Broad-spectrum Antibacterial Activity Research Articles

High-Efficiency Broad-Spectrum Antibacterial Activity of Chitosan/Zinc Ion/Polyoxometalate Composite Films for Water Treatment.

The development of multifunctional films with rapidly killing microorganisms and adsorbing residual antibiotics in wastewater remains a challenging endeavor. In this work, the chitosan/zinc ion/polyoxometalate (CS/Zn2+/POM) multifunctional films were prepared by the freeze-drying method using chitosan, ZnO, and POM. Notably, the CS/Zn2+/POM films exhibited excellent bactericidal properties against Gram-positive/negative bacterial strains including Staphylococcus aureus (S. aureus, 99.80%), Escherichia coli (E. coli, 99.82%), and drug-resistant E. coli bacterial strains (kanamycin-resistant E. coli, 87.76% and ampicillin-resistant E. coli, 99.71%). This may be due to the chelation of Zn2+ with CS disrupting the cell membrane and bringing POM into direct contact with bacteria, leading to bacterial death. In addition, the CS/Zn2+/POM films showed good adsorption performance to a tetracycline (TC) solution (adsorption rate 75.2%). Further studies showed that the main process of tetracycline removal by CS/Zn2+/POM films was controlled by a physical adsorption. This POM-based film material has an important potential for the synthesis of broad-spectrum antimicrobial materials for the removal of residual antibiotics from water pollutants such as tetracycline.

Gatifloxacin hydrochloride confers broad-spectrum antibacterial activity against phytopathogenic bacteria

Bacterial diseases pose significant threats to agriculture and natural ecosystems, causing substantial crop losses and impacting food security. Until now, there has been a less efficient control strategy against some bacterial diseases such as bacterial wilt, caused by Ralstonia solanacearum. In this study, we screened a library of 58 microorganism-derived natural products for their antibacterial activity against R. solanacearum. Gatifloxacin hydrochloride exhibited the best inhibitory effect with an inhibition rate of 95% at 0.0625 mg/L. Further experiments demonstrate that gatifloxacin hydrochloride inhibits R. solanacearum growth in a concentration-dependent manner, with the minimum inhibitory concentration of 0.125 mg/L. Treatment with 0.5 mg/L of gatifloxacin hydrochloride killed more than 95% of bacteria. Gatifloxacin hydrochloride significantly inhibited biofilm formation by R. solanacearum. Gatifloxacin hydrochloride also shows good antibacterial activity against Pseudomonas syringae pv. tomato DC3000 and Xanthomonas campestris pv. vesicatoria. Exogenous application of gatifloxacin hydrochloride suppressed disease development caused by R. solanacearum and P. syringae. In summary, our results demonstrate the great potential of microorganism-derived compounds as broad-spectrum antibacterial compounds, providing alternative ways for the efficient control of bacterial plant diseases.

Enhancing the solubility and antibacterial activity of novel molecular salts of enrofloxacin drug with isomeric pyridinedicarboxylic acids

Enrofloxacin (EFX) is a third-generation synthetic fluoroquinolone with a broad spectrum of antibacterial activity but suffers from low water solubility, affecting its bioavailability. This study attempts to enhance the physicochemical and biological properties of enrofloxacin by converting it into multicomponent forms using crystal engineering concepts. Cocrystallization of enrofloxacin with isomeric pyridine-2,n-dicarboxylic acids (n = 3,4,5,6) resulted in four new crystalline salts (1:1): EFX·Py2,3DCA, EFX·Py2,4DCA, EFX·Py2,5DCA·H2O and EFX·Py2,6DCA·H2O; two of these are monohydrates. The protonation of the nitrogen atom of the piperazine moiety and the presence of crystallization water molecules were confirmed by single-crystal X-ray diffraction and Fourier transform infrared spectroscopy. Thermogravimetric analysis provided information on the thermal behaviour of multicomponent forms. The biological studies showed that the obtained salts are characterized by high antibacterial activity against Gram-positive and Gram-negative bacteria, and their haemolytic activity is low. The new salts demonstrate significantly greater solubility in water compared to the parent drug, along with enhanced antibacterial activity; hence, pyridinedicarboxylic acids appear to be efficient cocrystallizing agents for improving the efficacy of pharmaceutical ingredients.

Identification and characterization of a novel bacteriocin PCM7-4 and its antimicrobial activity against Listeria monocytogenes

Listeria monocytogenes, a pathogenic bacterium causing zoonotic diseases, necessitates the urgent search for novel anti-Listeria monocytogenes drugs due to the continuous emergence of drug-resistant bacteria. In this study, we isolated and identified a bacteriocin-producing strain CM7–4 from seawater as Bacillus velezensis through 16S rRNA sequence analysis. Moreover, we successfully purified a novel bacteriocin named PCM7–4 from Bacillus velezensis CM7–4. The molecular weight of PCM7–4 was determined to be 40,228.99 Da. Notably, PCM7–4 exhibited broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria with a minimum inhibitory concentration (MIC) of 5.625 μg/mL against Listeria monocytogenes specifically. It demonstrated heat resistance and high stability within the pH range of 2–12 while being sensitive to proteinase K degradation without any observed hemolytic activity. Furthermore, SEM analysis revealed that PCM7–4 effectively inhibited biofilm formation and disrupted cell membranes in Listeria monocytogenes cells. Transcriptome analysis revealed that PCM7–4 exerts an impact on genes associated with crucial metabolic pathways, encompassing the biosynthesis of secondary metabolites, phosphotransferase systems (PTS), and starch/sucrose metabolism. These findings highlight the significant potential of bacteriocin PCM7–4 for the development of effective antimicrobial interventions targeting food-borne pathogenic bacteria.

Bacillus velezensis HBXN2020 alleviates Salmonella Typhimurium infection in mice by improving intestinal barrier integrity and reducing inflammation

Bacillus velezensis is a species of Bacillus that has been widely investigated because of its broad-spectrum antimicrobial activity. However, most studies on B. velezensis have focused on the biocontrol of plant diseases, with few reports on antagonizing Salmonella Typhimurium infections. In this investigation, it was discovered that B. velezensis HBXN2020, which was isolated from healthy black pigs, possessed strong anti-stress and broad-spectrum antibacterial activity. Importantly, B. velezensis HBXN2020 did not cause any adverse side effects in mice when administered at various doses (1×107, 1×108, and 1×109 CFU) for 14 days. Supplementing B. velezensis HBXN2020 spores, either as a curative or preventive measure, dramatically reduced the levels of S. Typhimurium ATCC14028 in the mice’s feces, ileum, cecum, and colon, as well as the disease activity index (DAI), in a model of infection caused by this pathogen in mice. Additionally, supplementing B. velezensis HBXN2020 spores significantly regulated cytokine levels (Tnfa, Il1b, Il6, and Il10) and maintained the expression of tight junction proteins and mucin protein. Most importantly, adding B. velezensis HBXN2020 spores to the colonic microbiota improved its stability and increased the amount of beneficial bacteria (Lactobacillus and Akkermansia). All together, B. velezensis HBXN2020 can improve intestinal microbiota stability and barrier integrity and reduce inflammation to help treat infection by S. Typhimurium.

Bacillus velezensis HBXN2020 alleviates Salmonella Typhimurium infection in mice by improving intestinal barrier integrity and reducing inflammation.

Bacillus velezensis is a species of Bacillus that has been widely investigated because of its broad-spectrum antimicrobial activity. However, most studies on B. velezensis have focused on the biocontrol of plant diseases, with few reports on antagonizing Salmonella Typhimurium infections. In this investigation, it was discovered that B. velezensis HBXN2020, which was isolated from healthy black pigs, possessed strong anti-stress and broad-spectrum antibacterial activity. Importantly, B. velezensis HBXN2020 did not cause any adverse side effects in mice when administered at various doses (1×107, 1×108, and 1×109 CFU) for 14 days. Supplementing B. velezensis HBXN2020 spores, either as a curative or preventive measure, dramatically reduced the levels of S. Typhimurium ATCC14028 in the mice's feces, ileum, cecum, and colon, as well as the disease activity index (DAI), in a model of infection caused by this pathogen in mice. Additionally, supplementing B. velezensis HBXN2020 spores significantly regulated cytokine levels (Tnfa, Il1b, Il6, and Il10) and maintained the expression of tight junction proteins and mucin protein. Most importantly, adding B. velezensis HBXN2020 spores to the colonic microbiota improved its stability and increased the amount of beneficial bacteria (Lactobacillus and Akkermansia). All together, B. velezensis HBXN2020 can improve intestinal microbiota stability and barrier integrity and reduce inflammation to help treat infection by S. Typhimurium.

In Situ Crosslinked Biodegradable Hydrogels Based on Poly(Ethylene Glycol) and Poly(ε-Lysine) for Medical Application.

Hydrogels have emerged as promising biomaterials due to their excellent performance; however, their biocompatibility, biodegradability, and absorbability still require improvement to support a broader range of medical applications. This paper presents a new biofunctionalized hydrogel based on in situ crosslinking between maleimide-terminated four-arm-poly(ethylene glycol) (4-arm-PEG-Mal) and poly(ε-lysine) (ε-PL). The PEG/ε-PL hydrogels, named LG-n, were rapidly formed via amine/maleimide reaction by mixing 4-arm-PEG-Mal and ε-PL under physiological conditions. The corresponding dry gels (DLG-n) were obtained through a freeze-drying technique. 1H NMR, FT-IR, and SEM were utilized to confirm the structures of 4-arm-PEG-Mal and LG-n (or DLG-n), and the effects of solid content on the physicochemical properties of the hydrogels were investigated. Although high solid content could increase the swelling ratio, all LG-n samples exhibited a low equilibrium swelling ratio of less than 30%. LG-7, which contained moderate solid content, exhibited optimal compression properties characterized by a compressive fracture strength of 45.2 kPa and a deformation of 69.5%. Compression cycle tests revealed that LG-n demonstrated good anti-fatigue performance. In vitro degradation studies confirmed the biodegradability of LG-n, with the degradation rate primarily governing the drug (ceftibuten) release efficiency, leading to a sustained release duration of four weeks. Cytotoxicity tests, cell survival morphology observation, live/dead assays, and hemolysis tests indicated that LG-n exhibited excellent cytocompatibility and low hemolysis rates (<5%). Furthermore, the broad-spectrum antibacterial activity of LG-n was verified by an inhibition zone method. In conclusion, the developed LG-n hydrogels hold promising applications in the medical field, particularly as drug sustained-release carriers and wound dressings.

In vitro activities of eravacycline against clinical bacterial isolates: a multicenter study in Guangdong, China.

Eravacycline (ERV), a novel tetracycline derivative, exhibits broad-spectrum antibacterial activity, but data on the bacterial activity against Chinese bacterial isolates are very scarce. This study aims to evaluate the activity of eravacycline against the common Gram-positive and Gram-negative bacteria isolates in Guangdong, China. The clinical isolates were collected from four centers between 1 November 2023 and 31 January 2024, and the susceptibility of eravacycline (MIC50, MIC90, and MIC) was determined using broth microdilution as a reference method and E-TEST strips to evaluate their consistency. A total of 594 strains were collected from the four centers, including Staphylococcus aureus (n = 126), Enterococcus faecalis (n = 58), Enterococcus faecium (n = 29), Klebsiella pneumoniae (n = 136), Escherichia coli (n = 187), and Acinetobacter baumannii (n = 58). The MIC50 and MIC90 (mg/L) of eravacycline were 0.12 and 1 for S. aureus, 0.06 and 0.12 for E. faecalis, 0.06 and 0.5 for E. faecium, 0.25 and 0.5 for E. coli, 0.5 and 2 for K. pneumoniae, and 0.25 and 2 for A. baumannii. Based on the FDA and EUCAST breakpoints, the susceptibility of eravacycline against S. aureus was 46.03% vs. 83.33%, 56.90% vs. 94.93% against E. faecalis, and 62.07% vs. 79.31% in E. faecium. The susceptibility rates of E. coli and K. pneumoniae were 90.37% and 58.09, respectively. To evaluate the performance between the broth microdilution test (BMD) and ETEST methods, we compared essential agreement (EA), categorical agreement (CA), very major error (VME), and major error (ME). The results demonstrated that compared with BMD, eravacycline measured by ETEST had higher VME and ME referring to FDA breakpoints than EUCAST breakpoints in the Gram-positive isolates. Since there were no intermediate breakpoints for the eravacycline, the MIC values measured by the ETEST method might result in lower CA and higher VME and ME. This study provides MIC values of eravacycline against Gram-positive and Gram-negative pathogens in four hospitals in Guangdong Province, and eravacycline is an effective therapeutic candidate for common bacteria.

Development of α-Helical Antimicrobial Peptides with Imperfect Amphipathicity for Superior Activity and Selectivity.

The advancement of antimicrobial peptides (AMPs) as therapeutic agents is hindered by their poor selectivity. Recent evidence indicates that controlled disruption of the amphipathicity of α-helical AMPs may increase the selectivity. This study investigated the role of imperfect amphipathicity in optimizing AMPs with varied sequences to enhance their activity and selectivity. Among these, the lead peptide RI-18, characterized by an imperfectly amphipathic α-helical structure, demonstrated potent and broad-spectrum antibacterial activity without inducing hemolytic or cytotoxic effects. RI-18 effectively eliminated planktonic and biofilm-associated bacteria as well as persister cells and exhibited high bacterial plasma membrane affinity, inducing rapid membrane permeabilization and rupture. Notably, RI-18 significantly reduced bacterial loads without promoting bacterial resistance, highlighting its therapeutic potential. Overall, this study identified RI-18 as a promising antimicrobial candidate. The rational strategy of tuning imperfect amphipathicity to enhance the AMP activity and selectivity may facilitate the design and development of AMPs.

In vitro antimicrobial and antioxidant activities of bioactive compounds extracted from Streptomyces africanus strain E2 isolated from Moroccan soil

This study aimed to isolate Streptomyces sp. from Moroccan terrestrial ecosystems and identify bioactive compounds through GC–MS analysis. Antimicrobial activity was assessed against various pathogenic microorganisms including Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Candida albicans ATCC 60193, and multi-drug resistant strains comprising Listeria monocytogenes, Klebsiella pneumoniae 19K 929, Proteus sp. 19K1313, Klebsiella pneumoniae 20B1572, Proteus vulgaris 16C1737, and Klebsiella pneumoniae 20B1572. Based on the results of the gene sequencing of gene 16S rRNA and phylogenetic analysis, the E2 isolate belongs to the genus Streptomyces with the highest degree of resemblance (97.51%) to the Streptomyces africanus strain NBRC 101005 (NR_112600.1). The isolate exhibited broad-spectrum antibacterial activity, with maximum efficacy against Klebsiella pneumoniae 20B1572 indicated by an inhibition zone diameter of 22.5 ± 0.71mm and a minimum inhibitory concentration (MIC) of 0.0625 mg/mL. The in vitro antioxidant potential of E2 strain was determined through screening of its ethyl acetate extract against sets of antioxidant assays. The results were indicative of E2 strain displaying strong antioxidant activity against ABTS, DPPH free radicals, and FRAP. Furthermore, there was a high significant correlation (p < 0.0001) between the total phenolic and flavonoid content and antioxidant activities. The GC–MS analysis of the extract identified six volatile compounds, with Eugenol (96%) and Maltol (93%) being the most prominent. Additionally, the HPLC–UV/vis analysis revealed six phenolic compounds: gallic acid, chlorogenic acid, vanillic acid, trans-ferulic acid, ellagic acid, and cinnamic acid. Overall, the study highlights Streptomyces sp. strain E2 as a potential source of potent antimicrobial and antioxidant metabolites, offering promise in addressing antibiotic resistance and oxidative stress-related conditions.

Homogeneous synthesis of cationic celluloses with broad-spectrum antibacterial activities for the treatment of vaginitis in mice

Microbial infection is a significant health issue for humans. Despite the development of numerous antibiotics, the continuous rise of drug-resistant bacteria highlights the urgent need for new materials to combat these problems. In this study, four water-soluble quaternized cellulose (QC) derivatives with degrees of substitution (DS) ranging from 0.23 to 0.45 were synthesized homogeneously from cellulose carbamate (CC) in NaOH/ZnO aqueous solution. The QC derivatives exhibited broad-spectrum antibacterial activity against gram-negative/positive bacteria, fungi and drug-resistance bacteria. Models of bacterial vaginitis (BV) and vulvovaginal candidiasis (VVC) were used to evaluate the application of QC derivatives visually. Secretion smears and tissue section staining revealed that treatment with QC derivatives led to a reduction in mycelia and spores in the vagina and secretions in the VVC model, along with improved inflammation. In the BV model, vaginal secretions were reduced, clue cells in smears significantly decreased, and inflammation markedly improved. Additionally, cell experiments and staining of mouse organ tissue sections demonstrated that QC derivatives exhibited good biocompatibility. Therefore, using QC derivatives in flushing douches represents a novel approach for treating vaginitis and could serve as a benchmark for addressing other infectious diseases.

Self-assembly antimicrobial peptide for treatment of multidrug-resistant bacterial infection

The wide-spreading of multidrug resistance poses a significant threat to human and animal health. Although antimicrobial peptides (AMPs) show great potential application, their instability has severely limited their clinical application. Here, self-assembled AMPs composed of multiple modules based on the principle of associating natural marine peptide N6 with ß-sheet-forming peptide were designed. It is noteworthy that one of the designed peptides, FFN could self-assemble into nanoparticles at 35.46 µM and achieve a dynamic transformation from nanoparticles to nanofibers in the presence of bacteria, resulting in a significant increase in stability in trypsin and tissues by 1.72–57.5 times compared to that of N6. Additionally, FFN exhibits a broad spectrum of antibacterial activity against multidrug-resistant (MDR) gram-positive (G+) and gram-negative (G−) bacteria with Minimum inhibitory concentrations (MICs) as low as 2 µM by membrane destruction and complemented by nanofiber capture. In vivo mouse mastitis infection model further confirmed the therapeutic potential and promising biosafety of the self-assembled peptide FFN, which can effectively alleviate mastitis caused by MDR Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and eliminate pathogenic bacteria. In conclusion, the design of peptide-based nanomaterials presents a novel approach for the delivery and clinical translation of AMPs, promoting their application in medicine and animal husbandry.Graphical

Novel Tree Shrew-Derived Antimicrobial Peptide with Broad-Spectrum Antibacterial Activity.

The number of cationic residues and net charge are critical for the activity of antimicrobial peptides (AMPs) due to their role in facilitating initial electrostatic interactions with negatively charged bacterial membranes. A cathelicidin AMP (TC-33) has been identified from the Chinese tree shrew in our previous work, which exhibited weak antimicrobial activity, likely due to its moderately cationic nature. In the current study, based on TC-33, we designed a novel AMP by peptide truncation and Glu substitutions to increase its net cationic charge from +4 to +8. The resulting peptide, TC-LAR-18, showed 4-128-fold enhanced antimicrobial activity relative to TC-33 without causing hemolysis and cytotoxicity within 100 μg/mL. TC-LAR-18 effectively eliminated both planktonic and biofilm-associated bacteria, demonstrating rapid bactericidal effects due to its ability to quickly penetrate and disrupt bacterial cell membranes with a low propensity to induce resistance. Notably, TC-LAR-18 provided substantial protection against skin bacterial infection in mice, underscoring its therapeutic potential. These findings not only highlight the importance of positively charged residues for the antibacterial activity of AMPs but also present a useful drug candidate for combating multidrug-resistant bacteria.

Evaluation of Antimicrobial Activity of Methanol Extract of Abrus precatorius Leaf Against Selected Clinical Isolates (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albican)

Abrus precatorius is one of the herbal plants that have been reported to have medicinal properties. The leaves is widely used for the treatment of cough, cancer and swollen tonsils. Abrus precatorius is also known for its abundant chemical constituents that could be very important antibacterial agent. This study evaluated the antimicrobial activity of Abrus precatorius leaf extracts against isolated clinical bacteria and fungi. The study employed agar disc diffusion method of antimicrobial sensitivity testing (50 µg/mL, 100 µg/mL, 200 µg/mL and 400 µg/mL), and Minimum Inhibitory Concentration (MIC) model. The results showed a dose dependent antimicrobial potential of Abrus precatorius leaf extract against the test organisms with zone of inhibition ranging from 4 – 18mm against Escherichia coli, 6 – 19mm against Pseudomonas aeruginosa, 4 -22mm against Staphylococcus aureus and 2 – 15mm against Candida albican. The extract also showed an MIC of 25mg/ml for Staphylococcus aureus, 50mg/ml for Escherichia coli and Pseudomonas aeruginosa and the least MIC of 100mg/ml for Candida albican. The outcome of the study suggest that Abrus precatorius leaf extract exert broad spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria. These findings validate the use of the plants for the treatment of infections, and indicate the potential roles of the plants in drug development programs of the pharmaceutical industry.

Mussel-like polydopamine-assisted aggregation-induced emission nanodot for enhanced broad-spectrum antimicrobial activity: In vitro and in vivo validation

Emerging luminogens with aggregation-induced emission properties, namely AIEgens, demonstrated excellent anti-bacteria activity potential. However, their application still limited by the low antibacterial activity caused by the poor binding with bacteria. Polydopamine (PDA), an important biological macromolecule, possesses superior adhesion ability toward various material surface, including bacteria. In this study, the novel mussel-like PDA-assisted AIE Nanodot was proposed, achieving with robust bacterial binding ability and enhanced broad-spectrum antibacterial activity. Binding ability inherited from the PDA enables the constructed PDA-assisted AIE Nanodot to adhere efficiently to the bacterial membrane surface. Meanwhile, the AIE properties endowed them with monitoring capability, allowing for tracking their interaction with bacteria through facile fluorescence imaging in real time. More importantly, excellent killing of both Gram-positive and Gram-negative bacteria were successfully achieved in vitro antibacterial tests with excellent biocompatibility. Furthermore, in the treatment of Methicillin-resistant S. aureus (MRSA)-infected mouse-wound model, the mice exhibited accelerated wound healing with low bacterial load. This novel integrated strategy introduced a simple but effectively design to enhance the binding and antibacterial ability of AIEgens and would diversify the existing pool of antibacterial agents.

Antimicrobial Peptide with a Bent Helix Motif Identified in Parasitic Flatworm Mesocestoides corti.

The urgent need for antibiotic alternatives has driven the search for antimicrobial peptides (AMPs) from many different sources, yet parasite-derived AMPs remain underexplored. In this study, three novel potential AMP precursors (mesco-1, -2 and -3) were identified in the parasitic flatworm Mesocestoides corti, via a genome-wide mining approach, and the most promising one, mesco-2, was synthesized and comprehensively characterized. It showed potent broad-spectrum antibacterial activity at submicromolar range against E. coli and K. pneumoniae and low micromolar activity against A. baumannii, P. aeruginosa and S. aureus. Mechanistic studies indicated a membrane-related mechanism of action, and circular dichroism spectroscopy confirmed that mesco-2 is unstructured in water but forms stable helical structures on contact with anionic model membranes, indicating strong interactions and helix stacking. It is, however, unaffected by neutral membranes, suggesting selective antimicrobial activity. Structure prediction combined with molecular dynamics simulations suggested that mesco-2 adopts an unusual bent helix conformation with the N-terminal sequence, when bound to anionic membranes, driven by a central GRGIGRG motif. This study highlights mesco-2 as a promising antibacterial agent and emphasizes the importance of structural motifs in modulating AMP function.

In-Situ and Green Synthesis of Silk Fibroin-Silver Nanoparticles Composite Microfibers for Enhanced Antibacterial Applications.

The antibacterial properties of modified silk fibroin microfibers (SF MFs) have been widely studied. Among various modifications, integration of silver nanoparticles (Ag NPs) and SF MFs has garnered significant attention due to the broad-spectrum antibacterial activities and long-term antibacterial effect of Ag nanomaterials. However, the traditional introduction of reducing agents or other additives during the synthesis of Ag-SF composite MFs potentially affects their structure and antibacterial properties. Facile, green and effective methods for the preparation of Ag-SF MFs with enhanced antibacterial properties are therefore highly desired. In this study, Ag NPs were uniformly in-situ deposited onto the optimized SF MFs by adjusting the pH and duration conditions under the guidance of green chemistry. The loaded Ag NPs have a good dispersibility and an average size of ~10 nm. The stability of SF MFs after the deposition of Ag NPs and the crystalline features of the loaded Ag NPs have been carefully investigated. Moreover, antibacterial experiments confirmed that Ag-SF MFs exhibited superior antibacterial activities. After co-incubating Ag-SF MFs with L929 cells, the cell viability reached 90 %, demonstrating the great biocompatibility of the modified fibers. This green in-situ synthetic method will promote the further medical use of Ag-SF MFs in antibacterial fields.

A BODIPY derivative for PDT/PTT synergistic treatment of bacterial infections

Phototherapeutic antimicrobials, including photodynamic and photothermal antimicrobials, are considered effective alternatives for antibiotic strategy due to their broad-spectrum antibacterial activity and low risk of resistance. Here, a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) derivative containing triphenylamine groups was co-assembled with Pluronic F-127 (F-127) to form nanoparticles (BICF NPs). BICF NPs have excellent photodynamic and photothermal properties and are demonstrated to be effective in inhibiting and disrupting bacterial biofilms, thereby promoting the healing of subcutaneous abscesses. This work provides a new avenue for antibiotic replacement therapy.

Omiganan-Based Synthetic Antimicrobial Peptides for the Healthcare of Infectious Endophthalmitis.

Bacterial endophthalmitis is a severe infection of the aqueous or vitreous humor of the eye that can lead to permanent vision loss. Due to the rapid emergence of antibiotic resistance and dose-limiting toxicities, the standard treatment of bacterial endophthalmitis via the intravitreal injection of broad-spectrum antibiotics remains inadequate. Membrane active cationic antimicrobial peptides (AMPs) have emerged as a promising class of effective and broad-spectrum antimicrobial agents with potential to overcome antibiotic resistance. In this work, we investigate, for the first time, the use of omiganan (IK-12), a 12-amino acid indolicidin derivative for the treatment of bacterial endophthalmitis. Additionally, IK-12 was used as a template to perform amino acid rearrangements, without altering the length or type of amino acids, to yield a series of new derivative AMPs with varying extents of secondary structure formation under membrane mimicking conditions. IK-12 and its derivatives demonstrated strong and broad-spectrum antibacterial activities against a panel of clinically isolated Gram-positive and Gram-negative bacteria, including methicillin-resistant Staphylococcus aureus commonly implicated in bacterial endophthalmitis. Interestingly, two of the new IK-12 derivatives, IP-12 and WP-12, showed lower geometric mean minimum inhibitory concentration and higher 50% hemolysis concentration values, which effectively translated into 2- to 3.4-fold higher bacterial selectivity than the parent IK-12. Furthermore, the intravitreal injection of IK-12, IP-12, and WP-12 in a rabbit model of MRSA-induced endophthalmitis led to considerably improved clinical presentation and reduced recruitment of inflammatory cells. In all, these results demonstrate the potential of IK-12 and its derivatives, IP-12 and WP-12, as promising candidates for the treatment of bacterial endophthalmitis.

Diversity and Anti-Infectious Components of Cultivable Rhizosphere Fungi Derived from Three Species of Astragalus Plants in Northwestern Yunnan, China.

Astragalus, a group of legume plants, has a pronounced rhizosphere effect. Many species of Astragalus with limited resource reserves are distributed in the high-altitude area of northern Yunnan, China. Although some of these plants have high medicinal value, the recognition of them is still at a low level. The aim of this research is to explore the species diversity of cultivable rhizofungi derived from Astragalus acaulis, A. forrestii and A. ernestii growing in a special high-cold environment of northwest Yunnan and discover anti-infective components from these fungi. A total of 93 fungal strains belonging to 38 species in 18 genera were isolated and identified. Antibacterial and antimalarial screening yielded 10 target strains. Among them, the ethyl acetate crude extract of the fermented substrate of the rhizofungus Aspergillus calidoustus AA12 derived from the plant A. acaulis showed broad-spectrum antibacterial activity and the best antimalarial activity. Further chemical investigation led to the first discovery of seven compounds from the species A. calidoustus, including sesterterpine 6-epi-ophiobolin G; three sesquiterpenes, penicisochroman A, pergillin and 7-methyl-2-(1-methylethylethlidene)-furo [3,2-H]isoquinoline-3-one; and three polyketides, trypacidin, 1,2-seco-trypacidin and questin. Among them, the compound 6-epi-ophiobolin G exhibited moderate to strong antibacterial activity against six Gram-positive pathogens with the minimum inhibitory concentration (MIC) ranging from 25 to 6.25 μg/mL and a prominent inhibitory effect on the biofilm of Streptococcus agalactiae at an MIC value of 3.125 μg/mL. This compound also displayed potent antimalarial activity against Plasmodium falciparum strains 3D7 and chloroquine-resistant Dd2 at the half-maximal inhibitory concentration (IC50) values of 3.319 and 4.340 µmol/L at 72 h, respectively. This study contributed to our understanding of the cultivable rhizofungi from characteristic Astragalus plants in special high-cold environments and further increased the library of fungi available for natural anti-infectious product screening.