Topical Antimicrobials in Burn Care: Part 1-Topical Antiseptics

Life Cycle of Functional All-Green Biocompatible Fibrous Materials Based on Biodegradable Polyhydroxybutyrate and Hemin: Synthesis, Service Life, and the End-of-Life via Biodegradation

This article addresses the entire life cycle of the all-green fibrous materials based on poly(3-hydroxybutyrate) (PHB) containing a natural biocompatible additive Hemin (Hmi): from preparation, service life, and the end of life upon in-soil biodegradation. Fibrous PHB/Hmi materials with a highly developed surface and interconnected porosity were prepared by electrospinning (ES) from Hmi-containing feed solutions. Structural organization of the PHB/Hmi materials (porosity, uniform structure, diameter of fibers, surface area, distribution of Hmi within the PHB matrix, phase composition, etc.) is shown to be governed by the ES conditions: the presence of even minor amounts of Hmi in the PHB/Hmi (below 5 wt %) serves as a powerful tool for the control over their structure, performance, and biodegradation. Service characteristics of the PHB/Hmi materials (wettability, prolonged release of Hmi, antibacterial activity, breathability, and mechanical properties) were studied by different physicochemical methods (scanning electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, differential scanning calorimetry, contact angle measurements, antibacterial tests, etc.). The effect of the structural organization of the PHB/Hmi materials on their in-soil biodegradation at the end of life was analyzed, and key factors providing efficient biodegradation of the PHB/Hmi materials at all stages (from adaptation to mineralization) are highlighted (high surface area and porosity, thin fibers, release of Hmi, etc.). The proposed approach allows for target-oriented preparation and structural design of the functional PHB/Hmi nonwovens when their structural supramolecular organization with a highly developed surface area controls both their service properties as efficient antibacterial materials and in-soil biodegradation upon the end of life.

Surviving Sepsis After Burn Campaign

INTRODUCTION

The Surviving Sepsis Campaign was developed to improve outcomes for all patients with sepsis. Despite sepsis being the primary cause of death after thermal injury, burns have always been excluded from the Surviving Sepsis efforts. To improve sepsis outcomes in burn patients, an international group of burn experts developed the Surviving Sepsis After Burn Campaign (SSABC) as a testable guideline to improve burn sepsis outcomes.

METHODS

The International Society for Burn Injuries (ISBI) reached out to regional or national burn organizations to recommend members to participate in the program. Two members of the ISBI developed specific "patient/population, intervention, comparison and outcome" (PICO) questions that paralleled the 2021 Surviving Sepsis Campaign [1]. SSABC participants were asked to search the current literature and rate its quality for each topic. At the Congress of the ISBI, in Guadalajara, Mexico, August 28, 2022, a majority of the participants met to create "statements" based on the literature. The "summary statements" were then sent to all members for comment with the hope of developing an 80% consensus. After four reviews, a consensus statement for each topic was created or "no consensus" was reported.

RESULTS

The committee developed sixty statements within fourteen topics that provide guidance for the early treatment of sepsis in burn patients. These statements should be used to improve the care of sepsis in burn patients. The statements should not be considered as "static" comments but should rather be used as guidelines for future testing of the best treatments for sepsis in burn patients. They should be updated on a regular basis.

CONCLUSION

Members of the burn community from the around the world have developed the Surviving Sepsis After Burn Campaign guidelines with the goal of improving the outcome of sepsis in burn patients.

Sprayable ciprofloxacin-loaded poloxamer hydrogels for wound infection treatment

Topical antimicrobial treatments for severe burns and chronic wounds provide effective treatment against infections, but cause pain and discomfort with application. This study aimed to develop an antimicrobial topical formulation comprising thermoreversible poloxamers (Pluronic F127 and F68) and a broad-spectrum antimicrobial agent (ciprofloxacin hydrochloride, CH), that could be sprayed to eliminate application pain while maintaining antimicrobial activity. Formulations were characterized to determine their sprayability under cold conditions, gelation temperature, final storage modulus at skin temperature, drug release profile, ex vivo permeation through impaired porcine skin, and inhibition against common bacterial pathogens that colonize wounds. All cold formulations were sprayable from simple hand-held, pump-action sprayers due to their low viscosity. Upon heating, 17 and 20% Pluronic F127 formulations produced hydrogels eight to ten degrees below skin temperature, independent of ciprofloxacin loading. Increasing concentrations of Pluronic F127 increased the final storage modulus and viscosity of the gels, while inclusion of Pluronic F68 reduced these properties, showing that hydrogel rheological properties at skin temperature can be tuned via choice of formulation. Drug release was directly correlated to the rheological properties, with stiffer gels resulting in a decrease in drug release rate. Overall, gels released about 65-90% of their load within 12 hours. Ex vivo skin permeation demonstrated that drug was well retained in impaired porcine skin, which is desired to continuously treat bacteria localized to the wound. A well-diffusion assay indicated that the hydrogels had greater bacterial inhibition against Pseudomonas aeruginosa, Escherichia coli, and two strains of Staphylococcus aureus when compared to commercial controls. Overall, the results show the potential of CH-loaded poloxamer formulations as suitable sprayable topical dressings to deliver antimicrobials directly to wounds.

Antimicrobial Wound Dressings: A Concise Review for Clinicians

Wound management represents a substantial clinical challenge due to the growing incidence of chronic skin wounds resulting from venous insufficiency, diabetes, and obesity, along with acute injuries and surgical wounds. The risk of infection, a key impediment to healing and a driver of increased morbidity and mortality, is a primary concern in wound care. Recently, antimicrobial dressings have emerged as a promising approach for bioburden control and wound healing. The selection of a suitable antimicrobial dressing depends on various parameters, including cost, wound type, local microbial burden and the location and condition of the wound. This review covers the different types of antimicrobial dressings, their modes of action, advantages, and drawbacks, thereby providing clinicians with the knowledge to optimize wound management.

In vitro efficacy of 0.2% and 0.4% sodium oxychlorosene against meticillin-resistant Staphylococcus pseudintermedius

BACKGROUND

There is a need for alternative topical therapies as a consequence of the increased prevalence of meticillin-resistant Staphylococcus pseudintermedius (MRSP) skin infections in dogs. Sodium oxychlorosene has been used as a topical antibacterial agent in human medicine since 1955.

OBJECTIVES

To determine whether 0.2% and 0.4% sodium oxychlorosene solutions have a bactericidal effect (>3-log reduction) on MRSP strains isolated from canine skin infections.

METHODS AND MATERIALS

A genetically heterogeneous collection of MRSP isolates from dogs was assembled from laboratories across the United States. Time-kill assays were performed with 0.2% and 0.4% sodium oxychlorosene on a 0.5 McFarland standard [approximately 10⁸ colony-forming units (cfu/ml)] suspension of each strain. The average bacterial counts (cfu/ml) of each MRSP strain then were determined at 5, 10, 20 and 60 s after exposure to sodium oxychlorosene; cfu/ml data were converted to log₁₀ scale to calculate microbial reduction.

RESULTS

The average bacterial counts following exposure to the 0.2% solution at 5, 10, 20 and 60 s were 6.94 × 10⁴ , 5.63 × 10³ , 2.96 × 10² and 1.48 × 10²  cfu/ml, respectively. For the 0.4% solution, the average bacterial count at 5 s was 2.12 × 10³  cfu/ml. No bacterial growth was observed for any MRSP strain by 10 s. The greatest reduction in cfu/ml occurred within 5 s following exposure to each solution 3.4-log and 4.9-log reduction for 0.2% and 0.4%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

0.2% and 0.4% sodium oxychlorosene solutions have a bactericidal effect (>99.9% reduction) against MRSP in vitro. Further in vivo studies are necessary to determine whether it is an appropriate alternative therapy for canine pyoderma.

Blue Light Improves Antimicrobial Efficiency of Silver Sulfadiazine Via Catalase Inactivation

Background: Blue light exhibits the ability to deactivate catalase present in pathogens, significantly improving the antimicrobial performance of compounds such as hydrogen peroxide (H2O2). However, H2O2 is not used within clinical settings due to its short half-life, limiting its potential applications. In this study, we explore the usage of Food and Drug Administration-approved and clinically used silver sulfadiazine (SSD) as a potential alternative to H2O2, acting as a reactive oxygen species (ROS)-producing agent capable of synergizing with blue light exposure. Materials and methods: For in vitro studies, bacterial strains were exposed to a continuous wave 405 nm light-emitting diode (LED) followed by treatment with SSD for varying incubation times. For in vivo studies, bacteria-infected murine abrasion wounds were treated with daily treatments of 405 nm LED light and 1% SSD cream for up to 4 days. The surviving bacterial population was quantified through agar plating and colony-forming unit quantification. Results: Through a checkerboard assay, blue light and SSD demonstrated synergistic interactions. Against both gram-negative and gram-positive pathogens, blue light significantly improved the antimicrobial response of SSD within both phosphate-buffered saline and nutrient-rich conditions. Examination into the mechanisms reveals that the neutralization of catalase significantly improves the ROS-producing capabilities of SSD at the exterior of the bacterial cell, producing greater amounts of toxic ROS capable of exerting antimicrobial activity against the pathogen. Additional experiments reveal that the incorporation of light improves the antimicrobial performance of SSD within methicillin-resistant Staphylococcus aureus (MRSA)- and Pseudomonas aeruginosa strain 1 (PAO-1)-infected murine abrasion wounds. Conclusions: As an established, clinically used antibiotic, SSD can act as a suitable alternative to H2O2 in synergizing with catalase-deactivating blue light, allowing for better translation of this technology to more clinical settings and further implementation of this treatment to more complex animal models.

Pediatric First-Degree Burn Management With Honey and 1% Silver Sulfadiazine (Ag-SD): Comparison and Contrast

Background The cardinal area of managing fire wounds is guided by adequately evaluating the burn-induced lesion's profundity and size. Superficial second-degree burns are often treated through daily reinstating with fresh sterile bandaging with appropriate topical antimicrobials to allow rapid spontaneous epithelialization. Around the world, a wide variety of substances are used to treat these wounds, from honey to synthetic biological dressings. Objective This study intended to determine honey's therapeutic potential compared with 1% silver sulfadiazine (Ag-SD) in arsenal-caused contusion medicament fulfillment. Methods A total of 70 cases were evaluated in this research work after fulfilling the required selection criteria during the study period of January 2014 to December 2014 and January 2017 to December 2017. Purposive selection criteria were adopted in the study to select research patients. The patients in Group-1 (n = 35) relied on honey as medication, while patients in Group-2 (n = 35) relied on 1% Ag-SD. Results In Group-1, exudation (68.4%) and sloughing (82.9%) were substantially reduced by Days 3 and 5 of therapeutic intervention, respectively. However, in Group-2, a reduction of exudation (17.1%) and sloughing (22.9%) occurred after Days 3 and 5 of treatment, respectively. Completion of the epithelialization process was observed among Group-1 and Group-2 cases. It was detected after Days 7 and 10 of treatment at 36.3% and 77% (Group-1) and 27% and 67% (Group-2), respectively. Around 3 ml of 1% honey was required per body surface area per dressing in Group-1. On the other hand, in Group-2, 2 gm Ag-SD was needed per body surface area per dressing. Conclusion Patients treated with honey found better clinical outcomes in managing superficial partial-thickness burns.

Robbing Peter to Pay Paul: Chlorhexidine gluconate demonstrates short-term efficacy and long-term cytotoxicity

Wound cleansing agents are routine in wound care and preoperative preparation. Antiseptic activity intends to prevent contaminating microbes from establishing an infection while also raising concerns of cytotoxicity and delayed wound healing. We evaluated the cytotoxicity of five clinically used wound cleaning agents (saline, povidone iodine, Dove® and Dial® soaps, and chlorhexidine gluconate [CHG]) using both an ex vivo and in vivo human skin xenograft mouse model, in contrast to classical in vitro models that lack the structural and compositional heterogeneity of human skin. We further established an ex vivo wound contamination model inoculated with ~100 cells of Pseudomonas aeruginosa or Staphylococcus aureus to evaluate antimicrobial efficacy. Scanning electron microscopy and confocal microscopy were used to evaluate phenotypic and spatial characteristics of bacterial cells in wound tissue. CHG significantly reduced metabolic activity of the skin explants, while all treatments except saline affected local cellular viability. CHG cytotoxicity persisted and progressed over 14 days, impairing wound healing in vivo. Within the contamination model, CHG treatment resulted in a significant reduction of P. aeruginosa wound surface counts at 24 h post-treatment. However, this effect was transient and serial application of CHG had no effect on both P. aeruginosa or S. aureus microbial growth. Microscopy revealed that viable cells of P. aeruginosa reside deep within wound tissue post-CHG application, likely serving as a reservoir to re-populate the tissue to a high bioburden. We reveal concerning cytotoxicity and limited antimicrobial activity of CHG in human skin using clinically relevant models, with the ability to resolve spatial localization and temporal dynamics of tissue viability and microbial growth.

Topical Antimicrobial Agents for the Prevention of Burn-Wound Infection. What Do International Guidelines Recommend? A Systematic Review

Background

Choosing adequate topical antimicrobial agents in burn patients still represents a challenge. Therefore, this systematic review was conducted to compile and evaluate current recommendations in international clinical practice guidelines (CPGs) to develop more consistent clinical guidance.

Methods

A systematic search for CPGs was conducted independently by two reviewers using PubMed, EMBASE, Google Scholar, and external citations. The quality of the selected CPGs was evaluated separately using the AGREE II instrument, and intraclass correlation coefficients were calculated. Statistical analysis was performed using R V 1.4.1 statistical software.

Results

Eleven CPGs were included in the study. Most guidelines tend to recommend silver-containing dressings over antiseptics or antibiotics, regardless of the depth of the burn. Silver sulfadiazine is the most recommended topical antimicrobial in low-resource settings. An overall mean appraisal AGREE II score of 68.2% was obtained. The global intraclass correlation coefficient was 0.62 (95% confidence intervals 0.54-0.69), which corresponds to a substantial global concordance between both appraisers.

Conclusions

Great heterogeneity was found between recommendations and CPGs. The three determining factors considered to issue a recommendation were the clinical scenario, burn-wound depth, and burn severity. There is consensus among the guidelines to use topical antimicrobials as a tool to prevent infection, and most of these recommend the use of silver-containing dressings for most scenarios. However, there is currently no ideal topical antimicrobial agent that can be recommended for all clinical scenarios. The development of more consistent recommendations is warranted to standardize clinical practice.

Satisfaction and Functional Outcome of Surgical Treatment in Patients with Brachial Plexus Injury: A Decade of Retrospective Comparative Study

Background

Brachial plexus injury (BPI) is a severe peripheral nerve injury resulting in physical disability. Few studies have investigated the postoperative functional status. We aimed to evaluate the satisfaction with surgical treatment in patients with BPI referred to the Panzdah-e Khordad Hospital, Tehran, Iran from 2011 to 2021.

Methods

In this descriptive-analytical retrospective comparative study, physical examination, along with BrAT, and DASH questionnaires were used to evaluate the patients' status. Then the collected data on the patients' functional status and movements were collected. To compare the mean of quantitative variables before and after the surgery, the dependent t-student was used.

Results

Generally, the patients stated that they still had considerable difficulty doing most of the items of the questionnaires. Nevertheless, there was a significant difference between the following variables before and after surgery; shoulder abduction goniometry (0-150) and force (M0:M5), shoulder external rotation goniometry (0-90) and force (M0:M5)), shoulder forward flexion goniometry (0-180) and force (M0:M5)), elbow flexion goniometry (0- 150), elbow extension force (M0:M5), and wrist and finger muscle force (M0:M5) (P<0.001).

Conclusion

Posterior approach in BPI surgery was associated with good outcomes in terms of shoulder external rotation and abduction. However, patients still suffered from difficulties in daily activities.

The effect of NPWT in wound healing and bacterial count on deep dermal burn injury model: An experimental study

Background

Sepsis is one of the main causes in burn victim's mortality. The use of negative pressure wound therapy (NPWT) provides an ideal environment to accelerate wound healing. We compare the use of normal saline (NS), intermittent NPWT, continuous NPWT and silver sulfadiazine in wound healing process.

Method

This study involved 6 Yorkshire pigs; each pig was induced with 20 burns on the flank area. Burns were divided into 4 treatment groups: NS gauze, intermittent NPWT, continuous NPWT, and silver sulfadiazine dressing. Burns were evaluated on day 1,3,7,14, and 21 for its morphology and bacterial colonization and on day 14 and 21 for the remaining burn surface area.

Result

Wound that received NPWT therapy appeared better in both granulation and crust formation. Remaining burn surface area (mm²) on day 14 in NS group, intermittent NPWT, continuous NPWT, and silver sulfadiazine were 107.43 ± 83.43, 178.07 ± 74.83, 146.10 ± 69.1, 126.03 ± 83.22, respectively(p = 0.457); on day 21 in NS group, intermittent NPWT, continuous NPWT, and silver sulfadiazine were 13.16 ± 16.86, 59.49 ± 20.72, 54.79 ± 46.59, 48.95 ± 39.84, respectively(p=0.169). There were no significant differences in each treatment group bacterial colonization(p>0.05). There were no significant correlation between bacterial colonization and remaining burn surface area (p>0.05).

Conclusion

While morphologically, the wound in NPWT treatment groups appeared better in granulation and crust formation, the remaining wound surface area and the number of bacterial colonization were not significantly difference compared to standard therapy (silver sulfadiazine and NS gauze). There were no significant correlation between the amount of bacterial colonization and remaining wound surface area on every treatment group.

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Sepsis is one of cause burn injury mortality.

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NPWT is promising burn injury treatment.

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There was no significant difference of wound healing in various treatments.

Staphylococcus saprophyticus Causing Infections in Humans Is Associated with High Resistance to Heavy Metals

Staphylococcus saprophyticus is a common pathogen of the urinary tract, a heavy metal-rich environment, but information regarding its heavy metal resistance is unknown. We investigated 422 S. saprophyticus isolates from human infection and colonization/contamination, animals, and environmental sources for resistance to copper, zinc, arsenic, and cadmium using the agar dilution method. To identify the genes associated with metal resistance and assess possible links to pathogenicity, we accessed the whole-genome sequence of all isolates and used in silico and pangenome-wide association approaches. The MIC values for copper and zinc were uniformly high (1,600 mg/liter). Genes encoding copper efflux pumps (copA, copB, copZ, mco, and csoR) and zinc transporters (zinT, czrAB, znuBC, and zur) were abundant in the population (20 to 100%). Arsenic and cadmium showed various susceptibility levels. Genes encoding the ars operon (arsRDABC), an ABC transporter and a two-component permease, were linked to resistance to arsenic (MICs ≥ 1,600 mg/liter; 14% [58/422]; P < 0.05). At least three cad genes (cadA or cadC and cadD-cadX or czrC) and genes encoding multidrug efflux pumps and hyperosmoregulation in acidified conditions were associated with resistance to cadmium (MICs ≥ 200 mg/liter; 20% [85/422]; P < 0.05). These resistance genes were frequently carried by mobile genetic elements. Resistance to arsenic and cadmium were linked to human infection and a clonal lineage originating in animals (P < 0.05). Altogether, S. saprophyticus was highly resistant to heavy metals and accumulated multiple metal resistance determinants. The highest arsenic and cadmium resistance levels were associated with infection, suggesting resistance to these metals is relevant for S. saprophyticus pathogenicity.

The Rediscovery of Honey for Skin Repair: Recent Advances in Mechanisms for Honey-Mediated Wound Healing and Scaffolded Application Techniques

Honey is a honey-bee product obtained mainly by the enzymatic processing of nectar from a variety of plants, which leads to the wide range of colours and flavours available on the market. These organoleptic and nutritional features are influenced by the chemical composition, which in turn depends on the botanical origin. Bioactive compounds account for honey beneficial activity in medical applications, which explains the extensive use of honey in ethno-pharmacology since antiquity, from cough remedies to dermatological treatments. Wound healing is one of the main therapeutic uses of honey, and various design options in pharmaceutical technology such as smart delivery systems and advanced dressings are currently being developed to potentiate honey’s valuable properties for better performance and improved final outcome. In this review, we will focus on the latest research that discloses crucial factors in determining what properties are most beneficial when considering honey as a medicinal product. We will present the most recent updates on the possible mechanisms responsible for the exceptional effects of this ageless therapeutical remedy on skin repair. Furthermore, the state-of-the-art in application techniques (incorporation into scaffolds as an alternative to direct administration) used to enhance honey-mediated wound-healing properties are explored.

A surfactant polymer wound dressing protects human keratinocytes from inducible necroptosis

Chronic wounds show necroptosis from which keratinocytes must be protected to enable appropriate wound re-epithelialization and closure. Poloxamers, a class of synthetic triblock copolymers, are known to be effective against plasma membrane damage (PMD). The purpose of this study is to evaluate the efficacy of a specific poloxamer, surfactant polymer dressing (SPD), which is currently used clinically as wound care dressing, against PMD in keratinocytes. Triton X-100 (TX100) at sub-lytic concentrations caused PMD as demonstrated by the efflux of calcein and by the influx of propidium iodide and FM1-43. TX100, an inducer of necroptosis, led to mitochondrial fragmentation, depletion of nuclear HMGB1, and activation of signaling complex associated with necroptosis (i.e., activation of RIP3 and phosphorylation of MLKL). All responses following exposure of human keratinocytes to TX100 were attenuated by pre- or co-treatment with SPD (100 mg/ml). The activation and translocation of phospho-MLKL to the plasma membrane, taken together with depletion of nuclear HMGB1, characterized the observed cell death as necroptosis. Thus, our findings show that TX100-induced plasma membrane damage and death by necroptosis were both attenuated by SPD, allowing keratinocyte survival. The significance of such protective effects of SPD on keratinocytes in wound re-epithelialization and closure warrant further studies.

Efficacy of Topical Antimicrobial Agents Against Bacterial Isolates From Burn Wounds

Topically applied antimicrobials are key to the prevention of infection and mortality in the acute burn population. The purpose of this study was to determine the in vitro effectiveness of commercially available topical antimicrobials, as well as topical preparations that were compounded in our burn care institution. One-hundred twenty microorganisms were tested against these topical antimicrobials and in vitro effectiveness was observed. Results showed that compounded preparations of 1:1:1 + Double Antibiotic (1 part bacitracin: 1 part silver sulfadiazine: 100,000 units/g nystatin + 5 mg/g neomycin sulfate + 500 units/g polymyxin B) and 3:1 + Double Antibiotic (3 part bacitracin: 1 part silver sulfadiazine + 5mg/g neomycin sulfate + 500 units/g polymyxin B) were effective against 100% of the isolates tested. Other topical agents showed moderate effectiveness, thus demonstrating the need for multiple topical agents to reach a broad spectrum of microorganisms. However, the development of topical antimicrobial resistance needs further study.

Antibiotic Delivery Strategies to Treat Skin Infections When Innate Antimicrobial Defense Fails

The epidermal skin barrier protects the body from a host of daily challenges, providing protection against mechanical insults and the absorption of chemicals and xenobiotics. In addition to the physical barrier, the epidermis also presents an innate defense against microbial overgrowth. This is achieved through the presence of a diverse collection of microorganisms on the skin (the "microbiota") that maintain a delicate balance with the host and play a significant role in overall human health. When the skin is wounded, the local tissue with a compromised barrier can become colonized and ultimately infected if bacterial growth overcomes the host response. Wound infections present an immense burden in healthcare costs and decreased quality of life for patients, and treatment becomes increasingly important because of the negative impact that infection has on slowing the rate of wound healing. In this review, we discuss specific challenges of treating wound infections and the advances in drug delivery platforms and formulations that are under development to improve topical delivery of antimicrobial treatments.