Design and Evaluation of Microemulsion-Based Drug Delivery Systems for Biofilm-Based Infection in Burns.

Normal skin is the first line of defense in the human body. A burn injury makes the skin susceptible to bacterial infection, thereby delaying wound healing and ultimately leading to sepsis. The chances of biofilm formation are high in burn wounds due to the presence of avascular necrotic tissue. The most common pathogen to cause burn infection and biofilm is Pseudomonas aeruginosa. The purpose of this study was to create a microemulsion (ME) formulation for topical application to treat bacterial burn infection. In the present study, tea tree oil was used as the oil phase, Tween 80 and transcutol were used as surfactants, and water served as the aqueous phase. Pseudo ternary phase diagrams were used to determine the design space. The ranges of components as suggested by the design were chosen, optimization of the microemulsion was performed, and in vitro drug release was assessed. Based on the characterization studies performed, it was found that the microemulsion were formulated properly, and the particle size obtained was within the desired microemulsion range of 10 to 300 nm. The I release study showed that the microemulsion followed an immediate release profile. The formulation was further tested based on its ability to inhibit biofilm formation and bacterial growth. The prepared microemulsion was capable of inhibiting biofilm formation.

Investigation into antibacterial and wound healing properties of platelets lysate against Acinetobacter baumannii and Klebsiella pneumoniae burn wound infections.

BACKGROUND AND AIM: Treatment of burn wound infections has become a global challenge due to the spread of multidrug-resistant bacteria; therefore, the development of new treatment options for the mentioned infections is essential. Platelets have drawn much attention for this purpose because they are a safe and cost-effective source of different antimicrobial peptides and growth factors. The present study evaluated antibacterial effects and wound healing properties of Platelet-derived Biomaterial (PdB) against Acinetobacter baumannii and Klebsiella pneumoniae burn wound infections. METHODS: PdB was prepared through the freezing and thawing process and then, in vitro antibacterial effect was determined by disk diffusion and broth microdilution methods. Afterward, burn wound was inflicted on 56 rats, infected with both bacteria, and topical administration was performed to evaluate antibacterial effects and wound healing properties of PdB. RESULTS: In vitro results showed that PdB inhibited the growth of A. baumannii in the highest dose (0.5), while we did not detect any inhibitory effects against K. pneumoniae. By contrast, PdB significantly inhibited the growth of bacteria in treated animal wounds compared to the control groups (P value < 0.05). Macroscopic assessments pointed to the significant enhancement of wound closure in the treated animals. In addition, histopathological examination demonstrated that treatment of rats with PdB led to a considerable increase in re-epithelialization and attenuated the formation of granulation tissue (P value < 0.05). CONCLUSION: The use of topical PdB is an attractive strategy for treating A. baumannii and K. pneumoniae burn wound infections because it inhibits bacterial growth and promotes wound healing properties.

ANTIMICROBIAL WOUND DRESSINGS FOR FULL-THICKNESS INFECTED BURN WOUNDS.

ABSTRACT: Infection of wounds delays healing, increases treatment costs, and leads to major complications. Current methods to manage such infections include antibiotic ointments and antimicrobial wound dressings, both of which have significant drawbacks, including frequent reapplication and contribution to antimicrobial resistance. In this work, we developed wound dressings fabricated with a medical-grade polyurethane coating composed of natural plant secondary metabolites, cinnamaldehyde, and alpha-terpineol. Our wound dressings are easy to change and do not adhere to the wound bed. They kill gram-positive and -negative microbes in infected wounds due to the Food and Drug Administration-approved for human consumption components. The wound dressings were fabricated by dip coating. Antimicrobial efficacy was determined by quantifying the bacteria colonies after a 24 h of immersion. Wound healing and bacterial reduction were assessed in an in vivo full-thickness porcine burn model. Our antimicrobial wound dressings showed a > 5-log reduction (99.999%) of different gram-positive and gram-negative bacteria, while maintaining absorbency. In the in vivo porcine burn model, our wound dressings were superior to bacitracin in decreasing bacterial burden during daily changes, without interfering with wound healing. Additionally, the dressings had a significantly lower adhesion to the wound bed. Our antimicrobial wound dressings reduced the burden of clinically relevant bacteria more than commercial antimicrobial wound dressings. In an in vivo infected burn wound model, our coatings performed as well or better than bacitracin. We anticipate that our wound dressings would be useful for the treatment of various types of acute and chronic wounds.

An ultrathin poly(L-lactic acid) nanosheet as a burn wound dressing for protection against bacterial infection.

Burn wounds are highly susceptible to bacterial infection due to impairment of the skin's integrity. Therefore, prevention of bacterial colonization/infection in the wound is crucial for the management of burns, including partial-thickness burn injuries. Although partial-thickness burn injuries still retain the potential for reepithelialization, the complication of wound infection severely impairs the reepithelialization even in such superficial burn injuries. We recently developed a biocompatible nanosheet consisting of poly(L-lactic acid) (PLLA). The PLLA nanosheets have many useful and advantageous biological properties for their application as a wound dressing, such as sufficient flexibility, transparency, and adhesiveness. We herein investigated the suitability of the PLLA nanosheets as a wound dressing for partial-thickness burn wounds in mice. The PLLA nanosheets tightly adhered to the wound without any adhesive agents. Although wound infection with Pseudomonas aeruginosa in the controls significantly impaired reepithelialization of burn wounds, dressing with the PLLA nanosheet markedly protected against bacterial wound infection, thereby improving wound healing in the mice receiving partial-thickness burn injuries. The PLLA nanosheet also showed a potent barrier ability for protecting against bacterial penetration in vitro. The ultrathin PLLA nanosheet may be applied as a protective dressing to reduce environmental contamination of bacteria in a partial-thickness burn wound.

Structural and biological evaluation of a multifunctional SWCNT-AgNPs-DNA/PVA bio-nanofilm.

A bio-nanofilm consisting of a tetrad nanomaterial (nanotubes, nanoparticles, DNA, polymer) was fabricated utilizing in situ reduction and noncovalent interactions and it displayed effective antibacterial activity and biocompatibility. This bio-nanofilm was composed of homogenous silver nanoparticles (AgNPs) coated on single-walled carbon nanotubes (SWCNTs), which were later hybridized with DNA and stabilized in poly(vinyl alcohol) (PVA) in the presence of a surfactant with the aid of ultrasonication. Electron microscopy and bio-AFM (atomic force microscopy) images were used to assess the morphology of the nanocomposite (NC) structure. Functionalization and fabrication were examined using FT-Raman spectroscopy by analyzing the functional changes in the bio-nanofilm before and after fabrication. UV-visible spectroscopy and X-ray powder diffraction (XRD) confirmed that AgNPs were present in the final NC on the basis of its surface plasmon resonance (370 nm) and crystal planes. Thermal gravimetric analysis was used to measure the percentage weight loss of SWCNT (17.5%) and final SWCNT-AgNPs-DNA/PVA (47.7%). The antimicrobial efficiency of the bio-nanofilm was evaluated against major pathogenic organisms. Bactericidal ratios, zone of inhibition, and minimum inhibitory concentration were examined against gram positive and gram negative bacteria. A preliminary cytotoxicity analysis was conducted using A549 lung cancer cells and IMR-90 fibroblast cells. Confocal laser microscopy, bio-AFM, and field emission scanning electron microscopy (FE-SEM) images demonstrated that the NCs were successfully taken up by the cells. These combined results indicate that this bio-nanofilm was biocompatible and displayed antimicrobial activity. Thus, this novel bio-nanofilm holds great promise for use as a multifunctional tool in burn therapy, tissue engineering, and other biomedical applications.

The Role of Common Solvents against Pseudomonas aeruginosa-Induced Pathogenicity in a Murine Burn Site Infection Model.

Dimethyl sulfoxide (DMSO) and polyethylene glycols (PEGs) are frequently used as potent excipients in pharmaceutical formulations. However, these agents also have an interesting antimicrobial and anti-inflammatory profile that could interfere with the efficacy testing of anti-infective compounds when the latter are solubilized in DMSO or PEGs. Here, we demonstrate the antimicrobial and anti-inflammatory effects of DMSO-PEG400 in a murine Pseudomonas aeruginosa infection model, aiming to draw attention to the appropriate selection of solvents for difficult-to-solubilize anti-infectives. IMPORTANCE Our study demonstrates the antimicrobial and anti-inflammatory effects of the combination of DMSO and PEG400 against Pseudomonas aeruginosa in vitro and in vivo in a murine infection model of heightened intestinal permeability. The aim of this study is to draw attention to the appropriate selection of solvents for difficult-to-solubilize anti-infective compounds, to avoid interference with the assay or system tested. This is an extremely important consideration, since potential antimicrobial and anti-inflammatory effects of the solvent vehicle are detrimental to research studies on the efficacy of new anti-infective agents, given that the vehicle effect can mask the effect of the tested compounds. Our results can therefore be of great value to the scientific community, as they can guide researchers in the future to avoid this significant pitfall that can cost substantial amounts of money and valuable time during investigations of the effects of novel, difficult-to-solubilize antimicrobial compounds.

Natural rubber dressing loaded with silver sulfadiazine for the treatment of burn wounds infected with Candida spp.

Millions of people are burned worldwide every year and 265,000 of the cases are fatal. The development of burn treatment cannot consist only of the administration of a single drug. Due to the infection risk, antibiotics are used in conjunction with gels and damp bandages. In this work, an inexpensive curative based on silver sulfadiazine (SS) and natural rubber latex (NRL) was developed to treat burn wounds. It was produced by the casting method. The infrared spectrum presented no interaction between drug and biopolymer. At the same time, electronic micrographs showed that the SS crystals are inserted on the polymeric dressing surface. Mechanical properties after the drug incorporation were considered suitable for dermal application. About 32.4% of loaded SS was released in 192 h by the dressings that also inhibited the growth of Candida albicans and Candida parapsilosis at 75.0 and 37.5 µg·mL-1, respectively. The curative proved to be biocompatible when applied to fibroblast cells, in addition to enhancing cellular proliferation and, in the hemocompatibility test, no hemolytic effects were observed. The good results in mechanical, antifungal and biological assays, combined with the average bandage cost of $0.10, represent an exciting alternative for treating burn wounds.

Photodisinfection effects of silver sulfadiazine nanoliposomes doped-curcumin on Acinetobacter baumannii: a mouse model.

Aim: To evaluate the antimicrobial effects of photoexcited silver sulfadiazine nanoliposomes (AgSD-NLs) doped by curcumin (AgSD-NLs@Cur) on Acinetobacter baumannii. Materials & methods: Following characterization, the cytotoxic and hemolytic activities of AgSD-NLs@Cur were evaluated. The antimicrobial activities of AgSD-NLs@Cur-mediated antimicrobial photodynamic therapy (aPDT) were determined. Histopathological examination of the burn wound sites of infected mice treated with photoexcited AgSD-NLs@Cur was assessed. Results: No significant cytotoxic and hemolytic activities were observed. There was a decrease in the Acinetobacter baumannii count in planktonic and biofilm forms and the gene expression level using AgSD-NLs@Cur-aPDT (p < 0.05). Histopathological analysis indicated the epidermis developed markedly and the bacterial load decreased significantly after aPDT. Conclusion: Photoexcited AgSD-NLs@Cur has an antimicrobial potential against A. baumannii.

Wound healing properties and antimicrobial activity of platelet-derived biomaterials.

We analyzed the potential antibacterial effects of two different PdB against methicillin-resistant S. aureus and P. aeruginosa. The third-degree burn wound healing effects of PdB was also studied. Blood samples were obtained from 10 healthy volunteers and biological assays of the PdB were performed and the antimicrobial activity against MRSA and P. aeruginosa was determined using disk diffusion (DD), broth microdilution (BMD), and time-kill assay methods. 48 Wistar albino rats were burned and infected with MRSA. Two groups were injected PdB, the control groups were treated with plasma and received no treatment respectively. In the next step, the rats were euthanized and skin biopsies were collected and histopathologic changes were examined. The results of DD and BMD showed that both PdB performed very well on MRSA, whereas P. aeruginosa was only inhibited by F-PdB and was less susceptible than MRSA to PdBs. The time-kill assay also showed that F-PdB has an antibacterial effect at 4 hours for two strains. Histopathological studies showed that the treated groups had less inflammatory cells and necrotic tissues. Our data suggest that PdB may possess a clinical utility as a novel topical antimicrobial and wound healing agent for infected burn wounds.

Multifunctional Antimicrobial Nanofiber Dressings Containing ε-Polylysine for the Eradication of Bacterial Bioburden and Promotion of Wound Healing in Critically Colonized Wounds.

Bacterial colonization of acute and chronic wounds is often associated with delayed wound healing and prolonged hospitalization. The rise of multi-drug resistant bacteria and the poor biocompatibility of topical antimicrobials warrant safe and effective antimicrobials. Antimicrobial agents that target microbial membranes without interfering with the mammalian cell proliferation and migration hold great promise in the treatment of traumatic wounds. This article reports the utility of superhydrophilic electrospun gelatin nanofiber dressings (NFDs) containing a broad-spectrum antimicrobial polymer, ε-polylysine (εPL), crosslinked by polydopamine (pDA) for treating second-degree burns. In a porcine model of partial thickness burns, NFDs promoted wound closure and reduced hypertrophic scarring compared to untreated burns. Analysis of NFDs in contact with the burns indicated that the dressings trap early colonizers and elicit bactericidal activity, thus creating a sterile wound bed for fibroblasts migration and re-epithelialization. In support of these observations, in porcine models of Pseudomonas aeruginosa and Staphylococcus aureus colonized partial thickness burns, NFDs decreased bacterial bioburden and promoted wound closure and re-epithelialization. NFDs displayed superior clinical outcome than standard-of-care silver dressings. The excellent biocompatibility and antimicrobial efficacy of the newly developed dressings in pre-clinical models demonstrate its potential for clinical use to manage infected wounds without compromising tissue regeneration.

Nano-engineered lipid-polymer hybrid nanoparticles of fusidic acid: an investigative study on dermatokinetics profile and MRSA-infected burn wound model.

Staphylococcus aureus (SA) and methicillin-resistant Staphylococcus aureus (MRSA) have been a major cause of morbidity in thermally injured patients. The skin barrier gets disrupted and loss of immunity further makes burn sites an easy target for bacterial colonization. In the current study, combined potential of lipid-polymer hybrid nanoparticles (LPHNs) with fusidic acid was explored as a promising strategy toward combating resistant bacteria in burn wound infection sites. The developed systems exhibited particle size (310.56 ± 5.22 nm), zeta potential (24.3 ± 4.18 mV) and entrapment efficiency (78.56 ± 3.56%) with a spherical shape. The hybrid nanoparticles were further gelled into carbopol and demonstrated better permeation (76.53 ± 1.55%) and retention characteristics (56.41 ± 4.67%) as compared to the conventional formulation. The topical delivery of FA into the skin layers by FA-LPHN gel was found to be significantly higher (p < 0.05) compared to FA-CC. The in vivo potential was further assessed in murine burn wound model inflicted with MRSA 33591 bacterium with the determination of parameters like bacterial burden, wound contraction, morphological and histopathological examination of wounds. The bacterial count decreased drastically in FA-LPHN gel group (5.22 log CFU/mL) on day 3 with significant difference in comparison to FA-CC. The wound size reduction in FA-LPHN gel (68.70 ± 3.65%) was higher as compared to FA-CC (73.30 ± 4.23%) and control groups (83.30 ± 4.40%) on day 5. The current study presents a safe and effective formulation strategy for the treatment of MRSA-infected burn wounds by providing moist environment and prevention from bacterial infection.

"Smart" polymer enhances the efficacy of topical antimicrobial agents.

The delivery of antimicrobial agents to surface wounds has been shown to be of central importance to the wound healing process. In this work, we prepared film forming wound care formulations containing 3 polymers (FTP) that provide broad-spectrum antimicrobial protection for prolonged periods. FTP formulations comprises of a smart gel matrix comprising of pH-degradable and temperature responsive polyacetals (smart polymer) which allow for the FTP films to be hydrophobic at room temperature, preventing accidental rubbing off, and hydrophilic at lower temperatures, allowing for easy removal. Two FTP smart-antimicrobial films were evaluated in this work: FTP-AgSD (Silver sulfadiazine actives), and FTP-NP (Neosporin actives). The in vitro and ex vivo antimicrobial efficacy studies show that FTP-AgSD films are significantly more effective for longer durations against Staphylococcus aureus (3 days), Candida albicans (9 days) and Pseudomonas aeruginosa (4 days) when compared to the cream formulations containing antimicrobials. FTP-NP films showed significantly improved antimicrobial activity for a minimum of 3 days for all pathogens tested. Moreover, when tested ex vivo in porcine skin, FTP-AgSD and FTP-NP showed average improvements of 0.89 log10 and 1.66 log10 respectively over standard cream counterparts. Dermal toxicity studies were carried out in a rat skin excision model which showed a similar wound healing pattern to that in rats treated with standard cream formulations as represented by reduction in wound size, and increase in wound healing markers.

Preparation of hydroxylated lecithin complexed iodine/carboxymethyl chitosan/sodium alginate composite membrane by microwave drying and its applications in infected burn wound treatment.

Improving the antibacterial properties of membrane wound dressings of natural polymers is crucial. Iodine is an important safe inorganic antibacterial agent, but was confined in the composition with polymer membranes due to the challenges of homogeneity and stability during drying. In the present work, iodine was complexed with hydroxylated lecithin (HL) to improve its stability and complexing efficiency for the composition with carboxymethly chitosan/sodium alginate. With the aid of microwave drying, hydroxylated lecithin complexed iodine/carboxymethly chitosan/sodium alginate (HLI/CMCS/SA) composite membranes with homogeneously distributions of HLI, high contents of activated iodine, good mechanical and swelling properties, proper water vapor permeability, pH controllable iodine release and excellent antibacterial properties were prepared. The composite membranes exhibited high repairing efficiencies for the infection of a rat model of the seawater immersed wound infection of deep partial-thickness burns. This novel antibacterial composite membrane can be potentially used as a high performance wound dressing for treating and repairing open trauma infections.

Bioadhesive polymeric films based on usnic acid for burn wound treatment: Antibacterial and cytotoxicity studies.

Usnic acid (UA) is a lichenic secondary metabolite useful for the treatment of burn wounds thanks to its antimicrobial activity, particularly toward strains responsible for their infections. However, the poor solubility is the main factor limiting the activity and thus its use in health care products. Adhesive polymeric films were designed to improve UA use by enhancing its bioavailability in the wounded tissues. Three different NaCMC hydrogel films, NaCMC 2% alone (F1), mixed to PVP K90 0.1% (F2) or to Carbopol 971 P 0.1% (F3), were prepared by casting method. Ex vivo experiments performed on pig skin samples showed their suitable adhesion capacity. in vitro release test, performed using the extraction cell, showed that film F2 provides the highest UA concentrations. Differential scanning calorimetry and X-ray analyses performed on the three films highlighted that UA is present in a more soluble form in F2. The in vitro antibacterial activity studies demonstrated that F2 is the most effective film against UA sensitive bacteria S. Epidermidis, E. Faecalis, B. Cereus and S. Pyogenes. In vitro cytotoxicity assays on human keratinocytes and fibroblasts showed that cells viability is not compromised.

Phenylboronic Acid Functionalized Polycarbonate Hydrogels for Controlled Release of Polymyxin B in Pseudomonas Aeruginosa Infected Burn Wounds.

While physically crosslinked polycarbonate hydrogels are effective drug delivery platforms, their hydrophobic nature and lack of side chain functionality or affinity ligands for controlled release of hydrophilic drugs underscore the importance of their chemical compositions. This study evaluates an array of anionic hydrogel systems of phenylboronic acid functionalized triblock copolymers prepared via reversible physical interactions. Variation of key chemical functionalities while maintaining similar core structural features demonstrates the influence of the substitution position and protection of the boronic acid functionality on gel viscoelasticity and mechanical strength at physiological pH. The optimum gel systems obtained from the meta-substituted copolymers (m-PAP) are stable at physiological pH and nontoxic to mammalian dermal cells. The polymyxin B loaded m-PAP hydrogels demonstrate controlled in vitro drug release kinetics and in vitro antimicrobial activity against Pseudomonas aeruginosa over 48 h. In vivo antimicrobial efficacy of the drug loaded hydrogels further corroborates the in vitro results, demonstrating sustained antimicrobial activity against P. aeruginosa burn wound infections. The current strategy described in this study demonstrates a straightforward approach in designing physiologically relevant boronic acid hydrogel systems for controlled release of cationic antimicrobials for future clinical applications.

A randomized comparative trial between Acticoat and SD-Ag in the treatment of residual burn wounds, including safety analysis.

OBJECTIVE: To investigate and evaluate the clinical efficacy and safety of Acticoat with nanocrystalline silver for external use on the management of the residual wounds post-burn. METHODS: One hundred and sixty-six wounds of 98 burn patients were enrolled and divided into Acticoat group and silver sulfadiazine group in the multi-center randomized clinical trial. Acticoat was used as the treated group for those who have redness, swelling, and excessive secretion ("heavy" exudates) in the wound, Acticoat was changed once a day. When there is not much secretion in the wound, or redness and swelling were not obvious, the dressings were changed once every 3 days. Silver sulfadiazine (SD-Ag) was used as control group, which was treated under the usual clinical routine. Healing time was observed up to 20 days. Healing percentage on the 15th day after treatment was determined. RESULTS: Healing time was 12.42+/-5.40 days after the application of Acticoat. This was significantly shorter than that of control wounds. The wounds of the trial group healed nearly 3.35 days earlier than the control ones. Healing percentage at 15 days in the trial wounds was 97.37%, which was higher than the control, but there was no significant difference between them. The bacterial clearance rate of the Acticoat group on the 6th and 12th day post-treatment was 16.67 and 26.67%, respectively, which was significantly higher than the control. CONCLUSIONS: Acticoat with nanocrystalline silver promotes the healing process of residual wounds post-burn effectively. No adverse reaction of Acticoat was found during the study.

Bio-inspired crosslinking and matrix-drug interactions for advanced wound dressings with long-term antimicrobial activity.

There is a growing demand for durable advanced wound dressings for the management of persistent infections after deep burn injuries. Herein, we demonstrated the preparation of durable antimicrobial nanofiber mats, by taking advantage of strong interfacial interactions between polyhydroxy antibiotics (with varying number of OH groups) and gelatin and their in-situ crosslinking with polydopamine (pDA) using ammonium carbonate diffusion method. Polydopamine crosslinking did not interfere with the antimicrobial efficacy of the loaded antibiotics. Interestingly, incorporation of antibiotics containing more number of alcoholic OH groups (NOH ≥ 5) delayed the release kinetics with complete retention of antimicrobial activity for an extended period of time (20 days). The antimicrobials-loaded mats displayed superior mechanical and thermal properties than gelatin or pDA-crosslinked gelatin mats. Mats containing polyhydroxy antifungals showed enhanced aqueous stability and retained nanofibrous morphology under aqueous environment for more than 4 weeks. This approach can be expanded to produce mats with broad spectrum antimicrobial properties by incorporating the combination of antibacterial and antifungal drugs. Direct electrospinning of vancomycin-loaded electrospun nanofibers onto a bandage gauze and subsequent crosslinking produced non-adherent durable advanced wound dressings that could be easily applied to the injured sites and readily detached after treatment. In a partial thickness burn injury model in piglets, the drug-loaded mats displayed comparable wound closure to commercially available silver-based dressings. This prototype wound dressing designed for easy handling and with long-lasting antimicrobial properties represents an effective option for treating life-threatening microbial infections due to thermal injuries.

Evaluation of a bi-layer wound dressing for burn care. II. In vitro and in vivo bactericidal properties.

We have recently designed a medicated bi-layer wound dressing to address the key requirements for treating external, contaminated war wounds. This study assessed the in vitro and in vivo bactericidal efficacies of the DRDC hydrogel/polyurethane wound dressing. Chloramphenicol- and chlorhexidine-loaded DRDC dressings produced significantly larger zones of inhibition against Pseudomonas aeruginosa than the other medicated dressings for 4 d. Chlorhexidine-loaded Allevyn and Hydrasorb remained bactericidal for 48 h only. Chloramphenicol-loaded Hydrasorb and Allevyn remained bactericidal for 1 and 3 d, respectively. Ps. aeruginosa and Staphylococcus epidermidis counts in wounds treated with chlorhexidine- and chloramphenicol-loaded DRDC dressings for 24 h were 1-3-log lower than those of control wounds. While Ps. aeruginosa counts in the wounds on day 4 were comparable following daily changes of either antiseptic-loaded dressings, chlorhexidine showed a 75% greater bactericidal efficacy against Staph. epidermidis than chloramphenicol. Though increasing the frequency of dressing changes led to a greater reduction in the wound bacterial load, the contamination levels of all antiseptic-treated wounds remained below 10(5) CFU/g of wound. Cerium nitrate-loaded dressings did not exert any bactericidal effect, irrespective of the experimental conditions. These data show that the DRDC dressing is effective in delivering medications, such as an antimicrobial agent, to the wound bed.

Nanoemulsion Therapy for Burn Wounds Is Effective as a Topical Antimicrobial Against Gram-Negative and Gram-Positive Bacteria.

The aim of this study is to investigate the antimicrobial efficacy of two different nanoemulsion (NE) formulations against Gram-positive and Gram-negative bacteria in an in vivo rodent scald burn model. Male Sprague-Dawley rats were anesthetized and received a partial-thickness scald burn. Eight hours after burn injury, the wound was inoculated with 1 × 10(8) colony-forming units of Pseudomonas aeruginosa or Staphylococcus aureus. Treatment groups consisted of two different NE formulations (NB-201 and NB-402), NE vehicle, or saline. Topical application of the treatment was performed at 16 and 24 hours after burn injury. Animals were killed 32 hours after burn injury, and skin samples were obtained for quantitative wound culture and determination of dermal inflammation markers. In a separate set of experiments, burn wound progression was measured histologically after 72 hours of treatment. Both NE formulations (NB-201 and NB-402) significantly reduced burn wound infections with either P. aeruginosa or S. aureus and decreased median bacterial counts at least three logs when compared with animals with saline applications (p < .0001). NB-201 and NB-402 also decreased dermal neutrophil recruitment and sequestration into the wound as measured by myeloperoxidase (MPO) assay and histopathology (p < .05). In addition, there was a decrease in the proinflammatory dermal cytokines (interleukin 1-beta [IL-1ß], IL-6, and tumor necrosis factor alpha [TNF-α]) and the neutrophil chemoattractants CXCL1 and CXCL2. Using histologic examination, it was found that both NB-201 and NB-402 appeared to suppress burn wound progression 72 hours after injury. Topically applied NB-201 and NB-402 are effective in decreasing Gram-positive and Gram-negative bacteria growth in burn wounds, reducing inflammation, and abrogating burn wound progression.

Comparison of silver-coated dressing (Acticoat), chlorhexidine acetate 0.5% (Bactigrass), and fusidic acid 2% (Fucidin) for topical antibacterial effect in methicillin-resistant Staphylococci-contaminated, full-skin thickness rat burn wounds.

Acticoat, chlorhexidine acetate 0.5%, and fusidic acid 2% were compared to assess the antibacterial effect of an application on experimental 15% BSA, full-thickness burn wounds in rats swabbed 24 h earlier with a 10(8) standard strain of methicillin-resistant Staphylococci. The swabbed organism was recovered from the eschar of all groups except the fusidic acid group. While there were significant differences between treatment groups and control group, the mean eschar concentrations did not differ significantly between the Acticoat and chlorhexidine acetate groups, but there were significant differences between the fusidic acid group and the other treatment groups. There were no statistically significant differences between treatment groups, and between control group and the chlorhexidine acetate group regarding recovery of the seeded organism from muscle, but there were significant differences between the control group and Acticoat group, and between control the group and the fusidic acid group. While no systemic spread was seen in the treatment groups, it was seen in six animals in the control group. The animal data suggest that fusidic acid is the most effective agent in the treatment of methicillin-resistant Staphylococcus aureus-contaminated burn wounds, and Acticoat is a choice of treatment with the particular advantage of limiting the frequency of replacement of the dressing.