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Sinopsis Antecedentes: Normalmente, las infecciones son tratadas con antimicrobianos (antibióticos, antisépticos, etc.). La resistencia antimicrobiana (AMR, por sus siglas en inglés) se ha convertido en una de las amenazas del siglo XXI más graves para la salud mundial. Las heridas pueden ser una fuente de infección al permitir la entrada libre de microorganismos dentro del cuerpo, incluyendo bacterias resistentes a antimicrobianos. El desarrollo de nuevos antimicrobianos (especialmente, antibióticos) no está siguiendo el ritmo de la evolución de microorganismos resistentes y de formas novedosas de abordar este problema con la urgencia que demanda. Una de estas iniciativas ha sido el desarrollo de programas de protección antimicrobiana (AMS, por sus siglas en inglés), que brindan capacitación a los trabajadores del área de la salud y controlan la prescripción, enfocándose en los antimicrobianos para reducir la probabilidad de que se produzca AMR. El uso de apósitos para herida que utilizan el aislamiento físico y el abordaje de retención, en vez de agentes antimicrobianos, para reducir la carga bacteriana ofrecen un abordaje novedoso para apoyar a los AMS. La fijación bacteriana por los apósitos y su retiro físico, en lugar de la muerte activa, minimiza su daño y, además, previene la liberación de endotoxinas dañinas. Objetivo: Resaltar los AMS para la promoción del uso correcto de antimicrobianos e investigar cómo los apósitos recubiertos con cloruro de dialquilcarbamilo (DACC) pueden ayudar a cubrir las metas de los AMS. Método: Se realizaron búsquedas en las bases de datos de revisiones sistemáticas, Medline, Cochrane y Google Scholar con el fin de identificar artículos publicados que describan los datos relacionados con los AMS, y el uso de una gran variedad de apósitos para heridas para la prevención y/o tratamiento de infecciones de la herida. La evidencia que respalda a los apósitos para heridas alternativos que pueden reducir la biocarga y prevenir y/o tratar la infección de heridas de forma tal que no maten ni dañen a los microorganismos (por ejemplo, fijándose activamente y retirando intactos a los microorganismos de las heridas) fue posteriormente revisada de forma oral. Conclusión: Algunos apósitos para heridas actúan a través de mecanismos que promueven la fijación y absorción física, aislamiento y retiro de microorganismos intactos de la base de la herida (por ejemplo, un apósito para heridas que utiliza la tecnología DACC para prevenir/reducir la infección). Esta es una herramienta valiosa que cumple con los requisitos del AMS (por ejemplo, reducción del uso de antimicrobianos en esquemas de tratamiento de heridas) al reducir la biocarga de la herida sin inducir/seleccionar bacterias resistentes.

Objective: To clarify the role of microbiological swabs in surgical decision-making, we investigated the effect of negative-pressure wound therapy (NPWT) and serial surgical debridement on bacterial bioburden in hard-to-heal wounds and ultimately correlated them with the success of surgical closure. Method: All patients were treated with surgical debridement, jet lavage and NPWT before their wounds were finally closed. The treatment effect was assessed by correlating microbiological swabs obtained immediately after intervention with those obtained after removal of the dressings during the following surgical procedures. The result of the last microbiological swab taken before definitive surgical closure was correlated with the requirement for revision surgery. Results: We included the results of 704 microbiological swabs from 97 patients in 110 wound localisations in this monocentric, retrospective study. NPWT did not improve bacterial bioburden in 77% of cases and the duration of NPWT did not affect the result. Furthermore, no significant effect of NPWT could be found for either anaerobic (p=0.96) or aerobic bacteria (p=0.43). In contrast, surgical debridement increased bacterial load in approximately 60% of cases. If sterile wound swabs could be obtained at all, it was during the first four surgical debridements in 60% of patients; after that only 10% became sterile. Conclusions: Sterile microbiological wound swabs before surgical closure were associated with lower rates of revision surgery, while low or medium bacterial loads did not increase revision rates.

Cleansing provides an opportunity to remove pathogens from the wound bed, thereby preventing an increase in the bioburden and delayed healing. This article describes the reported efficacy of hypochlorous acid-containing wound cleansers

The characteristic clinical signs of chronic wounds, which remain in a state of prolonged inflammation, include increased production of devitalised tissue and exudate, pain and malodour. The presence of necrotic tissue, slough and copious exudate encourages microbial proliferation, potentially resulting in planktonic and/or biofilm infection. For patients, the consequences can include leakage of exudate, pain and reduced mobility, which can impair their ability to socialise and perform activities of daily living. This can severely reduce their quality of life and wellbeing. Concentrated surfactant-based gels (Plurogel and Plurogel SSD) are used in wound cleansing to help manage devitalised tissue. In vitro studies indicate they can sequester planktonic microbes and biofilm from the wound bed, although there is, limited clinical evidence to support this. A group of health professionals who have used this concentrated surfactant gel, in combination with standard care, in their clinical practice for several years recently met at a closed panel session. Here, they present case studies where topical application of these gels resulted in positive clinical outcomes in previously long-standing recalcitrant wounds. In all cases, the reduction in inflammation and bioburden alleviated symptoms that previously severely impaired health-related quality of life and wellbeing.

Objective: The influence of different irrigation solutions, in conjunction with wet-to-moist cleansing, on the reduction of sessile, non-planktonic bacteria which colonise wounds, has not been investigated. In this study, the antibacterial effect of different irrigation solutions, during a 20-minute wet-to-moist cleansing, has been evaluated in chronic wounds. Methods: This study was designed as a prospective cohort study with 12 study arms and was conducted between June 2011 and April 2016. Patients with chronic wounds present for more than three months, irrespective of previous treatments, were recruited into this study. Quantitative wound swabs were obtained before and after a 20-minute, wet-to-moist cleansing, using different wound irrigation solutions. Sterile 0.9% saline served as a control. Results: We recruited 308 patients, of which 260 patients with 299 chronic wounds were eligible for analysis. Staphylococcus aureus was the most common recovered (25.5%) microorganism, of which 8% were meticillin-resistant Staphylococcus aureus (MRSA) strains. Although 0.9% saline supported cleansing of the wound bed, it did not significantly reduce the bacterial burden. The highest reduction of bacterial burden was achieved with an aqueous solution containing betaine, zinc and polyhexamethylene biguanide (polihexanide; ln RF=3.72), followed by a 3% saline solution containing 0.2% sodium hypochlorite (ln RF=3.40). The most statistically significant reduction of bacterial burden, although not the highest, was achieved with povidone-iodine (ln RF=2.98; p=0.001) and an irrigation solution containing sea salt 1.2% and NaOCl 0.04% (ln RF=2.51; p=0.002). Conclusion: If a reduction of bacterial burden is warranted, wound irrigation solutions containing a combination of hypochlorite/hypochlorous acid, or antiseptics such as polihexanide, octenidine or povidone-iodine, ought to be considered.

Background Topical antimicrobials, such as silver dressings, are progressively being used alongside systemic antibiotics to provide adjunctive, antimicrobial therapy to wounds that are clinically infected or at risk of infection. To help improve wound management, dressings that use Safetac soft silicone technology in combination with a silver-impregnated foam dressing material were developed by Mölnlycke Health Care (Gothenburg, Sweden). The range comprises Mepilex Ag, Mepilex Border Ag and Mepilex Transfer Ag. Aims A literature review was undertaken to identify and summarise clinical data from the entire evidence hierarchy, as well as data from in vitro tests, which support the use of silver-containing foam dressings with Safetac. Method The MEDLINE (National Library of Medicine, Bethesda, US) and EMBASE (Elsevier BV, Amsterdam, Netherlands) bibliographic databases were searched. In addition, abstract books and proceedings documents relating to national and international conferences were scanned in order to identify presentations (oral, e-poster and poster) of relevance to the review. Results In vitro test results showed that the silver-containing foam dressings with Safetac have both rapid and sustained activity against a range of wound pathogens, reducing planktonic and established biofilm cultures, and preventing biofilm formation. In numerous clinical studies, silvercontaining foam dressings with Safetac were used to manage wound bioburden effectively and resolve signs of localised infection in both acute wounds (such as surgical, traumatic and burn injuries) and chronic wounds (such as leg ulcers, pressure ulcers (PUs), diabetic foot ulcers (DFUs), and cancerous wounds). Studies reported that silver-containing foam dressings with Safetac are easy to use, provide an optimal environment for wound healing, and are associated with atraumatic and virtually painfree removal. As well as being clinically effective, they are reported to be cost-effective when used on wounds that require topical antimicrobial therapy. Conclusion The findings of both scientific and clinical studies clearly indicate that clinical, patient-related and economic benefits are associated with the use of Mepilex Ag, Mepilex Border Ag and Mepilex Transfer Ag with Safetac in the treatment of wounds where antimicrobial activity is needed to help manage bioburden.

Objective: The aim of this study was to investigate the bacterial bioburden in experimental in vitro wounds during the application of conventional negative pressure wound therapy (NPWT), with and without antimicrobial dressings (polyhexanide, silver), against NPWT instillation of octenidine. Method: Experimental wounds produced in an in vitro porcine wound model were homogenously contaminated with bacterial suspension and treated with NPWT and different options. Group A: non-antimicrobial polyurethane foam dressing; group B: antimicrobial polyurethane foam dressing containing silver; group C: antimicrobial gauze dressing containing polyhexanide; group D: non-antimicrobial polyurethane foam dressing intermittently irrigated with octenidine; group E: negative control (non-antimicrobial polyurethane foam dressing without NPWT). Standard biopsies were harvested after 24 and 28 hours. Results: This study demonstrated that the use of NPWT with intermitted instillation of octenidine (group D) or application of silver-based polyurethane foam dressings (group B) is significantly superior against Staphylococcus aureus colonisation in experimental wounds compared with non-antimicrobial polyurethane foam dressing (group A) after 48 hours. Surprisingly, the polyhexanide-based dressing (group C) used in this model showed no statistical significant effect compared with the control group (group E) after 24 or 48 hours of treatment. Conclusion: Both intermitted instillation of octenidine and silver-based dressings in standard NPWT were significantly superior compared with non-antimicrobial polyurethane foam dressings or PHMB coated gauze dressing after 48 hours.

Objective: Knowledge of wound bioburden can guide selection of therapies, for example, the use of negative pressure wound therapy (NPWT) devices with instillation in a heavily contaminated wound. Wound and periwound bacteria can be visualised in real-time using a novel, non-contact, handheld fluorescence imaging device that emits a safe violet light. This device was used to monitor bacterial burden in patients undergoing NPWT. Methods: Diverse wounds undergoing NPWT were imaged for bacterial (red or cyan) fluorescence as part of routine wound assessments. Results: We assessed 11 wounds undergoing NPWT. Bacterial fluorescence was detected under sealed, optically-transparent (routine) adhesive before dressing changes, on foam dressings, within the wound bed, and on periwound tissues. Bacterial visualisation in real-time helped to guide: (1) bioburden-based, personalised treatment regimens, (2) clinician selection of NPWT, with or without instillation of wound cleansers, and (3) the extent and location of wound cleaning during dressing changes. The ability to visualise bacteria before removal of dressings led to expedited dressing changes when heavy bioburden was detected and postponement of dressing changes for 24 hours when red fluorescence was not observed, avoiding unnecessary disturbance of the wound bed. Conclusion: Fluorescence imaging of bacteria prompted and helped guide the timing of dressing changes, the extent of wound cleaning, and selection of the appropriate and most cost-effective NPWT (standard versus instillation). These results highlight the capability of bacterial fluorescence imaging to provide invaluable real-time information on a wound's bioburden, contributing to clinician treatment decisions in cases where bacterial contamination could impede wound healing.

Objective: Chronic ulcers are an intractable problem in many patients and are associated with impaired quality of life and high health-care costs. In an attempt to improve outcome, our centre began cleansing wounds with a novel spray acidoxidising solution (Nexodyn) with unique physicochemical features, pH 1000mV; and free chlorine content (>95% HClO). Method: A retrospective analysis was conducted in patients with numerous comorbidities and an unsatisfactory response to standard therapy. The solution was administered for six weeks and the patients' clinical course evaluated using standard measures of wound healing, pain and bioburden. Results: We assessed 20 patients with a mean time since ulcer onset of 23.7 months. Complete resolution of the lesion was achieved in 25% of cases (p=0.005). In the group as a whole, wound size decreased significantly (11% mean reduction versus baseline; p=0.039). In the relatively short six-week observation period, significant reductions versus baseline were also observed in control of wound bioburden (p=0.005) and ulcer-related pain score (pConclusion: Encouraging initial results in a population refractory to standard management provide evidence that this new product may make a helpful contribution to the care of chronic ulcers. The integration of this cleansing solution into standard care contributes to the modulation of local microenvironmental responses that inhibit physiological healing processes while also contributing to the reduction of bacterial load.

Objective: The aim of this in vitro study was to demonstrate the binding capacity of multiple meticillin-resistant Staphylococcus aureus (MRSA) strains and compare the binding capacity to meticillin-sensitive Staphylococcus aureus. Method: The binding of Staphylococcus aureus to a surface was assessed by bioluminescent monitoring of the bacterial ATP levels. This assay can be used as an in vitro diagnostic model for bacteria binding in a critically colonised wound. Results: Eleven strains of Staphylococcus aureus were examined including MRSA, all of which efficiently and equally adhered to the dialkyl carbamoyl chloride (DACC)-coated dressing (Sorbact; Abigo Medical AB). The binding capacity was all in the same range 0.7–2.9×106CFU/cm2. regardless of the antibiotic resistance properties of the specific strain. Conclusion: The decrease of wound bioburden of Staphylococcus aureus including MRSA is the result of the high binding capacity shown in this study and by earlier data. The findings in this study strengthen the held view that development of antibiotic resistance has minimal impact on the surface structures of the microorganisms in wounds. Declaration of interest: This work was supported by Abigo Medical AB, Sweden. The laboratory facilities for the MRSA work were provided by Sahlgrenska University Hospital and the Department for Clinical Bacteriology, University of Gothenburg, Sweden. No animals or humans were used in this study..

Objective: To evaluate a novel aqueous oxygen peroxide (AOP) wound therapy (BioxyQuell) in a multi-centre, primary care-based, randomised, double-blind, placebo-controlled, parallel-group trial, monitoring long-term healing outcomes over 12 months. Method: Sixty-one patients with chronic, stable venous leg ulceration were treated with either AOP solution or sterile water placebo applied as a lavage over 2 weeks. The patients’ wounds were dressed weekly and assessed fortnightly over the following 6 weeks. Patients who completed the initial 8-week trial were invited into a 10-month follow-up trial. The primary endpoints of the study were wound healing at 8 weeks, 12 weeks, 6 months and 12 months, and wound size reduction during the treatment phase. Secondary endpoints were reductions in wound bioburden and pain. Results: Patients treated with AOP were more likely to heal at 6 months (p=0.014) and 12 months (p=0.006), but not at 8 weeks (p=0.979) or 12 weeks (p=0.263). Patients treated with AOP had greater wound area reduction (p=0.015), reductions in pain measured on a 100-point scale (p=0.001) and wound bioburden reduction (p=0.005) during the treatment phase. Conclusion: The addition of AOP treatment provides substantial benefits to patients with chronic venous leg ulceration compared with current best practice. Declaration of interest: This work was supported by Bioquell UK Ltd, manufacturers of the BioxyQuell system. Authors P. Winter, J. Otter, N. Adams and J. Chewins are employees of Bioquell UK Ltd.

Objective: To determine if targeted biofilm suppression of a specific wound improves the efficacy of cell-based therapy (CBT). Method: A retrospective study designed to compare a cohort of patients who received CBT in conjunction with biofilm-based wound management with published outcomes from randomised controlled trials in the literature, utilising standard care and CBT. Biofilm-based wound management is the use of multiple simultaneous strategies to suppress wound biofilm, specifically targeting the individual wound's bioburden with agents and methods to suppress the wound biofilm and improve wound-bed preparation. Results: A Kaplan-Meier analysis shows that all wound aetiologies receiving biofilm-based wound care and CBT showed better healing than published outcomes at 3 months and 6 months. Overall wound closure for all wound types combined was 79% at 3 months (versus 56% for the literature) and 92% at 6 months (compared with 63–78% in the literature). All wounds that failed to heal showed some impro...

Objective: This article reports the outcomes of the use of Surgihoney RO (SHRO), topical wound dressing in a multi-centre, international setting. The aims were to explore the clinical effects of SHRO, including a reduction in bacterial load and biofilm and improvement in healing in a variety of challenging non-healing and clinically infected wounds. Method: This was a non-comparative evaluation, where both acute and chronic wounds with established delayed healing were treated with the dressing. Clinicians prospectively recorded wound improvement or deterioration, level of wound exudate, presence of pain, and presence of slough and necrosis. Analysis of this data provided information on clinical performance of the dressing. Semi-quantitative culture to assess bacterial bioburden was performed where possible. Results: We recruited 104 patients, mean age 61 years old, with 114 wounds. The mean duration of wounds before treatment was 3.7 months and the mean duration of treatment was 25.7 days. During treatment 24 wounds (21%) healed and the remaining 90 (79%) wounds improved following application of the dressing. No deterioration in any wound was observed. A reduction in patient pain, level of wound exudate and in devitalised tissue were consistently reported. These positive improvements in wound progress were reflected in the wound cultures that showed a reduction in bacterial load in 39 out of the 40 swabs taken. There were two adverse events recorded: a stinging sensation following application of the dressing was experienced by 2 patients, and 2 elderly patients died of causes unrelated to the dressing or to the chronic wound. These patients' wounds and their response to SHRO have been included in the analysis. Conclusion: SHRO was well tolerated and shows great promise as an effective potent topical antimicrobial in the healing of challenging wounds. Declaration of interest: Matthew Dryden has become a shareholder in Matoke Holdings, the manufacturer of Surgihoney RO, since the completion of this study. Keith Cutting is a consultant to Matoke Holdings.

The concept of wound bed preparation can be implemented using the TIME paradigm. Chronic wounds are mostly characterised by prolonged inflammation and increased bioburden. Removal of wound biofilm and devitalised tissue, which is an ideal environment for bacterial growth, can help address the I in TIME. Wound cleansing aims to remove contaminants, debris, dressing remnants and superficial slough from the wound. Some wound cleansers contain surfactants, which reduce the surface tension of a liquid, enabling it to spread further over a surface. This article describes how these solutions can be used to debride the wound surface without damaging healthy cells.

Wound infections present a significant clinical challenge, impacting on patient morbidity and mortality, with significant economic implications. Silver-impregnated wound dressings have the potential to reduce both wound bioburden and healing time. The silver ion Ag+ is the active antimicrobial entity; it can interfere with thiol (−SH) groups and provoke the generation of reactive oxygen species (ROS), a major contributor to its antibacterial efficacy. Recently, silver nanoparticles have gained considerable interest in wound bioburden reduction and in anti-inflammation, as they can release Ag+ ions at a greater rate than bulk silver, by virtue of their large surface area. If released from dressings, they also have the potential to cross biological compartments. This review aims to consolidate recent findings as to the efficacy and safety of different formulations of silver used as an antiseptic agent in dressings, summarising the features of silver nanomaterials, with particular attention to the dose-dependencies for biological effects, highlighting the need for information on their uptake and potential biological effects.

The prevention and management of infection relies largely on the use of topical antimicrobial dressings. These treatments achieve their effects by killing bacteria, but this results in the presence of bacterial cell debris in the wound and the release of endotoxins, which may prolong inflammation. An alternative approach, where bacteria and fungi bind irreversibly to the wound dressing as a result of a hydrophobic interaction and are then removed at dressing change, avoids the risk of prolonged inflammation and the potential for resistance. A further benefit is that there is no risk of toxicity to healthy tissue or systemic absorption

Objective: This large, level a, retrospective cohort study set out to compare healing outcomes in three large cohorts of wound patients managed universally for bioburden: standard of care group, who were prescribed systemic antibiotics on the basis of empiric and traditional culture-based methodologies; treatment group 1, who were prescribed an improved selection of systemic antibiotics based on the results of molecular diagnostics; treatment group 2 who received personalised topical therapeutics (including antibiotics) based on the results of molecular diagnostics. Method: apart from the differences in diagnostic methods and antibiotic treatments described above, all three cohorts were subjected to the same biofilm-based wound care protocol, which included evaluation of the host and bioburden, frequent sharp debridement, use of wound dressings and comprehensive standard care (reperfusion therapy, nutritional support, offoading, compression and management of comorbidities). Results: In all, 1378 patients were recruited into the study. In the standard of care group 48.5% of patients (244/503) healed completely during the 7-month study period. This increased to 62.4% (298/479) in treatment group 1 and 90.4% (358/396) in treatment group 2. Cox proportional hazards analysis revealed the time to complete closure decreased by 26% in treatment group 1 (p200% better odds of healing at any given time point compared with the other cohorts. Conclusion: Implementation of personalised topical therapeutics guided by molecular diagnosis resulted in statistically and clinically significant improvements in outcome. The integration of molecular diagnostics and personalised medicine provides a directed and targeted approach to wound care. Conflict of interest: SED and RDW are owners of PathoGenius laboratories, a clinical diagnostic laboratory. SED and RDW are owners of Research and Testing laboratory, which develops molecular diagnostics. CJ and JK are clinical advisors for PathoGenius. CJ and JK are owners of Southeastern medical Compounding, Savannah, Ga and Southeastern medical Technologies, Savannah, Ga.

Polymerase chain reaction is a culture-free method of identifying pathogens. This case study describes how, unlike traditional culture reports, a modification of this technique rapidly determined that Pseudomonas spp. was present in a chronic wound

Aim: To assess the effectiveness of RescuDerm, an amorphous, water-soluble burn gel in controlling Pseudomonas aeruginosa growth in rat full-thickness wounds contaminated with 103, 105 or 107 CFU/g tissue. Method: Wounds were treated daily for 72 hours with a placebo gel, a 5% w/w mafenide acetate gel (Maf), or with four modalities of RescuDerm application. Results: All RescuDerm treatments were equally effective within 24 hours in preventing further Pseudomonas aeruginosa growth in wounds contaminated with 103 CFU/g tissue. Pseudomonas aeruginosa levels remained at or below this baseline count for 72 hours in all but one of the RescuDerm treatments. The bioburdens in Maf-treated wounds were negligible, averaging 0.14 ± 0.09 log10 CFU/g tissue. While RescuDerm and Maf remained bacteriostatic in wounds contaminated with 105 CFU/g tissue, this property disappeared at higher bioburdens. Conclusion: RescuDerm can be used for the management of cutaneous injuries sustained in environments deemed marginally or moderately contaminated. Heavily contaminated wounds would require irrigation prior to application to reduce their bioburden below 105 CFU/g tissue. Declaration of interest: This work was partly supported by NociPharm. Defence Research and Development Canada (DRDC) Toronto designed all the experimental protocols. The findings of this study were not constrained by the sponsoring body, and have never been presented at a scientific meeting or in another public context.

Unlike common antimicrobial dressings, the Cutimed Sorbact range does not kill pathogens, but instead binds them to its surface, so they can be safely removed at dressing change. As a result, it can be used long term with minimal risk of side effects. This supplement describes the evidence base on the efficacy of DACC technology

Objective: It is commonly believed that sharp surgical debridement provides adequate bacteria control for local wound beds, despite limited supporting scientific evidence. We undertook a prospective study to evaluate the reduction in planktonic bacteria pre- and post-operative debridement in critically colonised wounds. Method: Twelve patients, corresponding to 14 wounds, underwent debridement with either hydrodebridement or sharp steel debridement with pulse irrigation. Wound quantitative tissue cultures were taken pre- and post-debridement. There was no significant difference in wound aetiology or surface area between the two groups. Results: TThe bacterial counts before debridement were 1×107 colony-forming units per gram (CFU/g) in the hydrodebridement group vs 1.4×107 CFU/g in the sharp debridement group; and 2.5×106 CFU/g (hydrodebridement) vs 7.5×105 CFU/g (sharp) after debridement (p=0.41). The total bacteria reduction was 7.5×106 CFU/g after hydrodebridement vs 1.3×107 CFU/g after sharp steel debridement (p=0.37). The mean percentage of bacteria killed from baseline was 75% by hydrodebridement and 93% killed by sharp debridement (pConclusion: Extensive operative debridement using either modality does not provide adequate immediate reduction in wound planktonic bioburden. However, all wounds appeared clinically appropriate for closure after debridement and postoperative antibacterial therapy. Postoperative antibacterial therapy may be imperative in cases of critically colonised wounds to achieve good outcomes. Declaration of interest: The senior author receives research grant support from Healthpoint Biotherapeutics; KCI; Manuka Honey; Smith & Nephew; Medline Ind., Macrocure; CODA. In addition the senior author is a consultant for: Smith & Nephew and KCI and medical consultant and reviewer for Macrocure. While the study as presented evaluates in part the efficacy of a commercial product from Smith & Nephew, no industry support for this study was sought or provided.

This is a chapter taken from the book Microbiology of Wounds, published by CRC Press in 2010. It has traditionally been the case that reduction of wound bioburden has been achieved by the use of a topical antimicrobial agent, such as bactericidal antiseptics or antibiotics. This has worked well for many years, however, there are concerns about toxicity and resistance, which have prompted research into other mechanisms. There are various means of removing bacteria from the wound, without recourse to chemical agents; for example, larvae (maggots) ingest bacteria, together with the devitalised tissue of the wound. The control of exudate restricts the availability of free water, impeding the growth of those water-loving bacteria such as the staphylococci and pseudomonads. The discovery that some materials selectively adsorb, or sequester, bacteria has led to the development of bacteriostatic dressing materials, which do not rely on antiseptics for their action. These are designed to physically remove microorganisms, such as bacteria, from the wound, thus reducing bioburden. However, this still demands validation as a clinically relevant mechanism. Until that time, it remains a fascinating theoretical concept.

Objective: To determine the in vivo effect of a sustained-release silver sulphadiazine powder foam dressing on the bacterial burden of venous leg ulcers (VLUs), with a view to correlating the wound closure rate with the degree of bioburden and to assess other markers of its progression towards healing. Method: Patients attending a tertiary care wound practice were screened for a VLU bacterial count of >105 colony forming units (cfu/g) per gram of tissue. Patients were treated with the above topical dressing plus multilayer compression bandaging for 12 weeks. Quantitative cultures were taken at weeks 0, 2, 4 and 8. Wounds were assessed at each weekly visit using photography and planimetry. Results: Twenty-four of the 33 screened patients met the inclusion criteria. The average baseline wound size was 12.3cm2. At week 8, the bioburden had reduced to 5cfu/g in 54.2% of patients, with 41.7% achieving this reduction by week 2. At week 8, the median reduction was 0.7log10 (p75% wound area reduction and 45.8% achieved ulcer closure in a median of 80.5 days. Conclusion: Although the wound size and bacterial counts reduced significantly, there was no statistical correlation between the two. Nevertheless, the in vivo data show that this active antimicrobial dressing was associated with a very high healing rate in these hard-to-heal wounds. Conflict of interest: This research was supported by a grant from Smith & Nephew, Hull, UK. In addition, the principal investigator receives other grants from Smith & Nephew, Hull, UK.

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.

Objective: To assess the effect of octenidine dihydrochloride (Octenisept, Schülke & Mayr) on the clinical condition and bacterial flora in neoplastic ulcers. Method: Twenty-one patients with advanced cancer and neoplastic ulcers were included in the study. Octenisept-moistened gauze dressings were applied to the ulcers three times daily. The clinical and bacteriological status of the wounds were assessed at baseline and after three weeks of treatment. Results: Thirty-three bacterial strains were cultured at baseline. After three weeks of treatment, the tests were repeated on 16 patients. Clinical observations confirmed an improvement in the clinical condition of the ulcers, characterised by a reduction in necrosis, exudate levels, erythema and oedema. According to the bacteriological assessment, Staphylococcus aureus, Staphylococcus epidermidis and Proteus mirabilis were eradicated from the wounds. Enterococcus faecalis persisted in two patients, Escherichia coli in one patient and Pseudomonas aeruginosa in another patient. Conclusion: Octenispet was an effective antimicrobial: Staphylococcus aureus and Proteus mirabilis were eradicated in all ulcers. After three weeks of treatment, none of the ulcers developed an infection and there was an improvement in their clinical condition. Declaration of interest: Materials were supplied by Higiena Company, Warsaw, Poland.