Bacterial Wound Infection Research Articles

Construction of organic compatible kaolinite antibacterial material via a dry process and its enhanced antibacterial activity

In today’s world of antibiotic abuse and bacterial resistance, it is urgent to propose a non-antibiotic solution against bacterial wound infections. Hence, the present work prepared kaolinite (KAO)-based organic antibacterial material (CA/KAO) modified with chlorhexidine acetate (CA) via a dry process. And the potential of CA/KAO in the doping preparation of antibacterial wound dressings was evaluated with poly(vinyl alcohol) (PVA) as an organic matrix. The results demonstrated that a synergistic promotion system between CA and kaolinite was formed. Kaolinite optimized the thermal stability of CA and controlled it to achieve a demand-oriented release mode of “burst + slow” release. CA was mainly attached to the surface of kaolinite by hydrogen bonding to impart its antibacterial properties and enhanced organic compatibility. For Staphylococcus aureus (S. aureus), which is prone to induce wound infections, CA/KAO showed a low-level MIC of 11.72 mg/L and achieved a 98.37% antibacterial rate by contact inactivation and released CA sterilization. CA/KAO was homogeneously dispersed in PVA film and achieved inhibition zones of 15.393 mm and 12.663 mm against S. aureus and Escherichia coli (E. coli), respectively, at 30 wt% doping. It is expected that CA/KAO would be an option for the mass production of antibacterial wound dressings.

Poly(aspartic acid)-based self-healing hydrogel with precise antibacterial ability for rapid infected-wound repairing

The development of wound dressings with antibacterial activities and simultaneous pro-healing functions are always urgent in treating bacterial wound infection. Herein, a novel multifunctional self-healing hydrogel was designed and prepared by crosslinking quaternary ammonium/boronic acid modified poly(aspartic acid) and poly (vinyl alcohol) polymers with targeted peptide MP196- conjugated polydopamine. The formation of this hydrogel not only improves the biocompatibility of quaternary poly(aspartic acid), but also enhances antibacterial efficacy by pH-triggering dissociation under the low pH bacterial microenvironment. Moreover, precise photothermal treatment can be achieved. In vitro study suggested high synergistic antibacterial efficiency(∼100 %) under near-infrared light, significantly higher than a single antibacterial strategy (66.0–82.6 %). In vivo study suggested infected wounds treated with the hydrogel showed an optimal healing rate(92.0 %) after 7 days. The survival rate of the bacteria in the epidermal tissues was reduced to 2.3 %. Besides, the suitable self-healing property of this hydrogel facilitated its application in the diversity of wound shapes. Thus, the novel poly(aspartic acid) hydrogel might be a promising candidate for precise therapy of bacteria-infected wounds.

Self-Assembled Corrole/Chitosan Photothermal Nanoparticles for Accelerating Infected Diabetic Wound Healing.

Microvascular dysfunction caused by hyperglycemia leads to slow healing of diabetic wounds and significantly increases the risk of bacterial infection. The misuse of antibiotics can also lead to bacterial resistance, making the management of diabetic wounds more challenging. Thus, developing new antibacterial agents or strategies to overcome antibiotic resistance is highly pursued. Herein, novel supramolecular photothermal nanoparticles (MCC/CS NPs), assembled from mono-carboxyl corrole (MCC) and chitosan via hydrogen bonding and π-π stacking, are developed and used for treating bacterial wound infection. The MCC molecules possess good photothermal performance and the chitosan with inherent bioactivity can exert moderate antibacterial effects. The aggregation of MCC in MCC/CS NPs induced by chitosan-templated self-assembly further quenches molecular fluorescence and realizes an extraordinary photothermal conversion efficiency of 66.4%. Moreover, the highly positively charged MCC/CS NPs can selectively target bacteria via electrostatic interactions. Under near-infrared laser irradiation, the MCC/CS NPs achieve potent photothermal and inherent antimicrobial synergistic effects against Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) in vitro. Furthermore, the bacteria-infected diabetic wound model confirms that the MCC/CS NPs can effectively kill drug-resistant bacteria, accelerate wound healing and angiogenesis, and show good biocompatibility, representing a novel and efficient photothermal antibacterial nanoplatform.

Antibacterial activity of chitosan-polyethylene oxide nanofibers containing silver nanoparticles against aerobic and anaerobic bacteria

Bacterial wound infection is one of the foremost prevalent nosocomial infections. The overuse of antibiotics leads to the growing proliferation of antibiotic-resistant microorganisms, a specialty challenging to establish in anaerobic infections and even more so in mixed anaerobic-aerobic disorders. Consequently, alternate munitions are urgently needed to expedite wound healing and bactericidal impacts. Considering this, we determined the properties of antibacterial nanofibers (NFs) generated from electrospun chitosan/polyethylene oxide nanofibers (CS-PEO NFs) integrated with 1% (w/w) silver nanoparticles (SNPs). SNPs were efficiently produced via chemical reduction synthesis and confirmed by color changing to light brown during sonication. SNPs had no discernible influence on the morphology of CS-PEO NFs. Surface Plasmon resonance (SPR) investigated SNPs' size. This technique analyzed that increasing the sonication time to 30 min results in SNP formation with the proper size (4 nm). Following these procedures, the nanofibers' characteristics were assessed using physical and mechanical parameters, viscosity, Field Emission-Scanning Electron Microscopy (FESEM), and Fourier transform-infrared spectroscopy (FT-IR). Transmission electron microscopy (TEM) micrographs demonstrated that SNPs produced in chitosan had adequate dispersion.Moreover, in vitro SNP release and encapsulation efficiency were measured, showing a rapid release of up to 36% in the first two hours, and also the effect of CS-PEO NFs and CS-PEO/SNP NFs on the survival of human dermal fibroblast (HDF) and a normal fibroblast cell line (L929) were investigated by MTT colorimetric assay demonstrated the biocompatibility of cells with CS-PEO/SNP NFs. The nanofibers' antibacterial properties were compared to evaluate the antibacterial effects of SNPs in the form of CS-PEO/SNP NFs against aerobic and anaerobic bacteria. Antibacterial effect against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus was measured as aerobic microorganisms. Although a significant activity against Pseudomonas aeruginosa was observed, it was effective lesser against E. coli and Staphylococcus aureus. Pseudomonas aeruginosa also had an antibacterial impact against anaerobic bacteria such as Streptococcus mutans, Streptococcus sobrinus, and Streptococcus sanguis. CS-PEO/SNP NFs are smashing candidates for wound healing and mixed aerobic-anaerobic infections due to their natural origin and favorable results.

Novel Amoxicillin-Loaded Sericin Biopolymeric Nanoparticles: Synthesis, Optimization, Antibacterial and Wound Healing Activities.

Infected wounds are a major threat among diabetic patients. Technological advancements are currently increasing the number of new adjunctive therapies that may be potent agents for speeding recovery, lowering the amputation rate and limiting infection recurrences. A novel formula with promising antibacterial activity, namely sericin/propolis/Amoxicillin nanoparticles, was assessed as a potent treatment of infected wounds in normal and diabetic rats. Skin wound healing efficiency was assessed through wound healing scorings, bacterial load assessment and histological examinations. It was revealed that upon using sericin/propolis/Amoxicillin nanoparticles, complete wound healing was successfully achieved after 10 and 15 days postinjury for nondiabetic and diabetic rats, respectively. However, the bacterial load in the induced infected wounds was extremely low (0–10 CFU/mL) after 15 days post-treatment. The histological studies revealed that the dermis was more organized with new matrix deposition, and mature collagen fibers were observed among the treated animal groups. The present study is the first preclinical study which reported the importance of silk sericin in the form of nano-sericin/propolis loaded with Amoxicillin as an effective treatment against bacterial wound infections.

Germanene-modified chitosan hydrogel for treating bacterial wound infection: An ingenious hydrogel-assisted photothermal therapy strategy

The elaborate design of an ingenious hydrogel-assisted photothermal therapy (PTT) platform is a promising strategy for treating bacterial wound infections. Herein, a new generation of germanene nanocrystals (Ge NCs) with excellent photothermal performance are prepared via an ice-bath sonication liquid-phase exfoliation technique. Whereafter, by crosslinking interaction between chitosan and zinc acetate, as well as self-assembly property between Ge NCs and chitosan, we successfully construct an innovative germanene-modified chitosan antimicrobial hydrogel (CS/Ge NCs0.8) integrating capture and killing bacteria performances. When co-cultured with bacteria, CS/Ge NCs0.8 hydrogel with the positive charge can adsorb and restrict bacteria in the range of PTT destruction. Once the near-infrared laser is introduced, CS/Ge NCs0.8 hydrogel will effectively convert light energy into localized heat, further inducing bacterial death. By this entirely novel modality, CS/Ge NCs0.8 hydrogel exhibits marvelous antibacterial property against E. coli and S. aureus in vitro. Furthermore, in vivo studies demonstrate that CS/Ge NCs0.8 hydrogel possesses the ability to significantly rescue S. aureus-induced skin wound infections, suggesting CS/Ge NCs0.8 hydrogel can be served as an antibacterial dressing. Strikingly, this is the first-ever report of CS/Ge NCs0.8 hydrogel in the antibacterial field, which may spur a wave of developing Ge-based biomaterials to benefit biomedical applications.

A core–shell 2D-MoS2@MOF heterostructure for rapid therapy of bacteria-infected wounds by enhanced photocatalysis

As the increasing antibiotics resistance of bacteria, pathogenic bacterial infections aggravate the skin wounds and prevent it from healing and even induce serious complications. Here, we constructed a core–shell interface electric field at the interface between Prussian blue (PB) metal organic framework (MOF) and two-dimensional MoS2 nanosheets by in-situ growth of MoS2 on the surface of MOF (MoS2@PBMOF), which drove the transfer of photo-excited electrons and promoted the separation of photoinduced electron-hole pairs. Additionally, the lower O2 adsorption energy of MoS2@PBMOF endowed the heterostructure with much stronger O2 adsorption ability than MoS2 alone, which provided more oxygen species to capture the photogenerated electrons and holes and thus produced more radical oxygen species (ROS). Meanwhile, the excellent photothermal property of the composite could regulate the release of iron ions from MoS2@PBMOF under light irradiation by hyperpyrexia. Hence, under 660 nm visible illumination for 20 min, the MoS2@PBMOF killed 99.73 % S. aureus and 99.58 % E. coli, which attributed to the synergy of local hyperthermia, abundant ROS, and released iron ions through bacterial membrane damage, protein leakage, and the oxidation of glutathione. Importantly, this composite could promote the healing of damaged tissues with good biosafety by promoting the production of hemoglobin. This work provides new insight into the practical application of promising strategy for environmental disinfection and treating bacterial wound infections without using antibiotics.

H2O2-activated in situ polymerization of aniline derivative in hydrogel for real-time monitoring and inhibition of wound bacterial infection

Wound is highly susceptible to bacterial infection, which can cause chronic wound and serial complications. However, timely treatment is hampered by the lack of real-time monitoring of wound status and effective therapeutic systems. Herein, in situ biosynthesis of functional conjugated polymer in artificial hydrogel was developed via the utilization of biological microenvironment to realize monitoring in real time of wound infection and inhibition of bacteria for the first time. Specially, an easily polymerizable aniline dimer derivative (N-(3-sulfopropyl) p-aminodiphenylamine, SPA) was artfully in situ polymerized into polySPA (PSPA) in calcium alginate hydrogel, which was initiated via the catalysis of hydrogen peroxide (H2O2) overexpressed in infected wound to produce hydroxyl radical (•OH) by preloaded horseradish peroxidase (HRP). Benefitting from outstanding near infrared (NIR) absorption of PSPA, such polymerization can be ingeniously used for real-time monitoring of H2O2 via naked-eye and photoacoustic signal, as well as NIR light-mediated photothermal inhibition of bacteria. Furthermore, combining the persistent chemodynamic activity of •OH, the in vivo experimental data proved that the wound healing rate was 99.03% on the 11th day after treatment. Therefore, the present work opens the way to manipulate in situ biosynthesis of functional conjugated polymer in artificial hydrogels for overcoming the issues on wound theranostics.

Antibacterial Polyacrylamide and Dextran-Graft-Polyacrylamide Hydrogels for the Treatment of Open Wounds

Background. Open wound treatment requires a use of bandage material to prevent the development of pathogenic microflora and to provide the necessary conditions for tissue regeneration.
 The aim of the study was to compare the effectiveness of polyacrylamide (PAA) and dextran-graft-polyacrylamide (D-PAA) hydrogels loaded with silver nanoparticles (AgNPs), antibiotics, and photosensitizers for the treatment of bacterial infection of open wounds.
 Materials and Methods. PAA and D-PAA hydrogels with AgNPs, methylene blue (0.001%) without (MB) and with red light irradiation (660 nm) (MB+L), chlorhexidine (0.05%) and cefuroxime (0.1%) were used. There were tested in vitro and in vivo (a rat model) antibacterial activities against wild-type Staphylococcus aureus, Escherichia coli, antibiotic-resistant Escherichia coli and Klebsiella pneumoniae strains obtained from the wound. Clinical investigations were performed in patients with chronic venous ulcers of the lower extremities with no response to traditional treatments.
 Results. S. aureus, E. coli, and K. pneumoniae strains were sensitive to PAA and D-PAA hydrogels with AgNPs, chlorhexidine, and cefuroxime. Antibiotic-resistant E. coli was not inhibited by the hydrogels with cefuroxime. This strain was less sensitive to chlorhexidine and MB+L. There were no differences between unloaded PAA and D-PAA hydrogels; the antibacterial properties of the dressing were determined by an antibacterial component loaded into the hydrogel. The use of unloaded D-PAA hydrogels in vivo helped reduce the size of the wound by 28.6% and 42.8% three and five days after wound modeling, respectively. Similar results were obtained for D-PAA hydrogels loaded with cefuroxime, chlorhexidine, and MB+L. D-PAA hydrogel with AgNPs reduced wound size by 50% and 62.5% three and five days after wound induction, respectively, demonstrated greater antibacterial activity and was selected for clinical investigations. In a patient, 14 days after bandage application, the fibrin membrane disappeared, the ulcers were covered with pink granulations, marginal epithelialization appeared.
 Conclusions. PAA and D-PAA hydrogels can be loaded with the antibacterial compounds of various types. The type of polymer does not affect the antibacterial properties of the final hydrogels. The hydrogels with chlorhexidine and MB+L can be potentially used to treat bacterial contamination of wounds and ulcers. Nevertheless, their disadvantage is the inability to absorb or precipitate tissue breakdown products that interfere with normal regeneration and inflammation. D-PAA/AgNPs are the best option for treating ulcers due to the ability to control the properties of the hydrogels and nanoparticles, as well as multiple mechanisms of antibacterial action.

Antibacterial Mechanism of Action of Two Types of Honey against Escherichia coli through Interfering with Bacterial Membrane Permeability, Inhibiting Proteins, and Inducing Bacterial DNA Damage.

Honey is a sweet natural food produced by bees from flower nectar or some part of plant secretions that exhibit antimicrobial activity against many microorganisms. It has been used as traditional therapy for skin infections. Antibiotics play an essential role in managing wound infection; however, some pathogenic bacteria have begun to possess resistance against them, which may cause chronic infections and severe adverse effects. This study investigates the antibacterial activities and mechanism of action of Yemeni Sidr honey (SH) and Manuka honey (MH) against Escherichia coli. The inhibitory effects of SH and MH using the disk diffusion method on bacterial growth were remarkable at 700 mg/disk. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were similar for both kinds of honey. However, MH showed a better bactericidal effect (30%) than SH (50%). The antimicrobial mechanism of action showed that SH substantially impacted the bacterial membrane’s permeability and increased the potassium and protein leakage rate. On the contrary, MH demonstrated remarkable inhibition of bacterial protein synthesis, while both kinds of honey caused bacterial DNA damage. These data reveal that SH and MH could be used as a remedy for skin infections and might be further developed as a promising dressing for bacterial wound infections.

Colistimethate sodium-chitosan hydrogel for treating Gram-negative bacterial wound infections

The drug resistance is higher among Gram-negative bacteria and demands the usage of strong antibiotics which can in turn result in systemic toxicity. In the treatment of the chronic wounds harboring pathogenic Gram-negative bacteria, the demand for an antimicrobial product that can be topically administered has been on the rise. In an effort to address the above issue, we have developed Colistimethate sodium (a high-end antibiotic) loaded chitosan hydrogel and characterized. The prepared hydrogel is very stable and observed to be bio- and hemo-compatible in nature. The antibacterial activity of the prepared hydrogel was studied against both ATCC (American Type Culture Collection) strains and clinical isolates of Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae. The CMS incorporated hydrogel is also capable of inhibiting the biofilm formation. The developed hydrogel can be potentially being used for the treatment of Gram-negative bacterial infected wounds.

Copper Doped Carbon Dots for Addressing Bacterial Biofilm Formation, Wound Infection, and Tooth Staining.

Oral infectious diseases and tooth staining, the main challenges of dental healthcare, are inextricably linked to microbial colonization and the formation of pathogenic biofilms. However, dentistry has so far still lacked simple, safe, and universal prophylactic options and therapy. Here, we report copper-doped carbon dots (Cu-CDs) that display enhanced catalytic (catalase-like, peroxidase-like) activity in the oral environment for inhibiting initial bacteria (Streptococcus mutans) adhesion and for subsequent biofilm eradication without impacting the surrounding oral tissues via oxygen (O2) and reactive oxygen species (ROS) generation. Especially, Cu-CDs exhibit strong affinity for lipopolysaccharides (LPS) and peptidoglycans (PGN), thus conferring them with excellent antibacterial ability against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli), such that they can prevent wound purulent infection and promoting rapid wound healing. Additionally, the Cu-CDs/H2O2 system shows a better performance in tooth whitening, compared with results obtained with other alternatives, e.g., CDs and clinically used H2O2, particularly its negligible enamel and dentin destruction. It is anticipated that the biocompatible Cu-CDs presented in this work are a promising nano-mouthwash for eliminating oral pathogenic biofilms, prompting wound healing as well as tooth whitening, highlighting their significance in oral health management.

Alternative Treatment of Bacterial Wound Infections

Topical and systemic antibiotic treatment are essential in the prevention and treatment of wound infections. Systemic antibiotics, on the other hand, are strongly linked to mechanisms of resistance, which jeopardize the treatment process. The direction of systemic antibiotics to the eschar becomes less reliable the deeper the burn and the thicker the eschar becomes for local wound care . As a result, topical antibiotics appear as a viable treatment option, as they help to maintain a “high and sustained concentration of the antimicrobial at the infection site.
 Every year, wound treatment develops a high urgent clinical problem, as The requirement for wound care has an influence on a significant percentage of the global population. The system of healthcare in the United States spends $20 million a year on wounds . An Incisional, acute, and chronic wounds are all examples of wounds that can become infected and lead to more complications. 
 Incisional wounds and deep lacerations are often troublesome, and they account for a significant portion of the annual cost of wound healing products. While Wounds from incisions heal more quickly than chronic wounds, they always have challenges with appropriate closure as well as the formation of granulation tissue, which might lower one's quality of life. Wounds from incisions are also susceptible to infection, necessitating further care. Antiseptics, antibiotics, as well as silver dressings have traditionally is always used to treat wounds, however each of these therapies is ineffective against a wide range of microorganisms often present in wounds.

Topical liquid formulation of bacteriophages for metered-dose spray delivery

Bacteriophage (phage) therapy is a promising treatment strategy to combat antibiotic-resistant bacteria. Clinical reports from a century ago, as well as recent reports have revealed safety and efficacy of phage therapy for bacterial wound infections. However, the conventional liquid phage formulation and delivery platforms reported lack of dose control as it easily runs off from the infection site and it is impossible to determine total volume transfer. The aim of this study was to formulate phage liquids for topical delivery using a metered-dose spray. Two types of anti-Pseudomonas phages, PEV1 (myovirus) and PEV31 (podovirus) were formulated in 35% ethanol in water containing non-ionic polymers. The formulations were evaluated for physical properties, ease of spray, dripping upon spraying, drying time, in vitro release profiles, antibacterial activity, and storage stability. The optimized phage-polymer spray formulations were easily sprayable with minimal dripping and fast drying time. Phages were rapidly released from the formulation and inhibited the growth of Pseudomonas aeruginosa. Both PEV1 and PEV31 remained biologically stable in the optimized formulations during storage at 4 °C for eight weeks. This study showed the topical spray formulations containing non-ionic polymers in ethanol/water could be a promising and innovative therapeutic system for delivering phages.

Photocatalytic Cu2WS4 Nanocrystals for Efficient Bacterial Killing and Biofilm Disruption.

BackgroundBacterial biofilm-related wound infections threaten human health due to the lack of efficient treatments. Therefore, developing a novel strategy for wound infection care is urgently needed.MethodsCube-shaped Cu2WS4 nanocrystals (CWSNs) were successfully prepared via a microwave-assisted method. CWSNs, as photocatalysts, were first studied by using fluorescence spectroscopy for their ability to generate reactive oxygen species (ROS). The antibacterial and biofilm inhibition abilities of CWSNs were determined in vitro by using Staphylococcus aureus (S. aureus) as the model bacterium. Moreover, a CWSN gel was prepared and applied to treat S. aureus-infected wounds in mice. The toxicity of the CWSNs was evaluated through in vitro cell and in vivo animal experiments.ResultsStudies on the properties of the CWSNs demonstrated that these nanomaterials can catalyze the generation of hydroxyl radicals (•OH) without the addition of H2O2 after visible-light irradiation, indicating their photocatalytic ability. Moreover, the in vitro experimental results showed that the CWSNs not only adhered to the surfaces of S. aureus to kill the bacteria, but also inhibited S. aureus biofilm formation. The in vivo study showed that the CWSN gel produced excellent antibacterial effects against S. aureus infected wounds in mice and effectively promoted wound healing. Furthermore, toxicity tests showed that the CWSNs have negligible toxicity in vitro and in vivo.ConclusionThis work provides a potential photocatalytic antibacterial nanoagent for efficient bacterial killing, inhibition of biofilms growth and wound infection treatment.

Rapid, label-free pathogen identification system for multidrug-resistant bacterial wound infection detection on military members in the battlefield.

US military service members experiencing combat-related wounds have higher risk of infection by multidrug-resistant bacteria. The gold standard culture-based antimicrobial susceptibility testing (AST) is not feasible in the battlefield environment. Thus, a rapid deployable system for bacteria identification and AST directly from wound sample is urgently needed. We report the potential of a Rapid, Label-free Pathogen Identification (RAPID) diagnostic system based on ATR-FTIR method to detect and distinguish multi-drug resistant strains for six different species in the ESKAPEE group. Our RAPID system combines sample processing on-broad to isolate and enrich bacteria cells from wound sample, ATR-FTIR measurement to detect antimicrobial-induced bacterial cell spectral changes, and machine learning model for automated, objective, and quantitative spectral analysis and unknown sample classification. Based on experimental results, our RAPID system is a promising technology for label-free, sensitive (104 cfu/mL from mixture), species-specific (> 95% accuracy), rapid (< 10 min for identification, ~ 4 hours for AST) bacteria detection directly from wound samples.

Screening of Natural Molecules as Adjuvants to Topical Antibiotics to Treat Staphylococcus aureus from Diabetic Foot Ulcer Infections.

Diabetic foot ulcers (DFUs) are a common result of a complex secondary complication of diabetes mellitus. More than half of DFUs become infected due to frequent colonization with Staphylococcus aureus. The use of topical antibiotics is proposed, especially in combination with natural adjuvants, to minimize the negative impacts caused by generalized use of systemic antibiotics. In this study, 13 different phytochemicals—namely chalcone, juglone, cinnamic acid, trigonelline, Furvina—and four nitrovinylfuran derivatives—guaiazulene, α-bisabolol, farnesol and nerolidol—were selected to be tested as antibiotic enhancers. After minimum inhibitory and bactericidal concentration (MIC and MBC) determination of each molecule against different strains of S. aureus, including clinical isolates from diabetic foot wounds (CECT 976, Xu212, SA 1199B, RN4220, MJMC102, MJMC109, MJMC110 and MJMC111), their potentiation effects on the antibiotics fusidic acid, mupirocin, gentamicin, oxacillin and methicillin were evaluated through the disc diffusion method. Farnesol at sub-MIC was able to restore the activity of methicillin and oxacillin on the MJMC102 and MJMC111 strains, as well as two MRSA clinical isolates, and potentiated the effect of the remaining antibiotics. The results obtained demonstrate the great potential for the topical application of phytochemicals and derivatives as antibiotic resistance modifier agents to combat multidrug resistance in bacterial wound infections.

NIR-activated multi-hit therapeutic Ag2S quantum dot-based hydrogel for healing of bacteria-infected wounds

Hydrogel dressings are highly biocompatible and can maintain a moist wound environment, suggesting constructing an efficient multi-modal antibacterial hydrogel platform is a promising strategy for treating bacterial wound infections. In this work, a composite Ag2S quantum dot/mSiO2 NPs hydrogel (NP hydrogel) with antibacterial ability was constructed by incorporating Ag2S quantum dots (QDs) modified by mesoporous silica (mSiO2) into the network structure of 3-(trimethoxylmethosilyl) propyl methacrylate based on free radical polymerization. The NP hydrogel showed outstanding controllable photothermal and photodynamic characteristics under 808 nm near infrared (NIR) light irradiation, with a photothermal conversion efficiency of 57.3%. Additionally, the release of Ag+ could be controlled by the inherent volume change of the NP hydrogel made of N-isopropylacrylamide (NIPAAm) and acrylamide (AAm) during NIR laser exposure, with the embedded Ag2S QDs working as a reservoir to release Ag+ continuously from the hydrogel matrix to achieve bactericidal activity. The synergetic effects between hyperthermia, radical oxygen species, and Ag+ released under NIR radiation endowed the NP hydrogel with prominent antibacterial properties against Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA), with an inhibition rate of 99.7% and 99.8%, respectively. In vivo wound healing experiments indicated that the NP hydrogel could enhance bacterial clearance, increase collagen coverage area and up-regulate VEGF expression, exhibiting high biocompatibility. Overall, this study proposed an efficient and highly biocompatible multi-modal therapeutic nanohydrogel, opening up a new way for developing broad-spectrum antibacterial wound dressings to treat bacterial wound infections. Statement of significanceBacterial wound infection is still one of the most difficult medical problems. In this work, a stimulating NIR-responsive hydrogel encapsulating functional Ag2S QDs was prepared, which showed high photothermal conversion efficiency (57.3%) and outstanding antibacterial ability under 808 nm NIR laser, killing 99.7% and 99.8% of E. coli and MRSA in 4 min, respectively. During NIR light irradiation, the release rate of Ag+ could be regulated by the intrinsic volume transition of the hydrogel, leading to remarkable antibacterial properties in vitro and in vivo under the combined action of hyperthermia, radical oxygen species and Ag+ released. This study proposed a novel multi-modal therapeutic nanohydrogel, opening up a new way for developing broad-spectrum antibacterial wound dressings to treat bacterial wound infections.

Carboxymethyl chitosan-based multifunctional hydrogels incorporated with photothermal therapy against drug-resistant bacterial wound infection

Wound infection especially that induced by drug resistant bacteria has been considered an increasing medical crisis. Herein a biocompatible wound dressing is conveniently constructed by incorporating (Sr0.6Bi0.305)2Bi2O7 (denoted as SBO) with excellent photothermal performance into a facile antibacterial hydrogel (gel) obtained from multiple physical crosslinks among Ag+, carboxymethyl chitosan and polyacrylic acid. The prepared SBO gel features excellent bactericidal activities, hemostasis, adequate mechanical properties, adhesiveness and adsorption capacities to bacterial cells and toxin. The gel can disperse SBO homogeneously in the network and SBO effectively convert visible light energy into localized heat for synergistic sterilization. In vitro assays confirm the potent broad-spectrum bactericidal activities of SBO gel to some common pathogens and drug resistant strains such as MRSA and CAPA. Mice model of MRSA-induced wound infections verified the practical efficacy of SBO gel in combating bacterial infections and accelerating wound healing. Moreover, this is the first report of SBO as a photothermal agent applied in anti-infection treatment. All of these results highlight the potential application of SBO gel in drug-resistant bacteria associated wound management.

Postinjury Care and Complications Among U.S. Military Women With Combat-Related Major Limb Traumatic Amputation.

U.S. servicewomen may be at greater risk of injury in future conflicts as they integrate into combat occupations. More than 1,000 servicewomen were wounded during military conflicts in Iraq and Afghanistan. Some women sustained traumatic amputations, and research on their postinjury health is needed. To describe acute care, complications, and health care utilization among servicewomen with combat-related amputations, comparing them with injured men. In this retrospective matched-pairs study, women were identified from the Expeditionary Medical Encounter Database between 2003 and 2012 and matched with men on amputation injuries, injury severity, and age. Differences were assessed with nonparametric tests for paired data. Of 20 women identified for analysis, 13 received tourniquets, three were administered procoagulants, and six had massive transfusions. Women averaged 3.4 (SD = 1.6) postinjury complications, and the most frequent were heterotopic ossification (n = 17), posthemorrhagic anemias (n = 13), and bacterial wound infections (n = 10). Acute care and complications were similar among men. Women averaged more acute care days (M = 49.8, SD = 30.6) than men (M = 46.1, SD = 27.4) but fewer intensive care unit days (women: M = 2.6, SD = 4.0; men: M = 4.4, SD = 8.3). No statistical differences were observed. Postinjury care among servicewomen with combat-related amputations was comparable with servicemen, and complications were common. This information can aid providers and nursing staff in the management of these injuries.