Bacteriology of burns

High-Intensity Blue Light (450-460 nm) Phototherapy for Pseudomonas aeruginosa-Infected Wounds

Background: Nosocomial wound infection with Pseudomonas aeruginosa (PA) is a serious complication often responsible for the septic mortality of burn patients. Objective: High-intensity antimicrobial blue light (aBL) treatment may represent an alternative therapy for PA infections and will be investigated in this study. Methods: Antibacterial effects of a light-emitting diode array (450-460 nm; 300 mW/cm2; 15/30 min; 270/540 J/cm2) against PA were determined by suspension assay, biofilm assay, and a human skin wound model and compared with 15-min topically applied 3% citric acid (CA) and wound irrigation solution (Prontosan®; PRT). Results: aBL reduced the bacterial number [2.51-3.56 log10 colony-forming unit (CFU)/mL], whereas PRT or CA treatment achieved a 4.64 or 6.60 log10 CFU/mL reduction in suspension assays. aBL reduced biofilm formation by 60-66%. PRT or CA treatment showed reductions by 25% or 13%. Here, aBL reduced bacterial number in biofilms (1.30-1.64 log10 CFU), but to a lower extend than PRT (2.41 log10 CFU) or CA (2.48 log10 CFU). In the wound skin model, aBL (2.21-2.33 log10 CFU) showed a bacterial reduction of the same magnitude as PRT (2.26 log10 CFU) and CA (2.30 log10 CFU). Conclusions: aBL showed a significant antibacterial efficacy against PA and biofilm formation in a short time. However, a clinical application of aBL in wound therapy requires effective active skin cooling and eye protection, which in turn may limit clinical implementation.

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

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

Phototherapy of Pseudomonas aeruginosa-Infected Wounds: Preclinical Evaluation of Antimicrobial Blue Light (450-460 nm) Using In Vitro Assays and a Human Wound Skin Model

Objective: To determine effective treatment strategies against bacterial infections of burn wounds with Pseudomonas aeruginosa, we tested different treatment regimens with antibacterial blue light (BL). Background: Infections of burn wounds are serious complications and require effective and pathogen-specific therapy. Hereby, infections caused by P. aeruginosa pose a particular challenge in clinical practice due to its resistance to many antibiotics and topical antiseptics. Methods: LED-based light sources (450-460 nm) with different intensities and treatment times were used. Antibacterial effects against P. aeruginosa were determined by colony-forming unit (CFU) assays, human skin wound models, and fluorescence imaging. Results: In suspension assays, BL (2 h, 40 mW/cm², 288 J/cm²) reduced bacterial number (>5 log₁₀ CFU/mL). Applying 144 J/cm², using 40 mW/cm² for 1 h was more effective (>4 log₁₀ CFU) than using 20 mW/cm² for 2 h (>1.5 log₁₀ CFU). BL with low irradiance (24 h, 3.5 mW/cm², 300 J/cm²) only revealed bacterial reduction in thin bacteria-containing medium layers. In infected in vitro skin wounds only BL irradiation (2 h, 40 mW/cm², 288 J/cm²) exerted a significant antimicrobial efficacy (2.94 log₁₀ CFU/mL). Conclusions: BL treatment may be an effective therapy for P. aeruginosa-infected wounds to avoid radical surgical debridement. However, a significant antibacterial efficacy can only be achieved with higher irradiances and longer treatment times (min. 40 mW/cm²; >1 h), which cannot be easily integrated into regular clinical treatment protocols, for example, during a dressing change. Further studies are necessary to establish BL therapy for infected burns among tissue compatibility and interactions with previous therapeutic agents.

Epidemiological and Clinical Profile of Pediatric Burns in the COVID-19 Era: The Experience of a Reference Center

Pediatric burns represent a significant public health problem. We analyzed the characteristics of pediatric burns in a reference center, in order to identify better strategies for prevention and care. Burn patients admitted to the pediatric departments of our hospital from January 2020 to June 2022 were retrospectively evaluated. Age, gender, the etiology of injuries, the total burn surface area (TBSA), the degree of burns, the length of hospital stay (LOS), concomitant SARS-CoV-2 infection, and burn surface microbial colonization were analyzed. Forty-seven patients were included in the analysis (M:F = 1:0.67). Most of the cases involved patients between 0 and 4 years of age (83%). Hot liquid burns accounted for 79% of cases, flame burns for 9%, thermal burns for 6%, scald burns for 4% and chemical burns for 2%. Mean TBSA was 14 ± 11%. A second-degree lesion was detected in 79% of patients and third-degree in 21%. Mean LOS was 17 days. No additional infection risks or major sequelae were reported in patients with SARS-CoV-2 infection. Fifteen different species of bacteria plus C. parapsilosis were isolated, while no anaerobic microorganisms were detected. In the light of our experience, we recommend a carefully planned and proactive management strategy, always multidisciplinary, to ensure the best care for the burned child.

Cold Plasmamed Beam as a Supporting Treatment of Soft Tissue Injuries in Severe Covid-19 Patients: A Preliminary Report

Background

Cold plasma has many characteristics that allow for effective wound healing. Due to its efficacy, we have applied it in treating patients with severe Covid-19 who have soft tissue skin lesions and diseases including burns, pressure ulcers, shingles, and contact or atopic dermatitis. This study aims to assess the general characteristics of Covid-19 patients with soft tissue lesions and to conduct a fundamental evaluation of the efficacy of cold plasmamed beams in treating soft tissue wounds in patients with severe Covid-19.

Methods

This prospective study was conducted on 20 severe Covid-19 patients with soft tissue lesions at the Intensive Care Center for Covid-19 of Hue Central Hospital in Ho Chi Minh City from September 25 to November 11, 2021. These patients was performed cold plasma irradiation at any stage of wound progression, including new injuries and chronic wounds.

Results

Among 915 severe Covid-19 patients treated at our center, 20 patients had soft tissue lesions. Grade I, II, and III pressure ulcers accounted for 70% of the 20 cases of soft tissue lesions and 1.53% of the total patients at the time of the survey. Pressure ulcers were present in only 0.55% of patients (5/915 patients). Eleven out of 20 patients (55.0%) had lesions before admission, and 9 (45.0%) had lesions that appeared after admission. After 14 days of treatment, 14/20 patients had complete epithelialization (70%), and in 18/20 patients, wound exudation had ceased. The wounds became painless; after 3 weeks, the rashes had completely disappeared.

Conclusion

The study emphasizes that irradiation with cold plasma contributes to the wound healing process.

Carbon-Based Nanomaterials: Carbon Nanotubes, Graphene and Fullerenes in Control of Burns Infections and Wound Healing

Burn injuries are extremely debilitating, resulting in high morbidity and mortality rates around the world. The risk of infection escalates in correlation with impairment of skin integrity, creating a barrier to healing and possibly leading to sepsis. With its numerous advantages over traditional treatment methods, nanomaterial-based wound healing has immense capability for treating and preventing wound infections. Carbon-based nanomaterials (CNMs) owing to their distinctive physicochemical and biological properties have emerged as promising platform for biomedical applications. Carbon nanotubes, graphene, fullerenes, and their nanocomposites have demonstrated broad antimicrobial activity against invasive bacteria, fungi, and viruses causing burn wound infection. The specific mechanisms that govern the antimicrobial activity of CNMs must be understood in order to ensure the safe and effective incorporation of these structures into biomaterials. However, it is challenging to decouple individual and synergistic contributions of physical, chemical, and electrical effects of CNMs on cells. This review reported on significant advances in the application of CNMs in burn wound infection and wound healing, with brief discussion on the interaction between different families of CNMs and microorganisms to assess antimicrobial performance.

Study of quorum-sensing LasR and RhlR genes and their dependent virulence factors in Pseudomonas aeruginosa isolates from infected burn wounds

Background

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen responsible for burn-wound infection. High incidence, infection severity and increasing resistance characterize P. aeruginosa-induced burn infection.

Purpose

To estimate quorum-sensing (QS)-dependent virulence factors of P. aeruginosa isolates from burn wounds and correlate it to the presence of QS genes.

Methods

A cross-sectional descriptive study included 50 P. aeruginosa isolates from burn patients in Mansoura University Plastic and Burn Hospital, Egypt. Antibiotic sensitivity tests were done. All isolates were tested for their ability to produce biofilm using a micro-titration assay method. Protease, pyocyanin and rhamnolipid virulence factors were determined using skimmed milk agar, King’s A medium and CTAB agar test, respectively. The identity of QS lasR and rhlR genes was confirmed using PCR.

Results

In total, 86 % of isolates had proteolytic activity. Production of pyocyanin pigment was manifested in 66 % of isolates. Altogether, 76 % of isolates were rhamnolipid producers. Biofilm formation was detected in 96 % of isolates. QS lasR and rhlR genes were harboured by nearly all isolates except three isolates were negative for both lasR and rhlR genes and two isolates were positive for lasR gene and negative for rhlR gene. Forty-nine isolates were considered as extremely QS-proficient strains as they produced QS-dependent virulence factors. In contrast, one isolate was a QS deficient strain.

Conclusions

QS affects P. aeruginosa virulence-factor production and biofilm in burn wounds. Isolates containing lasR and rhlR seem to be a crucial regulator of virulence factors and biofilm formation in P. aeruginosa whereas the lasR gene positively regulates biofilm formation, proteolytic activity, pyocyanin production and rhamnolipid biosurfactant synthesis. The QS regulatory RhlR gene affects protease and rhamnolipid production positively.

Burn Wound Microbiology and the Antibiotic Susceptibility Patterns of Bacterial Isolates in Three Burn Units of Abbottabad, Pakistan

Infection is the leading cause of morbidity and mortality among burn patients and is accentuated multifold by the emergence of antimicrobial resistance among the nosocomial isolates. It is vital to know the common organisms involved in infected burn wound etiology and their respective antibiotic susceptibility patterns. These crucial findings can help in formulating a better and more efficient antimicrobial therapy plan for controlling burn wound infections. The current study was conducted to identify the common bacteria involved in causing infections in wounds of burn patients and their respective antibiotic susceptibility patterns in three hospitals of Abbottabad, Pakistan. A total of 100 patients were included from the burn units of three hospitals in Abbottabad. Wound swabs were taken from the deepest portions of infected burns, and the organisms involved were isolated via standard microbiological techniques. The Kirby-Bauer disc diffusion technique was used to monitor antibiotic susceptibility. Gram-positive organisms were found readily in infected burn wounds. Staphylococcus aureus (46%) was the most common isolate followed by Staphylococcus epidermidis (17%), Escherichia coli (16%), Proteus spp. (12%), Klebsiella pneumoniae (10%), and Pseudomonas aeruginosa, which was only 7%. Gram-positive bacteria were sensitive to amikacin, gentamicin, cefotaxime, and norfloxacin. In contrast, the gram-negative isolates were sensitive to amikacin, chloramphenicol, and nalidixic acid. Pseudomonas was resistant to most of the antibiotics tested in the present study.

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

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

Safety, Pharmacodynamics, and Efficacy of High- Versus Low-Dose Ascorbic Acid in Severely Burned Adults

In sepsis and burns, ascorbic acid (AA) is hypothesized advantageous during volume resuscitation. There is uncertainty regarding its safety and dosing. This study evaluated high dose AA (HDAA: 66 mg/kg/h for 24 hours) versus low dose AA (LDAA: 3.5 g/days) administration during the first 24 hours in severely burned adults. We conducted a retrospective study comparing fluid administration before and after switching from low dose to HDAA in severely burned adults. A total of 38 adults with burns >20% TBSA, who received either HDAA or LDAA were included in this retrospective study. AA serum concentrations were quantified at 0, 24, and 72 hours postburn. HDAA impact on hemodynamics, acid-base homeostasis, acute kidney injury, vasopressor use, resuscitation fluid requirement, urinary output, and the incidence of adverse effects was evaluated; secondary clinical outcomes were analyzed. AA plasma levels were 10-fold elevated in the LDAA and 150-fold elevated in the HDAA group at 24 hours and decreased in both groups afterwards. HDAA was not associated with a significantly increased risk of any complications. A significant reduction in colloid fluid requirements was noted (LDAA: 947 ± 1722 ml/24 hours vs HDAA: 278 ± 667 ml/24 hours, P = 0.029). Other hemodynamic and resuscitation measures, as well as secondary clinical outcomes were comparable between groups. HDAA was associated with higher AA levels and lower volumes of colloids in adults with severe burns. The rate of adverse events was not significantly higher in patients treated with HDAA. Future studies should consider prolonged administration of AA.

Infections in patients with burn injuries receiving extracorporeal membrane oxygenation

INTRODUCTION

Extracorporeal Membrane Oxygenation (ECMO) has only recently been described in patients with burn injuries. We report the incidence and type of infections in critically ill burn and non-burn patients receiving ECMO.

METHODS

A retrospective chart review was performed on all patients at Brooke Army Medical Center who received ECMO between September 2012 and May 2018.

RESULTS

78 patients underwent ECMO. Approximately half were men with a median age of 34 years with a median time on ECMO of 237 h (IQR 121-391). Compared to patients without burns (n = 58), patients with burns (n = 20) had no difference in time on ECMO, but had more overall infections (86 vs. 31 per 1000 days, p = 0.0002), respiratory infections (40 vs. 15 per 1000 days, p = 0.01), skin and soft tissue infections (21 vs. 5 per 1000 days, p = 0.02) and fungal infections (35% vs 10%, p = 0.02). Twenty percent of bacterial burn infections were due to drug resistant organisms.

CONCLUSION

This is the first study to describe the incidence of infection in burn injury patients who are undergoing ECMO. We observed an increase in infections in burn patients on ECMO compared to non-burn patients. ECMO remains a viable option for critically ill patients with burn injuries.

Infection of burn wound by Aspergillus fumigatus with gross appearance of fungal colonies

The morbidity of invasive aspergillosis in burn patients is low but the diagnosis is difficult and the mortality rate is high. A severe burned patient at the Vietnam National Institute of Burn was suspected of fungal wound infection (FWI) with fungal growth on the wound. The diagnosis of FWI caused by Aspergillus fumigatus was made by isolation and histological examination. This may be the first reported case of FWI caused by Aspergillus fumigatus in Vietnam.

Superintendence of antimicrobial resistance observed in bacterial flora isolated from human faecal carriage in Vellore, India

A frequent cross-sectional study was conducted to determine the patterns of antimicrobial resistance in 296 bacterial strains isolated from in-patient faecal samples of Government Vellore Medical College and Hospital, Vellore. Isolation and identification of bacterial strains were done using enrichment media, selective media, and biochemical tests. Antimicrobial susceptibility testing by the disc diffusion method and minimal inhibitory concentration method was conducted and the strains were subjected to extended spectrum beta-lactamases screening. Antibiotic sensitivity pattern of Staphylococcus spp. showed oxacillin resistance. Almost all the strains were sensitive to linezolid, vancomycin, gentamycin and chloramphenicol. In gram negative isolates ciprofloxacin and tobramycin showed better sensitivity and ceftazidime showed a higher percentage of resistance by MIC. Out of 250 isolates, Enterobacteriaceae showed positive for 86/250, 82/250 and 94/250 isolates and 3/10, 4/10 and 4/10 non-Enterobacteriaceae isolates were found to be positive for CTX-M gene, TEM gene and SHV gene, respectively. This study helps to assess/analyse the relation between the spectrum of microorganisms present in various grades of faecal carriage and their susceptibility pattern in this part of the Vellore town.

Molecular Typing and Carbapenem Resistance Mechanisms of Pseudomonas aeruginosa Isolated From a Chinese Burn Center From 2011 to 2016

Pseudomonas aeruginosa is the leading cause of infection in burn patients. The increasing carbapenem resistance of P. aeruginosa has become a serious challenge to clinicians. The present study investigated the molecular typing and carbapenem resistance mechanisms of 196 P. aeruginosa isolates from the bloodstream and wound surface of patients in our burn center over a period of 6 years. By multilocus sequence typing (MLST), a total of 58 sequence types (STs) were identified. An outbreak of ST111, a type that poses a high international risk, occurred in 2014. The isolates from wound samples of patients without bacteremia were more diverse and more susceptible to antibiotics than strains collected from the bloodstream or the wound surface of patients with bacteremia. Importantly, a large proportion of the patients with multisite infection (46.51%) were simultaneously infected by different STs in the bloodstream and wound surface. Antimicrobial susceptibility testing of these isolates revealed high levels of resistance to carbapenems, with 35.71% susceptibility to imipenem and 32.14% to meropenem. To evaluate mechanisms associated with carbapenem resistance, experiments were conducted to determine the prevalence of carbapenemase genes, detect alterations of the oprD porin gene, and measure expression of the ampC β-lactamase gene and the mexB multidrug efflux gene. The main mechanism associated with carbapenem resistance was mutational inactivation of oprD (88.65%), accompanied by overexpression of ampC (68.09%). In some cases, oprD was inactivated by insertion sequence element IS1411, which has not been found previously in P. aeruginosa. These findings may help control nosocomial P. aeruginosa infections and improve clinical practice.

Membrane-Active Amphipathic Peptide WRL3 with in Vitro Antibiofilm Capability and in Vivo Efficacy in Treating Methicillin-Resistant Staphylococcus aureus Burn Wound Infections

Methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly prevalent in hospitals, clinics, and the community. MRSA can cause significant and even lethal infections, especially in skin burn wounds. The currently available topical agents have largely failed to eliminate MRSA infections due to resistance. Therefore, there is an urgent need for new and effective approaches for treating MRSA. Here, we show that a novel engineered amphipathic peptide, WRL3 (WLRAFRRLVRRLARGLRR-NH2), exhibits potent antimicrobial activity against MRSA, even in the presence of various salts or serum. The cell selectivity of WRL3 was demonstrated by its ability to specifically eliminate MRSA cells over host cells in a coculture model. Additionally, WRL3 showed a synergistic effect against MRSA when combined with ceftriaxone and effectively inhibited sessile biofilm bacteria growth leading to a reduction in biomass. Fluorescent measurements and microscopic observations of live bacterial cells and artificial membranes revealed that WRL3 exerted its bactericidal activity possibly by destroying the bacterial membrane. In vivo studies indicate that WRL3 is able to control proliferation of MRSA in wound tissue and reduce bioburden and provides a more favorable environment for wound healing. Collectively, our data suggest that WRL3 has enormous potential as a novel antimicrobial agent for the treatment of clinical MRSA infections of skin burn wounds.

Anti-biofilm properties of a mupirocin spray formulation against Escherichia coli wound infections

Mupirocin ointment is a widely used topical drug for the treatment of bacterial skin infections. However, ointments have some limitations which motivated the development of a film forming spray of mupirocin. Mupirocin spray (2%) was formulated with Eudragit E100 as a film forming agent and tested for its antibacterial and anti-biofilm activities against Escherichia coli, a skin pathogen causing wound and surgical site infections. Treatment with mupirocin spray resulted in significant antibacterial and anti-biofilm activities (inhibition and disruption) with single spray and sub-actual dose concentrations at par with the commercial ointment concentration. The spray formulation was found to be non-toxic to fibroblast cells and greatly resisted removal from the site of application upon washing, in contrast to the ointment which was significantly removed after a single wash. This is the first study to develop and evaluate a spray formulation for mupirocin that forms a stable thin film for sustained release of the drug.

Cytoprotective effect of the enzyme-mediated polygallic acid on fibroblast cells under exposure of UV-irradiation

The poly(gallic acid), produced by laccase-mediated oxidation of gallic acid in aqueous media (pH5.5) to attain a novel material with well-defined molecular structure and high water solubility (500mg/mL at 25°C), has been investigated to understand its potential biological activities. In this regard, a biomedical approach based on cytoprotective effect on human fibroblast cells exposed to UV-irradiation in the presence of the polymer has been demonstrated. The results also shows that 200μg/mL of poly(gallic acid) inhibits the growth and migration of dermal fibroblasts and cancer cell lines without affecting cell viability. Poly(gallic acid) pretreatment with 10μg/mL protects dermal fibroblasts from UV induced cell death and additionally, the cytoprotective effect reduce ROS presence in the cells. This property can be correlated with the antioxidant power (IC₅₀ of 23.5μg/mL) of this novel material, which was ascertained by electronic paramagnetic resonance spectroscopy and spectrophotometrically. Additionally, the antimicrobial activity of this material was corroborated with the inhibition of Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 29212) strains (MIC=400mg/mL) common bacteria found in hospitals.

What should be the antibiotic prescription protocol for burn patients admitted in the department of burns, plastic and reconstructive surgery

This is a prospective study with the aim to determine specific patterns of burn wound bacterial colonisation and antimicrobial resistance profiles. There is a high incidence of infections and septicaemia in post-burn patients, which, in turn, are associated with high morbidity and mortality, a fact that compelled us to undertake this study. The study was conducted over a period 11 months, from 1 August 2014 to 30 June 2015, in 50 burn patients admitted in our burn unit. Wound cultures were taken after 72 hours of admission from all the patients, and then, empirical systemic antibiotics were administered. For wound cultures; 1 cubic cm tissue was taken and placed in aerobic and anaerobic culture vials and transported to the microbiology lab under all aseptic precautions as soon as possible. At the time of fever any time after 72 hours of admission, 16 ml of blood was drawn under all aseptic precautions. Both aerobic and anaerobic blood culture vials were filled with 8 ml of blood each and transported to the microbiology lab. The results of culture and sensitivity reports of 50 patients were recorded. The data obtained was analysed using appropriate statistical analytical tests. The most common organism responsible for bacteraemia is Pseudomonas (43%). Most of the strains of organisms isolated were resistant to commonly used antibiotics in the hospital; Pseudomonas was found 100% resistant to a combination of ampicillin + sulbactum, ceftriaxone and was most often sensitive to imipenem, amikacin and vancomycin. Methicillin-resistant Staphylococcus aureus (MRSA) was also found resistant to commonly used antibiotics like ceftriaxone, ampicillin + sulbactum and ceftazidime + calvulanic acid. Linzolid and vancomycin were effective in 83% and 100% cases, respectively. We conclude that similar institution-specific studies should be conducted, and such studies will be helpful in providing useful guidelines for choosing effective empirical therapy that will have a great impact on the prevention of infection and its complications in burn patients because of bacteraemia.

Microbiological findings in burn patients treated in a general versus a designated intensive care unit: Effect on length of stay

BACKGROUND

Infection is one of the most common causes of mortality and morbidity in burn patients. The incidence and frequency of microbiological micro-organisms are known to vary across different models of intensive care units. To date, no study has attempted to describe the different findings in burn patients treated in an open, general intensive care unit (GICU) versus a dedicated burns intensive care unit (BICU). Only limited data is available on the effect of these microbiological micro-organisms on patients' length of stay.

AIM

To characterize and compare the microbiological flora and antibiotic resistance patterns encountered in two different models of burn intensive care and to determine the effect of specific microbiological types on length of intensive care unit (ICU) and overall stay.

METHODS

A retrospective case-control study of 209 burn patients treated in two highly specialized, Western burn referral centres between September 2009 and March 2014.

RESULTS

9710 culture results were analysed, of which 2590 (26.7%) yielded positive results (1537 in the GICU and 1050 in the BICU). Gram-positive cultures were more frequently found in the GICU, whereas Gram-negative and yeast cultures were more prevalent in the BICU. The most frequently encountered micro-organisms in both units were similar and included Staphylococcus aureus, Pseudomonas aeruginosa, coagulase-negative staphylococci (CoNS) and Candida albicans. Significantly more resistant bacteria were detected in the BICU. Testing positive across all types of microbiological isolates, as well as for both Gram-positive and -negative bacteria significantly prolonged patient length of stay. This effect was even more pronounced if the micro-organisms were resistant to antimicrobial therapy.

CONCLUSION

There are notable differences in the microbiological isolate and antibiotic resistance patterns between burn patients treated in a GICU compared to a designated BICU. In both units, testing positive for resistant microbiological micro-organisms is significantly associated with longer hospital stay.

Foot Infections

Infections of the foot are very variable, some being complex in nature, causing pain, morbidity, and even mortality. In patients with diabetes mellitus, foot infections are common, ranging from chronic bacterial or fungal infections to serious limb-threatening ones. To manage infections, a sound knowledge of anatomy is essential. This article reviews the problems with respect to recent evidence and provides pathways to management and suggestions of changes with potential to wound healing.

Ciprofloxacin-loaded keratin hydrogels reduce infection and support healing in a porcine partial-thickness thermal burn

Infection is a leading cause of morbidity and mortality in burn patients. Current therapies include silver-based creams and dressings, which display limited antimicrobial effectiveness and impair healing. The need exists for a topical, point-of-injury antibiotic treatment that provides sustained antimicrobial activity without impeding wound repair. Fitting this description are keratin-based hydrogels, which are fully biocompatible and support the slow-release of antibiotics. Here we develop a porcine model of an infected partial-thickness burn to test the effects of ciprofloxacin-loaded keratin hydrogels on infection and wound healing. Partial-thickness burns were inoculated with either Pseudomonas aeruginosa or Methicillin-resistant Staphylococcus aureus, resulting in infections that persisted for >2 weeks that exceeded 10(5) and 10(6) cfu per gram of tissue, respectively. Compared to silver sulfadiazine, ciprofloxacin-loaded keratin hydrogel treatment significantly reduced the amount of P. aeruginosa and S. aureus in the burn by >99% on days 4, 7, 11, and 15 postinjury. Further, burns treated with ciprofloxacin-loaded keratin hydrogels exhibited similar healing patterns as uninfected burns with regards to reepithelialization, macrophage recruitment, and collagen deposition and remodeling. The ability of keratin hydrogels to deliver antibiotics to fight infection and support healing of partial-thickness burns make them a strong candidate as a first-line burn therapy.

Prevalence of Extended Spectrum β-Lactamase and Antimicrobial Susceptibility Pattern of Clinical Isolates of Pseudomonas from Patients of Khyber Pakhtunkhwa, Pakistan

Majority of gram negative pathogenic bacteria are responsible for extended spectrum β-lactamases (ESBLs) production, which show resistance to some newer generation of antibiotics. The study was aimed at evaluating the prevalence of ESBL and antibiotic susceptibility pattern of Pseudomonas isolates collected during 2010 to 2014 from tertiary care hospitals of Peshawar, Pakistan. Out of 3450 samples, 334 Pseudomonas spp. isolates comprised of 232 indoor and 102 outdoor patients were obtained from different specimens and their susceptibility pattern was determined against 20 antibiotics. Antimicrobial susceptibility testing was carried out using the Kirby-Bauer agar diffusion method and ESBL production was detected by Synergy Disc Diffusion technique. The mean age group of the patients was 29.9 + 9.15 years. Meronem showed best activity (91.02%) from class carbapenem, β-lactam and β-lactamase inhibitors exhibited 69.16% activity, and doxycycline had a diminished activity (10.18%) to Pseudomonas spp. Outdoor isolates were more resistant than the indoor and during the course of the study the sensitivity rate of antibiotics was gradually reducing. ESBL production was observed in 44.32% while the remaining was non-ESBL. The moderate active antibiotics were amikacin (50.7%), SCF (51.4%), TZP (52.7%), and MXF (54.1%) among ESBL producing isolates. Lack of antibiotic policy, irrational uses (3GCs particularly), and the emergence of antibiotic resistant organisms in hospitals may be causes of high antibiotic resistance.

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.

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.

Advanced Therapeutic Dressings for Effective Wound Healing--A Review

Advanced therapeutic dressings that take active part in wound healing to achieve rapid and complete healing of chronic wounds is of current research interest. There is a desire for novel strategies to achieve expeditious wound healing because of the enormous financial burden worldwide. This paper reviews the current state of wound healing and wound management products, with emphasis on the demand for more advanced forms of wound therapy and some of the current challenges and driving forces behind this demand. The paper reviews information mainly from peer-reviewed literature and other publicly available sources such as the US FDA. A major focus is the treatment of chronic wounds including amputations, diabetic and leg ulcers, pressure sores, and surgical and traumatic wounds (e.g., accidents and burns) where patient immunity is low and the risk of infections and complications are high. The main dressings include medicated moist dressings, tissue-engineered substitutes, biomaterials-based biological dressings, biological and naturally derived dressings, medicated sutures, and various combinations of the above classes. Finally, the review briefly discusses possible prospects of advanced wound healing including some of the emerging physical approaches such as hyperbaric oxygen, negative pressure wound therapy and laser wound healing, in routine clinical care.

Ciprofloxacin-Loaded Keratin Hydrogels Prevent Pseudomonas aeruginosa Infection and Support Healing in a Porcine Full-Thickness Excisional Wound

Objective: Cutaneous wound infection can lead to impaired healing, multiple surgical procedures, and increased hospitalization time. We tested the effectiveness of keratin-based hydrogels (termed "keratose") loaded with ciprofloxacin to inhibit infection and support healing when topically administered to porcine excision wounds infected with Pseudomonas aeruginosa. Approach: Using a porcine excisional wound model, 10 mm full-thickness wounds were inoculated with 10⁶ colony-forming units of P. aeruginosa and treated on days 1 and 3 postinoculation with ciprofloxacin-loaded keratose hydrogels. Bacteria enumeration and wound healing were assessed on days 3, 7, and 11 postinjury. Results: Ciprofloxacin-loaded keratose hydrogels reduced the amount of P. aeruginosa in the wound bed by 99.9% compared with untreated wounds on days 3, 7, and 11 postinjury. Ciprofloxacin-loaded keratose hydrogels displayed decreased wound contraction and reepithelialization at day 7 postinjury. By day 11, wounds treated with ciprofloxacin-keratose hydrogels contained collagen-rich granulation tissue and myofibroblasts. Wounds treated with ciprofloxacin-loaded keratose hydrogels exhibited a transient increase in macrophages in the wound bed at day 7 postinjury that subsided by day 11. Innovation: Current therapies for wound infection include systemic antibiotics, which could lead to antibiotic resistance, and topical antimicrobial treatments, which require multiple applications and can delay healing. Here, we show that ciprofloxacin-loaded keratose hydrogels inhibit cutaneous wound infection without interfering with key aspects of the healing process including granulation tissue deposition and remodeling. Conclusions: Ciprofloxacin-loaded keratose hydrogels have the potential to serve as a point-of-injury antibiotic therapy that prevents infection and supports healing following cutaneous injury.

Risk factors for, and the effect of MRSA colonization on the clinical outcomes of severely burnt patients

BACKGROUND

MRSA is an on-going problem for burn patients.

AIM

To analyze risk factors for, and the effect of MRSA colonization on burn patients' outcome.

METHODS

During 21 months burn patients' details and MRSA isolates were analyzed, and a case-control study performed.

RESULTS

Of 357 burn patients, 57 (16%) tested positive for MRSA. Compared to the MRSA negative group, MRSA positive patients had a higher median total burn surface area (15%[IQR 5-17%] vs. 5%[IQR 2-8%]; p<0.001), more admissions to ICU (54% vs. 26%; p<0.001), longer ICU length of stay (4.3 vs. 1.0 days; p<0.001), required more operations (1.6 vs. 0.8; p<0.001), and had longer total hospital length of stay (25.5 vs. 8.0 days; p<0.001). MRSA positivity was a significant independent predictor of increased length of stay (6.0 days, 95%CI 2.39-9.6 days; p=0.001) in a multivariable regression model correcting for patients TBSA and co-morbidities. Cardiac comorbidities (OR 5.14, 95%CI 1.76-15.62; p<0.001) and a longer exposure to the hospital environment (OR 1.05, 95%CI 1.02-1.09, p=0.005) increased the likelihood for MRSA positivity.

CONCLUSION

The negative impact of MRSA positivity on burn patients outcome indicates the need for improved screening procedures for early identification and further efforts toward MRSA infection control to prevent cross-infection as this may significantly impair patients' outcome.

Plasmid mediated antibiotic resistance in isolated bacteria from burned patients

BACKGROUND

Nowadays, the treatment of burned patients is difficult because of the high frequency of infection with antibiotic resistance bacteria.

OBJECTIVES

This study was conducted to evaluate the level of antibiotic resistance in Gram-negative bacteria and its relation with the existence of plasmid.

MATERIALS AND METHODS

The samples were collected from two hundred twenty hospitalized burned patients in Isfahan burn hospital during a three-month period (March 2012 to June 2012). The samples were isolated and the Gram-negative bacteria were identified using phenotypic method and API 20E System. Antibiotic susceptibility and plasmid profile were determined by standard Agar disc diffusion and plasmid spin column extraction methods.

RESULTS

Totally 117 Gram-negative bacteria were isolated, the most common were Pseudomonas aerugionsa (37.6%), P. fluorescens (25.6%), Acinetobacter baumanii (20/5%) and Klebsiella pneumoniae (7.6%), respectively. The isolates showed high frequency of antibiotic resistance against ceftazidime and co-amoxiclave (100%) and low frequency of antibiotic resistance against amikacin with (70%).The results indicated that 60% of the isolates harboured plasmid. On the other hand, the patients infected with A. baumanii and P. aeruginosa were cured (with 60% frequency) whereas, those infected with P. fluorescens were not cured. Hence, probably antibiotic resistance markers of A. baumanii and P. aeruginosa are plasmid mediated; however, P. fluorescens is chromosomally mediated.

CONCLUSIONS

Based on our findings, P. aerugionsa is a major causative agent of wound infections and amikacin could be considered as a more effective antibiotic for treatment of the burned patients.

Antibiotic Susceptibility Pattern of ESβL Producing Klebsiella pneumoniae Isolated from Urine Samples of Pregnant Women in Karnataka

BACKGROUND

Klebsiella pneumoniae possess a new problem to health care professionals worldwide, which complicates and limits therapeutic options. It is one of the leading nosocomial bacterial pathogens, and the present study aims to determine the prevalence of ESβL producing K. pneumoniae isolates with their antibiotic susceptibility pattern in urine samples of the pregnant women with UTI.

MATERIALS AND METHODS

Using standard isolation and identification procedures a total of 41 isolates were obtained from 417 midstream urine samples of pregnant women with suspected UTI in Karnataka. The antibiotic resistance profile of each isolate was performed by Kirby-Bauer disc diffusion method and ESβL production by standard phenotypic method.

RESULTS

Isolation rate of K. pneumoniae in pregnant women was 19.9% and overall incidence rate was 9.8%. Among the 41 K. pneumoniae isolates, 26 (63.4%) were ESβL producers and all were found to be Multi Drug Resistance (MDR). The antibiotic susceptibility test (AST) for the isolates revealed that the highest number of K. pneumoniae were resistant to ampicillin (75.6%) followed by, nitrofurontoin and cefuroxime (73.1%) and least to chloramphenicol (12.1%). ESβL producers were highly resistance to nitrofurontoin (69.2%) and cotrimonazole (65.2%) and lower resistance was (7.6%) to amaikacin, observed. A higher resistance pattern to these two antibiotics was observed against ESβL non producing K. pneumonia but lowest to polymyxin B (13.3%) instead of amikacin (26.6%). All the isolates were found to be susceptible to imipenem.

CONCLUSION

Present investigation revealed high prevalence of MDR- ESβL producing Klebsiella pneumoniae, which indicates dire need for effective ESβL surveillance in the community by using cost effective antimicrobials agents.

Dosing regimen of meropenem for adults with severe burns: a population pharmacokinetic study with Monte Carlo simulations

OBJECTIVES

To develop a population model to describe the pharmacokinetics (PK) of intravenous meropenem in adult patients with severe burns and investigate potential relationships between dosage regimens and antimicrobial efficacy.

PATIENTS AND METHODS

A dose of 1 g every 8 h was administered to adult patients with total body surface area burns of ≥15%. Doses for subsequent courses were determined using results from the initial course and the patient's clinical condition. Five plasma meropenem concentrations were typically measured over the dosage interval on one to four occasions. An open, two-compartment PK model was fitted to the meropenem concentrations using NONMEM and the effect of covariates on meropenem PK was investigated. Monte Carlo simulations investigated dosage regimens to achieve a target T>MIC for ≥40%, ≥60% or ≥80% of the dose interval.

RESULTS

Data comprised 113 meropenem concentration measurements from 20 dosage intervals in 12 patients. The parameters were CL (L/h) = 0.196 L/h/kg × [1 - 0.023 × (age - 46)] × [1 - 0.049 × (albumin - 15)], V1 = 0.273 L/kg × [1 - 0.049 × (albumin - 15)], Q = 0.199 L/h/kg and V2 = 0.309 L/kg × [1 - 0.049 × (albumin - 15)]. For a target of ≥80% T>MIC, the breakpoint was 8 mg/L for doses of 1 g every 4 h and 2 g every 8 h given over 3 h, but only 4 mg/L if given over 5 min.

CONCLUSIONS

Although 1 g 8 hourly should be effective against Escherichia coli and CoNS, higher doses, ideally with a longer infusion time, would be more appropriate for empirical therapy, mixed infections and bacteria with MIC values ≥4 mg/L.

Highly porous drug-eluting structures: from wound dressings to stents and scaffolds for tissue regeneration

For many biomedical applications, there is need for porous implant materials. The current article focuses on a method for preparation of drug-eluting porous structures for various biomedical applications, based on freeze drying of inverted emulsions. This fabrication process enables the incorporation of any drug, to obtain an "active implant" that releases drugs to the surrounding tissue in a controlled desired manner. Examples for porous implants based on this technique are antibiotic-eluting mesh/matrix structures used for wound healing applications, antiproliferative drug-eluting composite fibers for stent applications and local cancer treatment, and protein-eluting films for tissue regeneration applications. In the current review we focus on these systems. We show that the release profiles of both types of drugs, water-soluble and water-insoluble, are affected by the emulsion's formulation parameters. The former's release profile is affected mainly through the emulsion stability and the resulting porous microstructure, whereas the latter's release mechanism occurs via water uptake and degradation of the host polymer. Hence, appropriate selection of the formulation parameters enables to obtain desired controllable release profile of any bioactive agent, water-soluble or water-insoluble, and also fit its physical properties to the application.

Mechanical properties and in vitro characterization of polyvinyl alcohol-nano-silver hydrogel wound dressings

Polyvinyl alcohol (PVA) hydrogels are materials for potential use in burn healing. Silver nanoparticles can be synthesized within PVA hydrogels giving antimicrobial hydrogels. Hydrogels have to be swollen prior to their application, and the common medium available for that in hospitals is saline solution, but the hydrogel could also take up some of the wound's fluid. This work developed gamma-irradiated PVA/nano-Ag hydrogels for potential use in burn dressing applications. Silver nitrate (AgNO3) was used as nano-Ag precursor agent. Saline solution, phosphate-buffered solution (PBS) pH 7.4 and solution pH 4.0 were used as swelling media. Microstructural evaluation revealed an effect of the nanoparticles on PVA crystallization. The swelling of the PVA-Ag samples in solution pH 4.0 was low, as was their silver delivery, compared with the equivalent samples swollen in the other media. The highest swelling and silver delivery were related to samples prepared with 0.50% AgNO3, and they also presented lower strength in PBS pH 7.4 and solution pH 4.0. Both PVA-Ag samples were also non-toxic and presented antimicrobial activity, confirming that 0.25% AgNO3 concentration is sufficient to establish an antimicrobial effect. Both PVA-Ag samples presented suitable mechanical and swelling properties in all media, representative of potential burn site conditions.

The extracellular matrix Component Psl provides fast-acting antibiotic defense in Pseudomonas aeruginosa biofilms

Bacteria within biofilms secrete and surround themselves with an extracellular matrix, which serves as a first line of defense against antibiotic attack. Polysaccharides constitute major elements of the biofilm matrix and are implied in surface adhesion and biofilm organization, but their contributions to the resistance properties of biofilms remain largely elusive. Using a combination of static and continuous-flow biofilm experiments we show that Psl, one major polysaccharide in the Pseudomonas aeruginosa biofilm matrix, provides a generic first line of defense toward antibiotics with diverse biochemical properties during the initial stages of biofilm development. Furthermore, we show with mixed-strain experiments that antibiotic-sensitive “non-producing” cells lacking Psl can gain tolerance by integrating into Psl-containing biofilms. However, non-producers dilute the protective capacity of the matrix and hence, excessive incorporation can result in the collapse of resistance of the entire community. Our data also reveal that Psl mediated protection is extendible to E. coli and S. aureus in co-culture biofilms. Together, our study shows that Psl represents a critical first bottleneck to the antibiotic attack of a biofilm community early in biofilm development.

Many bacteria have the ability to form multicellular communities, termed biofilms. An important characteristic of a biofilm is the ability of cells to synthesize and secrete an extracellular matrix. This matrix offers structural support, community organization, and added protection, often making the cells impervious to desiccation, predation, and antimicrobials. In this study, we investigate the contributions of polysaccharide components found in the extracellular matrix of Pseudomonas aeruginosa at progressive stages in biofilm development. We first show that one specific polysaccharide, Psl, provides an added defense for P. aeruginosa biofilms against antimicrobials of different properties for young biofilms. Then, by cultivating biofilms that contain both Psl producing and Psl non-producing strains, we find that P. aeruginosa, E. coli, and S. aureus species that lack Psl take advantage of the protection offered by cells producing Psl. Collectively, the data indicate that Psl is likely to play a key protective role in early development of P. aeruginosa biofilm associated infections.

Antimicrobial susceptibility of bacterial isolates from burn units in Gaza

BACKGROUND

Bacterial infections continue to be a leading cause of morbidity and mortality among burn patients despite intensive prophylaxis and treatment. Often treatment is complicated by the emergence of antimicrobial resistance pathogens. There are no reports or published data on the susceptibility profiles of bacteria isolated from burn patients in the Gaza strip.

PATIENTS AND METHODS

A cross sectional study was performed in the two burn units of Al-Shifa and Naser hospitals for 6 months from October 2010 to March 2011. A total of 118 wound samples from burn patients, 97 environmental samples and 28 samples from health care workers (HCWs) were collected and cultured according to the standard microbiological procedures. The bacterial isolates were identified by conventional methods and the antibiotic susceptibility profiles were determined by the standard disc diffusion method according to CLSI guidelines.

RESULTS

The overall percentage of positive cultures from both hospitals was 45.8%, where Nasser burn unit revealed higher positive cultures than Al-Shifa burn unit. Pseudomonas aeruginosa was the most common pathogen isolated (50%) followed by Enterobacter cloacae (28.3%). Meanwhile, fingers and nasal samples that collected from HCWs showed 78.6% and 32.3% positive cultures respectively, where P. aeruginosa was the highest pathogen isolated (32.3%), followed by Coagulase Negative Staphylococci (CoNS) (29%). Environmental samples also showed higher isolation rate of Pseudomonas and CoNS. Pseudomonas isolates from patients samples were found to be resistant to most of antimicrobials used except for piperacillin-tazobactam. The family Enterobacteriaceae isolated from patients and environmental samples were resistant to most of the tested antimicrobials. However, the Enterobacteriaceae isolates from HCWs samples were sensitive to the most of the tested antimicrobials. The incidence of methicillin-resistant Staphylococci according to oxacillin sensitivity test was 60% in patient's samples, 77.8% in HCWs samples and 90% in environmental samples.

CONCLUSION

High percentage of resistance was found among clinical isolates in general to the commonly used antibiotics with a notable increase in MRSA incidence among both patients and environmental samples as well as HCWs.

Three-year review of bacteriological profile and antibiogram of burn wound isolates in Van, Turkey

The risk of infection in burns is well-known. In recent decades, the antimicrobial resistance of bacteria isolated from burn patients has increased. For this reason, a retrospective study was conducted at Van Training and Research Hospital to analyze the bacterial isolates from the wounds of patients admitted to the Burn Unit and to determine the susceptibility patterns of the commonly cultured organisms over a 3-year period, January 2009 to December 2011.A total of 250 microorganisms were isolated from burn wounds of 179 patients. Our results revealed that the most frequent isolate was Acinetobacter baumannii (23.6%), Pseudomonas aeruginosa (12%), Staphylococcus aureus (11.2%), Escherichia coli (10%) respectively. Multidrug-resistance has emerged as an important concern in our burn unit. Tigecycline, and colistin were found to be the most active drugs against Acinetobacter baumannii. Carbapenems and amikacin, were found to be the most active drugs against other gram negative bacteria. Vancomycin and linezolid were active against gram positive bacteria.Aggressive infection control measures should be applied to limit the emergence and spread of multidrug-resistant pathogens.

Polyox and carrageenan based composite film dressing containing anti-microbial and anti-inflammatory drugs for effective wound healing

Polyethylene oxide (Polyox) and carrageenan based solvent cast films have been formulated as dressings for drug delivery to wounds. Films plasticised with glycerol were loaded with streptomycin (30%, w/w) and diclofenac (10%, w/w) for enhanced healing effects in chronic wounds. Blank and drug loaded films were characterised by texture analysis (for mechanical and mucoadhesive properties), scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy. In addition, swelling, in vitro drug release and antibacterial studies were conducted to further characterise the films. Both blank and drug loaded films showed a smooth, homogeneous surface morphology, excellent transparency, high elasticity and acceptable tensile (mechanical) properties. The drug loaded films showed a high capacity to absorb simulated wound fluid and significant mucoadhesion force which is expected to allow effective adherence to and protection of the wound. The films showed controlled release of both streptomycin and diclofenac for 72 h. These drug loaded films produced higher zones of inhibition against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli compared to the individual drugs zones of inhibition. Incorporation of streptomycin can prevent and treat chronic wound infections whereas diclofenac can target the inflammatory phase of wound healing to relieve pain and swelling.

Therapeutic efficacy of an antibiotic-loaded nanosheet in a murine burn-wound infection model

Polymeric ultra-thin films (nanosheets) possess unique properties that make them suitable materials for various biomedical applications. In our previous study, we assessed the use of an antibiotic (tetracycline, TC)-loaded nanosheet (or "TC-nanosheet") for the treatment of gastrointestinal tissue defects. The nanosheet consisted of three functional layers: layer-by-layer nanosheet as a stable platform, TC as an antimicrobial agent with autofluorescence for tracing, and a poly(vinyl acetate) nanosheet to act as a protecting layer. The TC-nanosheet has high flexibility, adhesive strength and transparency. Here, we evaluated the effectiveness of the TC-nanosheet in preventing full thickness burn-wound infections. In an in vivo study, murine dorsal skin was injured by full-thickness burns and then infected with Pseudomonas aeruginosa (P. aeruginosa), a common bacterium causing burn-associated infections. The wound site was treated either with a TC-nanosheet, TC-unloaded nanosheet or left untreated. Wound management was facilitated by the high transparency of the TC-nanosheet. The TC-nanosheet significantly improved burn-wound infection by P. aeruginosa in mice. Indeed, all mice treated with the TC-nanosheet survived, whereas the other treatment groups displayed increased rates of mortality due to bacterial infection. According to histological analyses and viable bacterial counting in the liver (bacterial translocation), the TC-nanosheets were able to prevent not only the local inflammation but also systemic inflammation. We conclude that the TC-nanosheet can act as an effective treatment for full-thickness burn-wound infection. Hence, the TC-nanosheet is a promising therapeutic tool for burn-wound management in severely burn-injured patients.

Mannose-binding lectin and the balance between immune protection and complication

The innate immune system is evolutionarily ancient and biologically primitive. Historically, it was first identified as an element of the immune system that provides the first-line response to pathogens, and increasingly it is recognized for its central housekeeping role and its essential functions in tissue homeostasis, including coagulation and inflammation, among others. A pivotal link between the innate immune system and other functions is mannose-binding lectin (MBL), a pattern recognition molecule. Multiple studies have demonstrated that MBL deficiency increases susceptibility to infection, and the mechanisms associated with this susceptibility to infection include reduced opsonophagocytic killing and reduced activation of the lectin complement pathway. Results from our laboratory have demonstrated that MBL and MBL-associated serine protease (MASP)-1/3 together mediate coagulation factor-like activities, including thrombin-like activity. MBL and/or MASP-1/3-deficient hosts demonstrate in vivo evidence that MBL and MASP-1/3 are involved with hemostasis following injury. Staphylococcus aureus-infected MBL null mice developed disseminated intravascular coagulation, which was associated with elevated blood IL-6 levels (but not TNF-α) and systemic inflammatory responses. Infected MBL null mice also develop liver injury. These findings suggest that MBL deficiency may manifest as disseminated intravascular coagulation and organ failure with infection. Beginning from these observations, this review focuses on the interaction of innate immunity and other homeostatic systems, the derangement of which may lead to complications in infection and other inflammatory states.

Novel soy protein wound dressings with controlled antibiotic release: mechanical and physical properties

Naturally derived materials are becoming widely used in the biomedical field. Soy protein has advantages over various types of natural proteins employed for biomedical applications due to its low price, non-animal origin and relatively long storage time and stability. In the current study soy protein isolate (SPI) was investigated as a matrix for wound dressing applications. The antibiotic drug gentamicin was incorporated into the matrix for local controlled release and, thus, protection against bacterial infection. Homogeneous yellowish films were cast from aqueous solutions. After cross-linking they combined high tensile strength and Young's modulus with the desired ductility. The plasticizer type, cross-linking agent and method of cross-linking were found to strongly affect the tensile properties of the SPI films. Selected SPI films were tested for relevant physical properties and the gentamicin release profile. The cross-linking method affected the degree of water uptake and the weight loss profile. The water vapor transmission rate of the films was in the desired range for wound dressings (∼2300 g m(-2) day(-1)) and was not affected by the cross-linking method. The gentamicin release profile exhibited a moderate burst effect followed by a decreasing release rate which was maintained for at least 4 weeks. Diffusion was the dominant release mechanism of gentamicin from cross-linked SPI films. Appropriate selection of the process parameters yielded SPI wound dressings with the desired mechanical and physical properties and drug release behavior to protect against bacterial infection. These unique structures are thus potentially useful as burn and ulcer dressings.

Prevention of infections associated with combat-related burn injuries

Burns are a very real component of combat-related injuries, and infections are the leading cause of mortality in burn casualties. The prevention of infection in the burn casualty transitioning from the battlefield to definitive care provided at the burn center is critical in reducing overall morbidity and mortality. This review highlights evidence-based medicine recommendations using military and civilian data to provide the most comprehensive, up-to-date management strategies for initial care of burned combat casualties. Areas of emphasis include antimicrobial prophylaxis, debridement of devitalized tissue, topical antimicrobial therapy, and optimal time to wound coverage. This evidence-based medicine review was produced to support the Guidelines for the Prevention of Infections Associated With Combat-Related Injuries: 2011 Update contained in this supplement of Journal of Trauma.

Environmental decontamination of a hospital isolation room using high-intensity narrow-spectrum light

The performance of a new decontamination technology, referred to as 'high-intensity narrow-spectrum light environmental decontamination system' (HINS-light EDS) was evaluated by a series of three studies carried out in a hospital isolation room used to treat burns patients. The ceiling-mounted HINS-light EDS emits high-intensity 405nm light which, although bactericidal, is harmless to patients and staff thereby permitting continuous environmental disinfection throughout the day. Performance efficacy was assessed by contact agar plate sampling and enumeration of staphylococcal bacteria on environmental surfaces within the room before, during and after HINS-light EDS treatment. When the room was unoccupied, use of HINS-light EDS resulted in ∼90% reduction of surface bacterial levels and when the room was occupied by an MRSA-infected burns patient, reductions between 56% and 86% were achieved, with the highest reduction (86%) measured following an extended period of HINS-light EDS operation. In an on/off intervention study, surface bacterial levels were reduced by 62% by HINS-light EDS treatment and returned to normal contamination levels two days after the system was switched off. These reductions of staphylococci, including Staphylococcus aureus and meticillin-resistant S. aureus, by HINS-light EDS treatment were greater than the reductions achieved by normal infection control and cleaning activities alone. The findings provide strong evidence that HINS-light EDS, used as a supplementary procedure, can make a significant contribution to bacterial decontamination in clinical environments.