The impact of simultaneous inoculation of Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans on rodent burn wounds

Burn wound infection often involves a diverse combination of bacterial and fungal pathogens. In this study, we characterize the mixed species burn wound infection by inoculating the burn surface with 1 × 10^3/4/5 CFU of Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans in a 1:1:1 ratio. Using the revised Walker-Mason scald burn rat model, 168 male Sprague-Dawley rats (350-450 g) subject to ∼10% TBSA burn injury, with or without inoculation, were evaluated for 11 days after burn. In the wound, P. aeruginosa and S. aureus formed robust biofilms as determined by the bacterial tissue load, ∼1 × 10⁹ CFU/g, and expression of key biofilm genes. Interestingly, within 3 days C. albicans achieved tissue loads of ∼1 × 10⁶ CFU/g, but its numbers were significantly reduced beyond the limit of detection in the burn wound by day 7 in partial-thickness injuries and by day 11 in full-thickness injuries. The pathogenic biofilms contributed to burn depth progression, increased release of HMGB-1 into circulation from injured tissue, and significantly elevated the numbers of circulating innate immune cells (Neutrophils, Monocytes, and Basophils). This robust model of multi-species burn wound infection will serve as the basis for the development of new antimicrobials for combating biofilm-based wound infections.

Improving the Inhibitory Effect of Phages against Pseudomonas aeruginosa Isolated from a Burn Patient Using a Combination of Phages and Antibiotics

Antibiotic resistance causes around 700,000 deaths a year worldwide. Without immediate action, we are fast approaching a post-antibiotic era in which common infections can result in death. Pseudomonas aeruginosa is the leading cause of nosocomial infection and is also one of the three bacterial pathogens in the WHO list of priority bacteria for developing new antibiotics against. A viable alternative to antibiotics is to use phages, which are bacterial viruses. Yet, the isolation of phages that efficiently kill their target bacteria has proven difficult. Using a combination of phages and antibiotics might increase treatment efficacy and prevent the development of resistance against phages and/or antibiotics, as evidenced by previous studies. Here, in vitro populations of a Pseudomonas aeruginosa strain isolated from a burn patient were treated with a single phage, a mixture of two phages (used simultaneously and sequentially), and the combination of phages and antibiotics (at sub-minimum inhibitory concentration (MIC) and MIC levels). In addition, we tested the stability of these phages at different temperatures, pH values, and in two burn ointments. Our results show that the two-phages-one-antibiotic combination had the highest killing efficiency against the P. aeruginosa strain. The phages tested showed low stability at high temperatures, acidic pH values, and in the two ointments. This work provides additional support for the potential of using combinations of phage-antibiotic cocktails at sub-MIC levels for the treatment of multidrug-resistant P. aeruginosa infections.

Human organoid biofilm model for assessing antibiofilm activity of novel agents

Bacterial biofilms cause 65% of all human infections and are highly resistant to antibiotic therapy but lack specific treatments. To provide a human organoid model for studying host-microbe interplay and enabling screening for novel antibiofilm agents, a human epidermis organoid model with robust methicillin-resistant Staphylococcus aureus (MRSA) USA300 and Pseudomonas aeruginosa PAO1 biofilm was developed. Treatment of 1-day and 3-day MRSA and PAO1 biofilms with antibiofilm peptide DJK-5 significantly and substantially reduced the bacterial burden. This model enabled the screening of synthetic host defense peptides, revealing their superior antibiofilm activity against MRSA compared to the antibiotic mupirocin. The model was extended to evaluate thermally wounded skin infected with MRSA biofilms resulting in increased bacterial load, cytotoxicity, and pro-inflammatory cytokine levels that were all reduced upon treatment with DJK-5. Combination treatment of DJK-5 with an anti-inflammatory peptide, 1002, further reduced cytotoxicity and skin inflammation.

Predictors of multi-drug resistance in burn wound colonization following burn injury in a resource-limited setting

INTRODUCTION

Bacterial resistance to antibiotics is growing dramatically worldwide due to several contributing factors, including inappropriate antibiotic utilization in the clinical setting and widespread use in the food production industry. Consequently, it is imperative to characterize antibiotic resistance in high-risk populations, such as burn patients, particularly in resource-limited settings where prevention strategies may be high-yield and new antibiotics are not readily available. We therefore sought to characterize and identify predictors of multi-drug resistant (MDR) bacteria colonization in burn patients at our center in Malawi.

METHODS

This is a prospective analysis of burn patients presenting to Kamuzu Central Hospital in Lilongwe, Malawi within 72 h of burn injury. A swab of each patient's primary wound was collected at admission and each subsequent week. The primary aim was to determine predictors of colonization in burn wounds with multi-drug resistant bacteria using modified Poisson regression modeling.

RESULTS

99 patients were enrolled and analyzed. The median age was 4 years (IQR 2-12) with a median % total burn surface area (TBSA) of 14% (IQR 9-25). The most common burn injury type was scald (n = 61, 61.6%), followed by flame (n = 37, 37.4%). Overall, 54 patients (54.6%) were colonized with MDR bacteria at some point during their hospitalization, with increases each week. For flame burns, the predictors of MDR bacterial colonization were each 1% increase of %TBSA (RR 1.01, 95% CI 1.00, 1.03, p = 0.038) and the use of operative intervention for burn treatment (RR 1.90, 95% CI 1.17, 3.09, p = 0.010). No variables were predictive of MDR wound colonization in scald burns.

CONCLUSION

Our study identified that almost half of the patients in a Malawian burn unit had MDR bacteria colonizing burn wounds after only a week in the hospital. This increased to almost 70% during hospitalization. We also found that for patients with flame burns, increasing %TBSA, and operative intervention put patients at greater risk of MDR colonization. Interventions such as isolation of burn patients, consistent disinfection and sterilization of wards and operating rooms, and optimization of wound care management are imperative to decrease spread of MDR bacteria and to improve burn-associated clinical outcomes in resource-limited environments.

Amending the Efficiency of Antimicrobials against Multidrug-Resistant Pseudomonas aeruginosa by Low-Frequency Magnetic Fields

We studied the effect of 1- and 2-h exposure to low-frequency magnetic fields (0.3 and 0.42 mT) on the sensitivity of Pseudomonas aeruginosa to 18 antibiotics. P. aeruginosa samples were obtained from 20 patients with burns. Exposure to magnetic field reduced the resistance of P. aeruginosa and increased their susceptibility to antimicrobial drugs. This increase was positively correlated with field intensity and duration of exposure. After 2-h exposure to 0.42 mT, susceptibility of P. aeruginosa to antimicrobial drugs aztreonam, ceftazidime, colistin, imipenem, levofloxacin, and meropenem significantly increased. In addition, resensitization of P. aeruginosa to carbapenems, penicillin, quinolones, and aminoglycosides groups was observed.

Molecular profile of carbapenemase-producing Enterobacterales in burn patients

BACKGROUND

Carbapenemase-producing Enterobacterales (CPE) present a threat to public health worldwide.

AIM

To study their prevalence at the Trauma and Burn Center's Burn Unit and investigate their molecular characteristics and their associated antibiotics resistance patterns.

METHODS

This is a retrospective study conducted at the Trauma and Burn Center's laboratory between july 2017 and december 2018. It included all patients hospitalized in the Trauma and Burn Center's Burn Unit infected with Enterobacterales resistant to carbapenems. The search of the carbapenemases genes was performed by PCR amplification GeneXpert® IV (Cepheid, Sunnyvale, CA, USA) by Xpert® Carba-R kit.

RESULTS

During the study period, among 574 Enterobacterales, 64 strains (11.1%) were resistant to carbapenems, 58 strains (90.6%) of which were CPE. K. pneumoniae was the most predominant bacteria (n=50) fllowed by E. cloacae (n=7), P. mirabilis (n=3), E. aerogenes (n=2), E. coli (n=1) and P. rettgeri (n=1). The most common carbapenemase gene was blaNDM gene (58.6%) followed by blaOXA48 (24.1%). The co-existence of these two genes was identified in ten strains (17.3%). For the 58 CPE, resistance to ertapenem, imipenem and meropenem was 100%, 18.4% and 36.2%, respectively. The highest resistance rates were found to third-generation-cephalosporins (100%), ciprofloxacin (95%) and gentamicin (89.7%). Fosfomycin and colistin had the best susceptibility in vitro with only 5.2% and 4.8% of resistance, respectively.

CONCLUSION

The high prevalence of CPE in our center requires continued screening and reinforcement of hygiene measures.

Cerium Nitrate Treatment Provides Eschar Stabilization through Reduction in Bioburden, DAMPs, and Inflammatory Cytokines in a Rat Scald Burn Model

In this study, we used a clinically relevant rat scald burn model to determine the treatment effects of cerium nitrate (CN) for stabilizing burn eschars through reduction of damage-associated molecular patterns (DAMPs), inflammatory cytokines, and bioburden. Forty-two male Sprague-Dawley rats were anesthetized before undergoing a scald burn at 99°C for 6 seconds to create a 10% full-thickness burn. The test groups included sham burn, burn with water bathing, and burn with CN bathing. End point parameters included circulating DAMPs, proinflammatory cytokines, tissue myeloperoxidase activity, and quantification of resident flora in burn skin. The high mobility group protein box 1 was found to be elevated in burn animals at postoperative days (POD) 1 and 7. CN significantly alleviated the increase (P < .05 at POD 1 and P < .01 at POD 7). CN also lessened the heightened levels of hyaluronan in burn animals (P < .05 at POD 7). Additionally, CN significantly reduced the burn-induced increases in interleukin-1β, growth-regulated oncogene/keratinocyte chemoattractant, and macrophage inflammatory protein-1α in burn wounds. The anti-inflammatory effect of CN was also demonstrated in its ability to mitigate the upregulated circulatory xanthine oxidase/dehydrogenase and increased tissue neutrophil infiltration in burn animals. Last, CN suppressed postburn proliferation of resident skin microbes, resulting in a significant 2-log reduction by POD 7. In conclusion, these results suggest that CN attenuates the burn-induced DAMPs, tissue inflammatory responses, and regrowth of resident skin flora, all of which collectively could improve the quality of burn eschar when applied at the point of injury in prolonged field care situations.

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.

New markers for sepsis caused by Pseudomonas aeruginosa during burn infection

INTRODUCTION

Sepsis is a leading cause of mortality in burn patients. One of the major causes of sepsis in burn patients is Pseudomonas aeruginosa. We hypothesized that during dissemination from infected burn wounds and subsequent sepsis, P. aeruginosa affects the metabolome of the blood resulting in changes to specific metabolites that would serve as biomarkers for early diagnosis of sepsis caused by P. aeruginosa.

OBJECTIVES

To identify specific biomarkers in the blood after sepsis caused by P. aeruginosa infection of burns.

METHODS

Gas chromatography with time-of-flight mass spectrometry was used to compare the serum metabolome of mice that were thermally injured and infected with P. aeruginosa (B-I) to that of mice that were neither injured nor infected, mice that were injured but not infected, and mice that were infected but not injured.

RESULTS

Serum levels of 19 metabolites were significantly increased in the B-I group compared to controls while levels of eight metabolites were significantly decreased. Thymidine, thymine, uridine, and uracil (related to pyrimidine metabolism), malate and succinate (a possible sign of imbalance in the tricarboxylic acid cycle), 5-oxoproline (related to glutamine and glutathione metabolism), and trans-4-hydroxyproline (a major component of the protein collagen) were increased. Products of amino acid metabolism were significantly decreased in the B-I group, including methionine, tyrosine, indole-3-acetate, and indole-3-propionate.

CONCLUSION

In all, 26 metabolites were identified, including a unique combination of five metabolites (trans-4-hydroxyproline, 5-oxoproline, glycerol-3-galactoside, indole-3-acetate, and indole-3-propionate) that could serve as a set of biomarkers for early diagnosis of sepsis caused by P. aeruginosa in burn patients.

Smart Hydrogel-Based DVDMS/bFGF Nanohybrids for Antibacterial Phototherapy with Multiple Damaging Sites and Accelerated Wound Healing

Burn infection is one of the commonest causes of death in severely burned patients. Developing multifunctional biological nanomaterials has a great significance for the comprehensive treatment of burn infection. In this paper, we developed a hydrogel-based nanodelivery system with antibacterial activity and skin regeneration function, which was used for photodynamic antimicrobial chemotherapy (PACT) in the treatment of burns. The treatment system is mainly composed of porphyrin photosensitizer sinoporphyrin sodium (DVDMS) and poly(lactic-co-glycolic acid) (PLGA)-encapsulated basic fibroblast growth factor (bFGF) nanospheres that are embedded in carboxymethyl chitosan (CMCS)-sodium alginate to form CSDP hybrid hydrogel. We systematically evaluated the inherent antibacterial performance, rheological properties, fluorescence imaging, and biocompatibility of the CSDP nanosystem. Under mild photoirradiation (30 J/cm², 5 min), 10 μg/mL CSDP showed excellent antibacterial and anti-biofilm activities, which eradicated almost 99.99% of Staphylococcus aureus and multidrug-resistant (MDR) S. aureus in vitro. KEGG analysis identified that multiple signaling pathways were changed in MDR S. aureus after PACT. In the burn-infection model, CSDP-PACT successfully inhibited bacteria growth and concurrently promoted wound healing. Moreover, several regenerative factors were increased and some proinflammatory factors were reduced in the burn wounds of CSDP hydrogel treatment. These results suggest that the multifunctional CSDP hydrogel is a portable, light-triggered, antibacterial theranostic-platform and CSDP-PACT provides a promising strategy or the mechanically based synergistic treatment of burn infections.

The Effect of Lauric Acid on Pathogens Colonizing the Burn Wound: A Pilot Study

OBJECTIVE

Some of the most serious complications of burns include septic infections. Instead of fulfilling the function of a protective barrier, tissues damaged by high temperature create a niche that serves as an environment and source of nourishment for pathogens. An accepted practice is to use antibiotics to inhibit development of pathogens. Taking into consideration the characteristics of the burn wound and increasing antibiotic resistance, the search for new substances that have both antimicrobial and regenerative effects seems justified. The aim of the study was to determine the influence of lauric acid on bacteria-colonizing tissue samples taken during surgical treatment of burns.

METHODS

Lauric acid was combined with 5 different ointment bases: Anhydrous Eucerin DAB, Anhydrous Eucerin II, Hydrophilic Vaseline, White Vaseline, and Lekobaza. The content of lauric acid in the ointment bases was 10% to 20% w/w. The preparations were applied onto samples of burnt skin collected during surgery. The samples were subsequently subjected to a microbiological test with the use of model strains of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli.

RESULTS

With one exception (White Vaseline), lauric acid showed a more pronounced effect on bacteria in 20% w/w concentration. In a 10% lauric acid concentration, no effect on bacteria was observed on the Hydrophilic Vaseline ointment base. Lauric acid had the strongest inhibiting effect on microbial growth of Gram-positive Staphylococcus aureus. Satisfactory zones of inhibition were also observed in the case of Escherichia coli. Growth inhibition of Pseudomonas aeruginosa was observed only when pure lauric acid was used.

CONCLUSIONS

Due to its aseptic and regenerative effect on chemically damaged tissues, lauric acid can be a promising modifier of the burn healing process.

Effects of Silver Nanoparticles on Burn Wound Healing in a Mouse Model

Healing of injuries caused by exposure to heat has been discussed in many studies, although a few drugs have been shown to produce satisfactory results. In this study, 100 healthy mice randomly allocated into four categories (each = 25 mice) were analyzed. A deep second-degree burn on the back of each mouse was created. The burns were dressed daily with either AgNPs or silver sulfadiazine over 28 days of treatment. Safety evaluation of the AgNP treatment was performed by measuring the deposition rate of silver in the liver, brain, and kidney of treated mice. In the murine burn model, the speed of wound healing and the antibacterial effect of AgNPs were better than those in the silver sulfadiazine group. Burn wounds treated with SSD appeared to display a greater degree of inflammation as notable by the three clinical signs of the inflammatory process such as redness and swelling which appeared to be less after wounds treated with AgNPs. Also, AgNP treatment modified leukocytic infiltration and reduced collagen degeneration in treated mice and enhanced healing processes that were confirmed by morphological and histological investigations. Beside the potential significant effects of AgNPs on reduction of some microorganism counts that routinely isolated from burn wounds included aerobic organisms as Staphylococcus aureus and Escherichia coli when compared to both SSD and control groups. The deposition kinetics of AgNPs revealed lower distribution in the liver, brain, and kidney than that in silver sulfadiazine-treated mice with respect to both SSD and control groups.

Skin Infections and Outpatient Burn Management: Bacterial Skin Infections

Patients with bacterial skin and soft tissue infections (SSTIs) commonly present to family physicians. Common uncomplicated bacterial SSTIs include impetigo, ecthyma, cellulitis, erysipelas, abscesses, furuncles, and carbuncles. Risk factors for SSTIs include older age and chronic medical conditions, such as diabetes and cardiopulmonary or renal disease, and immunocompromise. Staphylococci and streptococci are the most common pathogens. Uncomplicated impetigo and ecthyma can be managed with topical antibiotics. Oral antibiotics should be prescribed for patients with complicated impetigo and ecthyma and for patients with cellulitis. For patients with cellulitis and systemic signs of infection, systemic antibiotics are indicated but hospitalization or intravenous administration may not be required. Erysipelas can be managed with oral or intravenous penicillin. Purulent SSTIs by definition involve collections of pus and include abscesses, furuncles, and carbuncles. Larger abscesses are appropriate for incision and drainage. Patients with uncomplicated carbuncles or abscesses may not require antibiotics afterward. However, antibiotics are recommended for patients with systemic inflammatory response syndrome (SIRS), patients with carbuncles or abscesses who have not improved with initial antibiotic therapy, patients with impaired host defenses, and patients with SIRS and hypotension.

Skin Infections and Outpatient Burn Management: Fungal and Viral Skin Infections

Fungal and viral skin infections are common and typically are managed by family physicians. The fungal skin infections commonly seen in family practice include the various forms of tinea: tinea corporis, tinea gladiatorum, tinea cruris, tinea pedis, tinea capitis, and tinea unguium (eg, onychomycosis). Common viral skin infections include herpes simplex virus infection, herpes zoster, cutaneous and genital warts, and molluscum contagiosum. Many fungal and viral skin infections have a classic appearance but variations and atypical manifestations can make patients with these conditions difficult to diagnose definitively. Confirmatory testing often is not required. In complex cases with atypical features, microscopy, culture, or blood tests can help in making a diagnosis. For some infections, treatment may be initiated before confirmatory test results are received. Most fungal skin infections can be managed effectively with topical antifungals. Tinea capitis and onychomycosis should be managed with oral drugs. Oral antiviral drugs are used to manage most viral skin infections but dosages vary based on the condition and phase of the infectious process. Cutaneous warts typically are managed with salicylic acid and/or cryotherapy.

New Nanotechnologies for the Treatment and Repair of Skin Burns Infections

Burn wounds are highly debilitating injuries, with significant morbidity and mortality rates worldwide. In association with the damage of the skin integrity, the risk of infection is increased, posing an obstacle to healing and potentially leading to sepsis. Another limitation against healing is associated with antibiotic resistance mainly due to the use of systemic antibiotics for the treatment of localized infections. Nanotechnology has been successful in finding strategies to incorporate antibiotics in nanoparticles for the treatment of local wounds, thereby avoiding the systemic exposure to the drug. This review focuses on the most recent advances on the use of nanoparticles in wound dressing formulations and in tissue engineering for the treatment of burn wound infections.

Temporal shifts in the mycobiome structure and network architecture associated with a rat (Rattus norvegicus) deep partial-thickness cutaneous burn

With a diverse physiological interface to colonize, mammalian skin is the first line of defense against pathogen invasion and harbors a consortium of microbes integral in maintenance of epithelial barrier function and disease prevention. While the dynamic roles of skin bacterial residents are expansively studied, contributions of fungal constituents, the mycobiome, are largely overlooked. As a result, their influence during skin injury, such as disruption of skin integrity in burn injury and impairment of host immune defense system, is not clearly delineated. Burn patients experience a high risk of developing hard-to-treat fungal infections in comparison to other hospitalized patients. To discern the changes in the mycobiome profile and network assembly during cutaneous burn-injury, a rat scald burn model was used to survey the mycobiome in healthy (n = 30) (sham-burned) and burned (n = 24) skin over an 11-day period. The healthy skin demonstrated inter-animal heterogeneity over time, while the burned skin mycobiome transitioned toward a temporally stabile community with declining inter-animal variation starting at day 3 post-burn injury. Driven primarily by a significant increase in relative abundance of Candida, fungal species richness and abundance of the burned skin decreased, especially in days 7 and 11 post-burn. The network architecture of rat skin mycobiome displayed community reorganization toward increased network fragility and decreased stability compared to the healthy rat skin fungal network. This study provides the first account of the dynamic diversity observed in the rat skin mycobiome composition, structure, and network assembly associated with postcutaneous burn injury.

Protective properties of kefir on burn wounds of mice that were infected with S. aureus, P. auroginasa and E. coli

Burns and burn wounds are very sensitive to infections and cause a large amount of death worldwide. Although burn wound is sterile at the beginning, because of the risk factors such as prolonged hospital stay, immune suppression and burn affecting large surface area, colonisation with Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli occur. For the burn therapy, one of the most important ways is to control bacterial infections. A probiotic fermented milk product kefir has antioxidant, antimicrobial, antiinflammatory, anticancer and various health promoting features. This study aims to examine possible protective properties of kefir which was used on the burn wounds that were infected with S. aureus, P. auroginasa and E. coli.  Swiss albino / Balb-c mice were seperated into four groups: (1) used as control group, (2) second-degree burn model+ burn wounds were infected with P.aeruginosa + S.aureus + E.coli, (3) second-burn wounds were treated with sterile pads dressed with kefir and (4) second-degree burn+burn wounds were infected with P. aeruginosa + S.aureus +E.coli before being treated with sterile pads dressed with kefir. The serum biochemical results verified the histopathological results and our findings showed that kefir is an effective product with cell-protecting properties.

Evaluation of Platensimycin and Platensimycin-Inspired Thioether Analogues against Methicillin-Resistant Staphylococcus aureus in Topical and Systemic Infection Mouse Models

Staphylococcus aureus is one of the most common pathogens causing hospital-acquired and community-acquired infections. Methicillin-resistant S. aureus (MRSA)-formed biofilms in wounds are difficult to treat with conventional antibiotics. By targeting FabB/FabF of bacterial fatty acid synthases, platensimycin (PTM) was discovered to act as a promising natural antibiotic against MRSA infections. In this study, PTM and its previously synthesized sulfur-Michael derivative PTM-2t could reduce over 95% biofilm formation by S. aureus ATCC 29213 when used at 2 μg/mL in vitro. Topical application of ointments containing PTM or PTM-2t (2 × 4 mg/day/mouse) was successfully used to treat MRSA infections in a BABL/c mouse burn wound model. As a potential prodrug lead, PTM-2t showed improved in vivo efficacy in a mouse peritonitis model compared with PTM. Our study suggests that PTM and its analogue may be used topically or locally to treat bacterial infections. In addition, the use of prodrug strategies might be instrumental to improve the poor pharmacokinetic properties of PTM.

Catechol cross-linked antimicrobial peptide hydrogels prevent multidrug-resistant Acinetobacter baumannii infection in burn wounds

Hospital-acquired infections are common in burn patients and are the major contributors of morbidity and mortality. Bacterial infections such as Staphylococcus aureus (S. aureus) and Acinetobacter baumannii (A. baumannii) are difficult to treat due to their biofilm formation and rapidly acquiring resistance to antibiotics. This work presents a newly developed hydrogel that has the potential for treating bacterial wound infections. The hydrogel formulation is based on an antimicrobial peptide (AMP), epsilon-poly-l-lysine (EPL) and catechol, which was cross-linked via mussel-inspired chemistry between the amine and phenol groups. In vitro studies showed that EPL-catechol hydrogels possess impressive antimicrobial and antibiofilm properties toward multidrug-resistant A. baumannii (MRAB). In addition, cytotoxicity study with the clonal mouse myoblast cell line (C2C12) revealed the good biocompatibility of this hydrogel. Furthermore, we created a second-degree burn wound on the mice dorsal skin surface followed by contamination with MRAB. Our results showed that the hydrogel significantly reduced the bacterial burden by more than four orders of magnitude in infected burn wounds. Additionally, there was no significant histological alteration with hydrogel application on mice skin. Based on these results, we concluded that EPL-catechol hydrogel is a promising future biomaterial to fight against multidrug-resistant bacterial infections.

Self-Assembly of Metallo-Nucleoside Hydrogels for Injectable Materials That Promote Wound Closure

Injectable hydrogels are increasingly being used as scaffolds for in situ tissue engineering and wound healing. Most of these injectable hydrogels are made from polymers, and there are fewer examples of such soft materials made via self-assembly of low-molecular weight gelators. We report the room-temperature synthesis of a functional hydrogel formed by mixing cytidine (C) with 0.5 equiv each of B(OH)₃ and AgNO₃. The structural basis for this supramolecular hydrogel (C-B-C·Ag⁺) involves orthogonal formation of cytidine borate diesters (C-B-C) and Ag⁺-stabilized C-C base pairs, namely, the C·Ag⁺·C dimer. The C-B-C·Ag⁺ hydrogels, which can have high water content (at least 99.6%), are stable (no degradation after 1 year in the light), stimuli-responsive, and self-supporting, with elastic moduli of up to 10⁴ Pa. Incorporation of Ag⁺ ions into the gel matrix endows the C-B-C·Ag⁺ hydrogel with significant antibacterial capability. Importantly, the rapid switching between the sol and gel states for this supramolecular hydrogel, as a response to shear stress, enables 3D printing of a flexible medical patch made from the C-B-C·Ag⁺ hydrogel. The C-B-C·Ag⁺ hydrogel was used to promote the closure of burn wounds in a mouse model.

Microbial profile of burn wound infections and their antibiotic sensitivity patterns at burn unit of allied hospital Faisalabad

Microbial infection is the most common and serious complication of burn injury, which is a major cause of morbidity and mortality. The aim of this study was to determine the bacteriological profiles and the antibiotic sensitivity patterns in burn unit of Allied Hospital Faisalabad over a period of 1 year. During the study period, 393 samples were collected and cultured by conventional method. Disk diffusion method was used to determine the sensitivity/resistance pattern of the isolates. Results were analyzed using SPPS version 20. Out of 393, 332 (84.5%) cases were found to be culture positive. Microbial contamination of the burn wounds was significantly (p<0.05) higher in males (89.3%) as compared to females (78.1%), and in 3rd degree burns (92.2%) as compared to 2nd degree burns (80.8%). Out of 393 patients, 258 (65.6%) cases were of Staphylococcus aurous followed by 169 (43.0%) of Pseudomonas aeruginosa 79 (20.1%) of Klebsiella pneumoniae and 67 (17.0%) of Escherichia coli. Among 258 cases of S. aurous, 153 (59.3%) were MRSA and 105 (40.7%) were MSSA. A large proportion (92.8%) of MRSA was sensitive to techoplanin and exhibited high-level resistant (96.7%) to fusidic acid whereas, significant proportion (74.4%) of MSSA isolates showed resistant to fusidic acid. A zero resistance was noted in coagulase negative staphylococci to linezolide, vancomycin and teichoplanin.. Pseudomonas aeruginosa exhibited high level resistance to tobramycin (91.7%) and were mostly sensitive (93.5%) to cefipiem. Klebsiella penumoniae was most sensitive to meropenem (100%) and most resistant to tobramycin (63.3%). E. coli showed zero resistance cefipiem and a small proportion of isolates (14.9%) exhibited resistance to tobramycin. In conclusion, S. aurous and P. aeruginosa represented the most common bacterial microbes of burn wounds which exhibited variable antibiotic susceptibility pattern. This study revealed a high potential for multiple microorganism outbreaks and emergence of resistant pathogens in burn patients due to the lack of patient screening and extended empirical use of antibiotics.

Assessment of biofilm formation among clinical isolates of Acinetobacter baumannii in burn wounds in the west of Iran

Burn wound infection by A. baumannii is one of the predominant cause of mortality worldwide. The present investigation aimed at determination of antimicrobial resistance profile and expression of the biofilm-related genes in A. baumannii isolated from hospitalized patients with burn wound infection in Kermanshah hospitals. Sixty four isolates of A. baumannii were recovered from burn wound of hospitalized patients at hospitals in Kermanshah. The antimicrobial susceptibility testing (AST) was performed. Biofilm formation was measured and antibiotic resistance was compared between before and after of biofilm formation. The polymerase chain reaction (PCR) and Real-Time PCR were performed to detect of abaI and pgaD genes. The biofilm producer isolates and the most resistant isolates were exposed to ozone gas .More than 70% strains were resistance to Erythromycin, Ofloxacin, Ceftazidime, Ceftriaxone, and Ticarcillin-clavulanic acid and 50% isolates were resistant to Imipenem. Thirty one (48.4%) isolates were biofilm producer. The pgaD and abaI genes were positive in 29 (45.3%) and 9 (14%) isolates, respectively. Real time PCR demonstrated that the copy numbers of the pgaD and abaI genes after biofilm formation were increased. After exposure to ozone, biofilm formation reduced in all very strong biofilm producing isolates. Our results showed that after biofilm formation, an increased resistance was observed in most isolates. Also rising expression of abaI gene was associated with biofilm formation and an increase of antibiotic resistance. In the current study, both biofilm formation and antibiotic resistance were reduced after O3 exposure.

Antifungal and antibacterial activity of densely dispersed silver nanospheres with homogeneity size which synthesized using chicory: An in vitro study

With increase in isolation of multi and extensive drug resistance hospital pathogens (MDR, XDR) in burn centers of many hospitals in the world, attempt to use nanomaterials for treatment of burn-infected patients is the focus of researches all around the world. In the present investigation silver nanospheres (Ag NSs) has been synthesized by chicory seed exudates (CSE). The various parameters influencing the mechanism of Ag NSs synthesis including temperature, concentration, pH and time were studied. Greener Ag NSs were formed when the reaction conditions were altered with respect to pH, concentration of AgNO3 and incubation temperature. Finally, we evaluated antimicrobial activity of silver nanospheres biosynthesized by chicory (Cichodrium intybus) against most prevalent burn bacteria pathogens Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, and fungus Fusarium solani. The UV visible spectroscopy, X-Ray diffraction (XRD), dynamic light scattering (DLS) used for primary screening of physicochemical properties. The transmission electron microscopy (TEM) images showed the Ag NSs (with globular shape) with a size less than 25nm that they have the same size about 8nm (more than 97% are 8nm). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Ag NSs against the standard strains of A. baumannii, P. aeruginosa and K. pneumonia showed a relatively high inhibitory and bactericidal activity (MIC 1.56μg/mL and MBC 3.12μg/mL) of the nanoparticles and F. solani cultures. In antifungal tests, the lowest level of zone of inhibition was observed at a concentration of 5μg/mL synthesized silver nanospheres with the 7% inhibition of growth. Ag NSs have high antimicrobial activity against three common burn bacteria pathogens and fungus F. solani. Therefore, Ag NSs can be used to prevent burn infection and for wound healing.