Recent Advances in Non-Conventional Antimicrobial Approaches for Chronic Wound Biofilms: Have We Found the 'Chink in the Armor'?

Post-vitrectomy endophthalmitis complicated with orbital cellulitis treated with hyperbaric oxygen therapy: A case report

RATIONALE

Infectious endophthalmitis developed in silicone oil (SO)-filled eyes after pars plana vitrectomy is a very rare but serious complication. Hyperbaric oxygen therapy (HBOT) has been reported to be effective in few studies of infectious endophthalmitis and orbital cellulitis.

PATIENT CONCERNS

This study reported a case of 71-year-old female with swelling of her left eye 1 week after pars plana vitrectomy and SO tamponade.

DIAGNOSES

Acute infectious endophthalmitis complicated with orbital cellulitis and compartment syndrome in a postvitrectomy SO-filled eye.

INTERVENTIONS

Intravitreal injection of antibiotics and HBOT.

OUTCOMES

The severe inflammatory condition of soft tissue with compartment syndrome and elevated intraocular pressure which could not be controlled ameliorated markedly after initiation of HBOT.

LESSONS

By taking advantages of the features of HBOT, it may be a good adjuvant treatment option for endophthalmitis cases along with antibiotics and surgical therapy.

Role of therapeutic treatment with antiseptic solutions in the care of diabetic foot ulcers

BACKGROUND

Diabetic foot ulcers (DFUs) are a prevalent and severe complication of diabetes, leading to significant morbidity, impaired health-related quality of life (HRQoL) and economic burden on healthcare systems. The complexity of DFUs often results in prolonged healing and high recurrence rates. Effective management strategies are crucial for improving outcomes and reducing complications.

AIM

This study aimed to review the efficacy of antiseptic solutions in the treatment and care of DFUs.

METHOD

A literature analysis was conducted to review clinical studies and guidelines on the use and efficacy of antiseptic solutions, particularly Octenisept® (0.1% octenidine dihydrochloride and 2% 2-phenoxyethanol). The review focused on the antimicrobial properties, biofilm-disruption capabilities and wound healing outcomes associated with the use of antiseptic solutions in DFU management.

RESULTS

Antiseptic solutions have potential to reduce bioburden, disrupt biofilm and modulate healing. There is a need to balance antimicrobial clinical efficacy with tolerability and cytotoxicity. The use and choice of adjunctive antiseptic solutions must be tailored to the patient, as antimicrobial efficacy can vary for antiseptic solutions, particularly for hypochlorous solutions. It is important to use products according to their instructions, with consideration of minimum contact time to maximise clinical efficacy. Low-pressure irrigation is adjunctive, and concurrent wound-bed preparation, including debridement, frequent inspection, infection and moisture control, remain important.

CONCLUSIONS

The therapeutic application of antiseptic solutions in DFU care presents a promising approach to enhancing wound healing and reducing infection risks. Integrating these solutions into standard wound care protocols could lower the incidence of complications, improve HRQoL and decrease the economic burden associated with diabetic foot disease. Further large-scale studies are recommended to validate these findings and refine guidelines for antiseptic use in DFU management.

Tissue-Adhesive and Antibacterial Hydrogel Promotes MDR Bacteria-Infected Diabetic Wound Healing via Disrupting Bacterial Biofilm, Scavenging ROS and Promoting Angiogenesis

Effective treatment of diabetic wounds remains challenging because of multidrug-resistant (MDR) bacterial infections, excessive oxidative stress, and impaired angiogenesis. In this study, a tissue-adhesive and antibacterial hydrogel incorporating MXene and deferoxamine (DFO)-loaded microspheres is developed for the treatment of MDR bacteria-infected diabetic wounds. The hydrogel is built based on covalent crosslinking between ε-poly(L-lysine) and o-phthalaldehyde-terminated four-arm poly(ethylene glycol). The hydrogel exhibited excellent mechanical properties, tissue adhesion strength, biocompatibility, and biodegradability. Under near-infrared (NIR) irradiation, the MXene converted light into heat and elevated the local temperature rapidly, enabling the rapid disintegration of MDR bacterial biofilms. Simultaneously, the hydrogel exerted inherent antibacterial activity, persistently killing planktonic bacteria, and effectively controlling wound infections. The encapsulated DFO is then released from the hydrogel in a sustained and controlled manner, and promoted angiogenesis during diabetic wound healing. Additionally, MXenes can scavenge excessive reactive oxygen species and alleviate wound inflammation. In the methicillin-resistant Staphylococcus aureus-infected diabetic wound model in mice, the composite hydrogel along with NIR irradiation efficiently reduced the infectious bacteria, and accelerated the wound healing by promoting angiogenesis and alleviating inflammation. This composite hydrogel has great clinical potential for the treatment of diabetic wounds, particularly in challenging healing environments involving motion and infection.

Comparative Genomic Analysis of 66 Bacteriophages Infecting Morganella morganii Strains

Bacteriophages are viruses that specifically target bacteria and play a crucial role in influencing bacterial evolution and the transmission of antibiotic resistance. In this study, we explored the genomic profiles of 66 bacteriophages that infect Morganella morganii, an opportunistic pathogen associated with difficult-to-treat nosocomial and urinary tract infections. Our findings highlight the extraordinary diversity within this phage population, reflected in their genomic features, evolutionary relationships, and potential contributions to bacterial pathogenicity. The 66 phage genomes exhibited diversity in size, spanning from 6 to 115 kilobase pairs, reflecting a heterogeneous genetic material and coding potential. Their guanine-cytosine (G+C) content varied widely, from 43.3% to 64.6%, suggesting diverse evolutionary origins and adaptive strategies. Phylogenetic analysis identified ten distinct evolutionary clusters, some classified as singletons, highlighting unique evolutionary pathways. Several clusters included phages capable of infecting multiple M. morganii strains, indicating a broader host range and the potential for horizontal gene transfer. Genomic analysis also determined a substantial number of hypothetical proteins, underscoring the need for further investigation to clarify their functions. Importantly, we identified a wide array of antibiotic resistance and virulence-associated genes within these phage genomes, illuminating their potential to impact the treatment of M. morganii infections and develop new, more virulent strains. These findings highlight the critical role of phage-mediated gene transfer in shaping bacterial evolution and facilitating the transmission of antibiotic resistance.

Evaluation of the antibacterial properties of four bioactive biomaterials for chronic wound management

AIM

Chronic wound infections present a prevalent medical issue and a multifaceted problem that significantly impacts healthcare systems worldwide. Biofilms formed by pathogenic bacteria are fundamental virulence factors implicated in the complexity and persistence of bacterial-associated wound infections, leading to prolonged recovery times and increased risk of infection. This study aims to investigate the antibacterial effectiveness of commonly employed bioactive wound healing compositions with a particular emphasis on their effectiveness against common bacterial pathogens encountered in chronic wounds - Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa to identify optimal wound product composition for managing chronic wound infections.

METHODS

This study tested the antibacterial and antibiofilm effectiveness of four bioactive wound healing materials by performing in vitro antibacterial assays and measuring ion release profiles.

RESULTS

The anti-biofilm effectiveness differed extensively among the biomaterials tested and slightly among the bacterial species. Particularly, copper and zinc-doped borate bioactive glass wound healing compositions inhibited the three clinically relevant bacteria in both planktonic and biofilm forms, which were found to be ascribed to the copper and zinc gradual release.

CONCLUSION

The findings suggest that copper and zinc-doped bioactive glasses hold great promise for improving chronic wound management by providing strong antibacterial action and promoting faster healing.

Evaluation of the Effects of Autologous Leukocyte- and Platelet-Rich Fibrin Membranes for Treating Chronic Wounds: A Prospective Study

(1) Background: The aim of this prospective study was to evaluate the efficacy of topical application of leukocyte- and platelet-rich fibrin (L-PRF) membranes for treating chronic cutaneous wounds in dogs. (2) Methods: Chronic wounds unresponsive to conventional treatments were assessed on digital photographs and classified using the Bates-Jensen Wound Assessment Tool (BWAT). Each lesion was treated with L-PRF membranes. Epithelialization, granulation tissue formation, wound healing rate, and contraction were statistically analyzed during follow-up. (3) Results: All but one of the cases were treated with a single application of L-PRF for a median of 30 days after onset. All wounds healed after a median of 22 days. The BWAT score, total wound area, and granulation tissue decreased significantly over time while wound contraction increased. The most significant reduction in the total wound area was observed within the first 3 weeks after treatment. None of the dogs required the administration of antibiotics. (4) Conclusions: L-PRF membrane promoted the wound healing process in dogs and is a valuable and cost-effective tool for treating chronic wounds, thereby reducing the need for antibiotics administration.

Advances in ionic liquid-based antimicrobial wound healing platforms

Wound infections, marked by the proliferation of microorganisms at surgical sites, necessitate the development of innovative wound dressings with potent bactericidal properties to curb microbial growth and prevent bacterial infiltration. This study explores the recent strides in utilizing ionic liquid-based polymers as highly promising antimicrobial agents for advanced wound healing applications. Specifically, cationic polymers containing quaternary ammonium, imidazolium, guanidinium, pyridinium, triazolium, or phosphonium groups have emerged as exceptionally effective antimicrobial compounds. Their mechanism of action involves disrupting bacterial membranes, thereby preventing the development of resistance and minimizing toxicity to mammalian cells. This comprehensive review not only elucidates the intricate dynamics of the skin's immune response and the various stages of wound healing but also delves into the synthesis methodologies of ionic liquid-based polymers. By spotlighting the practical applications of antimicrobial wound dressings, particularly those incorporating ionic liquid-based materials, this review aims to lay the groundwork for future research endeavors in this burgeoning field. Through a nuanced examination of these advancements, this article seeks to contribute to the ongoing progress in developing cutting-edge wound healing platforms that can effectively address the challenges posed by microbial infections in surgical wounds.

Distribution Patterns and Antibiotic Resistance Profiles of Bacterial Pathogens Among Patients with Wound Infections in the Jiaxing Region from 2021 to 2023

Purpose

To systematically assess the distribution and antimicrobial susceptibility of pathogens in wound infections, and analyze risk factors associated with multidrug resistance (MDR).

Patients and Methods

Retrospectively analyzing Jiaxing-region medical records between January 2021 and December 2023, we identified a cohort of 461 wound infection patients. Cultures were grown on various agars, with bacteria identified via Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry. The antimicrobial susceptibility of the organisms were conducted by VITEK 2 system, Kirby-Bauer disk diffusion method and Epsilometer test. Statistical Package for the Social Sciences (SPSS) version 22 was used for statistical analysis. Multivariable logistic regression models were developed to pinpoint risk factors for multidrug-resistant organism (MDRO) infections and predict occurrences.

Results

From 461 patients, 549 bacterial pathogens were isolated, predominantly consisting of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Enterobacter cloacae, and Enterococcus faecalis. Vancomycin, linezolid, and tigecycline maintained their efficacy against Staphylococcus aureus and Enterococcus species, while Pseudomonas aeruginosa demonstrated sensitivity to aminoglycosides. Conversely, Escherichia coli exhibited high amoxicillin resistance (85.4%). More than half of the isolates were resistant to levofloxacin, ceftriaxone, cotrimoxazole, and gentamicin, with Acinetobacter baumannii strains showing considerable resistance (65.8-68.4%) to advanced cephalosporins and carbapenems. Within this group, 58 MDROs were detected, primarily originating from Burn Plastic Surgery, Emergency, and Intensive Care Unit (ICU) departments. Multivariate logistic regression identified hyperglycemia, hypoalbuminemia, surgery, extended hospitalization, and exposure to multiple antibiotic classes as independent risk factors for MDRO wound infections. Based on these findings, a predictive model for MDRO occurrence in wounds was constructed, which had a sensitivity of 0.627, specificity of 0.933, and an Area Under the Curve (AUC) of 0.838.

Conclusion

Staphylococcus aureus and Pseudomonas aeruginosa dominated in wound infections with differential antibiotic resistance. Independent risk factors included hyperglycemia, hypoalbuminemia, surgery, extended hospitalization, and polyantibiotic use. We urge prioritizing culture, susceptibility tests, and personalized antibiotic strategies to address MDRO risks and improve wound infection management specificity and efficacy.

Nocardiopsis synnemataformans NBRM9, an extremophilic actinomycete producing extremozyme cellulase, using lignocellulosic agro-wastes and its biotechnological applications

Actinomycetes are an attractive source of lignocellulose-degrading enzymes. The search for actinomycetes producing extremozyme cellulase using cheap lignocellulosic waste remains a priority goal of enzyme research. In this context, the extremophilic actinomycete NBRM9 showed promising cellulolytic activity in solid and liquid assays. This actinomycete was identified as Nocardiopsis synnemataformans based on its phenotypic characteristics alongside phylogenetic analyses of 16S rRNA gene sequencing (OQ380604.1). Using bean straw as the best agro-waste, the production of cellulase from this strain was statistically optimized using a response surface methodology, with the maximum activity (13.20 U/mL) achieved at an incubation temperature of 40 °C, a pH of 9, an incubation time of 7 days, and a 2% substrate concentration. The partially purified cellulase (PPC) showed promising activity and stability over a wide range of temperatures (20-90 °C), pH values (3-11), and NaCl concentrations (1-19%), with optimal activity at 50 °C, pH 9.0, and 10% salinity. Under these conditions, the enzyme retained >95% of its activity, thus indicating its extremozyme nature. The kinetics of cellulase showed that it has a Vmax of 20.19 ± 1.88 U/mL and a Km of 0.25 ± 0.07 mM. The immobilized PPC had a relative activity of 69.58 ± 0.13%. In the in vitro microtiter assay, the PPC was found to have a concentration-dependent anti-biofilm activity (up to 85.15 ± 1.60%). Additionally, the fermentative conversion of the hydrolyzed bean straw by Saccharomyces cerevisiae (KM504287.1) amounted to 65.80 ± 0.52% of the theoretical ethanol yield. Overall, for the first time, the present work reports the production of extremozymatic (thermo, alkali-, and halo-stable) cellulase from N. synnemataformans NBRM9. Therefore, this strain is recommended for use as a biotool in many lignocellulosic-based applications operating under harsh conditions.

Oxygen Therapy to Enhance Wound Healing After Revascularization

Oxygen is one of the important factors for wound healing and infection control. The revascularization procedure is amended to correct the tissue hypoxia problem by increasing the blood flow to obtain an adequate amount of oxygen. Hypoxic wounds are still the issue in the cases of unsuccessful or incomplete revascularization. The issue needs to be clarified and confirmed by proper methods for management to achieve wound healing and prevent limb loss. Oxygen therapy may benefit in the case of remaining hypoxia or wound infection in postrevascularization.

The Effect of Mesenchymal Stem Cells on the Wound Infection

Wound infection often requires a long period of care and an onerous treatment process. Also, the rich environment makes the wound an ideal niche for microbial growth. Stable structures, like biofilm, and drug-resistant strains cause a delay in the healing process, which has become one of the important challenges in wound treatment. Many studies have focused on alternative methods to deal the wound infections. One of the novel and highly potential ways is mesenchymal stromal cells (MSCs). MSCs are mesoderm-derived pluripotent adult stem cells with the capacity for self-renewal, multidirectional differentiation, and immunological control. Also, MSCs have anti-inflammatory and antiapoptotic effects. MScs, as pluripotent stromal cells, differentiate into many mature cells. Also, MSCs produce antimicrobial compounds, such as antimicrobial peptides (AMP), as well as secrete immune modulators, which are two basic features considered in wound healing. Despite the advantages, preserving the structure and activity of MSCs is considered one of the most important points in the treatment. MSCs' antimicrobial effects on microorganisms involved in wound infection have been confirmed in various studies. In this review, we aimed to discuss the antimicrobial and therapeutic applications of MSCs in the infected wound healing processes.

Postbiotic as Novel Alternative Agent or Adjuvant for the Common Antibiotic Utilized in the Food Industry

BACKGROUND

Antibiotic resistance is a serious public health problem as it causes previously manageable diseases to become deadly infections that can cause serious disability or even death. Scientists are creating novel approaches and procedures that are essential for the treatment of infections and limiting the improper use of antibiotics in an effort to counter this rising risk.

OBJECTIVES

With a focus on the numerous postbiotic metabolites formed from the beneficial gut microorganisms, their potential antimicrobial actions, and recent associated advancements in the food and medical areas, this review presents an overview of the emerging ways to prevent antibiotic resistance.

RESULTS

Presently, scientific literature confirms that plant-derived antimicrobials, RNA therapy, fecal microbiota transplantation, vaccines, nanoantibiotics, haemofiltration, predatory bacteria, immunotherapeutics, quorum-sensing inhibitors, phage therapies, and probiotics can be considered natural and efficient antibiotic alternative candidates. The investigations on appropriate probiotic strains have led to the characterization of specific metabolic byproducts of probiotics named postbiotics. Based on preclinical and clinical studies, postbiotics with their unique characteristics in terms of clinical (safe origin, without the potential spread of antibiotic resistance genes, unique and multiple antimicrobial action mechanisms), technological (stability and feasibility of largescale production), and economic (low production costs) aspects can be used as a novel alternative agent or adjuvant for the common antibiotics utilized in the production of animal-based foods.

CONCLUSION

Postbiotic constituents may be a new approach for utilization in the pharmaceutical and food sectors for developing therapeutic treatments. Further metabolomics investigations are required to describe novel postbiotics and clinical trials are also required to define the sufficient dose and optimum administration frequency of postbiotics.

Phytochemical analysis of Brugmansia suaveolens Bercht. & J. Presl and its therapeutic potential for topical use

Brugmansia suaveolens Bercht. & J. Presl represents a promising source of new active molecules. Therefore, the aim of the study is to outline the profile of secondary metabolites and their therapeutic potential and in vitro safety properties. The identification of substances was carried out through the chromatographic profile, while the evaluation of therapeutic use was conducted through in vitro biological assays of antioxidant and antimicrobial activity and quantification of the total phenolic content. The safety of the extracts was evaluated using a cytotoxicity assay. The results found revealed the presence of different secondary metabolites, such as flavonoids and alkaloids. Biological assays showed promising antimicrobial activity in gram-negative strains. Regarding safety, greater cytotoxicity is observed in macrophage cells. The study demonstrated that the extracts are potent for therapeutic use, aiming at the development of a phytoproduct for topical use, providing an innovative, relevant and significant character for future research.

Microbial Biofilms: Applications, Clinical Consequences, and Alternative Therapies

Biofilms are complex communities of microorganisms that grow on surfaces and are embedded in a matrix of extracellular polymeric substances. These are prevalent in various natural and man-made environments, ranging from industrial settings to medical devices, where they can have both positive and negative impacts. This review explores the diverse applications of microbial biofilms, their clinical consequences, and alternative therapies targeting these resilient structures. We have discussed beneficial applications of microbial biofilms, including their role in wastewater treatment, bioremediation, food industries, agriculture, and biotechnology. Additionally, we have highlighted the mechanisms of biofilm formation and clinical consequences of biofilms in the context of human health. We have also focused on the association of biofilms with antibiotic resistance, chronic infections, and medical device-related infections. To overcome these challenges, alternative therapeutic strategies are explored. The review examines the potential of various antimicrobial agents, such as antimicrobial peptides, quorum-sensing inhibitors, phytoextracts, and nanoparticles, in targeting biofilms. Furthermore, we highlight the future directions for research in this area and the potential of phytotherapy for the prevention and treatment of biofilm-related infections in clinical settings.

Defensins of Lucilia sericata Larvae and Their Influence on Wound Repair Processes in Practical Assessment-A Study of Three Cases

Bacteria inhabiting chronic wounds form a biofilm that prolongs and slows down the healing process. Increasingly common antibiotic resistance requires clinicians to search for effective and alternative treatment methods. Defensins are the most common antimicrobial peptides capable of eradicating pathogens. Their discovery in maggot secretions allowed for a broader understanding of the healing mechanisms, and approving the use of Lucilia sericata fly larvae in the treatment of infected wounds resulted in an effective and safe procedure. The aim of the study was to present the possibility of biofilm elimination in a chronic wound by means of medical maggots (Lucilia sericata) with the example of three selected clinical cases. The observation included three women who met the inclusion criterion of having venous insufficiency ulcers with inhibited regeneration processes. Medical maggots were applied in a biobag for three days, and observation was conducted for 21 consecutive days. In 2 cases, a significant elimination of necrotic tissue from the wound bed with local granulation tissue was observed 72 h after application of a larvae colony on the wounds. In 1 case, the application of the larvae accelerated the repair process by reducing the wound area by approximately 40% at the time of observation. The formation of biofilm in a chronic wound is one of the main causes of disturbances in its effective healing. Combining procedures (scraping, antiseptic compresses, MDT, NPWT) related to wound debridement increases the effectiveness of biofilm elimination. The use of medical maggots is a safe and effective method of choice, and it enhances the processes of debridement. However, confirmed indisputable data on their effectiveness and frequency of use in the process of stimulating healing processes are still not available in the literature.

Evaluation of the Simultaneous Effects of Lactobacillus delbrueckii and Lactobacillus lactis on Biofilms of Isolates from Chronic Ulcer Infections with Multiple-drug Resistance

Background: Bacterial biofilm is a major barrier to chronic wound healing. Therefore, the prevention of biofilm formation has an effective role in accelerating the healing of these wounds. Today, probiotics' anti-biofilm and antibacterial activity have been proven, and bacteriotherapy by probiotics is a new strategy for treating chronic ulcer infections. Objectives: The present study aimed to investigate the synergistic effects of Lactobacillus delbrueckii and L. lactis on biofilms of bacterial agents isolated from these ulcers in the human plasma biofilm model (hpBIOM). Methods: This study examined 82 specimens of chronic ulcer biofilms and identified bacterial isolates using phenotypic and molecular methods. After preparing the hpBIOM, 50 µL of each probiotic (109 CFU/mL) was added in two doses separately and simultaneously. After 24 hours, 1 mL of bromelain (0.1 g/mL) was added to the complex and incubated at 37°C for two hours. Then, the surviving bacterial cells were counted by serial dilutions. Results: Among 119 bacterial isolates, Staphylococcus aureus (19%), Escherichia coli (17.0%), and Pseudomonas aeruginosa (14%) were the most common bacterial isolates. Lactobacillus delbrueckii showed anti-biofilm activity against multiple-drug resistance pathogens, Staphylococcus, P. aeruginosa, and K. pneumoniae. Although L. lactis had anti-biofilm activity against these three pathogens, its effect was less than that of L. delbrueckii. The two probiotics did not have any synergistic effect on the biofilms of the isolates. Conclusions: The results of the present study emphasized the potential of probiotics in destroying biofilms of isolates with multiple-drug resistance; however, their simultaneous use for this purpose requires further investigation.

The Impact of Antiseptic-Loaded Bacterial Nanocellulose on Different Biofilms-An Effective Treatment for Chronic Wounds?

Introduction: Pathogenic biofilms are an important factor for impaired wound healing, subsequently leading to chronic wounds. Nonsurgical treatment of chronic wound infections is limited to the use of conventional systemic antibiotics and antiseptics. Wound dressings based on bacterial nanocellulose (BNC) are considered a promising approach as an effective carrier for antiseptics. The aim of the present study was to investigate the antimicrobial activity of antiseptic-loaded BNC against in vitro biofilms. Materials and Methods: BNC was loaded with the commercially available antiseptics Prontosan^® and Octenisept^®. The silver-based dressing Aquacel^®Ag Extra was used as a positive control. The biofilm efficacy of the loaded BNC sheets was tested against an in vitro 24-hour biofilm of Staphylococcus aureus and Candida albicans and a 48-hour biofilm of Pseudomonas aeruginosa. In vivo tests using a porcine excisional wound model was used to analyze the effect of a prolonged treatment with the antiseptics on the healing process. Results: We observed complete eradication of S. aureus biofilm in BNC loaded with Octenisept^® and C. albicans biofilm for BNC loaded with Octenisept^® or Prontosan^®. Treatment with unloaded BNC also resulted in a statistically significant reduction in bacterial cell density of S. aureus compared to untreated biofilm. No difference on the wound healing outcome was observed for the wounds treated for seven days using BNC alone in comparison to BNC combined with Prontosan^® or with Octenisept^®. Conclusions: Based on these results, antiseptic-loaded BNC represents a promising and effective approach for the treatment of biofilms. Additionally, the prolonged exposure to the antiseptics does not affect the healing outcome. Prevention and treatment of chronic wound infections may be feasible with this novel approach and may even be superior to existing modalities.

Soluble chitosan derivative treats wound infections and promotes wound healing in a novel MRSA-infected porcine partial-thickness burn wound model

Burns are physically debilitating and potentially fatal injuries. The most common etiology of burn wound infections in the US is methicillin-resistant Staphylococcus aureus (MRSA), which is particularly recalcitrant when biofilms form. The current standard of care, silver sulfadiazine (SSD) is effective in reducing bacterial load, but less effective in improving burn wound healing. New treatments that can manage infection while simultaneously improving healing would provide a benefit in the treatment of burns. Porcine models are frequently used as a model for human wound healing but can be expensive due to the need to separate wounds to avoid cross contamination. The porcine model developed in this study offers the capability to study multiple partial thickness burn wound (PTBW) sites on a single animal with minimal crosstalk to study wound healing, infection, and inflammation. The current study evaluates a wound rinse and a wound gel formulated with a non-toxic, polycationic chitosan derivative that is hypothesized to manage infection while also promoting healing, providing a potential alternate to SSD. Studies in vitro and in this PTBW porcine model compare treatment with the chitosan derivative formulations to SSD. The wound rinse and wound gel are observed to disrupt mature MRSA biofilms in vitro and reduce the MRSA load in vivo when compared to that of the standard of care. In vivo data further show increased re-epithelialization and faster healing in burns treated with wound rinse/gel as compared to SSD. Taken together, the data demonstrate the potential of the wound rinse/gel to significantly enhance healing, promote re-epithelialization, and reduce bacterial burden in infected PTBW using an economical porcine model.

Multidrug-Resistant Biofilm, Quorum Sensing, Quorum Quenching, and Antibacterial Activities of Indole Derivatives as Potential Eradication Approaches

Challenges encountered in relapse of illness caused by resistance of microorganisms to antimicrobial agents (drugs) are due to factors of severe stress initiated by random use of antibiotics and insufficient beneficial approaches. These challenges have resulted to multiple drug resistance (MDR) and, subsequently, biofilm formation. A type of intercellular communication signal called quorum sensing (QS) has been studied to cause the spread of resistance, thereby enabling a formation of stable community for microorganisms. The QS could be inhibited using QS inhibitors (QSIs) called quorum-quenching (QQ). The QQ is an antibiofilm agent. Indole derivatives from plant sources can serve as quorum-quenching eradication approach for biofilm, as well as a promising nontoxic antibiofilm agent. In other words, phytochemicals in plants help to control and prevent biofilm formation. It could be recommended that combination strategies of these indoles' derivatives with antibiotics would yield enhanced results.

Pharmacokinetic control on the release of antimicrobial drugs from pH-responsive electrospun wound dressings

The acidic pH of healthy skin changes during wound healing due to the exposure of the inner dermal and subcutaneous tissue and due to the potential colonization of pathogenic bacteria. In chronic non-healing wounds, the pH values vary in a wide pH range but the appearance of an alkaline shift is common. After a wound is incurred, neutral pH in the wound bed is characteristic of the activation of the cascade of regenerative and remodeling processes. In order to adjust drug release to the specific pH of the wound, herein, drug-loaded wound dressings having pH-responsiveness containing antiseptics and antibiotics and exerting different release kinetics in order to have a perfect match between the drug release kinetics, and the pH conditions of each wound type, were developed. We have fabricated drug-loaded electrospun nanofibers loaded with the antiseptic chlorhexidine, with the broad-spectrum antibiotic rifampicin, and with the antimicrobial of natural origin thymol, using the pH-dependent methacrylic acid copolymer Eudragit® L100-55, which dissolves at pH > 5.5; those drugs were loaded within Eudragit® S100, which dissolves at pH > 7 and, finally, within the methacrylic ester copolymer Eudragit® RS100 which is pH independent and slowly erodes and releases its contained cargo. The antibacterial action of those advanced wound dressings has been evaluated against methicillin-sensitive S. aureus Newman strain expressing the coral green fluorescent protein (cGFP), as a model of a Gram-positive bacteria, and against E. coli S17 strain as a model of a Gram-negative bacteria. It was demonstrated that those combinational products integrate in one device the required characteristics for a wound dressing with the therapeutic action of a contained active principle and can be selected depending on the wound acidic or alkaline status for its appropriated management.

Dynamic Role of Oxygen in Wound Healing: A Microbial, Immunological, and Biochemical Perspective

A wound is a temporary break in the continuity of the protective skin barrier. Wound healing is central in maintaining the body's normal homeostatic mechanism, and open wounds raise the risk of microbial infection and amputation. A successful wound healing event is achieved through a series of evolutionarily conserved biochemical pathways orchestrated by various cytokines, growth factors, and immune cells. Chronic wounds are generally oxygen-deficient, and wound hypoxia impairs the wound healing process. Therefore, the use of external oxygen may improve wound health by reducing wound hypoxia, promoting tissue regeneration and granulation tissue formation, reducing anaerobic bacteria colonization, and promoting the growth of beneficial aerobic bacteria. Relevant data were searched and gathered from scientific databases, including PubMed, ScienceDirect, and Google Scholar using relevant keywords, such as "Chronic Wounds", "Topical Oxygen Therapy", "Inflammatory Markers/ Lactate/ Matrix Metalloproteinase", "Collagen", and "Wound Healing". Relevant articles were shortlisted and used in the present study. Chronic wounds show higher expression of pro-inflammatory mediators, such as C-reactive protein, and higher levels of tissue-degrading matrix metalloproteinases. In addition, chronic wounds are generally oxygen-deficient, and wound hypoxia is directly associated with wound deterioration. Several microbial, immunological, and biochemical markers show a direct association with the oxygen availability in the wound. Therefore, a detailed understanding of these microbial, immunological, and biochemical markers will certainly help clinicians understand the interplay between various factors and topical oxygen therapy and may improve patient outcomes.

Effect of the most common wound antiseptics on human skin fibroblasts

Background

Antiseptics are used for the cleansing of acute or chronic wounds to eliminate micro‐organisms from the wound bed. However, they have effects on the skin cells.

Aim

To determine the effects of hexetidine, povidone–iodine (PI), undecylenamidopropyl‐betaine/polyhexanide (UBP), chlorhexidine, disodium eosin and hydrogen peroxide on human skin fibroblasts.

Methods

CCD‐1064Sk cells were treated with hexetidine, PI, UBP, chlorhexidine, disodium eosin or hydrogen peroxide. Spectrophotometry was used to measure cell viability and flow cytometry was used to study apoptosis and necrosis after the treatment. In vitro wound scratch assays were performed to determine the gap closure.

Results

All antiseptics significantly reduced the viability of human skin fibroblasts compared with controls. The percentage wound closure was lower with hexetidine, PI and UBP. The scratch assay could not be measured after treatments with chlorhexidine, disodium eosin or hydrogen peroxide, owing to their cytotoxicity. The apoptosis/necrosis experiments evidenced a significant reduction in viable cells compared with controls. An increased percentage of apoptotic cells was observed after treatment with all antiseptics. Compared with controls, the percentage of necrotic cells was significantly increased with all antiseptics except for hexetidine.

Conclusion

The proliferation, migration and viability of human skin fibroblasts are reduced by treatment with hexetidine, PI, UBP, chlorhexidine, disodium eosin and hydrogen peroxide.

An Overview on the Recent Advances in the Treatment of Infected Wounds: Antibacterial Wound Dressings

A wound can be surgical, cuts from an operation or due to accident and trauma. The infected wound, as a result of bacteria growth within the damaged skin, interrupts the natural wound healing process and significantly impacts the quality of life. Wound dressing is an important segment of the skincare industry with its economic burden estimated at $ 20.4 billion (in 2021) in the global market. The results of recent clinical trials suggest that the use of modern dressings can be the easiest, most accessible, and most cost-effective way to treat chronic wounds and, hence, holds significant promise. With the sheer number of dressings in the market, the selection of correct dressing is confusing for clinicians and healthcare workers. The aim of this research was to review widely used types of antibacterial wound dressings, as well as emerging products, for their efficiency and mode of action. In this review, we focus on introducing antibiotics and antibacterial nanoparticles as two important and clinically widely used categories of antibacterial agents. The perspectives and challenges for paving the way for future research in this field are also discussed. This article is protected by copyright. All rights reserved.

Efficacy of antimicrobial peptide LL-37 against biofilm forming Staphylococcus aureus strains obtained from chronic wound infections

The antimicrobial peptide LL-37 showed inhibitory effects against Staphylococcus aureus strains, which often responsible for wound infections. Understanding the molecular mechanisms of biofilm-containing wound infections is important. Thus, this study aimed to investigate both the antimicrobial and biofilm efficacy of LL-37 against biofilm-positive methicillin-susceptible S. aureus (MSSA) strains and biofilm-positive methicillin-resistant S. aureus (MRSA) strains obtained from chronic wound infections and its effect on different quorum sensing and virulence genes at suboptimal concentrations. Fifteen biofilm-forming MRSA and 15 biofilm-forming MSSA strains were included in this study. The minimum inhibitory concentration (MIC) values and biofilm formation were tested by microdilution methods. Real-time PCR was performed to determine gene expression levels. MIC values for LL-37 were 89.6 mg/L and 132.3 mg/L for MSSA and MRSA strains, respectively. No statistically significant difference was found between MRSA and MSSA strains in terms of the effect of LL-37 on biofilm formation. A statistically significant difference was found between MRSA and MSSA strains for atlA, RNAIII, and agrA gene expression levels following exposure to a suboptimal concentration of LL-37. Ultimately, the required LL-37 antimicrobial concentration was quite high; however, LL-37 antibiofilm concentration may be acceptable for use in humans against biofilm-forming MRSA and MSSA strains. This is the first study to investigate to effect of a suboptimal LL-37 concentration on gene expression levels of biofilm-forming MSSA and MRSA strains. LL-37 affected quorum sensing and biofilm producing mechanisms, even at suboptimal MIC concentrations.

Antimicrobial and Regenerative Effects of Placental Multipotent Mesenchymal Stromal Cell Secretome-Based Chitosan Gel on Infected Burns in Rats

Background: There is a need for better strategies to promote burn wound healing and prevent infection. The aim of our study was to develop an easy-to-use placental multipotent mesenchymal stromal cell (MMSC) secretome-based chitosan hydrogel (MSC-Ch-gel) and estimate its antimicrobial and regenerative activity in Staphylococcus aureus-infected burn wounds in rats. Methods: Proteomic studies of the MMSC secretome revealed proteins involved in regeneration, angiogenesis, and defence responses. The MMSC secretome was collected from cultured cells and mixed with water-soluble chitosan to prepare the placental MSC-Ch-gel, which was stored in liquid phase at 4 °C. The wounds of rats with established II-IIIa-degree burns were then infected with S. aureus and externally covered with the MSC-Ch-gel. Three additional rat groups were treated with medical Vaseline oil, the antiseptic drug Miramistin®, or the drug Bepanthen® Plus. Skin wound samples were collected 4 and 8 days after burning for further microbiological and histological analysis. Blood samples were also collected for biochemical analysis. Results: Application of the MSC-Ch-gel cleared the wound of microorganisms (S. aureus wasn’t detected in the washings from the burned areas), decreased inflammation, enhanced re-epithelialisation, and promoted the formation of well-vascularised granulation tissue. Conclusions: MSC-Ch-gel effectively promotes infected wound healing in rats with third-degree burns. Gel preparation can be easily implemented into clinical practice.

Evaluation of the anti-biofilm activities of bacterial cellulose-tannic acid-magnesium chloride composites using an in vitro multispecies biofilm model

Chronic wounds are a serious worldwide problem, which are often accompanied by wound infections. In this study, bacterial cellulose (BC)-based composites introduced with tannic acid (TA) and magnesium chloride (BC-TA-Mg) were fabricated for anti-biofilm activities. The prepared composites' surface properties, mechanical capacity, thermal stability, water absorption and retention property, releasing behavior, anti-biofilm activities and potential cytotoxicity were tested. Results showed that TA and MgCl2 particles closely adhered to the nanofibers of BC membranes, thus increasing surface roughness and hydrophobicity of the membranes. While the introduction of TA and MgCl2 did not influence the transparency of the membranes, making it beneficial for wound inspection. BC-TA and BC-TA-Mg composites displayed increased tensile strength and elongation at break compared to pure BC. Moreover, BC-TA-Mg exhibited higher water absorption and retention capacity than BC and BC-TA, suitable for the absorption of wound exudates. BC-TA-Mg demonstrated controlled release of TA and good inhibitory effect on both singly cultured Staphylococcus aureus and Pseudomonas aeruginosa biofilm and co-cultured biofilm of S. aureus and P. aeruginosa. Furthermore, the cytotoxicity grade of BC-TA-6Mg membrane was eligible based on standard toxicity classifications. These indicated that BC-TA-Mg is potential to be used as wound dressings combating biofilms in chronic wounds.

Bacterial Cellulose: Functional Modification and Wound Healing Applications

Significance: Wound dressings are frequently used for wound covering and healing. Ideal wound dressings should provide a moist environment for wounds and actively promote wound healing and skin recovery. The materials used as ideal wound dressings should possess specific properties, thus accelerating skin tissue regeneration process. Recent Advances: Bacterial cellulose (BC) is a natural polymer synthesized by some bacteria. As a kind of natural biopolymer, BC shows good biological activity, biodegradability, and biological adaptability. It has many unique physical, chemical, and biological properties, such as ultrafine nanofiber network, high crystallinity, high water absorption and retention capacity, and high tensile strength and elastic modulus. These excellent properties of BC have laid the foundation for its application as dressing in wound healing. Critical Issues: To optimize the biocompatibility and antimicrobial activity of BC, different methods including microbial fermentation, physical modification, chemical modification, and compound modification have been adopted to modify BC to ensure a better application in wound healing. BC-based wound dressings have been applied in infected wounds, acute traumatic injuries, burns, and diabetic wounds, showing remarkable therapeutic effects on promoting wound healing. Furthermore, there have been some commercial BC-based dressings and they have been utilized in clinical practice. Future Directions: Because of its excellent physicochemical characteristics and biological properties, BC shows high clinical value to be used as a wound dressing for skin tissue regeneration.

Effects of Probiotics in the Management of Infected Chronic Wounds: From Cell Culture to Human Studies

BACKGROUND

Chronic wounds are commonly associated with polymicrobial biofilm infections. In the last years, the extensive use of antibiotics has generated several antibiotic-resistant variants. To overcome this issue, alternative natural treatments have been proposed, including the use of microorganisms like probiotics. The aim of this manuscript was to review current literature concerning the application of probiotics for the treatment of infected chronic wounds.

METHODS

Relevant articles were searched in the Medline database using PubMed and Scholar, using the keywords "probiotics" and "wound" and "injuries", "probiotics" and "wound" and "ulcer", "biofilm" and "probiotics" and "wound", "biofilm" and "ulcer" and "probiotics", "biofilm" and "ulcer" and "probiotics", "probiotics" and "wound".

RESULTS

The research initially included 253 articles. After removal of duplicate studies, and selection according to specific inclusion and exclusion criteria, 19 research articles were included and reviewed, accounting for 12 in vitro, 8 in vivo studies and 2 human studies (three articles dealing with animal experiments included also in vitro testing). Most of the published studies about the effects of probiotics for the treatment of infected chronic wounds reported a partial inhibition of microbial growth, biofilm formation and quorum sensing.

DISCUSSION

The application of probiotics represents an intriguing option in the treatment of infected chronic wounds with multidrug-resistant bacteria; however, current results are difficult to compare due to the heterogeneity in methodology, laboratory techniques, and applied clinical protocols. Lactobacillus plantarum currently represents the most studied strain, showing a positive application in burns compared to guideline treatments, and an additional mean in chronic wound infections.

CONCLUSIONS

Although preliminary evidence supports the use of specific strains of probiotics in certain clinical settings such as infected chronic wounds, large, long-term clinical trials are still lacking, and further research is needed.

Assessment of Antibiofilm Potencies of Nervonic and Oleic Acid against Acinetobacter baumannii Using In Vitro and Computational Approaches

Acinetobacter baumannii is a nosocomial pathogen, and its biofilms are tolerant to desiccation, nutrient starvation, and antimicrobial treatment on biotic and abiotic surfaces, tissues, and medical devices. Biofilm formation by A. baumannii is triggered by a quorum sensing cascade, and we hypothesized that fatty acids might inhibit its biofilm formation by interfering with quorum sensing. Initially, we investigated the antibiofilm activities of 24 fatty acids against A. baumannii ATCC 17978 and two clinical isolates. Among these fatty acids, two unsaturated fatty acids, nervonic and oleic acid, at 20 μg/mL significantly inhibited A. baumannii biofilm formation without affecting its planktonic cell growth (MICs were >500 μg/mL) and markedly decreased the motility of A. baumannii but had no toxic effect on the nematode Caenorhabditis elegans. Interestingly, molecular dynamic simulations showed that both fatty acids bind to the quorum sensing acyl homoserine lactone synthase (AbaI), and decent conformational stabilities of interactions between the fatty acids and AbaI were exhibited. Our results demonstrate that nervonic and oleic acid inhibit biofilm formation by A. baumannii strains and may be used as lead molecules for the control of persistent A. baumannii infections.

A General Overview on the Hyperbaric Oxygen Therapy: Applications, Mechanisms and Translational Opportunities

Hyperbaric oxygen therapy (HBOT) consists of using of pure oxygen at increased pressure (in general, 2-3 atmospheres) leading to augmented oxygen levels in the blood (Hyperoxemia) and tissue (Hyperoxia). The increased pressure and oxygen bioavailability might be related to a plethora of applications, particularly in hypoxic regions, also exerting antimicrobial, immunomodulatory and angiogenic properties, among others. In this review, we will discuss in detail the physiological relevance of oxygen and the therapeutical basis of HBOT, collecting current indications and underlying mechanisms. Furthermore, potential areas of research will also be examined, including inflammatory and systemic maladies, COVID-19 and cancer. Finally, the adverse effects and contraindications associated with this therapy and future directions of research will be considered. Overall, we encourage further research in this field to extend the possible uses of this procedure. The inclusion of HBOT in future clinical research could be an additional support in the clinical management of multiple pathologies.

The sensitivity of planktonic cultures and biofilms of gram-negative bacteria to commercial disinfectant and antiseptic preparations

The in vitro antibacterial activity of 11 commercial disinfectant preparations and 8 antiseptics against 10 strains of the bacteria Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloaceae and Providencia stuartii obtained from international collections and isolated from neuroresuscitation patients in Moscow in 2018 was studied. The sensitivity of planktonic cultures to the preparations was determined by the method of serial dilutions in broth and the spot method on solid nutrient media, the sensitivity of biofilms by the applicator method. A general pattern was revealed: the level of sensitivity to tested disinfectants in clinical strains was lower than in reference strains. It was found that the disinfectants «Mikrobak-Forte», «SAT-22», «Neobak-Oksi» at the concentrations recommended by the manufacturers were effective against bacteria of all test strains, both in the plankton state and in the form of biofilms. On the contrary, the disinfectant preparations «Biodez-Optima», «Biodez-Extra DVU», «Novodez-Aktiv», «Triosept-Oksi», «Tristel Fusion for Surfaces», «Effect-Forte Plus», «Lactic-Oxy» did not have sufficient effectiveness in the concentrations recommended by the manufacturers, therefore it is proposed to use these drugs in higher concentrations. It was found that the disinfectant «Biodez-Extra DVU» is able to inhibit the growth of biofilms of bacteria of the species K. pneumoniae. The ability to suppress the growth of bacterial biofilms of K. pneumoniae, A. baumannii, P. aeruginosa was revealed for the «Triestel Fusion for surfaces disinfectant». The bacteria of all used test strains in the planktonic state were sensitive to all tested antiseptic preparations. However, the biofilms of the clinical strains of P. aeruginosa and P. stuartii. possessed resistance to the antiseptics «Octenidol», «Octenisept», «Miramistin», «Hexoral». Our studies indicate the need for sensitivity analysis of antibacterial drugs in representatives of hospital pathogens, including the modeling of bacterial biofilms, which is a very relevant and important scientific direction, necessary to improve the control of nosocomial infections in the Russian Federation.

Microfluidic Tools for Enhanced Characterization of Therapeutic Stem Cells and Prediction of Their Potential Antimicrobial Secretome

Antibiotic resistance is creating enormous attention on the development of new antibiotic-free therapy strategies for bacterial diseases. Mesenchymal stromal stem cells (MSCs) are the most promising candidates in current clinical trials and included in several cell-therapy protocols. Together with the well-known immunomodulatory and regenerative potential of the MSC secretome, these cells have shown direct and indirect anti-bacterial effects. However, the low reproducibility and standardization of MSCs from different sources are the current limitations prior to the purification of cell-free secreted antimicrobial peptides and exosomes. In order to improve MSC characterization, novel label-free functional tests, evaluating the biophysical properties of the cells, will be advantageous for their cell profiling, population sorting, and quality control. We discuss the potential of emerging microfluidic technologies providing new insights into density, shape, and size of live cells, starting from heterogeneous or 3D cultured samples. The prospective application of these technologies to studying MSC populations may contribute to developing new biopharmaceutical strategies with a view to naturally overcoming bacterial defense mechanisms.

Update on the role of antiseptics in the management of chronic wounds with critical colonisation and/or biofilm

Biofilms play a major role in delaying chronic wounds from healing. A wound infiltrated with biofilm, or "critically colonised" wound, may become clinically infected if the number of microbes exceeds a critical level. Chronic wound biofilms represent a significant treatment challenge by demonstrating recalcitrance towards antimicrobial agents. However, a "window of opportunity" may exist after wound debridement when biofilms are more susceptible to topical antiseptics. Here, we discuss the role of antiseptics in the management of chronic wounds and biofilm, focusing on povidone-iodine (PVP-I) in comparison with two commonly used antiseptics: polyhexanide (PHMB) and silver. This article is based on the literature reviewed during a focus group meeting on antiseptics in wound care and biofilm management, and on a PubMed search conducted in March 2020. Compared with PHMB and silver, PVP-I has a broader spectrum of antimicrobial activity, potent antibiofilm efficacy, no acquired bacterial resistance or cross-resistance, low cytotoxicity, good tolerability, and an ability to promote wound healing. PVP-I represents a viable therapeutic option in wound care and biofilm management, with the potential to treat biofilm-infiltrated, critically colonised wounds. We propose a practical algorithm to guide the management of chronic, non-healing wounds due to critical colonisation or biofilm, using PVP-I.

Application of probiotics in candidiasis management

Candidiasis (e.g., oral, gastrointestinal, vaginal, urinary tract, systemic) is a worldwide growing problem, since antifungal resistance and immunosuppression states are rising. To address this problem, very few drugs are available for the treatment of Candida spp. infections. Therefore, novel therapeutic strategies are urgently required. Probiotics have been proposed for the prevention and treatment of bacterial infections due to their safety record and efficacy, however, little is still known about their potential role regarding fungal infections. The purpose of this review is to present an updated summary of the evidence of the antifungal effects of probiotics along with a discussion of their potential use as an alternative/complementary therapy against Candida spp. infections. Thus, we performed a literature search using appropriate keywords ("Probiotic + Candida", "Candidiasis treatment", and "Probiotic + candidiasis") to retrieve relevant studies (both preclinical and clinical) with special emphasis on the works published in the last 5 years. An increasing amount of evidence has shown the potential usefulness of probiotics in the management of oral and vulvovaginal candidiasis in recent years. Among other results, we found that, as for bacterial infections, Lactobacillus, Bifidobacterium, and Saccharomyces are the most studied and effective genus for this purpose. However, in other areas, particularly in skincandidiaisis, studies are low or lacking. Thus, further investigation is necessary including in vitro and in vivo studies to establish the usefulness of probiotics in the management of candidiasis.

Intelligent Nanoparticle-Based Dressings for Bacterial Wound Infections

Conventional wound dressing materials containing free antibiotics for bacterial wound infections are presented with several limitations, that is, lack of controlled and triggered release capabilities, and may often not be adequate to address the complex bacteria microenvironment of such infections. Additionally, the improper usage of antibiotics may also result in the emergence of drug resistant strains. While delivery systems (i.e., nanoparticles) that encapsulate antibiotics may potentially overcome some of these limitations, their therapeutic outcomes are still less than desirable. For example, premature drug release or unintended drug activation may occur, which would greatly reduce treatment efficacy. To address this, responsive nanoparticle-based antimicrobial therapies could be a promising strategy. Such nanoparticles can be functionalized to react to a single stimulus or multi stimulus within the bacteria microenvironment and subsequently elicit a therapeutic response. Such "intelligent" nanoparticles can be designed to respond to the microenvironment, that is, an acidic pH, the presence of specific enzymes, bacterial toxins, etc. or to an external stimulus, for example, light, thermal, etc. These responsive nanoparticles can be further incorporated into wound dressings to better promote wound healing. This review summarizes and highlights the recent progress on such intelligent nanoparticle-based dressings as potential wound dressings for bacteria-infected wounds, along with the current challenges and prospects for these technologies to be successfully translated into the clinic.

Wound Repair and Extremely Low Frequency-Electromagnetic Field: Insight from In Vitro Study and Potential Clinical Application

Wound healing is a complex, staged process. It involves extensive communication between the different cellular constituents of various compartments of the skin and its extracellular matrix (ECM). Different signaling pathways are determined by a mutual influence on each other, resulting in a dynamic and complex crosstalk. It consists of various dynamic processes including a series of overlapping phases: hemostasis, inflammation response, new tissue formation, and tissue remodeling. Interruption or deregulation of one or more of these phases may lead to non-healing (chronic) wounds. The most important factor among local and systemic exogenous factors leading to a chronic wound is infection with a biofilm presence. In the last few years, an increasing number of reports have evaluated the effects of extremely low frequency (ELF) electromagnetic fields (EMFs) on tissue repair. Each experimental result comes from a single element of this complex process. An interaction between ELF-EMFs and healing has shown to effectively modulate inflammation, protease matrix rearrangement, neo-angiogenesis, senescence, stem-cell proliferation, and epithelialization. These effects are strictly related to the time of exposure, waveform, frequency, and amplitude. In this review, we focus on the effect of ELF-EMFs on different wound healing phases.

Bacterial disinfection and cell assessment post ultraviolet-C LED exposure for wound treatment

Ultraviolet-C sourced LED (UVC-LED) has been widely used for disinfection purposes due to its germicidal spectrum. In this study, the efficiencies of UVC-LED for Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) disinfections were investigated at three exposure distances (1, 1.5, and 2 cm) and two exposure times (30 and 60 s). The respective bacterial inhibition zones were measured, followed by a morphological analysis under SEM. The viabilities of human skin fibroblast cells were further evaluated under the treatment of UVC-LED with the adoption of aforesaid exposure parameters. The inhibition zones were increased with the increment of exposure distances and times. The highest records of 5.40 ± 0.10 cm P. aeruginosa inhibition and 5.43 ± 0.11 cm S. aureus inhibition were observed at the UVC-LED distance of 2 cm and 60-s exposure. Bacterial physical damage with debris formation and reduction in size were visualized following the UVC-LED exposures. The cell viability percentages were in a range of 75.20-99.00% and 82-100.00% for the 30- and 60-s exposures, respectively. Thus, UVC-LED with 275-nm wavelength is capable in providing bacterial disinfection while maintaining accountable cell viability which is suitable to be adopted in wound treatment. Bacterial disinfection and human skin fibroblast cell assessment using UVC-LED.

In Vitro Efficacy of Bacterial Cellulose Dressings Chemisorbed with Antiseptics against Biofilm Formed by Pathogens Isolated from Chronic Wounds

Local administration of antiseptics is required to prevent and fight against biofilm-based infections of chronic wounds. One of the methods used for delivering antiseptics to infected wounds is the application of dressings chemisorbed with antimicrobials. Dressings made of bacterial cellulose (BC) display several features, making them suitable for such a purpose. This work aimed to compare the activity of commonly used antiseptic molecules: octenidine, polyhexanide, povidone-iodine, chlorhexidine, ethacridine lactate, and hypochlorous solutions and to evaluate their usefulness as active substances of BC dressings against 48 bacterial strains (8 species) and 6 yeast strains (1 species). A silver dressing was applied as a control material of proven antimicrobial activity. The methodology applied included the assessment of minimal inhibitory concentrations (MIC) and minimal biofilm eradication concentration (MBEC), the modified disc-diffusion method, and the modified antibiofilm dressing activity measurement (A.D.A.M.) method. While in 96-well plate-based methods (MIC and MBEC assessment), the highest antimicrobial activity was recorded for chlorhexidine, in the modified disc-diffusion method and in the modified A.D.A.M test, povidone-iodine performed the best. In an in vitro setting simulating chronic wound conditions, BC dressings chemisorbed with polyhexanide, octenidine, or povidone-iodine displayed a similar or even higher antibiofilm activity than the control dressing containing silver molecules. If translated into clinical conditions, the obtained results suggest high applicability of BC dressings chemisorbed with antiseptics to eradicate biofilm from chronic wounds.

Antimicrobial properties of olive oil phenolic compounds and their regenerative capacity towards fibroblast cells

Some micronutrients of vegetable origin are considered potentially useful as wound-healing agents because they can increase fibroblast proliferation and differentiation.

THE AIM OF THIS STUDY

was to evaluate the regenerative effects of selected olive oil phenolic compounds on cultured human fibroblasts and explore their antimicrobial properties.

MATERIAL AND METHODS

The CCD-1064Sk fibroblast line was treated for 24 h with 10^-6M luteolin, apigenin, ferulic, coumaric acid or caffeic acid, evaluating the effects on cell proliferation by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) spectrophotometric assay; the migratory capacity by the scratch assay and determining the expression of Fibroblast Growth Factor (FGF), Vascular Endothelial Growth Factor (VEGF), Transforming Growth Factor- β1 (TGFβ1), Platelet Derived Growth Factor (PDGF), and Collagen Type I (COL-I) genes by real-time polymerase chain reaction. The antimicrobial capacity of the polyphenols was evaluated by the disc diffusion method.

RESULTS

All compounds except for ferulic acid significantly stimulated the proliferative capacity of fibroblasts, increasing their migration and their expression of the aforementioned genes. With respect to their antimicrobial properties, treatment with the studied compounds inhibited the growth of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Proteus spp., and Candida Albicans.

CONCLUSIONS

The phenolic compounds in olive oil have a biostimulatory effect on the regeneration capacity, differentiation, and migration of fibroblasts and exert major antibacterial activity. According to the present findings, these compounds may have a strong therapeutic effect on wound recovery.

Liposomes-in-chitosan hydrogel boosts potential of chlorhexidine in biofilm eradication in vitro

Successful treatment of skin infections requires eradication of biofilms found in up to 90 % of all chronic wounds, causing delayed healing and increased morbidity. We hypothesized that chitosan hydrogel boosts the activity of liposomally-associated membrane active antimicrobials (MAA) and could potentially improve bacterial and biofilm eradication. Therefore, liposomes (∼300 nm) bearing chlorhexidine (CHX; ∼50 μg/mg lipid) as a model MAA were incorporated into chitosan hydrogel. The novel CHX-liposomes-in-hydrogel formulation was optimized for skin therapy. It significantly inhibited the production of nitric oxide (NO) in lipopolysaccharide (LPS)-induced macrophage and almost completely reduced biofilm formation. Moreover, it reduced Staphylococcus aureus and Pseudomonas aeruginosa adherent bacterial cells in biofilm by 64.2-98.1 %. Chitosan hydrogel boosted the anti-inflammatory and antimicrobial properties of CHX.

Ex situ model of biofilm-associated wounds: providing a host-like environment for the study of Staphylococcus aureus and Pseudomonas aeruginosa biofilms

AIM

This study aimed to assess an ex situ model of biofilm-associated wounds on porcine skin for the study of Staphylococcus aureus and Pseudomonas aeruginosa biofilms in a host-like environment, after 48 to 120 h of incubation.

MATERIAL AND RESULTS

Ex situ and in vitro biofilms were comparatively analysed. Overall, CFU-counts and matrix quantification yielded significantly (P < 0·05) higher results for ex situ than in vitro biofilms. Confocal microscopy revealed greater (P < 0·05) biomass and thickness at 48-72 h and greater (P < 0·05) robustness at 72 h of growth. S. aureus ex situ biofilms produced less (P < 0·05) siderophore and proteases than in vitro biofilms, while P. aeruginosa ex situ biofilms produced more (P < 0·05) siderophores and less proteases than in vitro biofilms.

CONCLUSIONS

Biofilms grown ex situ present a greater amount of bacterial cells and polymeric matrix than their in vitro counterparts, reaching maturity at 72 h of growth. Moreover the production of virulence factors differs between ex situ and in vitro biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings emphasize the importance of using ex situ biofilm models, once they mimic in vivo conditions. The use of these models brings perspectives for the pursuit of therapeutic alternatives, as tests may be performed in a host-like environment.

Interplay between ESKAPE Pathogens and Immunity in Skin Infections: An Overview of the Major Determinants of Virulence and Antibiotic Resistance

The skin is the largest organ in the human body, acting as a physical and immunological barrier against pathogenic microorganisms. The cutaneous lesions constitute a gateway for microbial contamination that can lead to chronic wounds and other invasive infections. Chronic wounds are considered as serious public health problems due the related social, psychological and economic consequences. The group of bacteria known as ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter sp.) are among the most prevalent bacteria in cutaneous infections. These pathogens have a high level of incidence in hospital environments and several strains present phenotypes of multidrug resistance. In this review, we discuss some important aspects of skin immunology and the involvement of ESKAPE in wound infections. First, we introduce some fundamental aspects of skin physiology and immunology related to cutaneous infections. Following this, the major virulence factors involved in colonization and tissue damage are highlighted, as well as the most frequently detected antimicrobial resistance genes. ESKAPE pathogens express several virulence determinants that overcome the skin's physical and immunological barriers, enabling them to cause severe wound infections. The high ability these bacteria to acquire resistance is alarming, particularly in the hospital settings where immunocompromised individuals are exposed to these pathogens. Knowledge about the virulence and resistance markers of these species is important in order to develop new strategies to detect and treat their associated infections.

In Vitro Evaluation of Polihexanide, Octenidine and NaClO/HClO-Based Antiseptics against Biofilm Formed by Wound Pathogens

Chronic wounds complicated with biofilm formed by pathogens remain one of the most significant challenges of contemporary medicine. The application of topical antiseptic solutions against wound biofilm has been gaining increasing interest among clinical practitioners and scientific researchers. This paper compares the activity of polyhexanide-, octenidine- and hypochlorite/hypochlorous acid-based antiseptics against biofilm formed by clinical strains of Candida albicans, Staphylococcus aureus and Pseudomonas aeruginosa. The analyses included both standard techniques utilizing polystyrene plates and self-designed biocellulose-based models in which a biofilm formed by pathogens was formed on an elastic, fibrinous surface covered with a fibroblast layer. The obtained results show high antibiofilm activity of polihexanide- and octenidine-based antiseptics and lack or weak antibiofilm activity of hypochlorite-based antiseptic of total chlorine content equal to 80 parts per million. The data presented in this paper indicate that polihexanide- or octenidine-based antiseptics are highly useful in the treatment of biofilm, while hypochlorite-based antiseptics with low chlorine content may be applied for wound rinsing but not when specific antibiofilm activity is required.

Small Molecule Inhibitors of the Bacterioferritin (BfrB)-Ferredoxin (Bfd) Complex Kill Biofilm-Embedded Pseudomonas aeruginosa Cells

Bacteria depend on a well-regulated iron homeostasis to survive adverse environments. A key component of the iron homeostasis machinery is the compartmentalization of Fe3+ in bacterioferritin and its subsequent mobilization as Fe2+ to satisfy metabolic requirements. In Pseudomonas aeruginosa Fe3+ is compartmentalized in bacterioferritin (BfrB), and its mobilization to the cytosol requires binding of a ferredoxin (Bfd) to reduce the stored Fe3+ and release the soluble Fe2+. Blocking the BfrB-Bfd complex in P. aeruginosa by deletion of the bfd gene triggers an irreversible accumulation of Fe3+ in BfrB, concomitant cytosolic iron deficiency and significant impairment of biofilm development. Herein we report that small molecules developed to bind BfrB at the Bfd binding site block the BfrB-Bfd complex, inhibit the mobilization of iron from BfrB in P. aeruginosa cells, elicit a bacteriostatic effect on planktonic cells, and are bactericidal to cells embedded in mature biofilms.

Evidence-Based Review of Antibiofilm Agents for Wound Care

Significance: Biofilms in vivo are small densely packed aggregations of microbes that are highly resistant to host immune responses and treatment. They attach to each other and to nearby surfaces. Biofilms are difficult to study and identify in a clinical setting as their quantification necessitates the use of advanced microscopy techniques such as confocal laser scanning microscopy. Nonetheless, it is likely that biofilms contribute to the pathophysiology of chronic skin wounds. Reducing, removing, or preventing biofilms is thus a logical approach to help clinicians heal chronic wounds. Recent Advances: Wound care products have demonstrated varying degrees of efficacy in destroying biofilms in in vitro and preclinical models, as well as in some clinical studies. Critical Issues: Controlled studies exploring the beneficial role of biofilm eradication and its relationship to healing in patients with chronic wounds are limited. This review aims to discuss the mode of action and clinical significance of currently available antibiofilm products, including surfactants, dressings, and others, with a focus on levels of evidence for efficacy in disrupting biofilms and ability to improve wound healing outcomes. Future Directions: Few available products have good evidence to support antibiofilm activity and wound healing benefits. Novel therapeutic strategies are on the horizon. More high-quality clinical studies are needed. The development of noninvasive techniques to quantify biofilms will facilitate increased ease of research about biofilms in wounds and how to combat them.

Antibiotics in Food Chain: The Consequences for Antibiotic Resistance

Antibiotics have been used as essential therapeutics for nearly 100 years and, increasingly, as a preventive agent in the agricultural and animal industry. Continuous use and misuse of antibiotics have provoked the development of antibiotic resistant bacteria that progressively increased mortality from multidrug-resistant bacterial infections, thereby posing a tremendous threat to public health. The goal of our review is to advance the understanding of mechanisms of dissemination and the development of antibiotic resistance genes in the context of nutrition and related clinical, agricultural, veterinary, and environmental settings. We conclude with an overview of alternative strategies, including probiotics, essential oils, vaccines, and antibodies, as primary or adjunct preventive antimicrobial measures or therapies against multidrug-resistant bacterial infections. The solution for antibiotic resistance will require comprehensive and incessant efforts of policymakers in agriculture along with the development of alternative therapeutics by experts in diverse fields of microbiology, biochemistry, clinical research, genetic, and computational engineering.

Antibacterial activity of human mesenchymal stem cells mediated directly by constitutively secreted factors and indirectly by activation of innate immune effector cells

Mesenchymal stem cells (MSC) have been shown to improve wound healing and suppress inflammatory immune responses. Newer research also indicates that MSC exhibit antimicrobial activity, although the mechanisms underlying this activity have not been fully elucidated. Therefore, we conducted in vitro and in vivo studies to examine the ability of resting and activated MSC to kill bacteria, including multidrug resistant strains. We investigated direct bacterial killing mechanisms and the interaction of MSC with host innate immune responses to infection. In addition, the activity of MSC against chronic bacterial infections was investigated in a mouse biofilm infection model. We found that MSC exhibited high levels of spontaneous direct bactericidal activity in vitro. Moreover, soluble factors secreted by MSC inhibited Staphylococcus aureus biofilm formation in vitro and disrupted the growth of established biofilms. Secreted factors from MSC also elicited synergistic killing of drug-resistant bacteria when combined with several major classes of antibiotics. Other studies demonstrated interactions of activated MSC with host innate immune responses, including triggering of neutrophil extracellular trap formation and increased phagocytosis of bacteria. Finally, activated MSC administered systemically to mice with established S. aureus biofilm infections significantly reduced bacterial numbers at the wound site and improved wound healing when combined with antibiotic therapy. These results indicate that MSC generate multiple direct and indirect, immunologically mediated antimicrobial activities that combine to help eliminate chronic bacterial infections when the cells are administered therapeutically.

Antibiotic Delivery Strategies to Treat Skin Infections When Innate Antimicrobial Defense Fails

The epidermal skin barrier protects the body from a host of daily challenges, providing protection against mechanical insults and the absorption of chemicals and xenobiotics. In addition to the physical barrier, the epidermis also presents an innate defense against microbial overgrowth. This is achieved through the presence of a diverse collection of microorganisms on the skin (the "microbiota") that maintain a delicate balance with the host and play a significant role in overall human health. When the skin is wounded, the local tissue with a compromised barrier can become colonized and ultimately infected if bacterial growth overcomes the host response. Wound infections present an immense burden in healthcare costs and decreased quality of life for patients, and treatment becomes increasingly important because of the negative impact that infection has on slowing the rate of wound healing. In this review, we discuss specific challenges of treating wound infections and the advances in drug delivery platforms and formulations that are under development to improve topical delivery of antimicrobial treatments.