heal wounds. Wounds were reported to have healed or improved in 79.4% and 88.1% of the patients after 7 and 14 days, respectively. After 14 days, the wounds were smaller (p<0.001), and the percentage of sloughy wound bed tissue had decreased (p<0.001), while the percentage of granulation tissue and epithelialisation increased significantly (p=0.024 and p=0.047, respectively). Tolerance of the dressing was good, with low levels of pain reported, both while wearing the dressing and on removal. On day 14, nurses reported a high level of satisfaction, while 70% and 42.7% of patients with acute and hard-to-heal wounds, respectively, were 'very satisfied'.

CONCLUSION

The Hydrofiber Technology dressings aided wound healing when used in the management of a wide range of acute and hard-to-heal wounds in medical and surgical indications. User satisfaction was high from both healthcare professionals and patients.

A tale of two alginates

BACKGROUND

All fibrous wound dressings are considered to have the same action and value to the support of wound healing. Although clear distinction has been accepted between cotton gauze and calcium alginates, there is still no formally recognised distinction between calcium alginates and the more rapidly gelling fibre dressings.

METHOD

Scientific and clinical evaluations were used to differentiate two different fibrous wound care products. One is derived from polymer extraction of algae (alginate dressings); the other has been manufactured from a uniquely patented carboxymethylation process that produces 100% carboxymethyl cellulose (CMC)-based dressings. Structural differences between these dressings were evaluated with respect to three important areas of wound care management: optimal wound moisture control; the ability to reduce risk of complication by locking away harmful components (e.g. bacteria); and reducing the overall cost of wound care by promoting more efficient use of nursing time.

RESULTS

Clear differentiation was illustrated through both scientific and clinical evaluations.

CONCLUSION

This study supports the potential advantages of using a technically advanced fibrous wound dressing over the traditional fibrous alginate wound care product.

Does the Application of a Semiocclusive Dressing Alter the Microflora of Healthy Intact Skin on the Foot?

BACKGROUND

The skin on human feet presents unique environments for the proliferation of potentially pathogenic commensals. This study examined microflora changes on healthy intact skin under a semiocclusive dressing on the medial longitudinal arch of the foot to determine changes in growth, distribution, and frequency of microflora under the dressing.

METHODS

Nine human participants wore a low-adherent, absorbent, semiocclusive dressing on the medial longitudinal arch of the left foot for 2 weeks. An identical location on the right foot was swabbed and used as a control. Each foot was swabbed at baseline, week 1, and week 2. The swabs were cultured for 48 hours. Visual identification, Gram staining, DNase test agar, and a latex slide agglutination test were used to identify genera and species.

RESULTS

Microflora growth was categorized as scant (0-10 colony-forming units [CFU]), light (11-50 CFU), moderate (51-100 CFU), or heavy (>100 CFU). Scant and light growth decreased and moderate and heavy growth increased under the dressing compared with the control. Seven different genera of bacteria were identified. Coagulase-negative Staphylococcus spp appeared most frequently, followed by Corynebacterium spp.

CONCLUSIONS

Changes in microflora distribution, frequency, and growth were found under the dressing, supporting historical studies. Microflora changes were identified as an increase in bioburden and reduction in diversity. The application of similar methods, using more sophisticated identification and analysis techniques and a variety of dressings, could lead to a better understanding of bacterial and fungal growth under dressings, informing better dressing selection to assist the healing process of wounds and prevent infection.

Dialkylcarbamoyl chloride-coated versus alginate dressings after pilonidal sinus excision: a randomized clinical trial (SORKYSA study)

Background

Disease of the pilonidal sinus is a common condition that affects mainly young adults. Options for management include excision of the sinus tracts, leaving the wound open to heal by secondary intention. The aim of this study was to compare wound healing with dialkylcarbamoyl chloride (DACC)‐coated dressings versus alginate dressings.

Methods

This multicentre trial randomized consecutive patients undergoing surgery for pilonidal disease to postoperative wound care with either DACC‐coated or alginate dressings. The primary outcome was the proportion of wounds healed after 75 days. Secondary outcomes were the local status of wounds during the healing process, the quality assessment of the dressings by the patient, and the time needed to return to usual activities.

Results

A total of 246 patients were included: 120 in the DACC‐coated group and 126 in the alginate group. In per‐protocol analysis, there were significantly more patients with completely healed wounds after 75 days in the DACC group than in the alginate group: 78 of 103 (75·7 per cent) versus 58 of 97 (60 per cent) respectively (odds ratio 2·55, 95 per cent c.i. 1·12 to 5·92; P = 0·023). During follow‐up, wounds with alginate dressings had more fibrin than those with DACC‐coated dressings, but the difference was not significant (P = 0·079). There was no difference between the two arms in patients' assessment of the dressings.

Conclusion

The number of wounds completely healed at 75 days was significantly higher for DACC‐coated compared with alginate dressings. However, the preplanned, clinically significant improvement in healing of 20 per cent was not reached. Registration number: NCT02011802 ( https://clinicaltrials.gov/).

An in vitro assessment of bacterial transfer by products used in debridement

OBJECTIVE

The aim of this in vitro study was to investigate the transfer of viable Pseudomonas aeruginosa biofilm microorganisms following treatment with debridement tools.

METHOD

The level of viable biofilm microorganisms transferred by debridement tools was compared following treatment that reflected the clinical practice of each product.

RESULTS

A significant level of microorganism transfer was seen in response to the mechanical debridement tool. Minimal transfer of microorganisms was seen when in vitro-established biofilms were treated with hydroresponsive wound dressing + polyhexamethylene biguanide (HRWD+PHMB, HydroClean plus). Less Pseudomonas aeruginosa was recovered from explants exposed to dressings compared with those exposed to debridement tools suggesting that there was less transfer of bacteria by dressings.

CONCLUSION

The reduced transfer of viable microorganisms by HRWD+PHMB may be the result of significant binding and retention of microbes by the superabsorbent polymer within the dressing, together with enhanced sequestered bacterial killing within the dressing by polymer-bound PHMB. The high levels of microbial transfer/transmission seen for debridement tools suggests that, in the clinical setting, a significant level of bacterial spread over the wound surface and/or surrounding skin by these cleansing tools is likely.

Gold nanoparticles for tracking bacteria clearance by regulated irrigation and negative pressure-assisted wound therapy

AIM

Regulated negative pressure-assisted wound therapy is a fundamental, nonpharmaceutical technology for acute and chronically infected wounds, yet bacterial clearance and biofilm buildup remain a challenge for healing. Regulated irrigation combined with negative pressure (RI-NPT) is emerging as an alternative therapeutic strategy for reducing bacterial load. Here, we analyzed RI-NPT hydrokinetics and efficacy of bacterial load reduction in wounds.

MATERIALS & METHODS

Escherichia coli were loaded with gold nanoparticles, quantified by flame atomic absorption spectroscopy. Computed tomography (CT) imaging tracked bacterial distribution over time in a low-flow rat wound model. Bacterial load was quantified using a novel CT ruler.

RESULT

Flame atomic absorption spectroscopy showed loading of 1.7 × 10³ ± 0.2 gold nanoparticles/cell. CT tracking revealed that while regulated negative pressure-assisted wound therapy reduced bacterial load to a limited extent (5%), RI-NPT significantly increased bacterial outflow and clearance (by 45%).

CONCLUSION

This nanotechnology-based approach demonstrates that RI-NPT is essential for reducing bacterial load and, thus, for promoting wound healing.

Enhanced Performance and Mode of Action of a Novel Antibiofilm Hydrofiber® Wound Dressing

Biofilm development in wounds is now acknowledged to be a precursor to infection and a cause of delayed healing. A next-generation antibiofilm carboxymethylcellulose silver-containing wound dressing (NGAD) has been developed to disrupt and kill biofilm microorganisms. This in vitro study aimed to compare its effectiveness against various existing wound dressings and examine its mode of action. A number of biofilm models of increasing complexity were used to culture biofilms of wound-relevant pathogens, before exposure to test dressings. Confocal microscopy, staining, and imaging of biofilm constituents, total viable counting, and elemental analysis were conducted to assess dressing antibiofilm performance. Live/dead staining and viable counting of biofilms demonstrated that the NGAD was more effective at killing biofilm bacteria than two other standard silver dressings. Staining of biofilm polysaccharides showed that the NGAD was also more effective at reducing this protective biofilm component than standard silver dressings, and image analyses confirmed the superior biofilm killing and removal performance of the NGAD. The biofilm-disruptive and silver-enhancing modes of action of the NGAD were supported by significant differences (p < 0.05) in biofilm elemental markers and silver donation. This in vitro study improves our understanding of how antibiofilm dressing technology can be effective against the challenge of biofilm.

Hydrofiber Dressing Saturated With Mafenide Acetate Extends the Duration of Antimicrobial Activity

Mafenide acetate is used in some burn wounds for its ability to penetrate eschar but requires frequent uncomfortable dressing changes for its application. The authors hypothesize that hydrofiber dressings will hold mafenide acetate solution for an extended period of time and maintain antimicrobial activity longer than traditional gauze, thus possibly obviating the need for frequent dressing changes. Four experimental arms included: 1) hydrofiber, stored on a dry well plate as control, 2) gauze saturated with 2.5% mafenide acetate, stored on nonsterile porcine skin, 3) hydrofiber saturated with mafenide acetate, stored on dry well plate, and 4) hydrofiber saturated with mafenide acetate, stored on nonsterile porcine skin. At 0, 24, 48, and 72 hours, a 1-cm disk was cut from the dressing sheet of each study arm, placed on agar plates seeded with Staphylococcus aureus and Pseudomonas aeruginosa, and incubated for 24 hours, and the zone of inhibition was measured. A zone of 2 mm or greater was indicative of susceptibility. Each arm of the experiment was performed four times to demonstrate reproducibility. Plain hydrofiber (control) demonstrated no zone of inhibition at any time point, thereby possessing no antimicrobial activity alone. Gauze saturated with mafenide acetate did not reliably demonstrate antimicrobial activity beyond 0 hours. Hydrofiber saturated with mafenide acetate, whether stored on a dry well plate or nonsterile porcine skin, consistently possessed sustained antimicrobial activity as demonstrated by zones of inhibition greater than 2 mm to both S. aureus and P. aeruginosa. Mafenide acetate-soaked hydrofiber dressings stay moist and maintain antimicrobial activity against S. aureus and P. aeruginosa for at least 72 hours without repeated soaks.

Clinical safety and effectiveness evaluation of a new antimicrobial wound dressing designed to manage exudate, infection and biofilm

The objective of this work was to evaluate the safety and effectiveness of a next-generation antimicrobial wound dressing (NGAD; AQUACEL^® Ag+ Extra™ dressing) designed to manage exudate, infection and biofilm. Clinicians were requested to evaluate the NGAD within their standard protocol of care for up to 4 weeks, or as long as deemed clinically appropriate, in challenging wounds that were considered to be impeded by suspected biofilm or infection. Baseline information and post-evaluation dressing safety and effectiveness data were recorded using standardised evaluation forms. This data included wound exudate levels, wound bed appearance including suspected biofilm, wound progression, skin health and dressing usage. A total of 112 wounds from 111 patients were included in the evaluations, with a median duration of 12 months, and biofilm was suspected in over half of all wounds (54%). After the introduction of the NGAD, exudate levels had shifted from predominantly high or moderate to low or moderate levels, while biofilm suspicion fell from 54% to 27% of wounds. Wound bed coverage by tissue type was generally shifted from sloughy or suspected biofilm towards predominantly granulation tissue after the inclusion of the NGAD. Stagnant (65%) and deteriorating wounds (27%) were shifted to improved (65%) or healed wounds (13%), while skin health was also reported to have improved in 63% of wounds. High levels of clinician satisfaction with the dressing effectiveness and change frequency were accompanied by a low number of dressing-related adverse events (n = 3; 2·7%) and other negative observations or comments. This clinical user evaluation supports the growing body of evidence that the anti-biofilm technology in the NGAD results in a safe and effective dressing for the management of a variety of challenging wound types.

Clinical Biofilms: A Challenging Frontier in Wound Care

Significance: Biofilms have been implicated in a variety of wound complications. Recent Advances: Research has confirmed that biofilms form in wounds of patients experiencing delayed healing and may be a precursor to infection. Critical Issues: Research into the strength of this association is still in its infancy. Is biofilm formation a cause of these complications, a step toward them, or a signal that unresolved factors injuring tissue or delaying healing are setting the stage for biofilm formation, infection, and healing delay? To qualify biofilms for use in informing clinical practice decisions, biofilm characteristics supporting those decisions need standardized definitions and valid evidence that they predict or diagnose healing or infection outcomes. Literature searches of relevant terms reviewed biofilm definitions and validation of their role in predicting and diagnosing delayed wound healing or infection. Future Directions: Further research is needed to provide a rapid accurate technique to identify and characterize biofilms in ways that optimize their validity in diagnosing or screening patient risk of infection or delayed healing and to inform clinical decisions. This research will help validate biofilm's capacity to support wound care clinical practice decisions and establish their importance in guiding clinical practice.

Comparative study of antibacterial effects and bacterial retentivity of wound dressings

OBJECTIVES

We are often confused on selecting a suitable wound dressing for the treatment of infected wounds from huge number of available wound dressings. Then, to help clinicians easily select a wound dressing, we compared the antibacterial effects and bacterial retentivity (ie, potency of keeping absorbed bacteria inside wound dressings and preventing them from leaking out) of wound dressings.

METHODS

Five wound dressings with antibacterial constituents were compared to research antibacterial effects against nonpathogenic Escherichia coli using an in vitro model. The 5 other wound dressings with no antibacterial constituent were compared to research bacterial retentivity. The relative amount of E coli was determined using cell proliferation reagent WST-1 (11644807001, Roche Applied Science, United States) with time.

RESULTS

The results have shown that the antibacterial effects and bacterial retentivity differed among various wound dressings. Silver ions quickly exerted a very strong antibacterial effect, and hydrofibers had a high potency of bacterial retentivity by gelling the absorbed bacteria in wound dressings.

CONCLUSIONS

The present study indicated the differences of antibacterial strength, time of onset and duration of the antibacterial effect, and bacterial retentivity between each wound dressing. Clinicians should use appropriate wound dressings according the wound condition in consideration of the different characteristics of wound dressings. The present results are helpful for clinicians to select appropriate wound dressing.

Moist occlusive dressing (Aquacel(®) Ag) versus moist open dressing (MEBO(®)) in the management of partial-thickness facial burns: a comparative study in Ain Shams University

INTRODUCTION

The face is the central point of the physical features; it transmits expressions and emotions, communicates feelings and allows for individual identity. Facial burns are very common and are devastating to the affected patient and results into numerous physical, emotional and psychosocial sequels. Partial thickness facial burns are very common especially among children. This study compares the effect of standard moist open technique management and a moist closed technique for partial thickness burns of the face.

PATIENTS AND METHODS

Patients with partial-thickness facial burns admitted in the burn unit, Ain Shams University, Cairo, Egypt in the period from April 2009 to December 2009 were included in this study. They were divided into two groups to receive either open treatment with MEBO(®) (n=20) or coverage with Aquacel(®) Ag (n=20). Demographics (age, gender, ethnicity, TBSA, burn areas), length of hospital stay (LOS), rate of infections, time to total healing, frequency of dressing changes, pain, cost benefit and patient discomfort were compared between the two groups. The long-term outcome (incidence of hypertrophic scarring) was assessed for up to 6 months follow-up period.

RESULTS

There were no significant differences in demographics between the two groups. In the group treated with the Aquacel(®) Ag, the mean time for re-epithelialization was 10.5 days, while it was 12.4 days in the MEBO(®) group (p<0.05). Frequency of changes, pain and patient discomfort were less with Aquacel(®) Ag. Cost was of no significant difference between the two groups. Scar quality improved in the Aquacel(®) Ag treatment group. Three and 6 months follow-up was done and long-term outcomes were recorded in both groups.

CONCLUSION

Moist occlusive dressing (Aquacel(®) Ag) significantly improves the management and healing rate of partial thickness facial burns with better long-term outcome compared to moist open dressing (MEBO(®)).

Evaluation of symptoms and QOL with calcium alginate versus chitin-coated gauze for middle meatus packing after endoscopic sinus surgery

OBJECTIVE

Nasal packing is used to control postoperative bleeding and wound healing, and it also exerts a very strong influence on the comfort of the patient. Sorbsan(®) (calcium alginate) is an absorbent packing that shows a potent hemostatic effect and is able to maintain wound surfaces in a moist environment by absorbing and gelling the wound exudate. The aim of this study was to evaluate the early symptoms and QOL with Sorbsan(®) versus Beschitin-F(®) (chitin-coated gauze) for middle meatus packing after endoscopic sinus surgery (ESS).

METHODS

We performed a cohort study of 40 patients who underwent ESS. Following ESS, the patients were randomly allocated into two groups of 20 patients each who underwent insertion of either Sorbsan(®) or Beschitin-F(®) into the middle meatus. A daily diary was used to record the symptoms and QOL, measured using visual analogue scales, before the ESS and on each day thereafter. Postoperative bleeding and local infection were also recorded.

RESULTS

The scores for each of the symptoms of nasal pain, headache, nasal bleeding and postnasal drip were statistically significantly lower in the Sorbsan(®) group. The scores for each of the QOL parameters, including the effect on their stay in the hospital and sleep disturbance, were also significantly lower in the Sorbsan(®) group. There were no findings of postoperative hemorrhage or local infection in either group.

CONCLUSION

Sorbsan(®) packing did not cause any major complications and has the potential to reduce nasal pain and suffering in post ESS patients compared with gauze packing.

Testing wound dressings using an in vitro wound model

OBJECTIVE

To determine whether or not there are any significant differences in the effects of wound dressings on bacterial bioburden.

METHOD

A selection of non-occlusive, non-adhesive dressings was tested for their effect on bacterial bioburden. The dressings selected included two dressings with antimicrobial properties (one containing silver and one containing PHMB), a cotton-based dressing enclosed in a perforated sleeve of poly(ethylene terephthalate), a carboxymethyl cellulose-based dressing, a fibre-free alginate dressing, and a 12-ply 100% cotton gauze. Using the colony-drip flow reactor (DFR) model, a meticillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa biofilm was grown underneath a dressing sample. Biofilm growth was examined via plate counts, fluorescent microscopy and scanning electron microscopy.

RESULTS

The dressings containing antimicrobial agents had the greatest effect on bacterial load. In the MRSA experiments, both antimicrobial dressings produced lower bacteria counts than the other dressings (p<0.001), while in the P. aeruginosa experiments, only the silver-containing sample had fewer bacteria (p<0.0001). However, neither antimicrobial dressing was able to completely eradicate the bacteria when testing with either microorganism.

CONCLUSION

The results presented herein illustrate that bacteria can grow unchallenged within the dressing environment and that an antimicrobial dressing can limit this bacterial growth.

DECLARATION OF INTEREST

None.

Topical silver-impregnated dressings and the importance of the dressing technology

A wide variety of silver-impregnated wound dressings has become available in recent years. This has given the practitioner choice but little evidence by which an appropriate dressing may be selected. In many instances, the ancillary function(s) of the dressing will become differentiating factors that influence choice. For example, the dressing capacity to manage exudate, maintain an optimum moist environment, reduce or avoid maceration, maintain an intimate contact with the wound bed, promote autolytic debridement, sequester bacteria and bind matrix metallo proteases (MMPs) are some of those functions that are of clinical significance and may dictate choice. In this article we present the evidence for these functions, thereby enabling practitioners to evaluate comparative dressing attributes, and so make an informed choice of which silver dressing best suits the needs of the wound under differing circumstances.

A review of the applications of the hydrofiber dressing with silver (Aquacel Ag) in wound care

Aquacel Ag((R)) (ConvaTec, Princeton, NJ, USA) is a new hydrofiber wound dressing consisting of soft non-woven sodium carboxymethylcellulose fibers integrated with ionic silver. It is a moisture-retention dressing, which forms a gel on contact with wound fluid and has antimicrobial properties of ionic silver. We present a current literature review on Aquacel Ag((R)), of both in vitro and in vivo efficacy and clinical applications. In vitro and in vivo studies have demonstrated the wide antimicrobial properties of Aquacel Ag((R)), and additionally demonstrated the cytotoxicity of ionic silver to keratinocytes and fibroblasts that cause delay in wound re-epithelialization. Clinical studies confirmed that Aquacel Ag((R)) is an effective and safe dressing for a variety of wound types, both acute and chronic. Incorporation of ionic silver into the hydrofibers does not cause undue alteration in the performance properties of the base dressing, which continues to provide favorable wound moisture and exudate management. The addition of ionic silver reduces local pain and dressing changes, and provides significant broad-spectrum antimicrobial properties, with no delay in wound healing.

The effect of a silver-containing Hydrofiber dressing on superficial wound bed and bacterial balance of chronic wounds

The treatment of chronic wounds represents a major cost to society and has a profound effect on the participant's quality of life. Chronic wounds may have an increased bacterial burden that can impair healing without all the clinical signs of infection. Silver dressings may provide an alternative topical method to control bacterial burden. The primary aim of this study was to evaluate the clinical improvement in chronic wounds through the effect on wound size, maceration, resolution of surface slough and conversion to healthy granulation during a 4-week application of the silver-containing Hydrofiber dressing. This was a single centre, open-label case series study which included a total of 30 evaluable participants: four with diabetic neuropathic foot ulcers, 13 venous stasis ulcers, four pressure ulcers and nine miscellaneous wounds that did not fit any of the previous categories. All participants had adequate vascular supply, indicating the potential to heal. The wounds were stalled or had the signs and symptoms consistent with critical colonisation. The underlying cause of the ulceration was identified and corrected, or the symptoms and signs were treated. This was followed by the application of silver-containing Hydrofiber dressings for a period of 4 weeks. The majority of wounds treated decreased in size (70%) with decreased exudate, decreased purulence and resolution of surface slough (75%). There was an increased quality and quantity of healthy granulation tissue. Unlike some silver dressings, the Hydrofiber and silver combination dressing was unlikely to cause burning and stinging on application. Peri-wound maceration was present in 54% of participants at baseline, and 85% of these resolved with this dressing. A desloughing action was seen in those patients with pre-existing slough at baseline and its removal will lower the bacterial burden of the wound.

Visualisation of bacterial sequestration and bactericidal activity within hydrating Hydrofiber wound dressings

The fluid handling and microbiological properties of a non-antimicrobial Hydrofiber(NAH) wound dressing have been compared with those of a silver salt-containing Hydrofiber (SCH). Fluorescent dyes (BacLight, Live/Dead Kit) were added to fresh cultures of two wound pathogens (Pseudomonas aeruginosa and Staphylococcus aureus), and used to visualise their viability. Live bacteria stained green and dead/dying bacteria turned red. When inoculated into samples of the NAH and SCH dressings, the viability of the bacteria could be effectively monitored over time using a rapid form of confocal laser scanning microscopy (RCLSM--Leica UK). When the NAH dressing was hydrated with stained bacterial culture, its fibres swelled quickly, reducing interstitial spaces between the fibres, resulting in the formation of a cohesive gel. Bacteria became immobilised in the gel, forming characteristic clumps, but remained largely green (viable) for more than 20 h with no apparent increase in numbers. The SCH initially behaved in a similar manner, however, using 3-D data from RCLSM time-lapse sequences P. aeruginosa was observed to turn progressively red (i.e. died) within 1.5-3 h and S. aureus similarly turned red within 5-7 h of contact with the SCH dressing. The ability of both Hydrofiber dressings to sequester and immobilise potentially pathogenic wound micro-organisms has been demonstrated. Additionally the SCH dressing was shown to kill immobilised bacteria, as a consequence of the ionic silver bactericide. These properties of the Hydrofiber dressings may contribute to providing an environment that is supportive to wound healing.