Bacterial Infections After Burn Injuries: Impact of Multidrug Resistance

A 10-year retrospective study of methicillin-resistant Staphylococcus aureus from burn wound infection in southeast China from 2013 to 2022

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most commonly encountered pathogens among burn patients incurring substantial morbidity and mortality. To investigate the epidemiology and features of MRSA in burn wound infections, we conducted a 10-year retrospective study on MRSA isolated from burn patients with burn wound infections from southeast China from 2013 to 2022.

Methods

One hundred MRSA isolates (10 isolates each year) from burn wound infection among burn patients from 2013 to 2022 were randomly selected and enrolled. In addition to the clinical data of the 100 burn patients, MRSA isolates were characterized by antimicrobial susceptibility testing, detection of toxin genes, and molecular typing.

Results

The median time from the onset of burns and admission to MRSA detected was 13 and 5 days, respectively. No MRSA isolate was found resistant to quinupristin/dalfopristin, linezolid, and vancomycin. Toxin gene seg was found most frequently (90%) followed by sea (70%) and eta (64%). CC8 (74%), ST239 (70%), and SCCmec III (72%) were the most common CC, ST, and SCCmec types, respectively.

Conclusion

ST239-III (70%) was the predominant clone found in MRSA from burn wound infection among burn patients in southeast China. ST239-III was less found from 2018 to 2022. A higher diversity of MRSA clones was observed in these recent 5 years than that from 2013 to 2017.

Exudate Absorbing and Antimicrobial Hydrogel Integrated with Multifunctional Curcumin-Loaded Magnesium Polyphenol Network for Facilitating Burn Wound Healing

Burns are among the most common causes of trauma worldwide. Reducing the healing time of deep burn wounds has always been a major challenge. Traditional dressings not only require a lengthy medical procedure but also cause unbearable pain and secondary damage to patients. In this study, we developed an exudate-absorbing and antimicrobial hydrogel with a curcumin-loaded magnesium polyphenol network (Cur-Mg@PP) to promote burn wound healing. That hydrogel was composed of an ε-poly-l-lysine (ε-PLL)/polymer poly(γ-glutamic acid) (γ-PGA) hydrogel (PP) and curcumin-loaded magnesium polyphenol network (Cur-Mg). Because of the strong water absorption property of ε-PLL and γ-PGA, Cur-Mg@PP powder can quickly absorb the wound exudate and transform into a moist and viscous hydrogel, thus releasing payloads such as magnesium ion (Mg2+) and curcumin (Cur). The released Mg2+ and Cur demonstrated good therapeutic efficacy on analgesic, antioxidant, anti-inflammation, angiogenesis, and tissue regeneration. Our findings provide a strategy for accelerating burn wound healing.

Antibacterial Efficacy of a Chitosan-Based Hydrogel Modified With Epsilon-Poly-l-Lysine Against Pseudomonas aeruginosa in a Murine-Infected Burn Wound Model

INTRODUCTION

Because antibiotic resistance is increasing worldwide and the leading cause of death in burn patients is an infection, an urgent need exists for nonantibiotic approaches to eliminate multidrug-resistant bacteria from burns to prevent their systemic dissemination and sepsis. We previously demonstrated the significant antibiofilm activity of a chitosan (CS) hydrogel containing the antimicrobial peptide epsilon-poly-l-lysine (EPL) against multidrug-resistant Pseudomonas aeruginosa using ex vivo porcine skin. In this study, we evaluated the in vivo antibacterial efficacy of a CS/EPL hydrogel against P. aeruginosa in a murine burn wound infection model.

MATERIALS AND METHODS

Full-thickness burns were created on the dorsum using a heated brass rod and were inoculated with bioluminescent, biofilm-forming P. aeruginosa (Xen41). Mice were treated with CS/EPL, CS, or no hydrogel applied topically 2 or 24 hours after inoculation to assess the ability to prevent or eradicate existing biofilms, respectively. Dressing changes occurred daily for 3 days, and in vivo bioluminescence imaging was performed to detect and quantitate bacterial growth. Blood samples were cultured to determine systemic infection. In vitro antibacterial activity and cytotoxicity against human primary dermal fibroblasts, keratinocytes, and mesenchymal stem cells were also assessed.

RESULTS

CS/EPL treatment initiated at early or delayed time points showed a significant reduction in bioluminescence imaging signal compared to CS on days 2 and 3 of treatment. Mice administered CS/EPL had fewer bloodstream infections, lower weight loss, and greater activity than the untreated and CS groups. CS/EPL reduced bacterial burden by two orders of magnitude in vitro and exhibited low cytotoxicity against human cells.

CONCLUSION

A topical hydrogel delivering the antimicrobial peptide EPL demonstrates in vivo efficacy to reduce but not eradicate established P. aeruginosa biofilms in infected burn wounds. This biocompatible hydrogel shows promise as an antimicrobial barrier dressing for the sustained protection of burn wounds from external bacterial contamination.

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.

Angiogenesis, hemocompatibility and bactericidal effect of bioactive natural polymer-based bilayer adhesive skin substitute for infected burned wound healing

Thermal wounds are complex and lethal with irregular shapes, risk of infection, slow healing, and large surface area. The mortality rate in patients with infected burns is twice that of non-infected burns. Developing multifunctional skin substitutes to augment the healing rate of infected burns is vital. Herein, we 3D printed a hydrogel scaffold comprising carboxymethyl chitosan (CMCs) and oxidized alginate grafted catechol (O-AlgCat) on a hydrophobic electrospun layer, forming a bilayer skin substitute (BSS). The functional layer (FL) was fabricated by physiochemical crosslinking to ensure favorable biodegradability. The gallium-containing hydrophobic electrospun layer or backing layer (BL) could mimic the epidermis of skin, avoiding fluid penetration and offering antibacterial activity. 3D printed FL contains catechol, gallium, and biologically active platelet rich fibrin (PRF) to adhere to both tissue and BL, show antibacterial activity, encourage angiogenesis, cell growth, and migration. The fabricated bioactive BSS exhibited noticeable adhesive properties (P ≤ 0.05), significant antibacterial activity (P ≤ 0.05), faster clot formation, and the potential to promote proliferation (P ≤ 0.05) and migration (P ≤ 0.05) of L929 cells. Furthermore, the angiogenesis was significantly higher (P ≤ 0.05) when evaluated in vivo and in ovo. The BSS-covered wounds healed faster due to low inflammation and high collagen density. Based on the obtained results, the fabricated bioactive BSS could be an effective treatment for infected burn wounds.

Serum Selenium-Binding Protein 1 (SELENBP1) in Burn Injury: A Potential Biomarker of Disease Severity and Clinical Course

Oxidative stress, systemic inflammation, and metabolic derangements are hallmarks of burn pathophysiology. Severely burned patients are highly susceptible to infectious complications. Selenium-binding protein 1 (SELENBP1) modulates intracellular redox homeostasis, and elevated serum concentrations have been associated with adverse clinical outcomes in trauma patients. We hypothesized that serum SELENBP1 at hospital admission and during hospitalization may constitute a meaningful biomarker of disease severity and the clinical course in burn injury, with pulmonary infection as primary endpoint. To this end, we conducted a prospective cohort study that included 90 adult patients admitted to the Burn Center of the University Hospital Zurich, Switzerland. Patients were treated according to the local standard of care, with high-dose selenium supplementation during the first week. Serum SELENBP1 was determined at nine time-points up to six months postburn and the data were correlated to clinical parameters. SELENBP1 was initially elevated and rapidly declined within the first day. Baseline SELENBP1 levels correlated positively with the Abbreviated Burn Severity Index (ABSI) (R = 0.408; p < 0.0001). In multiple logistic regression, a higher ABSI was significantly associated with increased pulmonary infection risk (OR, 14.4; 95% CI, 3.2-88.8; p = 0.001). Similarly, baseline SELENBP1 levels constituted a novel but less accurate predictor of pulmonary infection risk (OR, 2.5; 95% CI, 0.7-8.9; p = 0.164). Further studies are needed to explore the additional value of serum SELENBP1 when stratifying patients with respect to the clinical course following major burns and, potentially, for monitoring therapeutic measures aimed at reducing tissue damage and oxidative stress.

Nanofibrous Dressing with Nanocomposite Monoporous Microspheres for Chemodynamic Antibacterial Therapy and Wound Healing

The excessive use of antibiotics and consequent bacterial resistance have emerged as crucial public safety challenges for humanity. As a promising antibacterial treatment, using reactive oxygen species (ROS) can effectively address this problem and has the advantages of being highly efficient and having low toxicity. Herein, electrospinning and electrospraying were employed to fabricate magnesium oxide (MgO)-based nanoparticle composited polycaprolactone (PCL) nanofibrous dressings for the chemodynamic treatment of bacteria-infected wounds. By utilizing electrospraying, erythrocyte-like monoporous PCL microspheres incorporating silver (Ag)- and copper (Cu)-doped MgO nanoparticles were generated, and the unique microsphere-filament structure enabled efficient anchoring on nanofibers. The composite dressings produced high levels of ROS, as confirmed by the 2,7-dichloriflurescin fluorescent probe. The sustained generation of ROS resulted in efficient glutathione oxidation and a remarkable bacterial killing rate of approximately 99% against Staphylococcus aureus (S. aureus). These dressings were found to be effective at treating externally infected wounds. The unique properties of these composite nanofibrous dressings suggest great potential for their use in the medical treatment of bacteria-infected injuries.

TNF-R1 Cellular Nanovesicles Loaded on the Thermosensitive F-127 Hydrogel Enhance the Repair of Scalded Skin

Excessive inflammatory response after severe scalding is an important cause of delayed wound healing and is even life-threatening. Tumor necrosis factor α (TNF-α) is a key pro-inflammatory factor of skin trauma. Interacting with tumor necrosis factor receptor 1 (TNF-R1), TNF-α causes excessive inflammation and poor prognosis by activating NF-κB pathway. Antagonizing high levels of TNF-α is one of the therapeutic approaches for diseases associated with the overactivation of inflammatory responses. However, the available monoclonal antibodies are limited in their application due to their complex preparation process, high price, and the lack of cell targeting ability leading to systemic toxicity and side effects. In this study, by using a genetic bioengineering technique, we modified TNF-R1 on the cell membrane surface-derived nanovesicles (NVs). We confirmed that TNF-R1 NVs stably expressed TNF-R1 on the membrane surface and interacted with its ligand TNF-α. Furthermore, TNF-R1 NVs competitively antagonized the effect of TNF-α in the wound healing assay in vitro. In the scalded mouse model, TNF-R1 NVs were released continuously from the thermosensitive hydrogel Pluronic F-127, resulting in less inflammation and better wound healing. Our results revealed TNF-R1 NVs as promising cell-free therapeutic agents in alleviating TNF-α-mediated pro-inflammatory signaling and promoting wound repair.

Risk Factors and Pathogens of Wound Infection in Burn Inpatients from East China

BACKGROUND

Infection is the predominant contributor to morbidity and mortality in burn patients, and burn wound infection (BWI) is the most common reason. The objective of this research was to analyze the incidence, factors and progression of BWI, in terms of events and bacteria.

METHODS

Clinical variables of all qualified patients admitted to burn wards were analyzed retrospectively in 2021 at a tertiary hospital in eastern China through univariate analysis and multivariate logistic regression. The Kaplan-Meier method was also used for plotting survival curves. Isolates and resistance data were evaluated to demonstrate the evolution of targeted antibiotics of strains from BWI.

RESULTS

A total of 580 (median age, 39.5 years (23-56 years); 372/580 (64.14%) male) patients were evaluated, 348 (60.0%) of whom experienced BWI. A variety of factors are associated with BWI. Multivariate logistic regression analysis showed that depth and area of burn and duration from burn to first hospitalization are independent risk factors for BWI. For BWI onset in these patients, 47.24% (274/580) occurred in the first week. The most frequently isolated causative organism was Staphylococcus aureus (15.7%) in patients with BWI. The duration of transition from Gram-positive strains (median 3 days, (2-7 days)) to Gram-negative (median 10 days, (4-17 days)) ones isolated from burn wound shrunk. Hospital length of stay was considered as a protective factor for BWI.

CONCLUSION

The precise assessment of factors affecting BWI in burn patients enhances prompt and suitable management. Swab cultures for surveillance could be utilized to monitor the microbiological status of burn patients.

Meta-Analysis of Publicly Available Clinical and Preclinical Microbiome Data From Studies of Burn Injury

Following burn injury, alterations in host commensal microbiota across body spaces may leave patients susceptible to opportunistic pathogens and serious sequelae such as sepsis. Generally, studies examining the microbiome postburn have had a limited sample size and lack of longitudinal data, which coupled with experimental and analytic variation, impacts overall interpretation. We performed a meta-analysis of publicly available sequencing data from preclinical and clinical burn studies to determine if there were consistent alterations in the microbiome across various anatomical sites and hosts. Ten human and animal 16S rRNA sequencing studies spanning respiratory, urinary, cutaneous, and gastrointestinal microbiomes were included. Taxonomic classification and alpha and beta diversity metrics were analyzed using QIIME2 v2021.8. Alpha diversity was consistently higher in control samples compared to burn-injured samples which were also different based on host and anatomical location; however, phylogenetic evaluation (ie, Faith PD) elucidated more significant differences compared to taxonomic metrics (ie, Shannon entropy). Beta diversity analysis based on weighted UniFrac showed that rodent specimens clustered less closely to humans than pig samples for both rectal and skin sources. Host species and performing institute were found to have a significant impact on community structure. In rectal samples, bacterial composition in pig and human burn samples included Bacteroidetes, Firmicutes, and Proteobacteria, while rodent samples were dominated by Firmicutes. Proteobacteria and Firmicutes increased on burned skin in each host species. Our results suggest that host species and the performing institute strongly influence microbiome structure. Burn-induced alterations in microbiome diversity and taxa exist across hosts, with phylogenetic metrics more valuable than others. Coordinated, multicenter studies, both clinical and preclinical, within the burn community are needed to more completely realize the diagnostic and therapeutic potential of the microbiome for improving outcomes postburn.

Nosocomial Infection Among Burn Patients Admitted to a Tertiary Care Hospital of Bangladesh: A Cross-Sectional Study

Nosocomial infection is a major challenge for the appropriate management of burns. The present study aimed to investigate incidence, risk factors, and causative organisms of nosocomial infection in burn patients of Khulna, Bangladesh. This cross-sectional study was conducted among patients admitted to the Burn and Plastic Surgery Department of Khulna Medical College Hospital (KMCH) from January to December 2020. Relevant data were collected from the patients' hospital records. Samples of wound swabs and blood were collected and cultured in the microbiology laboratory of KMCH. Logistic regression models were used to determine risk factors for infective complications in burn patients. All statistical analyses were carried out using SPSS version 26.0. A total of 100 burn patients were included. Mean age was 29.2 years with a male-female ratio of 1.3:1. Flame burns were most prevalent among the patients (41%), followed by scald (23%) and electric burns (15%). Almost 40% patients had full thickness burn. The incidence of nosocomial infection was 42% (wound infection 33% and septicemia 9%). Total body surface area of burn >40% (OR 7.56, 95% CI 2.89-19.81), full thickness burn (OR 34.40, 95% CI 3.25-97.14) and prolonged hospital stay (aOR 1.31, 95% CI 1.15-1.51) were significant risk factors for nosocomial infection. Staphylococcus aureus was the most commonly isolated organism (45%), followed by Streptococcus (24%), Pseudomonas aeruginosa (19%) and Escherichia coli (12%). As the epidemiology of nosocomial infection is not the same in different health facilities, a facility-based comprehensive burn management protocol considering the local epidemiology and causative organisms of burn wound infection is crucial for the prevention and management of nosocomial infections in burn patients.

Subversion of the Complement System by Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen heavily implicated in chronic diseases. Immunocompromised patients that become infected with P. aeruginosa usually are afflicted with a lifelong chronic infection, leading to worsened patient outcomes. The complement system is an integral piece of the first line of defense against invading microorganisms. Gram-negative bacteria are thought to be generally susceptible to attack from complement; however, P. aeruginosa can be an exception, with certain strains being serum resistant. Various molecular mechanisms have been described that confer P. aeruginosa unique resistance to numerous aspects of the complement response. In this review, we summarize the current published literature regarding the interactions of P. aeruginosa and complement, as well as the mechanisms used by P. aeruginosa to exploit various complement deficiencies and the strategies used to disrupt or hijack normal complement activities.

Multidrug-Resistant Pathogens in Burn Wound, Prevention, Diagnosis, and Therapeutic Approaches (Conventional Antimicrobials and Nanoparticles)

Multidrug-resistant pathogens are one of the common causes of death in burn patients and have a high risk of nosocomial infections, especially pneumonia, urinary tract infections, and cellulitis. The role of prolonged hospitalization and empirical antibiotics administration in developing multidrug-resistant pathogens is undeniable. In the early days of admitting burn patients, Gram-positive bacteria were the dominant isolates with a more sensitive antibiotic pattern. However, the emergence of Gram-negative bacteria that are more resistant later occurs. Trustworthy guideline administration in burn wards is one of the strategies to prevent multidrug-resistant pathogens. Also, a multidisciplinary therapeutic approach is an effective way to avoid antibiotic resistance that involves infectious disease specialists, pharmacists, and burn surgeons. However, the emerging resistance to conventional antimicrobial approaches (such as systemic antibiotic exposure, traditional wound dressing, and topical antibiotic ointments) among burn patients has challenged the treatment of multidrug-resistant infections, and using nanoparticles is a suitable alternative. In this review article, we will discuss different aspects of multidrug-resistant pathogens in burn wounds, emphasizing the full role of these pathogens in burn wounds and discussing the application of nanotechnology in dealing with them. Also, some advances in various types of nanomaterials, including metallic nanoparticles, liposomes, hydrogels, carbon quantum dots, and solid lipid nanoparticles in burn wound healing, will be explained.

Hydrogel-Containing Biogenic Silver Nanoparticles: Antibacterial Action, Evaluation of Wound Healing, and Bioaccumulation in Wistar Rats

Wound infections are feared complications due to their potential to increase healthcare costs and cause mortality since multidrug-resistant bacteria reduce treatment options. This study reports the development of a carbomer hydrogel containing biogenic silver nanoparticles (bioAgNPs) and its effectiveness in wound treatment. This hydrogel showed in vitro bactericidal activity after 2 h, according to the time-kill assay. It also reduced bacterial contamination in rat wounds without impairing their healing since the hydrogel hydrophilic groups provided hydration for the injured skin. The high number of inflammatory cells in the first days of the skin lesion and the greater degree of neovascularization one week after wound onset showed that the healing process occurred normally. Furthermore, the hydrogel-containing bioAgNPs did not cause toxic silver accumulation in the organs and blood of the rats. This study developed a bioAgNP hydrogel for the treatment of wounds; it has a potent antimicrobial action without interfering with cicatrization or causing silver bioaccumulation. This formulation is effective against bacteria that commonly cause wound infections, such as Pseudomonas aeruginosa and Staphylococcus aureus, and for which new antimicrobials are urgently needed, according to the World Health Organization's warning.

Prevalence of Multidrug-Resistant Organism in ICU Burns Patients at Tertiary Care Hospital

Burns carries a high-risk of mortality and morbidity. This with increased chances of drug-resistant infections makes the management complicated. Hence this study was conducted to find out the prevalence of multidrug-resistant organisms (MDRO) in burns patients admitted to the intensive care unit at a tertiary care hospital. A 2-year retrospective study was conducted where burn patients reporting MDRO were included. Statistical analysis was performed using SPSS version 26 where a P-value < .05 was considered statistically significant. Out of 97 patients, tissue cultures of 65 patients revealed the presence of MDRO in 27 (27.8%) patients. A male predominance (17, 63.0%) was noted with a mean age of 29.0-year-old. Fire burn (15, 55.6%) was reported to be the most common cause of burn with an average of 29.9% of Total Body Surface Area (TBSA) involved. MDR Pseudomonas aeruginosa was the commonest organism reported in 12 (44%) patients. The average length of stay (LOS) was noted to be 11.3 days with a mortality rate of 48.1% (overall, in all MDRO'S infections). Patients who reported MDRO showed a tendency for longer hospitalization with a higher risk of mortality as the TBSA increased. However, in presence of other factors in burns like higher TBSA, inhalation injury and lack of advanced skin substitute these mortality figures, and their association can be debated. Lastly, the implementation of control measures, as basic as hand hygiene, should be partaken to reduce the burden of MDR infections.

Supramolecular hybrid hydrogels as rapidly on-demand dissoluble, self-healing, and biocompatible burn dressings

Despite decades of efforts, state-of-the-art synthetic burn dressings to treat partial-thickness burns are still far from ideal. Current dressings adhere to the wound and necessitate debridement. This work describes the first "supramolecular hybrid hydrogel (SHH)" burn dressing that is biocompatible, self-healable, and on-demand dissoluble for easy and trauma-free removal, prepared by a simple, fast, and scalable method. These SHHs leverage the interactions of a custom-designed cationic copolymer via host-guest chemistry with cucurbit[7]uril and electrostatic interactions with clay nanosheets coated with an anionic polymer to achieve enhanced mechanical properties and fast on-demand dissolution. The SHHs show high mechanical strength (>50 kPa), self-heal rapidly in ∼1 min, and dissolve quickly (4-6 min) using an amantadine hydrochloride (AH) solution that breaks the supramolecular interactions in the SHHs. Neither the SHHs nor the AH solution has any adverse effects on human dermal fibroblasts or epidermal keratinocytes in vitro. The SHHs also do not elicit any significant cytokine response in vitro. Furthermore, in vivo murine experiments show no immune or inflammatory cell infiltration in the subcutaneous tissue and no change in circulatory cytokines compared to sham controls. Thus, these SHHs present excellent burn dressing candidates to reduce the time of pain and time associated with dressing changes.

Etiology and Multi-Drug Resistant Profile of Bacterial Infections in Severe Burn Patients, Romania 2018-2022

Infections in severe burns and their etiology are and will remain a big concern for the medical field. The multi-drug resistant strains of bacteria are a challenge of today's medicine. The aim of our study was to identify the etiological spectrum of bacterial infections in severe burn patients in Romania and their multi-drug resistant patterns. We performed a prospective study that included 202 adult patients admitted to the intensive care unit (ICU) of the Clinical Emergency Hospital of Plastic, Reconstructive Surgery and Burns, Bucharest, Romania (CEHPRSB), from 1 October 2018 to 1 April 2022, a period which includes the first 2 years of the outbreak of COVID-19. From each patient, wound swabs, endotracheal aspirates, blood for blood culture, and urine were collected. The most frequently isolated bacterium was Pseudomonas aeruginosa (39%), followed by Staphylococcus aureus (12%), Klebsiella spp. (11%), and Acinetobacter baumannii (9%). More than 90% of Pseudomonas aeruginosa and Acinetobacter baumannii were MDR, regardless of the clinical specimen from which they were isolated.

Speeding up the Production of Clinical-Grade Skin Substitutes Using Off-the-shelf Decellularized Self-Assembled Dermal Matrices

Patients with deep and extensive wounds need urgent skin coverage to re-establish the cutaneous barrier that prevents life-threatening infections and dehydration. However, the current clinically-available skin substitutes intended for permanent coverage are limited in number, and a trade-off between production time and quality must be made. Here, we report the use of decellularized self-assembled dermal matrices to reduce by half the manufacturing process time of clinical-grade skin substitutes. These decellularized matrices can be stored for over 18 months and recellularized with patients' cells in order to generate skin substitutes that show outstanding histological and mechanical properties in vitro. Once grafted in mice, these substitutes persist over weeks with high graft take, few contraction events, and high stem cell content. These next-generation skin substitutes constitute a substantial advancement in the treatment of major burn patients, combining, for the first time, high functionality, rapid manufacturability and easy handling for surgeons and healthcare practitioners. Future clinical trials will be conducted to assess the advantages of these substitutes over existing treatments. STATEMENT OF SIGNIFICANCE: The number of patients in need for organ transplantation is ever-growing and there is a shortage in tissue and organ donors. In this study, we show for the first time that we can preserve decellularized self-assembled tissues and keep them in storage. Then, in only three weeks we can use them to produce bilayered skin substitutes that have properties very close to those of the native human skin. These findings therefore represent a major step forward in the field of tissue engineering and organ transplantation, paving the way toward a universal off-the-shelf biomaterial for tissue reconstruction and surgery that will be beneficial for many clinicians and patients.

Using the Galleria mellonella burn wound and infection model to identify and characterize potential wound probiotics

Burn wound infection is the leading cause of mortality among burn wound patients. One of the most commonly isolated bacterial burn wound pathogens is Pseudomonas aeruginosa, a notorious nosocomial multidrug-resistant pathogen. As a consequence of its recalcitrance to frontline antibiotic therapy, there is an urgent need to develop alternative treatment avenues to tackle this pathogen. One potential alternative infection prevention measure is to seed the wound bed with probiotic bacteria. Several species of Lactobacillus, a common commensal bacterium, have been previously reported to display growth inhibition activity against wound pathogens. Various species of this genus have also been shown to augment the wound healing process, which makes it a promising potential therapeutic agent. Due to the complexity of the burn wound trauma and burn wound infection, an in vivo model is required for the development of novel therapeutics. There are multiple in vivo models that are currently available, the most common among them being the murine model. However, mammalian burn wound infection models are logistically challenging, do not lend themselves to screening approaches and come with significant concerns around ethics and animal welfare. Recently, an invertebrate burn wound and infection model using G. mellonella has been established. This model addresses several of the challenges of more advanced animal models, such as affordability, maintenance and reduced ethical concerns. This study validates the capacity of this model to screen for potential wound probiotics by demonstrating that a variety of Lactobacillus spp. can limit P. aeruginosa burn wound infection and improve survival.

ARAG, an Antioxidant-Rich Gel, Shows Superiority to Mepilex Ag in the Treatment of Deep Partial Thickness Burns without Sacrificing Antimicrobial Efficiency

Current treatments for deep tissue burns are limited, and most serve only to enhance hydration or prevent bacterial growth. This leaves burn healing dependent on slow natural processes to debride the wound and reestablish the epidermal and dermal layers of the skin. Infections are well known to destabilize this process through a variety of mechanisms, most notably through increased inflammation and the resulting oxidative stress. In this study, we show that ARAG (an antioxidant-rich antimicrobial gel) can suppress the growth of multiple bacteria commonly found to infect burns (Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, and Staphylococcus aureus). This inhibition is comparable to that conferred by silver ion release from burn dressings such as Mepilex-Ag. We further show, using a porcine model for deep partial-thickness burns, that ARAG allows for enhanced wound healing over Mepilex-Ag, the current standard of care. Histological findings indicate this is likely due to increased wound debridement and dampening of late inflammatory processes, leading to more balanced physiologic healing. Taken together, these findings show promise for ARAG as a superior alternative to the current standard of care.

Role of medicinal herbs and phytochemicals in post burn management

Burn management is a natural and distinctly programmed process involving overlapping phases of hemostasis, inflammation, proliferation and remodeling. Burn wound healing involves initiation of inflammation, re-epithelialization, granulation, neovascularization and wound contraction. Despite the availability of multiple preparations for management of burn wound, there is dire need for efficacious alternative agents. Current approaches for burn wound management include pharmaceutical agents and antibiotics. However, high cost of synthetic drugs and accelerated resistance to antibiotics is challenging for both developed and developing nations. Among alternative options, medicinal plants have been a biocompatible, safe and affordable source of preventive/curative approaches. Due to cultural acceptance and patient compliance, there has been a focus on the use of botanical drugs and phytochemicals for burn wound healing. Keeping in consideration of medicinal herbs and phytochemicals as suitable therapeutic/adjuvant agents for burn wound management, this review highlights therapeutic potential of 35 medicinal herbs and 10 phytochemicals. Among these, Elaeis guineensis, Ephedra ciliate and Terminalia avicennioides showed better burn wound healing potential with varied mechanisms such as modulation of TNF-alpha, inflammatory cytokines, nitric oxide, eicosanoids, ROS and leukocyte response. Phytochemicals (oleanolic acid, ursolic acid, kirenol) also showed promising role in burn wound management though various pathways involving such as down regulation of TNF-alpha, IL-6 and inflammatory mediators including plasma proteases and arachidonic acid metabolites. This review provides a pavement for therapeutic/adjuvant use of potential botanical drugs and novel druggable phyto-compounds to target skin burn injury with diverse mechanisms, affordability and safety profile.

Burn wound conversion: clinical implications for the treatment of severe burns

The identification of novel treatments for severe burn wounds relies on accurate clinical assessments of the extent of injury. However, evaluation of burn wound depth can be challenging due to the tendency for burn wounds to progress over time in a little-understood process known as 'burn wound conversion'. Local factors affecting the burn wound, such as inflammation, oxidative stress-induced tissue damage, vasostasis and bacterial infections, lead to increased cell death by apoptosis or oncosis, while systemic events may promote burn wound conversion. Acute shock, metabolic derangements, age or immunomodulation can modify cytokine secretion, lower immune responses, decrease blood flow or cause bacterial infection at the burn wound site. Therefore, therapeutic approaches targeting specific mechanisms that reduce cell death, improve wound reperfusion and promote tissue regrowth should favourably enhance burn wound healing, and long-term functional and aesthetic outcomes. Our current understanding of these mechanisms mostly comes from animal studies, underscoring the need for extensive research in humans. A streamlined approach would be to investigate the parallels in other disease states that exhibit ischaemia and potential reperfusion, such as ischaemic stroke and myocardial infarction. Moreover, in view of the limited knowledge available on the subject, the need exists for further clinical research into burn wound conversion and novel target pathways to ameliorate its effects. This review describes events that affect the viability of cells at the burn wound site resulting in burn wound conversion, and identifies potential targets for clinical interventions that may diminish burn wound conversion.

Can Cold Atmospheric Plasma Be Used for Infection Control in Burns? A Preclinical Evaluation

Wound infection with Pseudomonas aeruginosa (PA) is a serious complication and is responsible for higher rates of mortality in burn patients. Because of the resistance of PA to many antibiotics and antiseptics, an effective treatment is difficult. As a possible alternative, cold atmospheric plasma (CAP) can be considered for treatment, as antibacterial effects are known from some types of CAP. Hence, we preclinically tested the CAP device PlasmaOne and found that CAP was effective against PA in various test systems. CAP induced an accumulation of nitrite, nitrate, and hydrogen peroxide, combined with a decrease in pH in agar and solutions, which could be responsible for the antibacterial effects. In an ex vivo contamination wound model using human skin, a reduction in microbial load of about 1 log₁₀ level was observed after 5 min of CAP treatment as well as an inhibition of biofilm formation. However, the efficacy of CAP was significantly lower when compared with commonly used antibacterial wound irrigation solutions. Nevertheless, a clinical use of CAP in the treatment of burn wounds is conceivable on account of the potential resistance of PA to common wound irrigation solutions and the possible wound healing-promoting effects of CAP.

Cu+/Ag+ Competition in Type I Copper Proteins (T1Cu)

Due to the similarity in the basic coordination behavior of their mono-charged cations, silver biochemistry is known to be linked to that of copper in biological systems. Still, Cu⁺/²⁺ is an essential micronutrient in many organisms, while no known biological process requires silver. In human cells, copper regulation and trafficking is strictly controlled by complex systems including many cytosolic copper chaperones, whereas some bacteria exploit the so-called "blue copper" proteins. Therefore, evaluating the controlling factors of the competition between these two metal cations is of enormous interest. By employing the tools of computational chemistry, we aim to delineate the extent to which Ag⁺ might be able to compete with the endogenous copper in its Type I (T1Cu) proteins, and where and if, alternatively, it is handled uniquely. The effect of the surrounding media (dielectric constant) and the type, number, and composition of amino acid residues are taken into account when modelling the reactions in the present study. The obtained results clearly indicate the susceptibility of the T1Cu proteins to a silver attack due to the favorable composition and geometry of the metal-binding centers, along with the similarity between the Ag⁺/Cu⁺-containing structures. Furthermore, by exploring intriguing questions of both metals' coordination chemistry, an important background for understanding the metabolism and biotransformation of silver in organisms is provided.

Cross-Border Antibiotic Resistance Patterns in Burn Patients

Background: Antimicrobial resistance (AMR) is a growing problem worldwide, with differences in regional resistance patterns partially driven by local variance in antibiotic stewardship. Trauma patients transferring from Mexico have more AMR than those injured in the United States; we hypothesized a similar pattern would be present for burn patients. Patients and Methods: The registry of an American Burn Association (ABA)-verified burn center was queried for all admissions for burn injury January 2015 through December 2019 with hospital length-of-stay (LOS) longer than seven days. Patients were divided into two groups based upon burn location: United States (USA) or Mexico (MEX). All bacterial infections were analyzed. Results: A total of 73 MEX and 826 USA patients were included. Patients had a similar mean age (40.4 years MEX vs. 42.2 USA) and gender distribution (69.6% male vs. 64.4%). The MEX patients had larger median percent total body surface area burned (%TBSA; 11.1% vs. 4.3%; p ≤ 0.001) and longer hospital LOS (18.0 vs. 13.0 days; p = 0.028). The MEX patients more often had respiratory infections (16.4% vs. 7.4%; p = 0.046), whereas rates of other infections were similar. The MEX patients had higher rates of any resistant organism (47.2% of organisms MEX vs. 28.1% USA; p = 0.013), and were more likely to have resistant infections on univariable analysis; however, on multivariable analysis country of burn was no longer significant. Conclusions: Antimicrobial resistance is more common in burn patients initially burned in Mexico than those burned in the United States, but location was not a predictor of resistance compared to other traditional burn-related factors. Continuing to monitor for AMR regardless of country of burn remains critical.

Molecular characterizations of antibiotic resistance, biofilm formation, and virulence determinants of Pseudomonas aeruginosa isolated from burn wound infection

BACKGROUND

Burn injuries result in disruption of the skin barrier against opportunistic infections. Pseudomonas aeruginosa is one of the main infectious agents colonizing burn wounds and making severe infections. Biofilm production and other virulence factors along with antibiotic resistance limit appropriate treatment options and time.

MATERIALS AND METHODS

Wound samples were collected from hospitalized burn patients. P. aeruginosa isolates and related virulence factors identified by the standard biochemical and molecular methods. Antibiotic resistance patterns were determined by the disc diffusion method and β-lactamase genes were detected by polymerase chain reaction (PCR) assay. To determine the genetic relatedness amongst the isolates, enterobacterial repetitive intergenic consensus (ERIC)-PCR was also performed.

RESULTS

Forty P. aeruginosa isolates were identified. All of these isolates were biofilm producers. Carbapenem resistance was detected in 40% of the isolates, and bla_TEM (37/5%), bla_VIM (30%), and bla_CTX-M (20%) were the most common β-lactamase genes. The highest resistance was detected to cefotaxime, ceftazidime, meropenem, imipenem and piperacillin, and 16 (40%) isolates were resistant to these antibiotics. The minimum inhibitory concentrations (MIC) of colistin was lower than 2 μg/mL and no resistance was observed. Isolates were categorized to 17 MDR, 13 mono-drug resistance, and 10 susceptible isolates. High genetic diversity was also observed among the isolates (28 ERIC types) and most carbapenem-resistant isolates were classified into four main types.

CONCLUSION

Antibiotic resistance, particularly carbapenem resistance was considerable among the P. aeruginosa isolates colonizing burn wounds. Combining carbapenem resistance with biofilm production and virulence factors would result in severe and difficult-to-treat infections.

Infections in Burn Patients

Infections are the leading cause of mortality in burn patients who survive their initial resuscitation. Burn injury leads to immunosuppression and a dysregulated inflammatory response which can have a prolonged impact. Early surgical excision along with support of the multidisciplinary burn team has improved mortality in burn patients. The authors review diagnostic and therapeutic challenges as well as strategies for management of burn related infections.

Staphylococcal Infections and Neonatal Skin: Data from Literature and Suggestions for the Clinical Management from Four Challenging Patients

Staphylococcal infections in neonates might be associated with skin blistering since early antibiotic therapy has been shown to limit infection spread and positively influence outcomes; therefore, neonatologists should be aware of these conditions. This review examines the recent literature on the management of Staphylococcal infections that involve neonatal skin, discussing the most appropriate clinical approach to four cases of neonatal blistering diseases with Staphylococcal infections: a case of Staphylococcal bullous impetigo, a case of Staphylococcal scalded skin syndrome (SSSS), a case of epidermolysis bullosa with overlapping Staphylococcal infection, and a case of burns with overlapping Staphylococcal infection. In treating Staphylococcal infections involving skin in neonates, the presence or absence of systemic symptoms should be considered. In the lack of evidence-based guidelines in this age category, treatment should be individualized according to several factors including the extension of the disease or further skin comorbidities (such as skin fragility), with a multidisciplinary approach.

[Research advances on the prevention and treatment of burn infection in the elderly]

Infection is a common complication after burns and the major cause of death in patients suffering severe burn injury. The infection of the elderly after burns is more serious due to their decreased immune function that is complicated with factors such as multiple chronic diseases and dysfunction of various organs. In addition, the burn infection in the elderly lacks the specific symptoms and signs, which brings great challenges to its diagnosis and treatment. To effectively prevent and control infection is very important for the treatment of elderly burn patients. Combined the clinical characteristics of burn infection in the elderly, this paper summarized the research advances of prevention and treatment for burn infection in the elderly from fluid resuscitation, wound treatment, antibiotic using, organ protection, nutritional support, and infection prevention, aiming to provide reference for clinical practice.

The antibacterial activity of LL-37 peptide against multidrug-resistant Pseudomonas aeruginosa isolated from burn infections

Multidrug-resistant Pseudomonas aeruginosa has emerged as a significant problem worldwide, posing a severe hazard to burn-infected patients. Antimicrobial peptides produced from humans or animals and synthetic peptides have received interest as antibiotic options for treating resistant bacteria, particularly those obtained from burn patients. The current work evaluated the role of antimicrobial peptide LL-37 as an antibacterial agent against multidrug P. aeruginosa isolates from burn infections. The study samples were collected between November 2021 and the end of February 2022 and included 157 clinical specimens as burn swabs from patients with burn infections admitted to four Baghdad hospitals in Baghdad, Iraq. The results of selective media, biochemical tests, and the ITEK2 system identified 39 isolates (24.8%) as p. aeruginosa from all collected bacterial cultures. The findings of the antimicrobial susceptibility test by disc diffusion method for the isolates under investigation revealed that P. aeruginosa clinical isolates were moderately resistant to antibiotics tested. Most P. aeruginosa isolates were highly resistant to Tetracycline (89.7%), Azithromycin (71.7%), and Amikacin, Cefepime, and Gentamycin. Also, the highest sensitivity was recorded for Ciprofloxacin, Piperacillin/tazobactam, C ceftazidime and Levofloxacin. The results of minimum inhibitory concentrations (MICs) of LL-37 against (8) multidrug-resistant P. aeruginosa isolates revealed that the concentration range of LL-37 was (15.6-1000 µg/ml), indicating that LL-37 has a significant effect on P. aeruginosa growth at low concentrations. In conclusion, t using the antimicrobial peptides LL-37 in treating life-threaded infections could lead to developing a new generation of antimicrobials that can overcome bacterial resistance mechanisms. Keywords: Antibacterial, Burns, LL-37, Pseudomonas aeruginosa

Analysis of Potential Risk Factors for Multidrug-Resistance at a Burn Unit

BACKGROUND

Infections by multidrug-resistant (MDR) microorganisms are associated with increased morbidity and mortality in burn patients. This study aimed to analyze the evolution of MDR bacteria over a five-year period at Coimbra Burns Unit (CBU) in Portugal, seeking to assess the possible associations of specific bacteria with presumed risk factors.

METHODS

The data obtained consisted of identified bacteria present in any microbiological sample from each patient (including blood, central venous catheter, urine, tracheal aspirate and/or wound exudate). Univariate models and a multivariate model were constructed for each of the MDR bacteria species that infected at least 50 patients or that had five or more MDR strains. Statistical hypothesis tests with a p-value less than 0.05 were considered significant.

RESULTS

Of a total of 341 samples obtained, 107 were MDR, corresponding to 10 species. Globally, there was no significant variation in MDR bacteria frequency over the period under analysis. Some risk factors and/or trends were identified for some species, but none was linked to all of them.

CONCLUSIONS

The risks for the development of MDR in bacteria in burn patients are multifactorial, mainly linked to longer hospital stays, the use of invasive devices and inadequate antimicrobial treatment. However, the influence of these risks regarding specific bacterial species is not straightforward and may rely on individual characteristics, type of treatment and/or local prevalent flora. Due to the severity of multidrug-resistant infections, continued microbiological surveillance with the aid of rapid diagnostic tests and prompt institution of appropriate antimicrobial therapy are crucial to improving outcomes for burn patients.

Infections in Pediatric Patients With Burn Injury: 6 Years of Experience

BACKGROUND

This study aimed to determine the frequency of bloodstream and wound infections and their possible risk factors in hospitalized children with burn injury.

METHODS

We performed this retrospective descriptive study from 2015 to 2021. The study subjects consisted of all the pediatric patients hospitalized in the burn unit, from whom microorganisms were isolated either from blood or wound culture samples.

RESULTS

We detected a total of 142 microorganisms from 97 blood culture samples and 45 wound culture samples. Among the 115 patients, 44 (38.3%) were females and 71 (61.7%) were males, with a median age of 21 months (interquartile range: 14-39 months). Gram-positive bacteria were the most common causative agents of bloodstream infections in patients with burns (54.6%), followed by Gram-negative bacteria (32.9%) and fungi (12.3%). Gram-negative bacteria were the most common causative agent of wound infections (86.7%). Prolonged hospitalization positively correlated with the extent of the burn surface area (P: 0.031), degree of burn (P: 0.001), use of central venous catheter (P: 0.028), and intensive care unit stay (P: 0.044). Independent risk factors for Gram-negative bacteremia and Gram-negative wound infections were the extent of the burn surface area (P: 0.018), degree of burn (P: 0.024) and intensive care unit stay (P: 0.023). The independent risk factor for fungemia was prolonged hospitalization (P: 0.026).

CONCLUSIONS

To reduce infections, minimizing invasive procedures using a multidisciplinary approach would be beneficial, especially in patients who have a large burn surface area and are expected to have a long hospital stay.

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.

Patterns of multidrug resistant organism acquisition in an adult specialist burns service: a retrospective review

Background

Multidrug resistant organisms (MDROs) occur more commonly in burns patients than in other hospital patients and are an increasingly frequent cause of burn-related mortality. We examined the incidence, trends and risk factors for MDRO acquisition in a specialist burns service housed in an open general surgical ward, and general intensive care unit.

Methods

We performed a retrospective study of adult patients admitted with an acute burn injury to our specialist statewide tertiary burns service between July 2014 and October 2020. We linked patient demographics, injury, treatment, and outcome details from our prospective burns service registry to microbiology and antimicrobial prescribing data. The outcome of interest was first MDRO detection, stratified into the following groups of interest: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), two groups of Pseudomonas (carbapenem resistant, and piperacillin-tazobactam or cefepime resistant), carbapenem-resistant Acinetobacter species, Stenotrophomonas maltophilia, carbapenem-resistant Enterobacteriaceae (CRE), and extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE). We used a Cox proportional hazards model to evaluate the association between antibiotic exposure and MDRO acquisition.

Results

There were 2,036 acute admissions, of which 230 (11.3%) had at least one MDRO isolated from clinical specimens, most frequently wound swabs. While acquisition rates of individual MDRO groups varied over the study period, acquisition rate of any MDRO was reasonably stable over time. Carbapenem-resistant Pseudomonas was acquired at the highest rate over the study period (3.5/1000 patient days). The 12.8% (29/226) of MDROs isolated within 48 h were predominantly MRSA and Stenotrophomonas. Median (IQR) time from admission to MDRO detection was 10.9 (5.6–20.5) days, ranging from 9.8 (2.7–24.2) for MRSA to 23.6 (15.7–36.0) for carbapenem-resistant P. aeruginosa. Patients with MDROs were older, had more extensive burns, longer length of stay, and were more likely to have operative burn management. We were unable to detect a relationship between antibiotic exposure and emergence of MDROs.

Conclusions

MDROs are a common and consistent presence in our burns unit. The pattern of acquisition suggests various causes, including introduction from the community and nosocomial spread. More regular surveillance of incidence and targeted interventions may decrease their prevalence, and limit the development of invasive infection.

Partnering on vaccines to counter multi-drug resistant threats: Workshop proceedings, Biomedical Advanced Research and Development Authority

On March 12, 2021, the Biomedical Advanced Research and Development Authority (BARDA) sponsored a virtual market research workshop, "Partnering on Vaccines to Counter Multi-Drug Resistant Threats," to discuss the threat of antimicrobial resistance in the context of BARDA's mission space and the challenges encountered during the development of vaccines for specific antimicrobial resistant bacteria. The workshop convened representatives with expertise in vaccine development from government, academia, and industry. This report summarizes the presentations and subsequent discussions from the workshop and highlights existing challenges to advance the development of vaccine candidates for antimicrobial resistant pathogens, including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus.

Characteristics of bloodstream infection and initial antibiotic use in critically ill burn patients and their impact on patient prognosis

To investigate the bacterial epidemiology of blood cultures taken during the treatment of critically ill burn patients, the use of antibiotics at admission and before the observation of positive blood cultures, and their effect on prognosis. A retrospective study method was used. From January 1, 2010, to December 31, 2019, burn patients who met the inclusion criteria and were treated at the Burn Department, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, were enrolled in the study. Data were collected from the patients' electronic medical records. General patient information, including length of hospital stay, length of intensive care unit (ICU) stay, in-hospital mortality, the bacteria epidemiological characteristics of blood cultures, and the use of antibiotics within 24 h after admission and before a positive blood culture was observed, was collected. Independent sample t tests and χ² tests were used to compare the effects of a positive blood culture and the use of appropriate antibiotics within 24 h after admission and before the observation of a positive blood culture on prognosis. (1) The three most frequently detected bacteria in the blood cultures were Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, and the amount of K. pneumoniae detected increased gradually. (2) Compared with the group of patients who were negative for bloodstream infection , the positive bloodstream infection group had a larger total body burn surface area (TBSA) (t = - 5.097, P = 0.000) and third-degree burn area (t = - 5.133, P = 0.000), a significantly longer length of hospital stay (t = 3.003, P = 0.003) and the length of ICU stay (t = 4.258, P = 0.000), and a significantly higher rate of in-hospital mortality (χ² = 8.485, P = 0.004). When K. pneumoniae was detected, the length of hospital stay (t = 2.148, P = 0.035) and the length of ICU stay (t = 2.880, P = 0.005) were significantly prolonged. (3) The two antibiotics that were most frequently used in patients with acute burns within 24 h after admission were lincomycin (90 cases, 29.32%) and carbapenems (79 cases, 25.73%). Comparing the clinical characteristics of the lincomycin group and the carbapenem group, the TBSA (t = - 3.34, P = 0.001) and the third-degree burn area (t = - 6.08, P = 0.000) of the patients in the carbapenem group were larger, and the length of hospital stay (t = - 2.136, P = 0.035) and length of ICU stay (t = - 5.18, P = 0.000) were longer, but the difference in in-hospital mortality was not statistically significant (χ² = 1.983, P = 0.159). (4) Comparing the group with appropriate initial antibiotic use within 24 h of admission to the inappropriate use group, the TBSA (t = - 0.605, P = 0.547), the third-degree burn area (t = 0.348, P = 0.729), the length of hospital stay (t = - 0.767, P = 0.445), the length of ICU stay (t = - 0.220, P = 0.827) and in-hospital mortality (χ² = 1.271, P = 0.260) were not significantly different. (5) Comparing the group with appropriate antibiotic use before a positive blood culture was observed to the group with inappropriate antibiotic use, the TBSA (t = - 0.418, P = 0.677), the third-degree burn area (t = 0.266, P = 0.791), the length of hospital stay, the length of ICU stay (t = 0.995, P = 0.322) and in-hospital mortality (χ² = 1.274, P = 0.259) were not significantly different. We found that patients with a positive blood culture had a larger burn area and a worse prognosis; that the greater the amount of K. pneumoniae in the bloodstream of burn patients was, the longer the hospital and ICU stays were; that whether appropriate antibiotics were administered to acute critical burn patients 24 h after admission had no effect on the prognosis; and that whether appropriate antibiotics were administered before a positive blood culture was observed had no effect on prognosis.

The role and therapeutic potential of gut microbiome in severe burn

Severe burn is a serious acute trauma that can lead to significant complications such as sepsis, multiple organ failure, and high mortality worldwide. The gut microbiome, the largest microbial reservoir in the human body, plays a significant role in this pathogenic process. Intestinal dysbiosis and disruption of the intestinal mucosal barrier are common after severe burn, leading to bacterial translocation to the bloodstream and other organs of the body, which is associated with many subsequent severe complications. The progression of some intestinal diseases can be improved by modulating the composition of gut microbiota and the levels of its metabolites, which also provides a promising direction for post-burn treatment. In this article, we summarised the studies describing changes in the gut microbiome after severe burn, as well as changes in the function of the intestinal mucosal barrier. Additionally, we presented the potential and challenges of microbial therapy, which may provide microbial therapy strategies for severe burn.

Clinical characteristics and predictors of burn complicated with smoke inhalation injury: A retrospective analysis

Fire smoke enters the human lungs through the respiratory tract. The damage to the respiratory tract and lung tissue is known as smoke inhalation injury (SII). Fire smoke can irritate airway epithelium cells, weaken endothelial cell adhesion and lyse alveolar type II epithelia cells, leading to emphysema, decreased lung function, pneumonia and risk of acute lung injury/acute respiratory distress syndrome (ARDS). The purpose of the present study was to analyze the clinical characteristics of patients with SII and the risk factors affecting their prognosis. A total of 103 patients with SII admitted between January 2016 to December 2021 to the Burns Unit of the Characteristic Medical Center of Chinese People's Armed Police Force and 983 Hospital of the Joint Logistics Support Force of the Chinese People's Liberation Army were selected for the present study. The demographics and clinical features between different severities of SII were analyzed. Univariate/multivariate logistic regression was used to analyze the potential predictors for severity, ARDS and mortality of patients with SII. Receiver operating characteristic (ROC) curves were used to screen independent risk factors and identify their prediction accuracy. It was concluded that total body surface area (TBSA), III burn area (of total %TBSA), cases of respiratory infections, ARDS morbidity, mortality, acute physiology and chronic health evaluation II, lung injury prediction score, lactic acid, white blood cells (WBC), alanine transaminase, blood urea nitrogen, serum creatinine and uric acid were indicators that were raised with increasing severity of SII. However red blood cells, hemoglobin, platelet count, total protein, albumin, and albumin/globulin were decreased with the increasing severity of SII (P<0.05). WBC >20.91 (10⁹/l) was a reliable indicator for severe SII. Lactic acid >9.60 (mmol/l) demonstrated a high degree of accuracy in predicting ARDS development in patients with SII. Hemoglobin <83.00 (g/l) showed a high degree of accuracy in predicting mortality. In summary, the highlighted assessment parameters could be used to contribute to devising improved treatment plans to preempt worsening conditions (such as shock, ARDS, multiple organ dysfunction syndrome and death).

A case of toxic epidermal necrolysis comorbid with severe burns

Toxic epidermal necrolysis (TEN) and severe burns both have high mortality rates, but coexistence is extremely rare. The specificity of developing TEN in burn patients is not well understood and its treatment strategy is not established.

CASE PRESENTATION

A 68-year-old man was carried to our hospital with severe burns covering 35% of his body surface area. He developed bacteremia during treatment of burns and required antimicrobial therapy. However, erythema appeared on the trunk and upper limbs and rapidly spread to the extremities, leading to a diagnosis of TEN. The rash gradually improved after terminating antimicrobial therapy and administrating of 1,000 mg/day methylprednisolone for 3 days. The rash caused by TEN was confined to non-burned areas, suggesting that TEN may less likely occur at burn sites.

CONCLUSION

It is necessary to pay attention because burn patients can develop TEN concomitantly. Corticosteroids therapy may be effective for TEN even in severe burn patients.

Pioglitazone Modifies Kupffer Cell Function and Protects against Escherichia coli-Induced Bacteremia in Burned Mice

Infectious complications and subsequent sepsis in severely burned patients lead to high morbidity and mortality in response to uncontrolled innate immune responses mediated by macrophages. Peroxisome proliferator-activated receptor gamma (PPARγ) has anti-inflammatory activity and acts as a master regulator of macrophage polarization. In this study, we investigated whether the administration of a PPARγ agonist could modulate the Kupffer cell phenotype and thereby ameliorate the dysregulated innate response during post-burn bacterial infection. C57BL/6 mice were subjected to severe burns and randomized to receive either the PPARγ agonist, pioglitazone, or the vehicle control five days after injury, followed by the subsequent analysis of hepatic macrophages. Survival from the bacterial infection was monitored for seven days. Pioglitazone protected burned mice against bacterial infection. A single treatment with pioglitazone significantly enhanced phagocytosis, phagosome acidification, bacterial clearance, and reduction in inflammatory mediators in Kupffer cells. In conclusion, PPARγ activation by pioglitazone prevents clinical deterioration due to post-burn bacterial infection and improves survival. Our findings suggest that pioglitazone may be an effective therapeutic candidate for post-burn infectious complications.

Mechanobactericidal, Gold Nanostar Hydrogel-Based Bandage for Bacteria-Infected Skin Wound Healing

The emergence of multidrug resistant (MDR) microorganisms has led to the development of alternative approaches for providing relief from microbial attacks. The mechano-bactericidal action as a substitute for antimicrobials has become the focus of intensive research. In this work, nanostructure-conjugated hydrogel are explored as a flexible dressing against Staphylococcus aureus (S. aureus)-infected skin wounds. Herein gold nanostars (AuNst) with spike lengths reaching 120 nm are probed for antibacterial action. The bacterial killing of >95% is observed for Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli), while up to 60% for Gram-positive S. aureus. AuNst conjugated hydrogel (AuNst₁₂₀@H) reduced >80% colonies of P. aeruginosa and E. coli. In comparison, around 35.4% reduction of colonies are obtained for S. aureus. The viability assay confirmed the presence of about 85% of living NIH-3T3 cells when grown with hydrogels. An animal wound model is also developed to assess the efficiency of AuNst₁₂₀@H. A significant reduction in wound size is observed on the 10th day in AuNst₁₂₀@H treated animals with fully formed epidermal layers, hair follicles, new blood vessels, and arrector muscles. These findings suggest that novel dressing materials can be developed with antimicrobial nanotextured surfaces.

Epidemiology and Early Bacteriology of Extremely Severe Burns from an LPG Tanker Explosion in Eastern China

The incidence of liquefied petroleum gas (LPG)-related accidents in China has increased over the recent years. In addition, infection remains a big challenge in cases of severe burns. Therefore, the present study aimed to provide valuable information for a better control of infections in the event of such disasters. In this study, a total of 16 patients who suffered extremely severe burns after an LPG tanker explosion were included. Thereafter, bacteriological culture results were collected within a week. Of 16 patients, 13 (81.25%) were male and the average age of all patients was 60.63 years. In addition, the mean burned area was 83.03% TBSA. Additionally, a total of 553 organism cultures were conducted out of which 287 isolates (51.90%) showed positive results. Notably, 38.52% were Gram-negative bacteria, 7.59% were Gram-positive bacteria and 5.79% were fungi. Moreover, the most prevalent Gram-negative bacteria were Stenotrophomonas maltophilia (28.97%) followed by Acinetobacter baumannii (28.53%), and Klebsiella pneumoniae (14.02%). On the other hand, the three most predominant Gram-positive bacteria were Enterococcus faecalis (33.33%), Staphylococcus aureus (28.89%) and Staphylococcus sciuri (17.78%). Furthermore, the most common fungi included Candida (38.24%), Fusarium (20.59%) and Aspergillus fumigatus (14.71%). With regard to the bacterial resistance patterns, carbapenem-resistant organisms included Acinetobacter baumannii (97.80%), Pseudomonas aeruginosa (67.57%), and Klebsiella pneumoniae (75.56%). In addition, Staphylococcus sciuri, Staphylococcus epidermidis, and Staphylococcus haemolyticus were identified to be methicillin-resistant. This study revealed that there was a high incidence of infection in victims of severe burns as a result of mass burn accidents, accompanied by early fungal infection.

Multidrug-Resistant Gram-Negative Bacteria in Burn Patients

Patients with burn injuries are at high risk for infectious complications, and infections are the most common cause of death after the first 72 h of hospitalization. Hospital-acquired infections caused by multidrug resistant (MDR) Gram-negative bacteria (GNB) in this population are concerning. Here, we evaluated carriage with MDR GNB in patients in a large tertiary-care burn intensive care unit. Twenty-nine patients in the burn unit were screened for intestinal carriage. Samples were cultured on selective media. Median time from admission to the burn unit to first sample collection was 9 days (IQR 5 - 17 days). In 21 (72%) patients, MDR GNB were recovered; the most common bacterial species isolated was Pseudomonas aeruginosa, which was found in 11/29 (38%) of patients. Two of these patients later developed bloodstream infections with P. aeruginosa. Transmission of KPC-31-producing ST22 Citrobacter freundii was detected. Samples from two patients grew genetically similar C. freundii isolates that were resistant to ceftazidime-avibactam. On analysis of whole-genome sequencing, blaKPC-31 was part of a Tn4401b transposon that was present on two different plasmids in each C. freundii isolate. Plasmid curing experiments showed that removal of both copies of blaKPC-31 was required to restore susceptibility to ceftazidime-avibactam. In summary, MDR GNB colonization is common in burn patients and patient-to-patient transmission of highly resistant GNB occurs. These results emphasize the ongoing need for infection prevention and antimicrobial stewardship efforts in this highly vulnerable population.

Metabolically Specific In Situ Fluorescent Visualization of Bacterial Infection on Wound Tissues

The ability to effectively detect bacterial infection in human tissues is important for the timely treatment of the infection. However, traditional techniques fail to visualize bacterial species adhered to host cells in situ in a target-specific manner. Dihydropteroate synthase (DHPS) exclusively exists in bacterial species and metabolically converts p-aminobenzoic acid (PABA) to folic acid (FA). By targeting this bacterium-specific metabolism, we have developed a fluorescent imaging probe, PABA-DCM, based on the conjugation of PABA with a long-wavelength fluorophore, dicyanomethylene 4H-pyran (DCM). We confirmed that the probe can be used in the synthetic pathway of a broad spectrum of Gram-positive and negative bacteria, resulting in a significantly extended retention time in bacterial over mammalian cells. We validated that DHPS catalytically introduces a dihydropteridine group to the amino end of the PABA motif of PABA-DCM, and the resulting adduct leads to an increase in the FA levels of bacteria. We also constructed a hydrogel dressing containing PABA-DCM and graphene oxide (GO), termed PABA-DCM@GO, that achieves target-specific fluorescence visualization of bacterial infection on the wounded tissues of mice. Our research paves the way for the development of fluorescent imaging agents that target species-conserved metabolic pathways of microorganisms for the in situ monitoring of infections in human tissues.

Outbreak of Carbapenemase-Producing Enterobacteriaceae in a Regional Burn Center

Antimicrobial resistance is an increasing problem in hospitals worldwide; however, the prevalence of carbapenemase-producing Enterobacteriaceae (CPE) in our region is low. Burn patients are vulnerable to infection because of the loss of the protective skin barrier, thus burn centers prioritize infection prevention and control (IP&C). This report describes a CPE outbreak in a regional burn center. In a period of 2.5 months, four nosocomial cases of CPE were identified, three containing the Klebsiella pneumoniae carbapenemase (KPC) gene and one Verona integrin-encoded metallo-β-lactamase (VIM) gene. The first two cases were identified while there was no CPE patient source on the unit. CPE KPC gene was then isolated in sink drains of three rooms. In addition to rigorous IP&C practices already in place, we implemented additional outbreak measures including restricting admissions to patients with complex burns or burns ≥10% TBSA, admitting patients to other in-patient units, and not permitting elective admissions. We began cohorting patients using nursing team separation for CPE-positive and -negative patients and geographical separation on the unit. Despite aggressive IP&C measures already in place, hospital-acquired CPE colonization/infection occurred. Given that CPE contaminated sinks of the same enzyme were identified, we believe hospital sink drains may the source. This highlights the importance of sink design and engineering solutions to prevent the formation of biofilm and reduce splashing. CPE infections are associated with poor outcomes in patients and significant health system costs due to a longer length of stay and additional institutional resources.

Increased Innate Immune Susceptibility in Hyperpigmented Bacteriophage-Resistant Mutants of Pseudomonas aeruginosa

Bacteriophage (phage) therapy is an alternative to traditional antibiotic treatments that is particularly important for multidrug-resistant pathogens, such as Pseudomonas aeruginosa. Unfortunately, phage resistance commonly arises during treatment as bacteria evolve to survive phage predation. During in vitro phage treatment of a P. aeruginosa-type strain, we observed the emergence of phage-resistant mutants with brown pigmentation that was indicative of pyomelanin. As increased pyomelanin (due to hmgA gene mutation) was recently associated with enhanced resistance to hydrogen peroxide and persistence in experimental lung infection, we questioned if therapeutic phage applications could inadvertently select for hypervirulent populations. Pyomelanogenic phage-resistant mutants of P. aeruginosa PAO1 were selected for upon treatment with three distinct phages. Phage-resistant pyomelanogenic mutants did not possess increased survival of pyomelanogenic ΔhmgA in hydrogen peroxide. At the genomic level, large (~300 kb) deletions in the phage-resistant mutants resulted in the loss of ≥227 genes, many of which had roles in survival, virulence, and antibiotic resistance. Phage-resistant pyomelanogenic mutants were hypersusceptible to cationic peptides LL-37 and colistin and were more easily cleared in human whole blood, serum, and a murine infection model. Our findings suggest that hyperpigmented phage-resistant mutants that may arise during phage therapy are markedly less virulent than their predecessors due to large genomic deletions. Thus, their existence does not present a contraindication to using anti-pseudomonal phage therapy, especially considering that these mutants develop drug susceptibility to the familiar FDA-approved antibiotic, colistin.