Over-the-counter topical antimicrobials: effective treatments?

A novel dressing with silver to treat meticillin-resistant Staphylococcus aureus biofilm infection in a pig model

OBJECTIVE

The purpose of this study was to use an in vivo biofilm porcine model to examine a new polyvinyl alcohol-based gelling fibre dressing with silver and compare it to other commercial dressings containing: polyvinyl alcohol-based gelling fibre without silver; carboxymethyl cellulose-based fibre with silver, benzethonium chloride and ethylenediaminetetraacetic acid; and untreated control.

METHODS

A total of 52 deep partial-thickness wounds (10x7x0.5mm) were created on each of three animals and inoculated with 25µl of meticillin-resistant Staphylococcus aureus (MRSA) (10⁶ colony forming units (CFU)/ml). Wounds were covered for 24 hours to allow biofilm formation and were randomly designated to one of the four treatments. Samples were recovered for microbiological and histological analysis on days 3, 5 and 7 post-treatment.

RESULTS

Polyvinyl alcohol-based gelling fibre dressing with silver was able to significantly reduce biofilm more effectively than the other treatment groups. By day 7, wounds treated with the dressing had a 2.72±0.01 log CFU/g reduction in MRSA count versus untreated control wounds and a 2.59±0.01 log CFU/g reduction versus baseline counts. For histology analysis, all wounds reached 100% re-epithelialisation by day 5.

CONCLUSION

The results of this study indicated that polyvinyl alcohol-based gelling fibre dressing with silver was effective against biofilm of antibiotic-resistant staphylococcal strains without inhibiting the wound healing process, and may have important clinical implications when treating acute and/or hard-to-heal wounds.

A PEGylated fibrin hydrogel-based antimicrobial wound dressing controls infection without impeding wound healing

Combat injuries are associated with a high incidence of infection, and there is a continuing need for improved approaches to control infection and promote wound healing. Due to the possible local and systemic adverse effects of standard 1% cream formulation (Silvadene), we had previously developed a polyethylene glycol (PEGylated) fibrin hydrogel (FPEG)-based wound dressing for the controlled delivery of silver sulfadiazine (SSD) entrapped in chitosan microspheres (CSM). In this study, we have evaluated the antimicrobial and wound healing efficacy of SSD-CSM-FPEG using a full-thickness porcine wound infected with Pseudomonas aeruginosa. Infected wounds treated with a one-time application of the SSD-CSM-FPEG wound dressing demonstrated significantly reduced bacterial bioburden over time (99·99% of reduction by day 11; P < 0·05) compared with all the other treatment groups. The epithelial thickness and granulation of the wound bed was significantly better on day 7 (150·9 ± 13·12 µm), when compared with other treatment groups. Overall, our findings demonstrate that the SSD-CSM-FPEG wound dressing effectively controls P. aeruginosa infection and promotes wound healing by providing a favourable environment that induces neovascularisation. Collectively, sustained release of SSD using fibrin hydrogel exhibited enhanced benefits when compared with the currently available SSD treatment, and this may have significant implications in the bacterial reduction of infected wounds in military and civilian populations.

The role of secreted heat shock protein-90 (Hsp90) in wound healing - how could it shape future therapeutics?

INTRODUCTION

Defects in tissue repair or wound healing pose a clinical, economic and social problem worldwide. Despite decades of studies, there have been few effective therapeutic treatments. Areas covered: We discuss the possible reasons for why growth factor therapy did not succeed. We point out the lack of human disorder-relevant animal models as another blockade for therapeutic development. We summarize the recent discovery of secreted heat shock protein-90 (Hsp90) as a novel wound healing agent. Expert commentary: Wound healing is a highly complex and multistep process that requires participations of many cell types, extracellular matrices and soluble molecules to work together in a spatial and temporal fashion within the wound microenvironment. The time that wounds remain open directly correlates with the clinical mortality associated with wounds. This time urgency makes the healing process impossible to regenerate back to the unwounded stage, rather forces it to take many shortcuts in order to protect life. Therefore, for therapeutic purpose, it is crucial to identify so-called 'driver genes' for the life-saving phase of wound closure. Keratinocyte-secreted Hsp90α was discovered in 2007 and has shown the promise by overcoming several key hurdles that have blocked the effectiveness of growth factors during wound healing.

Effectiveness of a polyhexanide irrigation solution on methicillin-resistant Staphylococcus aureus biofilms in a porcine wound model

Irrigation and removal of necrotic debris can be beneficial for proper healing. It is becoming increasingly evident that wounds colonized with biofilm forming bacteria, such as Staphylococcus aureus (SA), can be more difficult to eradicate. Here we report our findings of the effects of an irrigation solution containing propyl-betaine and polyhexanide (PHMB) on methicillin-resistant Staphylococcus aureus (MRSA) biofilms in a porcine wound model. Thirty-nine deep partial thickness wounds were created with six wounds assigned to one of six treatment groups: (i) PHMB, (ii) Ringer's solution, (iii) hypochlorous acid/sodium hypochlorite, (iv) sterile water, (v) octenidine dihydrochloride, and (vi) octenilin. Wounds were inoculated with MRSA and covered with a polyurethane dressing for 24 hours to allow biofilm formation. The dressings were then removed and the wounds were irrigated twice daily for 3 days with the appropriate solution. MRSA from four wounds were recovered from each treatment group at 3 days and 6 days hours after initial treatment. Irrigation of wounds with the PHMB solution resulted in 97·85% and 99·64% reductions of MRSA at the respective 3 days and 6 days assessment times when compared to the untreated group. Both of these reductions were statistically significant compared to all other treatment groups (P values <0·05).

Keratinocyte-Secreted Heat Shock Protein-90alpha: Leading Wound Reepithelialization and Closure

Significance: Delayed and nonhealing wounds pose a health, economic, and social problem worldwide. For decades, the conventional wisdom pointed to growth factors as the driving force of wound healing and granted them a center stage for therapeutic development. To date, few have obtained US FDA approvals or shown clinical effectiveness and safety. Critical Issue: Wound closure is the initial and most critical step during wound healing. Closing chronic wounds to shut down continued infection is the primary and likely the only achievable goal at the clinic in the foreseeable future. The critical question here is to identify the factor(s) in wounded tissues that drives the initial wound closure. Recent Advances: We made an unexpected discovery of the secreted form of heat shock protein-90alpha (Hsp90α) for promoting skin cell motility, reepithelialization, and wound closure. Secreted Hsp90α possesses unique properties to remain functional under the hostile wound environment that compromises conventional growth factors' effectiveness. Through the common lipoprotein receptor-related protein-1 cell surface receptor and activation of the Akt signaling pathway, topical application of human recombinant Hsp90α protein greatly accelerates excision, burn, and diabetic skin wound closure in rodent and porcine models. Future Directions: In almost all cells, the 2-3% of their total proteins (∼7,000 per cell) are Hsp90 (α and β), a long unraveled puzzle. Our new finding of Hsp90 secretion in wounded tissues suggests that the stockpile of Hsp90α by all cells is to rapidly supply the need for extracellular Hsp90α to repair damaged tissues. We propose that keratinocytes at the wound edge secrete Hsp90α that leads the reepithelialization process to close the wound.

Antimicrobial activity of topically-applied soyaethyl morpholinium ethosulfate micelles against Staphylococcus species

Aim: Here we evaluated the antibacterial efficacy of soyaethyl morpholinium ethosulfate (SME) micelles as an inherent bactericide against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Methodology: The antimicrobial activity was examined by in vitro culture model and murine model of skin infection. Cationic micelles formed by benzalkonium chloride or cetylpyridinium chloride were used for comparison. Results: The minimum inhibitory concentration and minimum bactericidal concentration against S. aureus and MRSA were 1.71–3.42 and 1.71–6.84 μg/ml, respectively. Topical administration of SME micelles significantly decreased the cutaneous infection and MRSA load in mice. The killing of bacteria was caused by direct cell wall/membrane rupture. SME micelles also penetrated into the bacteria to elicit a Fenton reaction and oxidative stress. Conclusion: SME micelles have potential as antimicrobial agents due to their lethal effect against S. aureus and MRSA with a low toxicity to mammalian cells.

Impact of a novel, antimicrobial dressing on in vivo, Pseudomonas aeruginosa wound biofilm: quantitative comparative analysis using a rabbit ear model

The importance of bacterial biofilms to chronic wound pathogenesis is well established. Different treatment modalities, including topical dressings, have yet to show consistent efficacy against wound biofilm. This study evaluates the impact of a novel, antimicrobial Test Dressing on Pseudomonas aeruginosa biofilm-infected wounds. Six-mm dermal punch wounds in rabbit ears were inoculated with 10(6) colony-forming units of P. aeruginosa. Biofilm was established in vivo using our published model. Dressing changes were performed every other day with either Active Control or Test Dressings. Treated and untreated wounds were harvested for several quantitative endpoints. Confirmatory studies were performed to measure treatment impact on in vitro P. aeruginosa and in vivo polybacterial wounds containing P. aeruginosa and Staphylococcus aureus. The Test Dressing consistently decreased P. aeruginosa bacterial counts, and improved wound healing relative to Inactive Vehicle and Active Control wounds (p < 0.05). In vitro bacterial counts were also significantly reduced following Test Dressing therapy (p < 0.05). Similarly, improvements in bacterial burden and wound healing were also achieved in polybacterial wounds (p < 0.05). This study represents the first quantifiable and consistent in vivo evidence of a topical antimicrobial dressing's impact against established wound biofilm. The development of clinically applicable therapies against biofilm such as this is critical to improving chronic wound care.

Identification of the critical therapeutic entity in secreted Hsp90α that promotes wound healing in newly re-standardized healthy and diabetic pig models

Chronic and non-healing skin wounds represent a significant clinical, economic and social problem worldwide. Currently, there are few effective treatments. Lack of well-defined animal models to investigate wound healing mechanisms and furthermore to identify new and more effective therapeutic agents still remains a major challenge. Pig skin wound healing is close to humans. However, standardized pig wound healing models with demonstrated validity for testing new wound healing candidates are unavailable. Here we report a systematic evaluation and establishment of both acute and diabetic wound healing models in pigs, including wound-creating pattern for drug treatment versus control, measurements of diabetic parameters and the time for detecting delayed wound healing. We find that treatment and control wounds should be on the opposite and corresponding sides of a pig. We demonstrate a strong correlation between duration of diabetic conditions and the length of delay in wound closure. Using these new models, we narrow down the minimum therapeutic entity of secreted Hsp90α to a 27-amino acid peptide, called fragment-8 (F-8). In addition, results of histochemistry and immunohistochemistry analyses reveal more organized epidermis and dermis in Hsp90α-healed wounds than the control. Finally, Hsp90α uses a similar signaling mechanism to promote migration of isolated pig and human keratinocytes and dermal fibroblasts. This is the first report that shows standardized pig models for acute and diabetic wound healing studies and proves its usefulness with both an approved drug and a new therapeutic agent.

Noncontact, low-frequency ultrasound as an effective therapy against Pseudomonas aeruginosa-infected biofilm wounds

Bacterial biofilms, a critical chronic wound mediator, remain difficult to treat. Energy-based devices may potentially improve healing, but with no evidence of efficacy against biofilms. This study evaluates noncontact, low-frequency ultrasound (NLFU) in the treatment of biofilm-infected wounds. Six-millimeter dermal punch wounds in rabbit ears were inoculated with 10(7) colony-forming units of Pseudomonas aeruginosa or left as sterile controls. A biofilm was established in vivo using our published model. NLFU treatment was carried out every other day or every day, with contralateral ear wounds acting as internal, untreated controls. Wounds were harvested for several quantitative endpoints and scanning electron microscopy to evaluate the biofilm structure. The P. aeruginosa biofilm consistently impaired wound epithelialization and granulation. NLFU, both every other day and every day, improved healing and reduced bacterial counts relative to untreated controls (p < 0.05). Scanning electron microscopy confirmed a qualitative decrease in bacteria after both treatments. NLFU also reduced inflammatory cytokine expression (p < 0.05). Our study suggests that NLFU is an effective therapy against P. aeruginosa wound biofilm. This represents the first in vivo evidence of energy-based modalities' impact on wound biofilm, setting the foundation for future mechanistic studies. Continued wound care technology research is essential to improving our understanding, and treatment, of biofilm-infected chronic wounds.

Antiseptic cyclodextrin-functionalized hydrogels and gauzes for loading and delivery of benzalkonium chloride

Prevention and management of wound infections receive a lot of attention, since the presence of micro-organisms interferes with the wound-healing process. The aim of this work was to use cyclodextrins (CDs) to endow hydrogels and gauzes with the ability to take up antiseptics and sustain their delivery for several hours. Benzalkonium chloride (BzCl) can form inclusion complexes with cross-linked CDs that regulate the release through an affinity-driven mechanism. Grafting of CDs to cotton gauzes using citric acid as the linker, at 190 °C and for 15 min, led to grafting yields of about 148%, much larger than those obtained at 180 °C or with shorter reaction times. Microbiological tests revealed that the BzCl-loaded networks can inhibit the growth of Staphylococcus epidermidis and Escherichia coli both on agar plates and in liquid medium. Furthermore, the antiseptic-loaded gauzes were able to inhibit biofilm formation by Staphylococcus aureus RN1HG pMV158GFP when applied in early stages of biofilm formation and could reduce the number of living cells in preformed biofilms grown in a chronic wound biofilm model. These findings highlight the role of CDs as main components of hydrogels and gauzes for the efficient delivery of antiseptics.

Allergic dermatitis due to topical antibiotics

In this report we present a case of allergic dermatitis from chronic use of antibiotic ointment mistakenly diagnosed as a localized finger infection.

Do Indonesian community pharmacy workers respond to antibiotics requests appropriately?

OBJECTIVE

To quantify antibiotics sales without a prescription and to explore provision of patient assessment and medicine information related to antibiotics requested with or without a prescription in Surabaya community pharmacies.

METHODS

Scenarios of specific product requests (ciprofloxacin tablets and tetracycline capsules) and a request of amoxicillin dry syrups based on a new prescription were presented by simulated patients to 105 purposively selected pharmacies. Data were recorded by simulated patients after their purchase of each product. They documented the questions asked in patient assessment, the content of information given, recommendations provided and pharmacy workers' characteristics.

RESULTS

Antibiotics requested without a prescription were sold in 80 (91%) pharmacies. Information related to ciprofloxacin tablets and tetracycline capsules was only provided when requested by the simulated patient in 69% and 68% of pharmacies for the two scenarios, respectively. Very few pharmacies assessed patients. Medicine information on indication, dosing, duration and direction for use was provided more frequently in all cases. Medicine information was more likely to be given when a new prescription of amoxicillin dry syrups being presented. Overall, the majority of sampled pharmacies responded antibiotics requests inappropriately.

CONCLUSION

Inappropriate responses to antibiotic requests with or without a prescription remain an issue in Indonesia with pharmacy workers often failing to adequately assess patients. The illegality of delivering antibiotics without a prescription is of a considerable concern. Therefore, strategies to control antibiotics dispensing in community pharmacies should be seriously considered.

Use of prophylactic antibiotics in preventing infection of traumatic injuries

In managing traumatic wounds, the primary goal is to achieve rapid healing with optimal functional and esthetic results. This is best accomplished by providing an environment that prevents infection of the wound during healing. Despite good wound care, some infections still occur. Accordingly, some investigators argue that prophylactic antibiotics have an important role in the management of certain types of wounds. This article reviews the basis of antibiotic use in preventing wound infection in general and its use in oral and facial wounds in particular.

Incorporating wound healing strategies to improve palliation (symptom management) in patients with chronic wounds

BACKGROUND

Palliative wound care should be centered on symptom management and is a viable option for patients whose chronic wounds do not respond to standard interventions, or when the demands of treatment are beyond the patient's tolerance or stamina. Palliative wound care is the incorporation of strategies that prioritize symptomatic relief and wound improvement ahead of wound healing (total closure). Palliative wound care strategies must also work in conjunction with curative treatment objectives as wounds often heal completely in spite of serious illness and advanced disease. Palliative wound care is much more than pain, exudate and odor management. Common curative treatment goals such as physical correction of the underlying pathology, addressing nutrition and other supportive aspects of care, and sensible (nonharmful) local wound treatments should never be ignored.

OBJECTIVE

(1) To provide a fresh and effective approach to palliative wound care by integrating individual clinical expertise with clinical and laboratory evidence from the (curative) wound healing literature and (2) to share our (Calvary Hospital) experience and approach to palliative wound care in an inpatient, home, and outpatient setting. This approach can be summarized with the mnemonic S-P-E-C-I-A-L (S = stabilizing the wound, P = preventing new wounds, E = eliminate odor, C = control pain, I = infection prophylaxis, A = advanced, absorbent wound dressings, L = lessen dressing changes). Throughout this paper we will offer rationale, principles and recipes, for each of the steps of the "SPECIAL" approach in an effort to facilitate the caring for chronic wounds in palliative medicine.

CONCLUSIONS

A practical marriage of wound palliation (symptom management) with current wound healing concepts to provide options for the palliative care provider and improve the practice of palliative medicine.

Controlling methicillin resistant Staphyloccocus aureus and Pseudomonas aeruginosa wound infections with a novel biomaterial

Wound infections, especially those associated with methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, offer considerable challenges for clinicians. Our laboratory has recently developed novel composite biomaterials (DRDC) for wound dressing applications, and demonstrated their in vitro bactericidal efficacy. In the present study, we assessed the proliferation of planktonic and sessile Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus in porcine full-thickness wounds covered for up to 48 h with either saline- or mafenide acetate-loaded DRDC puffs and meshes. All biomaterials were applied 4 h following bacterial inoculation of the wounds with methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa, to allow colonization of the tissues and initiation of biofilm formation. The drug-loaded biomaterials eradicated both the planktonic and biofilm bacteria in the wounds within 24 h (p <. 05), irrespective of the bacterial strain or architecture of the dressing. While the wound bioburdens increased in the ensuing 24 h, they remained approximately 2 log(10) colony-forming units (CFU) below (p <. 05) their respective baseline values. Similarly, less than 4 log(10) CFU was recovered in the drug-loaded DRDC biomaterials throughout the study. These data show that the DRDC puffs and meshes are effective in delivering certain medications, such as antimicrobial agents, to the wound bed, suggesting considerable value of this material for treating wounds, especially those with irregular shapes, contours, and depths.

Use of Appropriate Antimicrobials in Wound Management

The primary goal of wound management is to achieve a functional closure with minimal scarring. Preventing infection is important to facilitate the healing process. Most simple, uncomplicated wounds do not need systemic antibiotics but benefit from the use of topical antibiotics. Judicious use of antibiotics reduces unnecessary adverse events and helps reduce the development of resistance. Although antibiotics can help reduce infection risk and promote healing, they are not a substitute for good local wound care, in particular irrigation and surgical débridement. This article reviews the role of antibiotics in emergency department wound management.

The diabetic foot: the importance of biofilms and wound bed preparation

Biofilms are ubiquitous and medically important complex structures consisting of microbial-associated cells embedded in self-produced extracellular matrix of hydrated extrapolymeric substances, which are irreversibly attached to a biological or nonbiological surface. Bacteria that reside as biofilms are resistant to traditional therapy. This alternative community in which microbes exist has recently attracted interest as a potential reason why chronic wounds do not heal. This may be especially important for diabetic foot ulcers, which are often characterized by their refractory nature, their predisposition to have associated underlying infection, and their improvement with débridement. Animal and in vitro models have been developed to better study biofilms, which will allow a venue for therapeutic intervention. Potential opportunities exist that include prevention of bacterial attachment, prevention of biofilm formation, disruption of the biofilm to allow penetration of topical antimicrobial agents, interference with quorum sensing, and enhancement of bacteria dispersion from biofilms to a more easily destroyed planktonic state.