Effects of burn wound excision on bacterial colonization and invasion

Selective Inactivation of Pseudomonas aeruginosa and Staphylococcus epidermidis with Pulsed Electric Fields and Antibiotics

Objective: Increasing numbers of multidrug-resistant bacteria make many antibiotics ineffective; therefore, new approaches to combat microbial infections are needed. In addition, antibiotics are not selective-they kill pathogenic organisms as well as organisms that could positively contribute to wound healing (bio flora). Approach: Here we report on selective inactivation of Pseudomonas aeruginosa and Staphylococcus epidermidis, potential pathogens involved in wound infections with pulsed electric fields (PEFs) and antibiotics (mix of penicillin, streptomycin, and nystatin). Results: Using a Taguchi experimental design in vitro, we found that, under similar electric field strengths, the pulse duration is the most important parameter for P. aeruginosa inactivation, followed by the number of pulses and pulse frequency. P. aeruginosa, a potential severe pathogen, is more sensitive than the less pathogenic S. epidermidis to PEF (alone or in combination with antibiotics). Applying 200 pulses with a duration of 60 μs at 2.8 Hz, the minimum electric fields of 308.8 ± 28.3 and 378.4 ± 12.9 V/mm were required to inactive P. aeruginosa and S. epidermidis, respectively. Addition of antibiotics reduced the threshold for minimum electric fields required to inactivate the bacteria. Innovation: This study provides essential information, such as critical electric field parameters for bacteria inactivation, required for developing in vivo treatment and clinical protocols for using PEF for wound healing. Conclusion: A combination of PEFs with antibiotics reduces the electric field threshold required for bacteria disinfection. Such an approach simplifies devices required to disinfect large areas of infected wounds.

Infection Prevention: Unique Aspects of Burn Units

BACKGROUND

Infection is a common complication of burn injury caused by the loss of skin (the primary defense against micro-organisms) as well as burn-induced immunosuppression. Essentially, survival after burn injury is determined by whether wound healing or infection predominates. The purpose of this article is to describe how burn unit structure and design may impact the incidence of infection after burn injury.

METHODS

This article describes the special considerations for burn unit structure and design based on burn pathophysiology, including burn-related immunosuppression and wound treatment. Particular emphasis is placed on how burn unit design should consider the immunosuppressed state of the burn patient.

RESULTS

Because many of the factors that promote wound healing also promote infection, burn unit design must prioritize infection prevention, including segregation and containment, environment layout and function, room cleaning, and isolation. Burn centers should have dedicated facilities with separation of patients, specialized room environment/equipment, and cleaning and wound care disinfection capabilities, with particular attention paid to surfaces, ventilation, temperature control, and patient movement to the operating room, radiology, and therapy.

CONCLUSIONS

Because of the high infection potential associated with burn injury, burn units require meticulous attention to design and function to minimize patient infection risk.

Colonization with Multidrug-Resistant Enterobacteriaceae is Associated with Increased Mortality Following Burn Injury in Sub-Saharan Africa

BACKGROUND

Multidrug-resistant (MDR) bacteria are an emerging international concern in low- and middle-income countries that threaten recent public health gains. These challenges are exacerbated in immunocompromised hosts, such as those with burn injury. This study sought to describe the epidemiology and associated clinical outcomes of burn wound colonization in a Malawian tertiary burn center.

METHODS

This is a prospective analysis of burn patients presenting to Kamuzu Central Hospital in Lilongwe, Malawi, within 72 h of burn injury. A swab of each patient's primary wound was collected at admission and each subsequent week. The primary exposure was burn wound colonization with MDR bacteria, particularly Enterobacteriaceae. The primary outcome was in-hospital mortality. A log binomial model estimated the association between the exposure and outcome, adjusted for confounders.

RESULTS

Ninety-nine patients were enrolled with a median age of 4 years (IQR 2-12) and a male preponderance (54%). Median total body surface area burn (TBSA) was 14% (IQR 9-25), and crude in-hospital mortality was 19%. Enterobacteriaceae were the most common MDR bacteria with 36% of patients becoming colonized. Wound colonization with MDR Enterobacteriaceae was associated with increased in-hospital mortality with a risk ratio of 1.86 (95% CI 1.38, 2.50, p < 0.001) adjusted for TBSA, burn type (scald vs. flame), sex, age, length of stay, and methicillin-resistant Staphylococcus aureus colonization.

CONCLUSION

MDR bacteria, especially Enterobacteriaceae, are common and are associated with worse burn injury outcomes. In resource-poor environments, a greater emphasis on prevention of MDR bacterial colonization, improved isolation precautions, affordable diagnostics, and antibiotic stewardship are imperative.

Thermoresponsive gels containing gold nanoparticles as smart antibacterial and wound healing agents

Thermoresponsive gels containing gold nanoparticles (AuNPs) were prepared using Pluronic®127 alone (F1) and with hydroxypropyl methylcellulose (F2) at ratios of 15% w/w and 15:1% w/w, respectively. AuNPs were evaluated for particle size, zeta-potential, polydispersity index (PDI), morphology and XRD pattern. AuNP-containing thermoresponsive gels were investigated for their gelation temperature, gel strength, bio-adhesive force, viscosity, drug content, in vitro release and ex-vivo permeation, in addition to in vitro antibacterial activity against bacteria found in burn infections, Staphylococcus aureus. In vivo burn healing and antibacterial activities were also investigated and compared with those of a commercial product using burn-induced infected wounds in mice. Spherical AuNPs sized 28.9-37.65 nm displayed a surface plasmon resonance band at 522 nm, a PDI of 0.461, and a zeta potential of 34.8 mV with a negative surface charge. F1 and F2 showed gelation temperatures of 37.2 °C and 32.3 °C, bio-adhesive forces of 2.45 ± 0.52 and 4.76 ± 0.84 dyne/cm2, viscosities of 10,165 ± 1.54 and 14,213 ± 2.31 cP, and gel strengths between 7.4 and 10.3 sec, respectively. The in vitro release values of F1 and F2 were 100% and 98.03% after 6 h, with permeation flux values of (J1) 0.2974 ± 2.85 and (J2) 0.2649 ± 1.43 (µg/cm2·h), respectively. The formulations showed antibacterial activity with the highest values for wound healing properties, as shown in vivo and by histopathological studies. This study demonstrates that a smart AuNPs thermoresponsive gel was successful as an antibacterial and wound healing transdermal drug delivery system.

Bacterial Infections After Burn Injuries: Impact of Multidrug Resistance

Patients who are admitted to the hospital after sustaining a large burn injury are at high risk for developing hospital-associated infections. If patients survive the initial 72 hours after a burn injury, infections are the most common cause of death. Ventilator-associated pneumonia is the most important infection in this patient population. The risk of infections caused by multidrug-resistant bacterial pathogens increases with hospital length of stay in burn patients. In the first days of the postburn hospitalization, more susceptible, Gram-positive organisms predominate, whereas later more resistant Gram-negative organisms are found. These findings impact the choice of empiric antibiotics in critically ill burn patients. A proactive infection control approach is essential in burn units. Furthermore, a multidisciplinary approach to burn patients with a team that includes an infectious disease specialist and a pharmacist in addition to the burn surgeon is highly recommended.

Sepsis criteria versus clinical diagnosis of sepsis in burn patients: A validation of current sepsis scores

BACKGROUND

Sepsis remains an ongoing diagnostic challenge in burns, especially with the signs of sepsis being ubiquitously present during the acute period after injury. We aimed to determine the predictive validity of 3 current sepsis criteria in the burn population. The criteria of interest included the American Burn Association sepsis criteria, Mann-Salinas et al predictors of sepsis, and the Sepsis-3 consensus definition.

METHODS

Adult patients with an acute burn injury who were diagnosed prospectively with sepsis by the burn team using specific clinical markers were included in this cohort study. Sepsis predictors were collected from patient charts and used to calculate the results of the 3 criteria, then subsequently compared to the clinical diagnosis.

RESULTS

Of the 418 patients in the study, which took place from 2000 until 2016, 88 (21%) were septic; the mean age was 50 ± 18 years with a mean percent total body surface area burn of 30% ± 17%. Inhalation injury was present in 50%, median length of stay was 49 (29-71) days, and mortality was 19%. The American Burn Association, Mann-Salinas, and Sepsis-3 criteria were positive in 59%, 28%, and 85% respectively, P < .05. The most reliable predictors included increased oxygen requirements, altered mental status, hypothermia, hyperthermia, tachycardia, and hypotension.

CONCLUSION

The Sepsis-3 criteria was the most predictive, followed by the American Burn Association and Mann-Salinas criteria. However, no criterion alone had the accuracy to be a diagnostic standard within this burn population. We recommend sepsis is clinically assessed, diagnosed, and documented prospectively by the burn team, and not by the application of retrospective criteria.

Cutaneous Burn Injury Promotes Shifts in the Bacterial Microbiome in Autologous Donor Skin: Implications for Skin Grafting Outcomes

INTRODUCTION

The cutaneous microbiome maintains skin barrier function, regulates inflammation, and stimulates wound-healing responses. Burn injury promotes an excessive activation of the cutaneous and systemic immune response directed against commensal and invading pathogens. Skin grafting is the primary method of reconstructing full-thickness burns, and wound infection continues to be a significant complication.

METHODS

In this study, the cutaneous bacterial microbiome was evaluated and subsequently compared to patient outcomes. Three different full-thickness skin specimens were assessed: control skin from non-burned subjects; burn margin from burn patients; and autologous donor skin from the same cohort of burn patients.

RESULTS

We observed that skin bacterial community structure of burn patients was significantly altered compared with control patients. We determined that the unburned autologous donor skin from burn patients exhibits a microbiome similar to that of the burn margin, rather than unburned controls, and that changes in the cutaneous microbiome statistically correlate with several post-burn complications. We established that Corynebacterium positively correlated with burn wound infection, while Staphylococcus and Propionibacterium negatively correlated with burn wound infection. Both Corynebacterium and Enterococcus negatively correlated with the development of sepsis.

CONCLUSIONS

This study identifies distinct differences in the cutaneous microbiome between burn subjects and unburned controls, and ascertains that select bacterial taxa significantly correlate with several comorbid complications of burn injury. These preliminary data suggest that grafting donor skin exhibiting bacterial dysbiosis may augment infection and/or graft failure and sets the foundation for more in-depth and mechanistic analyses in presumably "healthy" donor skin from patients requiring skin grafting procedures.

Multiple-Drug Resistance in Burn Patients: A Retrospective Study on the Impact of Antibiotic Resistance on Survival and Length of Stay

Despite improvements in early treatment, survival following burn injury remains challenged by sepsis and multiple organ dysfunction syndrome (MODS). Additionally, susceptibility to infections and growing antibiotic resistance places burn patients at increased risk for infections with multiple-drug resistant organisms (MDROs). We therefore aimed to evaluate the impact of MDRO infections on survival and hospital length of stay, as well as examine the role of these organisms in the development of complications, such as acute kidney injury, sepsis, and MODS. To study this, we included all burn patients with infections, admitted between January 1, 2012, and December 31, 2013. Patients were divided into two groups: patients with infections caused by MDROs and patients with infections caused by susceptible organisms. Data were collected on all available cultures, as well as demographic, injury, and treatment-related variables from the medical record. The number of operative procedures (median: 2 vs 1, P < .0001), ventilator days (21 vs 0 days, P < .0001), total antibiotic days (21 vs 7days, P < .0001), and length of hospitalization (39 vs 14 days, P < .0001) were significantly different in the MDRO group vs the nonresistant group. While MDRO infection was not associated with patient mortality, univariable logistic regression analyses demonstrated >20% TBSA (odds ratio [OR] = 4.30, 95% confidence interval [CI]: 1.14-16.29, P = .03), acute kidney injury (OR = 10.93, 95% CI: 2.74-43.57, P = .001), sepsis (OR = 19.20, 95% CI: 3.79-97.27, P < .001), and MODS (OR = 85.49, 95% CI: 12.97-563.28, P < .0001) significantly increased the odds of patient mortality. These findings suggest that infections with MDROs are associated with a greater number of surgical procedures, longer duration of mechanical ventilation, more antibiotic days, and longer hospitalization.

Topical Antimicrobials in Burn Care: Part 1-Topical Antiseptics

Burn wounds disrupt the body's primary defense against invasion and colonization by microorganisms. Topical antimicrobials are one component in burn wound care. These agents suppress microbial growth to advantage skin cells and wound healing. Topical antimicrobials can be divided into 2 superclasses: antiseptics and antibiotics. We review the 4 main classes of topical antiseptics (emulsifiers, acids, oxidizers, and heavy metals) and antiseptic-impregnated dressings in current clinical use and address the mechanisms, as well as the advantages and disadvantages of each antiseptic for burn wound management.

Role of slough and biofilm in delaying healing in chronic wounds

The management of biofilms with maintenance desloughing and antimicrobial therapy is fast becoming the accepted treatment strategy for chronic wounds.

The P50 Research Center in Perioperative Sciences: How the investment by the National Institute of General Medical Sciences in team science has reduced postburn mortality

Since the inception of the P50 Research Center in Injury and Peri-operative Sciences (RCIPS) funding mechanism, the National Institute of General Medical Sciences has supported a team approach to science. Many advances in critical care, particularly burns, have been driven by RCIPS teams. In fact, burns that were fatal in the early 1970s, prior to the inception of the P50 RCIPS program, are now routinely survived as a result of the P50-funded research. The advances in clinical care that led to the reduction in postburn death were made by optimizing resuscitation, incorporating early excision and grafting, bolstering acute care including support for inhalation injury, modulating the hypermetabolic response, augmenting the immune response, incorporating aerobic exercise, and developing antiscarring strategies. The work of the Burn RCIPS programs advanced our understanding of the pathophysiologic response to burn injury. As a result, the effects of a large burn on all organ systems have been studied, leading to the discovery of persistent dysfunction, elucidation of the underlying molecular mechanisms, and identification of potential therapeutic targets. Survival and subsequent patient satisfaction with quality of life have increased. In this review article, we describe the contributions of the Galveston P50 RCIPS that have changed postburn care and have considerably reduced postburn mortality.

Effect of human placental extract in the management of biofilm mediated drug resistance - A focus on wound management

Management of infectious wounds, particularly chronic wounds and burn injuries, is a matter of global concern. Worldwide estimates reveal that, billions of dollars are being spent annually for the management of such chronic ailments. Evidently, bacterial biofilms pose a greater problem in the effective management of infection in chronic wounds, since most of the currently available antibiotics are unable to act on the microorganisms residing inside the protected environment of the biofilms. Accordingly, in the present study, we have attempted to evaluate the anti-biofilm properties of human placental extract (PLX) and also other virulence factors that are mediated via the quorum sensing (QS) signalling system. PLX is well known for its anti inflammatory action and it has been shown earlier some anti microbial and enzymatic activity also. PLX was found to produce significant inhibition of biofilm formation and also decreased the levels of pyoverdin and pyocyanin. The microscopic analysis (both light microscopy and atomic force microscopy) of biofilms was also used for substantiating the findings from spectrophotometric (crystal violet estimation) and fluorescence analysis (resazurin uptake). PLX pre-treatment decreased the hydrophobicity of gram-positive and gram negative cells, indicating the effect of placental extract on adherence property of planktonic cell, serving as an indicator for its antibiofilm effect on microorganisms. The reduced extracellular DNA (eDNA) content in biofilm matrix following treatment with PLX also indicates the effectiveness of placenta extract on bacterial adherence, which in turn serves as evidence substantiating the antibiofilm effects of the PLX. Furthermore, PLX was also found to be significantly effective in the in vitro wound biofilm model. Thus the present study, the first of its kind with PLX, establishes the therapeutic benefit of the same particularly in infected wounds, opening up newer avenue for further exploration.

A systematic review of quantitative burn wound microbiology in the management of burns patients

BACKGROUND

The early diagnosis of infection or sepsis in burns are important for patient care. Globally, a large number of burn centres advocate quantitative cultures of wound biopsies for patient management, since there is assumed to be a direct link between the bioburden of a burn wound and the risk of microbial invasion. Given the conflicting study findings in this area, a systematic review was warranted.

METHODS

Bibliographic databases were searched with no language restrictions to August 2015. Study selection, data extraction and risk of bias assessment were performed in duplicate using pre-defined criteria. Substantial heterogeneity precluded quantitative synthesis, and findings were described narratively, sub-grouped by clinical question.

RESULTS

Twenty six laboratory and/or clinical studies were included. Substantial heterogeneity hampered comparisons across studies and interpretation of findings. Limited evidence suggests that (i) more than one quantitative microbiology sample is required to obtain reliable estimates of bacterial load; (ii) biopsies are more sensitive than swabs in diagnosing or predicting sepsis; (iii) high bacterial loads may predict worse clinical outcomes, and (iv) both quantitative and semi-quantitative culture reports need to be interpreted with caution and in the context of other clinical risk factors.

CONCLUSION

The evidence base for the utility and reliability of quantitative microbiology for diagnosing or predicting clinical outcomes in burns patients is limited and often poorly reported. Consequently future research is warranted.

Important Developments in Burn Care

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Explain the epidemiology of severe burn injury in the context of socioeconomic status, gender, age, and burn cause. 2. Describe challenges with burn depth evaluation and novel methods of adjunctive assessment. 3. Summarize the survival and functional outcomes of severe burn injury. 4. State strategies of fluid resuscitation, endpoints to guide fluid titration, and sequelae of overresuscitation. 5. Recognize preventative measures of sepsis. 6. Explain intraoperative strategies to improve patient outcomes, including hemostasis, restrictive transfusion, temperature regulation, skin substitutes, and Meek skin grafting. 7. Translate updates in the pathophysiology of hypertrophic scarring into novel methods of clinical management. 8. Discuss the potential role of free tissue transfer in primary and secondary burn reconstruction.

SUMMARY

Management of burn-injured patients is a challenging and unique field for plastic surgeons. Significant advances over the past decade have occurred in resuscitation, burn wound management, sepsis, and reconstruction that have improved outcomes and quality of life after thermal injury. However, as patients with larger burns are resuscitated, an increased risk of nosocomial infections, sepsis, compartment syndromes, and venous thromboembolic phenomena have required adjustments in care to maintain quality of life after injury. This article outlines a number of recent developments in burn care that illustrate the evolution of the field to assist plastic surgeons involved in burn care.

Recombinant human granulocyte macrophage colony stimulating factor in deep second-degree burn wound healing

BACKGROUND

The aim of this study was to explore the effects of recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF) on deep second-degree burn wound healing.

METHODS

In this study, 95 patients with a total of 190 burn wounds were treated with either rhGM-CSF or placebo, separated into 2 groups by treatment type. Wound healing rate, wound healing time, histopathological condition, and scar scale were all compared between the 2 groups.

RESULTS

The healing rates in the rhGM-CSF group were remarkably higher than those in the placebo group (P < .01). The wound healing time in the rhGM-CSF group (18.8 ± 7.6 days) was significantly shorter than that in the placebo group (25.5 ± 4.6 days, P < .01). On the 14th day and 28th day, the average optical density of vascular endothelial factor (VEGF) in the rhGM-CSF group was larger than that in the placebo group. Meanwhile, the average optical density of fibroblast growth factor (FGF) in the rhGM-CSF group was also larger than that in the placebo group. Furthermore, the Vancouver scar scale scores of pigmentation, pliability, height, and vascularity were notable lower in the rhGM-CSF group than those in the placebo group (P < .01).

CONCLUSION

The results suggest that rhGM-CSF can significantly accelerate deep second-degree burn wound healing.

Burn Injury Leads to Increased Long-Term Susceptibility to Respiratory Infection in both Mouse Models and Population Studies

Background

Burn injury initiates an acute inflammatory response that subsequently drives wound repair. However, acute disruption to the immune response is also common, leading to susceptibility to sepsis and increased morbidity and mortality. Despite increased understanding of the impact of burn injury on the immune system in the acute phase, little is known about long-term consequences of burn injury on immune function. This study was established to determine whether burn injury has long-term clinical impacts on patients’ immune responses.

Methods

Using a population-based retrospective longitudinal study and linked hospital morbidity and death data from Western Australia, comparative rates of hospitalisation for respiratory infections in burn patients and a non-injured comparator cohort were assessed. In addition, a mouse model of non-severe burn injury was also used in which viral respiratory infection was induced at 4 weeks post-injury using a mouse modified version of the Influenza A virus (H3NN; A/mem/71-a).

Results and conclusions

The burn injured cohort contained 14893 adult patients from 1980–2012 after removal of those patients with evidence of smoke inhalation or injury to the respiratory tract. During the study follow-up study a total of 2,884 and 2,625 respiratory infection hospital admissions for the burn and uninjured cohorts, respectively, were identified. After adjusting for covariates, the burn cohort experienced significantly elevated admission rates for influenza and viral pneumonia (IRR, 95%CI: 1.73, 1.27–2.36), bacterial pneumonia (IRR, 95%CI: 2.05, 1.85–2.27) and for other types of upper and lower respiratory infections (IRR, 95% CI: 2.38, 2.09–2.71). In the mouse study an increased viral titre was observed after burn injury, accompanied by a reduced CD8 response and increased NK and NKT cells in the draining lymph nodes. This data suggests burn patients are at long-term increased risk of infection due to sustained modulation of the immune response.

Burns and long-term infectious disease morbidity: A population-based study

BACKGROUND

There is a growing volume of data that indicates that serious injury suppresses immune function, predisposing individuals to infectious complications. With recent evidence showing long-term immune dysfunction after less severe burn, this study aimed to investigate post-burn infectious disease morbidity and assess if burn patients have increased long-term hospital use for infectious diseases.

METHODS

A population-based longitudinal study using linked hospital morbidity and death data from Western Australia for all persons hospitalised for a first burn (n=30,997) in 1980-2012. A frequency matched non-injury comparison cohort was randomly selected from Western Australia's birth registrations and electoral roll (n=123,399). Direct standardisation was used to assess temporal trends in infectious disease admissions. Crude annual admission rates and length of stay for infectious diseases were calculated. Multivariate negative binomial and Cox proportional hazards regression modeling were used to generate adjusted incidence rate ratios (IRR) and hazard ratios (HR), respectively.

RESULTS

After adjustment for demographic factors and pre-existing health status, the burn cohort had twice (IRR, 95% confidence interval (CI): 2.04, 1.98-2.22) as many admissions and 3.5 times the number of days in hospital (IRR, 95%CI: 3.46, 3.05-3.92) than the uninjured cohort for infectious diseases. Higher rates of infectious disease admissions were found for severe (IRR, 95%CI: 2.37, 1.89-2.97) and minor burns (IRR, 95%CI: 2.22, 2.11-2.33). Burns were associated with significantly increased incident admissions: 0-30days (HR, 95%CI: 5.18, 4.15-6.48); 30days-1year (HR, 95%CI: 1.69, 1.53-1.87); 1-10 years (HR, 95%CI: 1.40:1.33-1.47); >10years (HR, 95%CI: 1.16, 1.08-1.24). Respiratory, skin and soft tissue and gastrointestinal infections were the most common. The burn cohort had a 1.75 (95%CI: 1.37-2.25) times greater rate of mortality caused by infectious diseases during the 5-year period after discharge than the uninjured cohort.

CONCLUSIONS

These findings suggest that burn has long-lasting effects on the immune system and its function. The increase in infectious disease in three different epithelial tissues in the burn cohort suggests there may be common underlying pathophysiology. Further research to understand the underlying mechanisms are required to inform clinical interventions to mitigate infectious disease after burn and improve patient outcomes.

Infection in Burns

BACKGROUND

Developments in critical care and surgical approaches to treating burn wounds, together with newer antimicrobial treatments, have significantly reduced the morbidity and mortality rates associated with this injury.

METHODS

Review of the pertinent English-language literature.

RESULTS

Several resistant organisms have emerged as the maleficent cause of invasive infection in burn patients, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, Pseudomonas, Acinetobacter, non-albicans Candida spp., and Aspergillus. Advances in antimicrobial therapies and the release of new classes of antibiotics have certainly added to the armamentarium of therapeutic resources for the clinician.

CONCLUSION

Strict infection control measures, constant wound surveillance with regular sampling of tissues for quantitative culture, and early excision and wound closure remain the principal adjuncts to control of invasive infections in burn patients.

Respiratory Morbidity After Childhood Burns: A 10-Year Follow-up Study

BACKGROUND AND OBJECTIVE

The systemic responses triggered by burns and resuscitative measures may cause pulmonary damage and edema in the acute phase. These effects may occur in the absence of inhalation injury. Currently, there is a paucity of data on the recovery of the respiratory system postburn. This study aimed to examine 10-year hospital service use for respiratory morbidity in children with cutaneous burns and no smoke inhalation injury.

METHODS

A population-based longitudinal study with 10-year follow-up using linked hospital and death from Western Australia for children <5 years when hospitalized for a first burn injury (n = 5290) between 1980 and 2012 and a frequency matched noninjury comparison cohort, randomly selected from Western Australia's birth registrations (n = 27 061). Multivariate negative binomial and Cox proportional hazards regression models were used to generate adjusted incidence rate ratios (IRR) and hazard ratios, respectively.

RESULTS

After adjustment for demographic factors and preexisting health status, the burn cohort had higher rates of admissions for influenza and viral pneumonia (IRR, 1.78; 95% confidence interval [CI], 1.10-2.87), bacterial pneumonia (IRR, 1.34; 95% CI, 1.06-1.70), and other respiratory infections (IRR, 1.65; 95% CI, 1.43-1.90. No significant difference was found for other upper respiratory tract conditions (IRR, 1.10; 95% CI, 0.98-1.23) or chronic lower respiratory diseases (IRR, 0.99; 95% CI, 0.80-1.23) compared with the uninjured cohort.

CONCLUSIONS

These findings demonstrated increased respiratory infection admissions after burns. These outcomes suggest that immune changes triggered by a burn injury may persist in some children for at least 10 years after wound healing.

Burn-associated bloodstream infections in pediatric burn patients: Time distribution of etiologic agents

BACKGROUND

Infections are the leading cause of morbidity and mortality in patients with burns in burn units. Bloodstream infections (BSIs) in patients with burns may result from burn wound infection, use of invasive devices such as central venous catheters, and translocation of the gastrointestinal flora.

OBJECTIVE

In this study, we investigated the distribution and antimicrobial drug resistance of causative pathogens in children with burns and the durational changes of microorganisms in the distribution of BSIs in children.

METHODS

This study was conducted at the Pediatric Burn Unit (PBU) of Dr. Behçet Uz Children Research and Training Hospital during the period of November 2008-April 2015. The study subjects were all the patients admitted to the PBU, in whom microorganisms were isolated at least from one of the cultures, including blood and catheter cultures.

RESULTS

Gram-positive bacteria were the most common causative agents of BSI in patients with burns (66.4%), followed by gram-negative bacteria (22.1%) and fungi (11.5%). The median duration of development of BSIs caused by gram-positive bacteria from the time of burn was 5 days (ranging from 2 to 54 days of burn), which was significantly shorter than that of BSIs caused by gram-negative bacteria (12 days) and fungal pathogens (13 days).

CONCLUSION

The etiologic agents of BSIs in children may differ from those in adults. Gram-negative drug-resistant bacteria such as multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii were important agents of BSI in patients with burns, especially in the long term; however, gram-positive bacteria should also be considered while deciding the antimicrobial therapy, especially in the early periods of burn.

Pediatric Burn Resuscitation

Children have unique physiologic, physical, psychological, and social needs compared with adults. Although adhering to the basic tenets of burn resuscitation, resuscitation of the burned child should be modified based on the child's age, physiology, and response to injury. This article outlines the unique characteristics of burned children and describes the fundamental principles of pediatric burn resuscitation in terms of airway, circulatory, neurologic, and cutaneous injury management.

Surveillance of antibiotic susceptibility in a Swedish Burn Center 1994-2012

Patients with burn trauma are at risk for infections caused by antibiotic resistant bacteria (ABR) with subsequent increase in morbidity and mortality. As part of the Swedish strategic program against antibiotic resistance in intensive care (ICU-Strama), we have surveyed the distribution of species and ABR in isolates from patients admitted to a Swedish burn center at Linköping University Hospital from 1994 through 2012. In an international comparison Strama has been successful in reducing the antibiotic consumption among animals and humans in primary care. The aim of this study was to investigate the antibiotic consumption pressure and resistance rates in a Swedish burn unit.

METHODS

Microbiology data, total body surface area (TBSA), patient days, and mortality were collected from a hospital database for all patients admitted to the Burn Center at the University Hospital of Linköping from April 1994 through December 2012.

RESULTS

A total of 1570 patients were admitted with a mean annual admission rate of 83 patients (range: 57-152). 15,006 microbiology cultures (approximately 10 per patient) were collected during the study period and of these 4531 were positive (approximately 3 per patient). The annual mean total body surface area (TBSA) was 13.4% (range 9.5-18.5) with an annual mortality rate of 5.4% (range 1-8%). The MRSA incidence was 1.7% (15/866) which corresponds to an MRSA incidence of 0.34/1000 admission days (TAD). Corresponding figures were for Escherichia coli resistant to 3(rd) generation cephalosporins (ESBL phenotype) 8% (13/170) and 0.3/TAD, Klebsiella spp. ESBL phenotype 5% (6/134) and 0.14/TAD, carbapenem resistant Pseudomonas aeruginosa 26% (56/209) and 1.28/TAD, and carbapenem resistant Acinetobacter spp. 3% (2/64) and 0.04/TAD.

CONCLUSIONS

Our results show a sustained low risk for MRSA and high, although not increasing, risk for carbapenem resistant P. aeruginosa.

Paracrine Factors from Irradiated Peripheral Blood Mononuclear Cells Improve Skin Regeneration and Angiogenesis in a Porcine Burn Model

Burn wounds pose a serious threat to patients and often require surgical treatment. Skin grafting aims to achieve wound closure but requires a well-vascularized wound bed. The secretome of peripheral blood mononuclear cells (PBMCs) has been shown to improve wound healing and angiogenesis. We hypothesized that topical application of the PBMC secretome would improve the quality of regenerating skin, increase angiogenesis, and reduce scar formation after burn injury and skin grafting in a porcine model. Full-thickness burn injuries were created on the back of female pigs. Necrotic areas were excised and the wounds were covered with split-thickness mesh skin grafts. Wounds were treated repeatedly with either the secretome of cultured PBMCs (Sec(PBMC)), apoptotic PBMCs (Apo-Sec(PBMC)), or controls. The wounds treated with Apo-Sec(PBMC) had an increased epidermal thickness, higher number of rete ridges, and more advanced epidermal differentiation than controls. The samples treated with Apo-Sec(PBMC) had a two-fold increase in CD31+ cells, indicating more angiogenesis. These data suggest that the repeated application of Apo-Sec(PBMC) significantly improves epidermal thickness, angiogenesis, and skin quality in a porcine model of burn injury and skin grafting.

Major Transcriptome Changes Accompany the Growth of Pseudomonas aeruginosa in Blood from Patients with Severe Thermal Injuries

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes serious infections in immunocompromised hosts including severely burned patients. After multiplying within the burn wound, P. aeruginosa translocate into the bloodstream causing bacterial sepsis frequently leading to organ dysfunction and septic shock. Although the pathogenesis of P. aeruginosa infection of thermally-injured wounds has been extensively analyzed, little is known regarding the ability of P. aeruginosa to adapt and survive within the blood of severely burned patients during systemic infection. To identify such adaptations, transcriptome analyses (RNA-seq) were conducted on P. aeruginosa strain PA14 that was grown in whole blood from a healthy volunteer or three severely burned patients. Compared with growth in blood from healthy volunteers, growth of PA14 in the blood from severely burned patients significantly altered the expression of 2596 genes, with expression of 1060 genes enhanced, while that of 1536 genes was reduced. Genes whose expression was significantly reduced included genes related to quorum sensing, quorum sensing-controlled virulence factors and transport of heme, phosphate, and phosphonate. Genes whose expression was significantly enhanced were related to the type III secretion system, the pyochelin iron-acquisition system, flagellum synthesis, and pyocyanin production. We confirmed changes in expression of many of these genes using qRT-PCR. Although severe burns altered the levels of different blood components in each patient, the growth of PA14 in their blood produced similar changes in the expression of each gene. These results suggest that, in response to changes in the blood of severely burned patients and as part of its survival strategy, P. aeruginosa enhances the expression of certain virulence genes and reduces the expression of others.

Experience and efficacy of surgery for retaining viable subcutaneous tissue in extensive full-thickness burns

BACKGROUND AND AIM

For adult patients with extensive full-thickness burns (EFTB), a fascial excision is mostly used but it causes a very significant deformity. This study aims to summarize experience and efficacy of surgery for retaining viable subcutaneous tissue in EFTB.

METHOD

Clinical data were reviewed for 31 consecutive adult patients with full-thickness burn (FTB) over 70% total body surface area (TBSA) and undergoing first tangential excision and skin grafting on subcutaneous tissue wound (TESGSTW) within 7 days post burn at our burn center between 2002 and 2013.

RESULTS

Average age, total burn area, and FTB area of 31 patients were 32.4 ± 12.8 years, 89.0 ± 6.2% and 80.4 ± 7.6% TBSA, respectively. Of these, 80.6% combined with inhalation injury and 71.0% supervened early shock. Eighteen patients who survived (58.1%) totally underwent 121 times of surgery, of which TESGSTW and autologous skin grafting were 41 and 88 times, respectively. Their average time and area of first tangential excision was 4.1 ± 0.6 days post burn and 33.8 ± 7.6% TBSA, respectively, and accumulated tangential excision area was 58.4 ± 10.8% TBSA. In 39 times of TESGSTW within 14 days post burn, cryopreserved alloskin or fresh young pigskin was applied on 84.6%, and average time and take rate of autologous skin grafting instead of grafted alloskin or xenoskin was 14.6 ± 0.7 days and 89.5 ± 1.4%, respectively. Scalp was the main donor site for autologous skin, especially microskin grafting. Systemic wound healing time roughly was 67.3 ± 1.9 days post burn, meanwhile, viable subcutaneous tissue was retained. Healed wounds were plump, and their extensibility and sensitivity were better by follow-up.

CONCLUSION

The surgical treatment in EFTB is practicable and effective.

The Role of CHI3L1 (Chitinase-3-Like-1) in the Pathogenesis of Infections in Burns in a Mouse Model

In severe burn injury the unique setting of a depleted, dysfunctional immune system along with a loss of barrier function commonly results in opportunistic infections that eventually proof fatal. Unfortunately, the dynamic sequence of bacterial contamination, colonization and eventually septic invasion with bacteria such as Pseudomonas species is still poorly understood although a limiting factor in clinical decision making. Increasing evidence supports the notion that inhibition of bacterial translocation into the wound site may be an effective alternative to prevent infection. In this context we investigated the role of the mammalian Chitinase-3-Like-1 (CHI3L1) non-enyzmatic protein predominately expressed on epithelial as well as innate immune cells as a potential bacterial-translocation-mediating factor. We show a strong trend that a modulation of chitinase expression is likely to be effective in reducing mortality rates in a mouse model of burn injury with superinfection with the opportunistic PA14 Pseudomonas strain, thus demonstrating possible clinical leverage.

Burn wound healing and treatment: review and advancements

Burns are a prevalent and burdensome critical care problem. The priorities of specialized facilities focus on stabilizing the patient, preventing infection, and optimizing functional recovery. Research on burns has generated sustained interest over the past few decades, and several important advancements have resulted in more effective patient stabilization and decreased mortality, especially among young patients and those with burns of intermediate extent. However, for the intensivist, challenges often exist that complicate patient support and stabilization. Furthermore, burn wounds are complex and can present unique difficulties that require late intervention or life-long rehabilitation. In addition to improvements in patient stabilization and care, research in burn wound care has yielded advancements that will continue to improve functional recovery. This article reviews recent advancements in the care of burn patients with a focus on the pathophysiology and treatment of burn wounds.

An Ounce of Prevention Saves Tons of Lives: Infection in Burns

BACKGROUND

Modern day burn care continues to wage an uphill battle against an enemy that evolves faster than we can develop weapons. Bacteria (bioburden) are everywhere and can infiltrate anywhere within our susceptible population of burn patients. This is why prevention of infection is key to improving their survival and outcome.

PURPOSE

To reduce the incidence of infection in the burn patient population.

MATERIALS

Review of pertinent recent literature regarding infection prevention and control in the intensive care unit setting.

RESULTS

We propose that bioburden is one of the central elements in the infectious cycle that is ever-present in burn units. The mechanism of bacterial entry into the unit and subsequent transmission and infection are delineated. Recommendations for mitigating this risk are provided to guide future clinicians in their care of burn patients.

CONCLUSIONS

The treatment of infection and sepsis against highly adaptable bacteria is often insurmountable by ill patients. In this process, bioburden needs to be corralled to have any success. Thus, preventing organisms from entering the unit and transferring onto other patients, and eliminating the bacteria dwelling in the unit are all necessary actions in this battle. Ultimately, maintaining a culture that is constantly wary of this risk only can achieve this goal.

Propranolol attenuates hemorrhage and accelerates wound healing in severely burned adults

Introduction

Propranolol, a nonselective β-blocker, exerts an indirect effect on the vasculature by leaving α-adrenergic receptors unopposed, resulting in peripheral vasoconstriction. We have previously shown that propranolol diminishes peripheral blood following burn injury by increasing vascular resistance. The purpose of this study was to investigate whether wound healing and perioperative hemodynamics are affected by propranolol administration in severely burned adults.

Methods

Sixty-nine adult patients with burns covering ≥30% of the total body surface area (TBSA) were enrolled in this IRB-approved study. Patients received standard burn care with (n = 35) or without (control, n = 34) propranolol. Propranolol was administered within 48 hours of burns and given throughout hospital discharge to decrease heart rate by approximately 20% from admission levels. Wound healing was determined by comparing the time between grafting procedures. Blood loss was determined by comparing pre- and postoperative hematocrit while factoring in operative graft area. Data were collected between first admission and first discharge.

Results

Demographics, burn size, and mortality were comparable in the control and propranolol groups. Patients in the propranolol group received an average propranolol dose of 3.3 ± 3.0 mg/kg/day. Daily average heart rate over the first 30 days was significantly lower in the propranolol group (P <0.05). The average number of days between skin grafting procedures was also lower in propranolol patients (10 ± 5 days) than in control patients (17 ± 12 days; P = 0.02), indicative of a faster donor site healing time in the propranolol group. Packed red blood cell infusion was similar between groups (control 5.3 ± 5.4 units vs. propranolol 4.4 ± 3.1 units, P = 0.89). Propranolol was associated with a 5 to 7% improvement in perioperative hematocrit during grafting procedures of 4,000 to 16,000 cm² compared to control (P = 0.002).

Conclusions

Administration of propranolol during the acute hospitalization period diminishes blood loss during skin grafting procedures and markedly improves wound healing in severely burned adults. As burn patients require serial surgical interventions for motor and cosmetic repair, restricting blood loss during operative intervention is optimal.

Management of Burns and Anesthetic Implications

Burn injuries are highly complex and affect almost every major organ system in the body. The treatment of burn patients requires the presence of a well-organized team of caregivers who understand the multifaceted consequences of burn injuries and who are adept at coordinating care. An understanding of the multitude of abnormalities that must be addressed helps to guide therapy in these patients. Careful anesthetic and perioperative management of these patients carries special importance in this fragile patient population as a part of their often lengthy recovery and rehabilitation.

Microparticles of Aloe vera/vitamin E/chitosan: microscopic, a nuclear imaging and an in vivo test analysis for burn treatment

The use of drug-loaded nanoparticles and microparticles has been increasing, especially for cosmetic and drug delivery purposes. In this work, a new microparticle formulation was developed for use in the healing process of skin burns in a composition of Aloe vera/vitamin E/chitosan. In order to observe the morphological properties, Raman and atomic force microscopy evaluation were performed. The biodistribution studies were analyzed by using a nuclear methodology, labeling the microparticles with Technetium-99m and in vivo test was procedure to analyzed the cicatrization process. The results of AFM analysis show the formation and the adherence property of the microparticles. Raman analyses show the distribution of each component in the microparticle. The nuclear method used shows that the biodistribution of the microparticles remained in the skin. The in vivo cicatrization test showed that the poloxamer gel containing the microparticles make a better cicatrization in relation to the other formulations tested.

Bloodstream infection as a predictor for mortality in severe burn patients: an 11-year study

In this study we collected and analysed data of the severe burn patients at our institution over an 11-year period in order to shed light on the controversial role of bloodstream infection (BSI) as a predictive factor for mortality in this burn population. The factors examined were age, total body surface area, smoke inhalation, presence of BSI, and BSI with resistant bacteria. In total 1081 burn patients were hospitalized from 2001 to 2011, of whom 4% died. We focused here on 158 severe burn patients, 74 of whom developed BSI, and 35 who died. Using univariate analysis, it appeared that the BSI group had a threefold greater chance of mortality compared to the non-BSI group. Patients with a Ryan score 3 had a 100% chance of mortality and those with a score 0 had 0%. Thus, focusing only on Ryan score 1 and score 2 patients, BSI did not contribute to mortality, nor was it shown to contribute to mortality in a multivariate analysis in which the score and BSI were included together. When BSI did occur, it predicted longer hospitalization periods. We conclude that BSI predicts longer length of hospitalization stay but does not contribute to the prediction of mortality beyond that offered by the Ryan score in a severe burn population.

Is the length of time in acute burn surgery associated with poorer outcomes?

BACKGROUND

Acute wound closure surgery improves outcomes, after burn particularly mortality, but also imposes physiological stress on the patient. The duration of surgery is associated with adverse outcomes in other populations. This study aimed to examine if extended acute burn surgery duration was associated with poorer in-hospital outcomes.

METHODS

This retrospective cohort study included adult burn patients who required a single wound closure surgery at Royal Perth Hospital between 2004 and 2011. Multivariable regression analyses were used to assess the influence of patient and injury factors on surgery duration and length of stay (LOS).

RESULTS

Surgery duration independently increased LOS (incidence rate ratio [IRR]=1.004, p<0.001). This translates to a predicted 13% increase in LOS for a 30min increase in surgery 'knife to skin' time. Total body surface area (TBSA) was identified as a significant predictor of surgery duration (IRR=1.047, p<0.001), estimating that a 10% TBSA increase results in a 59% increase in surgery duration.

CONCLUSION

The results show that surgery duration is associated with LOS after adjusting for size of burn and other factors. The study justifies the need to explore strategies to reduce acute burn surgery duration.