Septicaemia after burn injury: a comparative study

The impact of infection on length of stay in adult burns: A scoping review

BACKGROUND

The disruption to the immune system and profound metabolic response to burn injury gives rise to a unique susceptibility to infection. Indeed, infection is one of the most frequently encountered post-burns complications placing significant burden on patients and healthcare system. Advancements in burn care have led to marked improvements in burn-related mortality and morbidity; however, scarce hospital resources hamper adequate burn-related care, and patient length of stay (LOS) in hospital is an important drain on such resources. The aim of this review was to assess and evaluate the existing literature relating to the impact of infections on LOS in hospitalised, adult burn patients.

METHODS

Electronic searches were performed in Medline and Embase. Eligible studies were those reporting on LOS and infection in adult burn populations. Articles published before 2000 were excluded to ensure that the analysis was focused on contemporary literature that reflects current, clinical management of burn patients.

RESULTS

Nineteen studies (54,397 burn patients) were included in the review. All studies were retrospective, with the majority undertaken in North America (14 studies). The mean age range was 38-67 years and the majority of patients were male. Inhalation injury was recorded in eleven studies. The most common types of infection included pneumonia, blood stream infections (BSI) and burn wound infections. Overall, there was a trend towards a positive association between infection and LOS.

CONCLUSION

The results of this scoping review provide an overview of the existing literature on the relationship between infection and LOS in adult burn populations. However, significant gaps remain in knowledge which call for further high-quality research. Standardised definitions for the collection of infection data and the use of burns specific infection control guidelines are also critical to understanding and improving patient outcomes.

Evolution of Burn Care: Past, Present, and Future

Burn care evolved slowly from primitive treatments depicted in cave drawings 3500 years ago to a vibrant medical specialty which has made remarkable progress over the past 200 years. This evolution involved all areas of burn care including superficial dressings, wound assessment, fluid resuscitation, infection control, pathophysiology, nutritional support, burn surgery, and inhalation injury. Major advances that contributed to current standards of care and improved outcomes are highlighted in this article. New innovations are making possible a future where severe burn injuries will require less morbid interventions for acute care and outcomes will restore patients more closely to their pre-injury condition.

Cerium Nitrate Stiffens In Vitro Skin Models and Reduces Pseudomonas aeruginosa Pathogenicity and Penetration Through Skin Models

Objective: Cerium nitrate (CeN) plus silver sulfadiazine (SSD) cream has been used for 40-plus years to manage burns. CeN produces a hardened eschar believed to resist bacterial colonization/infection. To evaluate this potential mechanism, we treated in vitro skin models or Pseudomonas aeruginosa with CeN and measured mechanical properties of the models and bacterial virulence, respectively. Approach: We treated three-dimensional-collagen matrix and ex-vivo-burned porcine skin with CeN and evaluated stiffness and P. aeruginosa penetration. In addition, we treated P. aeruginosa with CeN and evaluated the bacteria's motility, skin model penetration, susceptibility to be phagocytized by the human monocytic cell line THP-1, and ability to stimulate this cell line to produce cytokines. Results: CeN treatment of skin models stiffened them and made them resistant to P. aeruginosa penetration. Inversely, CeN treatment of P. aeruginosa reduced their motility, penetration through skin models (ex-vivo-burned porcine skin), and ability to stimulate cytokine production (tumor necrosis factor-α [TNF-α] and interleukin 8 [IL-8]) by THP-1 cells. In addition, CeN-treated Pseudomonas was more readily phagocytized by THP-1 cells. Finally, P. aeruginosa inoculated on CeN-treated ex-vivo-burned porcine skin was more susceptible to killing by a silver dressing. Innovation: In vitro skin models offer a platform for screening drugs that interfere with bacterial penetration into wounded tissue. Conclusion: CeN treatment reduced P. aeruginosa virulence, altered the mechanical properties of ex-vivo-burned porcine skin and collagen matrix, retarded penetration of P. aeruginosa through the skin models, and resulted in increased vulnerability of P. aeruginosa to killing by antimicrobial wound dressings. These data support the use of CeN in burn management.

Pseudomonas aeruginosa: Infections and novel approaches to treatment "Knowing the enemy" the threat of Pseudomonas aeruginosa and exploring novel approaches to treatment

Pseudomonas aeruginosa is an aerobic Gram-negative rod-shaped bacterium with a comparatively large genome and an impressive genetic capability allowing it to grow in a variety of environments and tolerate a wide range of physical conditions. This biological flexibility enables the P. aeruginosa to cause a broad range of infections in patients with serious underlying medical conditions, and to be a principal cause of health care associated infection worldwide. The clinical manifestations of P. aeruginosa include mostly health care associated infections and community-acquired infections. P. aeruginosa possesses an array of virulence factors that counteract host defence mechanisms. It can directly damage host tissue while utilizing high levels of intrinsic and acquired antimicrobial resistance mechanisms to counter most classes of antibiotics. P. aeruginosa co-regulates multiple resistance mechanisms by perpetually moving targets poses a significant therapeutic challenge. Thus, there is an urgent need for novel approaches in the development of anti-Pseudomonas agents. Here we review the principal infections caused by P. aeruginosa and we discuss novel therapeutic options to tackle antibiotic resistance and treatment of P. aeruginosa infections that may be further developed for clinical practice.

Review of History of Basic Principles of Burn Wound Management

Thermal energy is an essential and useful resource to humans in modern society. However, a consequence of using heat carelessly is burns. Burn injuries have various causes, such as exposure to flame, radiation, electrical, and chemical sources. In this study, we reviewed the history of burn wound care while focusing on the basic principles of burn management. Through this review, we highlight the need for careful monitoring and customization when treating burn victims at each step of wound care, as their individual needs may differ. We also propose that future research should focus on nanotechnology-based skin grafts, as this is a promising area for further improvement in wound care.

Functional Hydrogel Dressings for Treatment of Burn Wounds

The therapy of burns is a challenging clinical issue. Burns are long-term injuries, and numerous patients suffer from chronic pain. Burn treatment includes management, infection control, wound debridement and escharotomy, dressing coverage, skin transplantation, and the use of skin substitutes. The future of advanced care of burn wounds lies in the development of “active dressings”. Hydrogel dressings have been employed universally to accelerate wound healing based on their unique properties to overcome the limitations of existing treatment methods. This review briefly introduces the advantages of hydrogel dressings and discusses the development of new hydrogel dressings for wound healing along with skin regeneration. Further, the treatment strategies for burns, ranging from external to clinical, are reviewed, and the functional classifications of hydrogel dressings along with their clinical value for burns are discussed.

A New Dermal Substitute Containing Polyvinyl Alcohol with Silver Nanoparticles and Collagen with Hyaluronic Acid: In Vitro and In Vivo Approaches

The experimental use of poly (alcohol-vinyl) (PVA) as a skin curative is increasing widely. However, the use of this hydrogel is challenging due to its favorable properties for microbiota growth. The association with silver nanoparticles (AgNPs) as an antimicrobial agent turns the match for PVA as a dressing, as it focuses on creating a physical barrier to avoid wound dehydration. When associated with extracellular components, such as the collagen matrix, the device obtained can create the desired biological conditions to act as a skin substitute. This study aimed to analyze the anti-microbiological activity and the in vitro and in vivo responses of a bilaminar device of PVA containing AgNPs associated with a membrane of collagen-hyaluronic acid (col-HA). Additionally, mesenchymal stem cells were cultured in the device to evaluate in vitro responses and in vivo immunomodulatory and healing behavior. The device morphology revealed a porous pattern that favored water retention and in vitro cell adhesion. Controlled wounds in the dorsal back of rat skins revealed a striking skin remodeling with new epidermis fulfilling all previously injured areas after 14 and 28 days. No infections or significant inflammations were observed, despite increased angiogenesis, and no fibrosis-markers were identified as compared to controls. Although few antibacterial activities were obtained, the addition of AgNPs prevented fungal growth. All results demonstrated that the combination of the components used here as a dermal device, chosen according to previous miscellany studies of low/mid-cost biomaterials, can promote skin protection avoiding infections and dehydration, minimize the typical wound inflammatory responses, and favor the cellular healing responses, features that give rise to further clinical trials of the device here developed.

A Murine Model of Full-Thickness Scald Burn Injury with Subsequent Wound and Systemic Bacterial Infection

Infection is the leading cause of death and prolonged hospitalization in severely burned patients that survive the acute phase of injury. Here we describe a murine model of severe burn injury followed by subsequent postburn infection, both local and systemic, that leads to sepsis. A detailed description of the full-thickness scald burn procedure is provided, followed by description of infection with two common burn-associated nosocomial pathogens, Pseudomonas aeruginosa and Staphylococcus aureus.

Measures of Systemic Innate Immune Function Predict the Risk of Nosocomial Infection in Pediatric Burn Patients

Critical injury-induced immune suppression has been associated with adverse outcomes. This acquired form of immunosuppression is poorly understood in pediatric burn patients, who have infectious complication rates as high as 71%. Our primary objectives were to determine if thermal injury results in early innate immune dysfunction and is associated with increased risk for nosocomial infections (NI). We performed a prospective, longitudinal immune function observational study at a single pediatric burn center. Whole blood samples from burn patients within the first week of injury were used to assess innate immune function. Nosocomial infections were defined using CDC criteria. Immune parameters were compared between patients who went on to develop NI and those that did not. We enrolled a total of 34 patients with 12 developing a NI. Within the first 3 days of injury, children whom developed NI had significantly lower whole blood ex vivo LPS-induced TNFα production capacity (434 pg/mL vs 960 pg/mL, P = .0015), CD14+ monocyte counts (273 cells/µL vs 508 cells/µL, P = .01), and % HLA-DR expression on CD14+ monocytes (54% vs 92%, P = .02) compared with those that did not develop infection. Plasma cytokine levels did not have a significant difference between the NI and no NI groups. Early innate immune suppression can occur following pediatric thermal injury and appears to be a risk factor for the development of nosocomial infections. Plasma cytokines alone may not be a reliable predictor of the development of NI.

The association between vitamin D levels and burn factors in different burn types

Background

Patients with burns present with different clinical features depending on the types of burn injury and burn patients with lower levels of vitamin D have worse prognoses and more complications. The study aims to investigate the association between vitamin D levels and burn factors according to each burn type in relation to early intensive rehabilitation therapy initiated for inpatients with burns.

Methods

In this retrospective study, we enrolled 757 of 1716 inpatients who underwent rehabilitative therapy between May 2013 and April 2017. Burn types were divided into flame burn, electrical burn and other burns, including scalding, contact and chemical burns. Age, burned body surface area (BSA), wound healing time (WHT), length of hospital stay (LOS) and body mass index were analysed between vitamin D deficient and non-deficient patient groups using Student’s t-tests, or Mann-Whitney U test and among three burn types using one-way analysis of variance (ANOVA) or Kruskal-Wallis one-way ANOVA. The relationship between vitamin D levels and burn factors was evaluated using Pearson's or Spearman's correlation coefficient tests, and multiple linear regression analysis in different burn groups.

Results

In total, 88.9% patients were vitamin D deficient, and these patients had a larger burned BSA (p = 0.015) and longer WHT and LOS (all p < 0.001) than non-deficient patients. Burned BSA, WHT and vitamin D levels showed significant differences in their mean values according to three burn types (all p < 0.001). WHT was a communal factor significantly associated with vitamin D levels in all three burn types (p < 0.05). The WHT cut-off points to predict vitamin D deficiency were 55 days for flame burn (p < 0.001) and 62.5 days for electrical burn (p = 0.001).

Conclusions

WHT across all three burn types was a common factor associated with vitamin D levels for inpatients with burns who had undergone rehabilitative therapy. Electrical burn patients with vitamin D deficiency, even those with a low burned BSA percentage, showed prolonged wound healing over a two-month post-burn period. Independent of burned BSA, nutritional intervention concerning vitamin D in relation to burn wound healing should be considered to guide early initiation of intensive rehabilitation therapy.

A Critical Update of the Assessment and Acute Management of Patients with Severe Burns

Significance: Burns are debilitating, life threatening, and difficult to assess and manage. Recent advances in assessment and management have occurred since a comprehensive review of the care of patients with severe burns was last published, which may influence research and clinical practice. Recent Advances: Recent advances have occurred in the understanding of burn pathophysiology, which has led to the identification of potential biomarkers of burn severity, such as protein C. There is new evidence about the potential superiority of natural colloids over crystalloids during fluid resuscitation, and new evidence about components of initial and perioperative management, including an improved understanding of pain following burns. Critical Issues: The limitations of the clinical examination highlight the need for imaging and biomarkers to assist in estimations of burn severity. Fluid resuscitation reduces mortality, although there is conjecture over the ideal method. The subsequent perioperative period is associated with significant morbidity and the evidence for preventing and treating pain, infection, and fluid overload while maximizing wound healing potential is described. Future Directions: Promising developments are ongoing in imaging technology, histopathology, biomarkers, and wound healing adjuncts such as hyperbaric oxygen therapy, topical negative pressure therapy, stem cell treatments, and skin substitutes. The greatest benefit from further research on management of patients with burns would most likely be derived from the elucidation of optimal fluid resuscitation protocols, pain management protocols, and surgical techniques from randomized controlled trials.

Negative Pressure Wound Therapy with Instillation and Dwell for the Management of a Complex Burn: A Case Report and Review of the Literature

Research over the last 50 years has led to significant improvements in outcomes for burn victims. Advances in infection control, attenuation of the hypermetabolic response, and new improved surgical approaches have led to decreased morbidity and mortality. Early wound excision eliminates the devitalized tissue, which is the main reservoir for pathogen propagation. Immediate autografting reestablishes the natural barrier of the skin, which blocks pathogen access to the host. Advances in burn care have increased treatment options for patients with devastating injuries presenting with multiple comorbidities. Over the last 20 years, negative pressure assisted wound therapy (NPWT) has shown to improve wound management and healing as well as decrease the length of recovery in burn patients. As NPWT applications evolve, the development of negative pressure wound therapy with instillation and dwell time (NPWTi-d) for the management of complex and infected wounds has proven vital for patient care. We present the case of a 68-year-old male patient presenting with a three-day-old third-degree burn wound spanning 46% of the total body surface area (TBSA). After the infected wound was treated unsuccessfully with the standard of care (excision, debridement, and grafting), the team utilized NPWTi-d in order to mitigate the infection and promote the formation of granulation tissue, leading to the successful grafting of the burn wound. NPWTi-d was a useful adjunct in treating and stimulating wound healing in a complex patient. This is the first case report of its kind, utilizing a whole-body vacuum assisted closure (VAC) with NPWTi-d, with successful results showing a decreased bacterial burden, decreased morbidity and mortality, and patient wound closure.

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.

Local Burn Injury Promotes Defects in the Epidermal Lipid and Antimicrobial Peptide Barriers in Human Autograft Skin and Burn Margin: Implications for Burn Wound Healing and Graft Survival

Burn injury increases the risk of morbidity and mortality by promoting severe hemodynamic shock and risk for local or systemic infection. Graft failure due to poor wound healing or infection remains a significant problem for burn subjects. The mechanisms by which local burn injury compromises the epithelial antimicrobial barrier function in the burn margin, containing the elements necessary for healing of the burn site, and in distal unburned skin, which serves as potential donor tissue, are largely unknown. The objective of this study was to establish defects in epidermal barrier function in human donor skin and burn margin, to identify potential mechanisms that may lead to graft failure and/or impaired burn wound healing. In this study, we established that epidermal lipids and respective lipid synthesis enzymes were significantly reduced in both donor skin and burn margin. We further identified diverse changes in the gene expression and protein production of several candidate skin antimicrobial peptides (AMPs) in both donor skin and burn margin. These results also parallel changes in cutaneous AMP activity against common burn wound pathogens, aberrant production of epidermal proteases known to regulate barrier permeability and AMP activity, and greater production of proinflammatory cytokines known to be induced by AMPs. These findings suggest that impaired epidermal lipid and AMP regulation could contribute to graft failure and infectious complications in subjects with burn or other traumatic injury.

Microbiology in burns patients with blood stream infections: trends over time and during the course of hospitalization

BACKGROUND

Bloodstream infections (BSI) are a major cause of mortality in burns patients. Knowledge of the microbiology is crucial to direct empirical therapy. We sought to determine the causative microorganisms and antibiotic resistance in burns patients with BSI.

METHODS

All consecutive BSI episodes in a tertiary hospital burns unit from 2000 to 2014 were included. The following three subperiods were compared: 2000-2004, 2005-2009 and 2010-2014. Changes in BSI occurring during early and late hospitalization periods were evaluated.

RESULTS

A total of 103 BSI episodes were included. The cumulative incidence was 2.4 episodes/1000 patient days. A positive trend in the frequency of Gram-negative BSI, especially in the upsurge of Pseudomonas aeruginosa and Klebsiella spp. BSI after 2004, was observed. The most common causative pathogens in early BSI were Gram-positive microorganisms. P. aeruginosa and Klebsiella spp. became the predominant aetiology in the fourth week of hospitalization and beyond. There was a progressive increase in imipenem-resistant P. aeruginosa over time (0%, 67%, 75% in 2000-2004, 2005-2009, 2010-2014, respectively) and during the hospital stay (50% vs. 85.7%, in <7 days-BSI vs. >30 days-BSI, respectively). A higher SOFA (Sepsis-related Organ Failure Assessment) score was associated with Gram-negative BSI versus non-Gram-negative BSI (median: 2.5 vs. 0; p = 0.041).

CONCLUSIONS

There is a changing trend in the types of pathogens causing BSI in burns patients over the 14-year period and during the course of hospitalization. The problematic increase in carbapenem-resistance highlights the need for new antimicrobial stewardship policies and antibiotic prescribing protocols.

History and Advancement of Burn Treatments

Advances in burn care have accelerated within the last 50 years. The principal modalities of and approaches to burn treatment include dressings, antimicrobials, fluid resuscitation, burn wound excision, skin grafting, and use of skin substitutes. This review presents a historical outline of these approaches, their current status, and prospects for the future of burn care.

Antiseptics for burns

BACKGROUND

Burn wounds cause high levels of morbidity and mortality worldwide. People with burns are particularly vulnerable to infections; over 75% of all burn deaths (after initial resuscitation) result from infection. Antiseptics are topical agents that act to prevent growth of micro-organisms. A wide range are used with the intention of preventing infection and promoting healing of burn wounds.

OBJECTIVES

To assess the effects and safety of antiseptics for the treatment of burns in any care setting.

SEARCH METHODS

In September 2016 we searched the Cochrane Wounds Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations), Ovid Embase, and EBSCO CINAHL. We also searched three clinical trials registries and references of included studies and relevant systematic reviews. There were no restrictions based on language, date of publication or study setting.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that enrolled people with any burn wound and assessed the use of a topical treatment with antiseptic properties.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, risk of bias assessment and data extraction.

MAIN RESULTS

We included 56 RCTs with 5807 randomised participants. Almost all trials had poorly reported methodology, meaning that it is unclear whether they were at high risk of bias. In many cases the primary review outcomes, wound healing and infection, were not reported, or were reported incompletely.Most trials enrolled people with recent burns, described as second-degree and less than 40% of total body surface area; most participants were adults. Antiseptic agents assessed were: silver-based, honey, Aloe Vera, iodine-based, chlorhexidine or polyhexanide (biguanides), sodium hypochlorite, merbromin, ethacridine lactate, cerium nitrate and Arnebia euchroma. Most studies compared antiseptic with a topical antibiotic, primarily silver sulfadiazine (SSD); others compared antiseptic with a non-antibacterial treatment or another antiseptic. Most evidence was assessed as low or very low certainty, often because of imprecision resulting from few participants, low event rates, or both, often in single studies. Antiseptics versus topical antibioticsCompared with the topical antibiotic, SSD, there is low certainty evidence that, on average, there is no clear difference in the hazard of healing (chance of healing over time), between silver-based antiseptics and SSD (HR 1.25, 95% CI 0.94 to 1.67; I² = 0%; 3 studies; 259 participants); silver-based antiseptics may, on average, increase the number of healing events over 21 or 28 days' follow-up (RR 1.17 95% CI 1.00 to 1.37; I² = 45%; 5 studies; 408 participants) and may, on average, reduce mean time to healing (difference in means -3.33 days; 95% CI -4.96 to -1.70; I² = 87%; 10 studies; 979 participants).There is moderate certainty evidence that, on average, burns treated with honey are probably more likely to heal over time compared with topical antibiotics (HR 2.45, 95% CI 1.71 to 3.52; I² = 66%; 5 studies; 140 participants).There is low certainty evidence from single trials that sodium hypochlorite may, on average, slightly reduce mean time to healing compared with SSD (difference in means -2.10 days, 95% CI -3.87 to -0.33, 10 participants (20 burns)) as may merbromin compared with zinc sulfadiazine (difference in means -3.48 days, 95% CI -6.85 to -0.11, 50 relevant participants). Other comparisons with low or very low certainty evidence did not find clear differences between groups.Most comparisons did not report data on infection. Based on the available data we cannot be certain if antiseptic treatments increase or reduce the risk of infection compared with topical antibiotics (very low certainty evidence). Antiseptics versus alternative antisepticsThere may be some reduction in mean time to healing for wounds treated with povidone iodine compared with chlorhexidine (MD -2.21 days, 95% CI 0.34 to 4.08). Other evidence showed no clear differences and is of low or very low certainty. Antiseptics versus non-antibacterial comparatorsWe found high certainty evidence that treating burns with honey, on average, reduced mean times to healing in comparison with non-antibacterial treatments (difference in means -5.3 days, 95% CI -6.30 to -4.34; I² = 71%; 4 studies; 1156 participants) but this comparison included some unconventional treatments such as amniotic membrane and potato peel. There is moderate certainty evidence that honey probably also increases the likelihood of wounds healing over time compared to unconventional anti-bacterial treatments (HR 2.86, 95% C 1.60 to 5.11; I² = 50%; 2 studies; 154 participants).There is moderate certainty evidence that, on average, burns treated with nanocrystalline silver dressings probably have a slightly shorter mean time to healing than those treated with Vaseline gauze (difference in means -3.49 days, 95% CI -4.46 to -2.52; I² = 0%; 2 studies, 204 participants), but low certainty evidence that there may be little or no difference in numbers of healing events at 14 days between burns treated with silver xenograft or paraffin gauze (RR 1.13, 95% CI 0.59 to 2.16 1 study; 32 participants). Other comparisons represented low or very low certainty evidence.It is uncertain whether infection rates in burns treated with either silver-based antiseptics or honey differ compared with non-antimicrobial treatments (very low certainty evidence). There is probably no difference in infection rates between an iodine-based treatment compared with moist exposed burn ointment (moderate certainty evidence). It is also uncertain whether infection rates differ for SSD plus cerium nitrate, compared with SSD alone (low certainty evidence).Mortality was low where reported. Most comparisons provided low certainty evidence that there may be little or no difference between many treatments. There may be fewer deaths in groups treated with cerium nitrate plus SSD compared with SSD alone (RR 0.22, 95% CI 0.05 to 0.99; I² = 0%, 2 studies, 214 participants) (low certainty evidence).

AUTHORS' CONCLUSIONS

It was often uncertain whether antiseptics were associated with any difference in healing, infections, or other outcomes. Where there is moderate or high certainty evidence, decision makers need to consider the applicability of the evidence from the comparison to their patients. Reporting was poor, to the extent that we are not confident that most trials are free from risk of bias.

Targeting bacterial adherence inhibits multidrug-resistant Pseudomonas aeruginosa infection following burn injury

Classical antimicrobial drugs target proliferation and therefore place microbes under extreme selective pressure to evolve resistance. Alternative drugs that target bacterial virulence without impacting survival directly offer an attractive solution to this problem, but to date few such molecules have been discovered. We previously discovered a widespread group of bacterial adhesins, termed Multivalent Adhesion Molecules (MAMs) that are essential for initial binding of bacteria to host tissues and virulence. Thus, targeting MAM-based adherence is a promising strategy for displacing pathogens from host tissues and inhibiting infection. Here, we show that topical application of polymeric microbeads functionalized with the adhesin MAM7 to a burn infected with multidrug-resistant Pseudomonas aeruginosa substantially decreased bacterial loads in the wound and prevented the spread of the infection into adjacent tissues. As a consequence, the application of this adhesion inhibitor allowed for vascularization and wound healing, and maintained local and systemic inflammatory responses to the burn. We propose that MAM7-functionalized microbeads can be used as a topical treatment, to reduce bacterial attachment and hence prevent bacterial colonization and infection of wounds. As adhesion is not required for microbial survival, this anti-infective strategy has the potential to treat multidrug-resistant infections and limit the emergence of drug-resistant pathogens.

Local Application of Probiotic Bacteria Prophylaxes against Sepsis and Death Resulting from Burn Wound Infection

Objective

To determine if local prophylactic application of probiotic bacteria to burn wounds will prevent death in a mouse model of burn wound sepsis.

Background

Infection remains the most common complication after burn injury and can result in sepsis and death, despite the use of topical and systemic antibiotics. Pseudomonas aeruginosa is a frequently implicated pathogen. Local application of probiotics directly to burn wounds is an attractive novel intervention that avoids the pitfalls of standard antibiotic therapies.

Methods

A burn-sepsis model was established using a sub-eschar injection of bioluminescent P. aeruginosa; infection was tracked using a charge-coupled camera. Full-thickness burn injuries were placed on the dorsums of adult mice; the injured sites were then treated with vehicle (burn wound control), probiotics (Lactobacillus plantarum only), pathogenic bacteria (Pseudomonas aeruginosa only), or probiotics plus pathogen (Lactobacillus plus Pseudomonas). Animals were monitored until death/moribundity or for one week, then sacrificed. Harvested tissues were subjected to imaging and molecular assays.

Results

Control and probiotic-only animals showed no mortality (100% survival) at one week. Pseudomonas-only animals showed > 90% mortality within 40 hours of infection. In contrast, animals treated with probiotics plus Pseudomonas showed less than 10% mortality. Use of bioluminescent Pseudomonas bacteria demonstrated that probiotic therapy inhibited septicemic accumulation of the pathogen in remote organs. In addition, probiotic therapy successfully suppressed the infection-dependent induction of TNF-α and interleukins 6 and 10 in the liver.

Conclusions

Local probiotic therapy shows great potential as a valuable adjunct in the management of complicated burn injury.

Full-thickness porcine burns infected with Staphylococcus aureus or Pseudomonas aeruginosa can be effectively treated with topical antibiotics

Burn and blast injuries are frequently complicated by invasive infections, which lead to poor wound healing, delay in treatment, disability, or death. Traditional approach centers on early debridement, fluid resuscitation, and adjunct intravenous antibiotics. These modalities often prove inadequate in burns, where compromised local vasculature limits the tissue penetration of systemic antibiotics. Here, we demonstrate the treatment of infected burns with topical delivery of ultrahigh concentrations of antibiotics. Standardized burns were inoculated with Staphylococcus aureus or Pseudomonas aeruginosa. After debridement, burns were treated with either gentamicin (2 mg/mL) or minocycline (1 mg/mL) at concentrations greater than 1,000 times the minimum inhibitory concentration. Amount of bacteria was quantified in tissue biopsies and wound fluid following treatment. After six days of gentamicin or minocycline treatment, S. aureus counts decreased from 4.2 to 0.31 and 0.72 log CFU/g in tissue, respectively. Similarly, P. aeruginosa counts decreased from 2.5 to 0.0 and 1.5 log CFU/g in tissue, respectively. Counts of both S. aureus and P. aeruginosa remained at a baseline of 0.0 log CFU/mL in wound fluid for both treatment groups. The findings here demonstrate that super-therapeutic concentrations of antibiotics delivered topically can rapidly reduce bacterial counts in infected full-thickness porcine burns. This treatment approach may aid wound bed preparation and accelerate time to grafting.

The Burn Wound Microenvironment

Significance: While the survival rate of the severely burned patient has improved significantly, relatively little progress has been made in treatment or prevention of burn-induced long-term sequelae, such as contraction and fibrosis. Recent Advances: Our knowledge of the molecular pathways involved in burn wounds has increased dramatically, and technological advances now allow large-scale genomic studies, providing a global view of wound healing processes. Critical Issues: Translating findings from a large number of in vitro and preclinical animal studies into clinical practice represents a gap in our understanding, and the failures of a number of clinical trials suggest that targeting single pathways or cytokines may not be the best approach. Significant opportunities for improvement exist. Future Directions: Study of the underlying molecular influences of burn wound healing progression will undoubtedly continue as an active research focus. Increasing our knowledge of these processes will identify additional therapeutic targets, supporting informed clinical studies that translate into clinical relevance and practice.

Dimerization of the type IV pilin from Pseudomonas aeruginosa strain K122-4 results in increased helix stability as measured by time-resolved hydrogen-deuterium exchange

Truncated pilin monomers from Pseudomonas aeruginosa strain K122-4 (ΔK122) have been shown to enter a monomer-dimer equilibrium in solution prior to oligomerization into protein nanotubes. Here, we examine the structural changes occurring between the monomeric and dimeric states of ΔK122 using time-resolved hydrogen-deuterium exchange mass spectrometry. Based on levels of deuterium uptake, the N-terminal α-helix and the loop connecting the second and third strands of the anti-parallel β-sheet contribute significantly to pilin dimerization. Conversely, the antiparallel β-sheet and αβ loop region exhibit increased flexibility, while the receptor binding domain retains a rigid conformation in the equilibrium state.

Role of G-CSF in monophosphoryl lipid A-mediated augmentation of neutrophil functions after burn injury

Infection is the leading cause of death in severely burned patients that survive the acute phase of injury. Neutrophils are the first line of defense against infections, but hospitalized burn patients frequently cannot mount an appropriate innate response to infection. Thus, immune therapeutic approaches aimed at improving neutrophil functions after burn injury may be beneficial. Prophylactic treatment with the TLR4 agonist monophosphoryl lipid A is known to augment resistance to infection by enhancing neutrophil recruitment and facilitating bacterial clearance. This study aimed to define mechanisms by which monophosphoryl lipid A treatment improves bacterial clearance and survival in a model of burn-wound sepsis. Burn-injured mice were treated with monophosphoryl lipid A or vehicle, and neutrophil mobilization was evaluated in the presence or absence of Pseudomonas aeruginosa infection. Monophosphoryl lipid A treatment induced significant mobilization of neutrophils from the bone marrow into the blood and sites of infection. Neutrophil mobilization was associated with decreased bone marrow neutrophil CXCR4 expression and increased plasma G-CSF concentrations. Neutralization of G-CSF before monophosphoryl lipid A administration blocked monophosphoryl lipid A-induced expansion of bone marrow myeloid progenitors and mobilization of neutrophils into the blood and their recruitment to the site of infection. G-CSF neutralization ablated the enhanced bacterial clearance and survival benefit endowed by monophosphoryl lipid A in burn-wound-infected mice. Our findings provide convincing evidence that monophosphoryl lipid A-induced G-CSF facilitates early expansion, mobilization, and recruitment of neutrophils to the site of infection after burn injury, allowing for a robust immune response to infection.

History of burns: The past, present and the future

Burn injuries are one of the most common and devastating afflictions on the human body. In this article we look back at how the treatment of burns has evolved over the centuries from a primarily topical therapy consisting of weird and wonderful topical concoctions in ancient times to one that spans multiple scientific fields of topical therapy, antibiotics, fluid resuscitation, skin excision and grafting, respiratory and metabolic care and nutrition. Most major advances in burn care occurred in the last 50 years, spurred on by wars and great fires. The use of systemic antibiotics and topical silver therapy greatly reduced sepsis related mortality. This along with the advent of antiseptic surgical techniques, burn depth classification and skin grafting allowed the excision and coverage of full-thickness burns which resulted in greatly improved survival rates. Advancements in the methods of assessing the surface area of burns paved way for more accurate fluid resuscitation, minimising the effects of shock and avoiding fluid over-loading. The introduction of metabolic care, nutritional support and care of inhalational injuries further improved the outcome of burn patients. We also briefly discuss some future directions in burn care such as the use of cell and pharmalogical therapies.

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.

Antibiotic prophylaxis for preventing burn wound infection

BACKGROUND

Infection of burn wounds is a serious problem because it can delay healing, increase scarring and invasive infection may result in the death of the patient. Antibiotic prophylaxis is one of several interventions that may prevent burn wound infection and protect the burned patient from invasive infections.

OBJECTIVES

To assess the effects of antibiotic prophylaxis on rates of burn wound infection.

SEARCH METHODS

In January 2013 we searched the Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid MEDLINE - In-Process & Other Non-Indexed Citations (2013); Ovid EMBASE; EBSCO CINAHL and reference lists of relevant articles. There were no restrictions with respect to language, date of publication or study setting.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that evaluated the efficacy and safety of antibiotic prophylaxis for the prevention of BWI. Quasi-randomised studies were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed the risk of bias, and extracted relevant data. Risk ratio (RR) and mean difference (MD) were estimated for dichotomous data and continuous data, respectively. When sufficient numbers of comparable RCTs were available, trials were pooled in a meta-analysis to estimate the combined effect.

MAIN RESULTS

This review includes 36 RCTs (2117 participants); twenty six (72%) evaluated topical antibiotics, seven evaluated systemic antibiotics (four of these administered the antibiotic perioperatively and three administered upon hospital admission or during routine treatment), two evaluated prophylaxis with non absorbable antibiotics, and one evaluated local antibiotics administered via the airway.The 11 trials (645 participants) that evaluated topical prophylaxis with silver sulfadiazine were pooled in a meta analysis. There was a statistically significant increase in burn wound infection associated with silver sulfadiazine compared with dressings/skin substitute (OR = 1.87; 95% CI: 1.09 to 3.19, I(2) = 0%). These trials were at high, or unclear, risk of bias. Silver sulfadiazine was also associated with significantly longer length of hospital stay compared with dressings/skin substitute (MD = 2.11 days; 95% CI: 1.93 to 2.28).Systemic antibiotic prophylaxis in non-surgical patients was evaluated in three trials (119 participants) and there was no evidence of an effect on rates of burn wound infection. Systemic antibiotics (trimethoprim-sulfamethoxazole) were associated with a significant reduction in pneumonia (only one trial, 40 participants) (RR = 0.18; 95% CI: 0.05 to 0.72) but not sepsis (two trials 59 participants) (RR = 0.43; 95% CI: 0.12 to 1.61).Perioperative systemic antibiotic prophylaxis had no effect on any of the outcomes of this review.Selective decontamination of the digestive tract with non-absorbable antibiotics had no significant effect on rates of all types of infection (2 trials, 140 participants). Moreover, there was a statistically significant increase in rates of MRSA associated with use of non-absorbable antibiotics plus cefotaxime compared with placebo (RR = 2.22; 95% CI: 1.21 to 4.07).There was no evidence of a difference in mortality or rates of sepsis with local airway antibiotic prophylaxis compared with placebo (only one trial, 30 participants).

AUTHORS' CONCLUSIONS

The conclusions we are able to draw regarding the effects of prophylactic antibiotics in people with burns are limited by the volume and quality of the existing research (largely small numbers of small studies at unclear or high risk of bias for each comparison). The largest volume of evidence suggests that topical silver sulfadiazine is associated with a significant increase in rates of burn wound infection and increased length of hospital stay compared with dressings or skin substitutes; this evidence is at unclear or high risk of bias. Currently the effects of other forms of antibiotic prophylaxis on burn wound infection are unclear. One small study reported a reduction in incidence of pneumonia associated with a specific systematic antibiotic regimen.

The broad landscape of immune interactions with Staphylococcus aureus: from commensalism to lethal infections

Staphylococcus aureus is a gram-positive bacterium that is present in the nostrils of a quarter of the general population without causing any apparent disease. However, S. aureus can also act as a pathogen to cause severe infections. The factors determining the balance between its commensal and pathogenic states are not understood. Emerging evidence suggests that S. aureus, in addition to inducing a pro-inflammatory response, may have the capacity to modulate the host immune system. The latter is in part the result of recognition of specific molecules embedded in the peptidoglycan layer of the staphylococcal cell wall that bind to TLR2 on host antigen-presenting cells and induce a strong IL-10 response that down regulates the adaptive T cell response. This mechanism can partially explain the duality of interactions between S. aureus and the human immune system by favoring nasal colonization instead of staphylococcal diseases. In this review, we discuss the molecular and cellular basis of this mechanism and explore its clinical implications.

Blood stream infections (BSI) in severe burn patients--early and late BSI: a 9-year study

Bloodstream infections (BSI) and sepsis are among the most common complications occurring in severe burn patients. This study was designed to evaluate changes in BSI pathogens over almost a decade in severe burn patients at Rambam Healthcare Campus, and BSI occurrence during early and late hospitalization periods. Retrospective computerized data was retrieved from all severe burn patients hospitalized in our institution during the years 2001-2009. BSI in the first week was defined as early BSI, and in the second week and beyond, late BSI. Of 159 severe burns patients, 74 had at least one BSI episode. Most first BSI episodes were diagnosed during the first week of hospitalization. In late BSI, an increased prevalence of resistant bacteria (methicillin-resistant Staphylococcus aureus [MRSA], carbapenem-resistant Klebsiella pneumoniae [CRKP], imipenem-resistant Pseudomonas aeruginosa [PSE-IMP]) and Candida spp. were observed. However, over the 9-year study period, only CRKP increased significantly. In summary, except for the sudden appearance and increase in CRKP (8% increase; p=0.045), we did not observe a significant change in the BSI pathogen profile over the 9-year period. Nevertheless, over the hospitalization period, there is a clear change in the BSI bacteria profile, especially after 4 weeks of hospitalization.

The impact of the types of microorganisms isolated from blood and wounds on the results of treatment in burn patients with sepsis

Despite development of combustiology, infections continue to be the most important cause of death among patients with burns. Sepsis is the most severe clinical presentation of infection in patients after thermal injuries who require immediate treatment. Early diagnosis and proper treatment of sepsis are important in the clinical management that is often hampered for multiple reasons, e.g. impaired patient immunity, problems with microorganisms with multi-antibacterial drug resistance. The aim of the study was to assess effect of type of a microorganism isolated from blood and wound on results of treatment of sepsis in patients with burns.

MATERIAL AND METHODS

Effect of type of microorganisms isolated from blood and wound on the result of treatment of sepsis was studied in 338 patients hospitalized immediately after an injury in Centre for Burn Treatment in Siemianowice Śląskie in years 2003 - 2004 (at the age of 18 - 96 years, 66 women and 272 men). Clinical symptoms of generalized infection were found in all study subjects. The study group was divided into two subgroups: cured patients and patients who died of sepsis. The following parameters were assessed in both subgroups: type of microorganism isolated from blood, type of microorganism isolated from wound as well as occurrence of the same and different infections of blood and burn wound.

RESULTS

positive blood cultures were found in 165 patients (48.8%), 106 (64.2%) were cured, 59 (35.8%) died. The most commonly isolated microorganisms in cured patients were Gram(+) Staphylococcus epidermidis MRSE (19.81%) and Staphylococcus aureus MRSA (18.87%). Gram(-) intestinal rods were least commonly isolated from this group. The most commonly isolated microorganisms from blood of patients who were to die, included non-fermenting Gram(-) rods Acinetobacter baumannii (35.59%) and Pseudomonas aeruginosa (22.03%). Mixed bacterial flora was found in the blood of 22.03% patients. Among patients who were to die, the same microorganisms were found in the blood and in the wound in 32.2% of patients, while this rate was 17.92 in cured patients. The most commonly found bacteria in the blood and burn wound in the cured patients included Staphylococcus aureus MRSA (31.58%) and Staphylococcus aureus (21.05%). In the group of patients who were to die, the most common bacteria isolated simultaneously from the blood and burn wound included Acinetobacter baumannii (47.37%) and Pseudomonas aeruginosa (36.84%).

CONCLUSIONS

1. The patients with thermal injuries are at higher risk of death in the event of sepsis caused by Gram(-) bacteria versus Gram(+) bacteria. 2. Infection of blood and burn wound caused by the same bacteria Pseudomonas aeruginosa and Acinetobacter baumanni increases the risk of death due to sepsis in patients with burns following thermal injuries.

[Antimicrobial treatment in burn injury patients]

Infections are a great diagnostic and therapeutic challenge in intensive care patients with burn injuries. The major problems are due to bacteria with hospital-acquired multiresistance to antibiotics but fungal and viral infections may also be life-threatening. The main key points addressing pharmacotherapy with antibiotic, antifungal and antiviral agents in this special setting are exact diagnosis, early therapy with suitable drugs, adequate duration of treatment and adequate doses based on pharmacokinetic and pharmacodynamic characteristics of these compounds. The latter parameters are significantly altered in burn patients and show a wide interindividual and intraindividual variation in drug response as a result of the characteristic phases of burn injury. Drug concentration analysis may help to avoid inadequate dosing. In this review the main characteristics of burn injuries and the pharmacology of antibiotics, antifungal and antiviral agents in these patients are presented.

Epidemiology of bloodstream infections in burn-injured patients: a review of the national burn repository

Bloodstream infections (BSIs) are a major cause of morbidity and mortality in thermally injured patients. However, these infections have not been well defined in this patient population. Therefore, the authors performed a retrospective case-control study to characterize the epidemiology, microbiology, and outcomes of burn-associated BSIs. A retrospective review of all patients in the National Burn Repository (NBR) between the years 1981 and 2007 was performed. All cases that had infection listed under complications were included in this study. For each case, two randomly selected patients from the same time period served as controls. Patient demographic data, extent of %TBSA, and type of infection were extracted. Primary end point was mortality. Secondary endpoints were hospital length of stay (LOS), intensive care unit LOS, total ventilator days, and hospital charges. Further analysis of the data involved case-matching patients by TBSA deciles, adjustment for the effects of TBSA and other potential confounders, and a sensitivity analysis of the effects of including or excluding sites that might have failed to consistently capture BSI information. A total of 11,793 patients (3931 cases and 7862 control) were included in the study. Of cultures revealing a Gram-positive organism, Staphylococcus aureus (32%) was the most common. From samples where isolation of a Gram-negative species occurred, Pseudomonas aeruginosa (35%) was more prominent. Infected patients were older (40.9 vs 32.8, P < .05) and had higher %TBSA (22.2 vs 7.9, P < .05). BSI was associated with significantly higher mortality (21.9% vs 3.09%), hospital LOS (47.4 vs 8.8 days) intensive care unit LOS (30.8 vs 2.6 days), ventilator days (29.2 vs 1.4 days), and hospital charge ($339,909.91 vs $33,272.43); P < .001 for all values. On evaluation of case-matched controls, mortality was higher for patients with BSI only <50% TBSA strata. Conclusions were unaffected by adjustment for TBSA and other possible confounders and was not influenced by possible failure of some sites to consistently capture BSI information. Development of BSI in hospitalized burn patients is associated with significant increases in morbidity, mortality, and resource utilization.

Infection control in the burn unit

The survival rates for burn patients have improved substantially in the past few decades due to advances in modern medical care in specialized burn centers. Burn wound infections are one of the most important and potentially serious complications that occur in the acute period following injury. In addition to the nature and extent of the thermal injury influencing infections, the type and quantity of microorganisms that colonize the burn wound appear to influence the future risk of invasive wound infection. The focus of medical care needs to be to prevent infection. The value of infection prevention has been acknowledged in organized burn care since its establishment and is of crucial importance. This review focuses on modern aspects of the epidemiology, diagnosis, management, and prevention of burn wound infections and sepsis.

Pseudomonas aeruginosa bacteraemia in burns patients: Risk factors and outcomes

INTRODUCTION

We aimed to identify the risk factors for, and outcomes of Pseudomonas aeruginosa bacteraemia in adult burns patients.

METHOD

All adult burns patients who developed a Gram-negative bacteraemia over a period of 7 years were included. Retrospective data analysed included patient demographics, organisms cultured, antibiotic susceptibility patterns, isolation of P. aeruginosa in non-blood isolates, treatment, length of stay and mortality.

RESULTS

Forty-three patients developed a Gram-negative bacteraemia over the study period, 12 of whom had Pseudomonas bacteraemia during the course of their admission. In eight patients (18.6%) P. aeruginosa was the first Gram-negative isolated. The only factor predicting P. aeruginosa bacteraemia as a first episode (compared to another Gram-negative) was prior isolation of Pseudomonas at other sites (wound sites, urine or sputum). Overall length of stay was less in patients who developed P. aeruginosa as a first episode, mainly because of increased mortality in this group. Prior non-blood isolates of P. aeruginosa could have correctly predicted the sensitivity pattern of the strain of P. aeruginosa organism in 75% of patients who did not receive appropriate initial antibiotics.

CONCLUSION

Prior colonisation with P. aeruginosa predicts P. aeruginosa in blood cultures, as opposed to other Gram-negative bacteria. Clinicians should have a high index of suspicion for P. aeruginosa bacteraemia where a septic burns patient has a prior history of non-blood P. aeruginosa cultures. Empirical antibiotic regimes based on the antibiotic-sensitivity patterns of previous non-blood P. aeruginosa isolates in each patient should be given at the time blood cultures are taken.

Contribution of bacterial and viral infections to attributable mortality in patients with severe burns: an autopsy series

Bacterial infections are a common cause of mortality in burn patients and viral infections, notably herpes simplex virus (HSV) and cytomegalovirus (CMV) have also been associated with mortality. This study is a retrospective review of all autopsy reports from patients with severe thermal burns treated at the US Army Institute of Research (USAISR) burn unit over 12 years. The review focused on those patients with death attributed to a bacterial or viral cause by autopsy report. Of 3751 admissions, 228 patients died with 97 undergoing autopsy. Death was attributed to bacteria for 27 patients and to virus for 5 patients. Bacterial pathogens associated with mortality included Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. This association with mortality was independent of % total body surface area burn, % full-thickness burn, inhalation injury, and day of death post-burn. Bloodstream infection was the most common cause of bacteria related death (50%), followed by pneumonia (44%) and wound infection (6%). Time to death following burn was < or =7 days in 30%, < or =14 days in 59% and < or =21 days in 67%. All of the viral infections associated with mortality involved the lower respiratory tract, HSV for 4 and CMV for 1. Four of these 5 patients had evidence of inhalation injury by bronchoscopy, all had facial and neck burns, and 2 had concomitant Staphylococcus pneumonia. Time to death following burn ranged from 14 to 42 days for the 5 patients. Despite advances in care, gram negative bacterial infections and infection with S. aureus remain the most common cause of bacteria related mortality early in the hospital course. Viral infections are also associated with mortality and numbers have remained stable when compared to data from prior years.

Active immunization using exotoxin A confers protection against Pseudomonas aeruginosa infection in a mouse burn model

BACKGROUND

Pseudomonas aeruginosa is an important cause of nosocomial infection and may lead to septicemia and death. We evaluated the immunogenicity of semi-purified exotoxin A from the bacterium in a mouse burn model.

METHODS

The toxoid was prepared from exotoxin A taken from toxigenic strains of P. aeruginosa (PA 103). 50 mice were immunized with the toxoid, burned with hot metal and infected with 1 x 10(8) CFU of toxigenic strains of P. aeruginosa (experimental group); 25 non-immunized mice were also burned and infected (control group). The mortality rate and presence of any exotoxin and P. aeruginosa in the sera, liver and spleen were determined.

RESULTS

In the experimental group, 2 mice died before the burns were administered and were excluded from the study. The remainder (48 mice) were challenged with a lethal dose of P. aeruginosa and followed for 70 days. 3 of these mice died. Neither P. aeruginosa nor exotoxin A was not detected in the liver, spleen or sera of the surviving mice. The protective efficacy of toxoid vaccination was therefore 93.8%. In the control group, all mice died from bacteremia and septicemia, most (80%) within 6 days, and P. aeruginosa and exotoxin A were isolated from sera, spleen and liver.

CONCLUSION

Active immunization of mice using a semi-purified exotoxin A derived from P. aeruginosa was 93.8% effective at protecting mice from subsequent P. aeruginosa infections in a mouse burn model.

Infection in patients with severe burns: causes and prevention thereof

The better understanding of burn pathophysiology has resulted in effective fluid resuscitation in the acute stage, but the morbidity and mortality of burn patients are mostly linked to the burn wound consequences. Once the initial acute phase is over, the burn wound becomes the source of virtually all ill effects, local and systemic. The dysfunction of the immune system, a large cutaneous bacterial load, the possibility of gastrointestinal bacterial translocation, prolonged hospitalization, and invasive diagnostic and therapeutic procedures all contribute to infectious complications. Wound infection may lead to septicemia that may not only consume additional resources but is associated with significant morbidity and mortality despite the advances in burn care.

A MODEL OF MYOCARDIAL INFLAMMATION AND DYSFUNCTION IN BURN COMPLICATED BY SEPSIS

Numerous studies have described that an initial injury alters immune function, disposing the injured subject to infectious complications. The mechanisms by which an initial injury primes the subject, exacerbating the responses to a second injury, remain unclear; however, inflammatory cytokines have been implicated. The development of "2-hit" models has allowed investigators to determine the role of inflammatory mediators in susceptibility to infection after injury. A high incidence rate of pneumonia after burn injury and a significant increase in postburn mortality led us to develop models of either Gram-positive (Streptococcus pneumoniae) or Gram-negative (Klebsiella pneumoniae) sepsis after burn injury on 40% of total body surface area in rodents. In this present model, we used adult Sprague-Dawley rats to evaluate cardiac function in vitro (using Langendorff method) and myocardial inflammation (myocyte secretion of cytokines measured using enzyme-linked immunosorbent assay) after burn complicated by sepsis. Either burn injury alone or sepsis alone produced myocardial inflammatory responses and contractile dysfunction. Either Gram-negative or Gram-positive infection exacerbated the myocardial inflammation (increased myocyte secretion of tumor necrosis factor alpha, interleukin 1beta, and interleukin 6) above that which occurred with burn alone or with infection alone. Burn complicated by sepsis exacerbated the myocardial contraction and relaxation defects observed with either sepsis alone or burn alone. Inasmuch as sepsis, which occurs after a previous injury, increases myocardial inflammation/dysfunction and mortality, the development of therapeutic strategies that either decrease inflammatory response to the initial injury or provide cardiac support during the postinjury period may improve the outcome in injured patients who are at risk for developing sepsis.

The establishment of a Pseudomonas aeruginosa-infected burn-wound sepsis model and the effect of imipenem treatment

INTRODUCTION

We present a standardized Pseudomonas aeruginosa (PA) infected burn-wound model in mice for evaluating new antimicrobials and therapy strategies for PA infections and demonstrate the effect of the antibiotic imipenem in this model.

METHODS

A 6%-8% total body surface area, full-thickness, scald-burn wound was induced in anesthetized mice. Two study groups (PA-infected burn) were compared with 1 treatment group (systemic imipenem) and 3 control groups (noninfected burn, infected nonburned, and burn with distant infection). Seven-day mortality, quantitative culture from eschars and from spleens, weight loss, and time to healing were compared.

RESULTS

The 25%-100% mortality rate in the nontreated PA-infected burn group was directly related to the infecting inoculum. Imipenem treatment reduced the mortality rate to 0-17%. No control animal died. Systemic bacterial dissemination at 48 hours was significantly higher in the study group. Morbidity paralleled survival results. Wound healing was quicker in the imipenem-treated group and control groups compared with the infected nontreated group.

CONCLUSIONS

The mice model is a useful tool for evaluating new antibacterial agents and strategies for treating PA-infected burn injuries. Imipenem was found to be efficacious in the treatment of severe PA sepsis.

Burn wound infections

Burns are one of the most common and devastating forms of trauma. Patients with serious thermal injury require immediate specialized care in order to minimize morbidity and mortality. Significant thermal injuries induce a state of immunosuppression that predisposes burn patients to infectious complications. A current summary of the classifications of burn wound infections, including their diagnosis, treatment, and prevention, is given. Early excision of the eschar has substantially decreased the incidence of invasive burn wound infection and secondary sepsis, but most deaths in severely burn-injured patients are still due to burn wound sepsis or complications due to inhalation injury. Burn patients are also at risk for developing sepsis secondary to pneumonia, catheter-related infections, and suppurative thrombophlebitis. The introduction of silver-impregnated devices (e.g., central lines and Foley urinary catheters) may reduce the incidence of nosocomial infections due to prolonged placement of these devices. Improved outcomes for severely burned patients have been attributed to medical advances in fluid resuscitation, nutritional support, pulmonary and burn wound care, and infection control practices.

Early burn related gram positive systemic infection in children admitted to a pediatric surgical ward

BACKGROUND

Gram positive infections, including toxic shock syndrome (TSS), may be an early complication following burns, especially in children.

OBJECTIVE

To identify risk factors associated with early burn related gram positive systemic infection (EBGI) in children admitted to a Pediatric Surgical Ward.

METHODS

A retrospective analysis of the records of all EBGI patients treated from January 1995 to December 2004. EBGI patients were defined as having systemic signs of infection appearing in the first 48 h following the burn and associated with: (1) clinical signs of toxin mediated illness and/or (2) positive blood culture of either Staphylococcus aureus or group A beta hemolytic Streptococcus. Demographic and clinical data were also collected from the charts of 150 randomly selected burn patients admitted during the study period.

RESULTS

We identified 13 cases of EBGI (2.5%) among 518 children admitted for thermal burns (mean age: 2.4 years). Three had bacteremia without rash. The 10 other patients were diagnosed as having a toxin mediated disease. S. aureus grew from the burn wound in six patients. All EBGI patients recovered following antibiotic therapy. Significant differences between the groups included: percentage of burned body surface area (6.9% versus 3.9%), and head and face localization (64% versus 31%) in the EBGI and control groups, respectively.

CONCLUSIONS

EBGI is not rare even in pediatric patients with minor-moderate burns. Burns localized to the face or the head may be predisposing factor for such an infection.

Burn wound infections

Burns are one of the most common and devastating forms of trauma. Patients with serious thermal injury require immediate specialized care in order to minimize morbidity and mortality. Significant thermal injuries induce a state of immunosuppression that predisposes burn patients to infectious complications. A current summary of the classifications of burn wound infections, including their diagnosis, treatment, and prevention, is given. Early excision of the eschar has substantially decreased the incidence of invasive burn wound infection and secondary sepsis, but most deaths in severely burn-injured patients are still due to burn wound sepsis or complications due to inhalation injury. Burn patients are also at risk for developing sepsis secondary to pneumonia, catheter-related infections, and suppurative thrombophlebitis. The introduction of silver-impregnated devices (e.g., central lines and Foley urinary catheters) may reduce the incidence of nosocomial infections due to prolonged placement of these devices. Improved outcomes for severely burned patients have been attributed to medical advances in fluid resuscitation, nutritional support, pulmonary and burn wound care, and infection control practices.