Early prediction of the bactericidal and bacteriostatic effect of imipenem and doxycycline using tabletop scanning electron microscopy.

Introduction: Our work aims at establishing a proof-of-concept for a method that allows the early prediction of the bactericidal and bacteriostatic effects of antibiotics on bacteria using scanning electron microscopy (SEM) as compared to traditional culture-based methods. Methods: We tested these effects using Imipenem (bactericidal) and Doxycycline (bacteriostatic) with several strains of sensitive and resistant Escherichia coli. We developed a SEM-based predictive score based on three main criteria: Bacterial Density, Morphology/Ultrastructure, and Viability. We determined the results for each of these criteria using SEM micrographs taken with the TM4000Plus II-Tabletop-SEM (Hitachi, Japan) following an optimized, rapid, and automated acquisition and analysis protocol. We compared our method with the traditional culture colony counting gold standard method and classic definitions of the two effects. Results: Our method revealed total agreement with the CFU method and classic definition by visualizing the effect of the antibiotic at 60 minutes and 120 minutes using SEM. Discussion: This early prediction allows a rapid and early identification of the bactericidal and bacteriostatic effects as compared to culture that would take a minimum of 18 hours. This has several future applications in the development of SEM-automated assays coupled to machine learning models that identify the antibiotic effect and facilitate determination of bacterial susceptibility.

Effect of onion skin powder on color, lipid, and protein oxidative stability of premade beef patty during cold storage.

The impact of premade beef patty (BBP) with red onion skin powder (OSP) at 0, 1, 2, and 3% levels on color, lipid, and protein oxidative stability, and infection degree of microorganisms during cold storage was investigated. The objective was to determine the effect of color by L*, a*, b*, and the content of MetMb. The inhibitory effect of OSP on the oxidation of lipid and protein was studied based on TBARS and the carbonyl content of protein in samples at different storage times. TVB-N content was used to characterize the degree of infection of microorganisms and their effect on meat quality. The results showed that the addition of OSP reduced the pH, L *, a*, and b * values of BBP, and improved the hardness, springiness, gumminess, and cohesiveness of BBP, but had no significant effect on the chewiness of BBP (p > 0.05). After 12 days of storage, the carbonyl group and TBARS content in the BBP supplemented with 3%OSP was significantly lower than that in the control group (p < 0.05). Furthermore, the addition of OSP significantly inhibited the TVB-N increase during beef patty storage. These results indicated that OSP has a good research prospect as a natural antioxidant or preservative.

Crystal Structure, Photophysical Properties and Antibacterial Activity of a Cd(II) Complex with Trans-2,3,4-Trimethoxycinnamic Acid and 4,4'-Bipyridine Ligands.

A new coordination polymer {[Cd(C12H13O5)2(4,4'-bpy)(H2O)2]}n (Cd-Tmca-bpy) was constructed with trans-2,3,4-Trimethoxycinnamic acid (HTmca) and 4,4'-Bipyridine (4,4'-bpy) ligands. This complex was structurally characterized on the basis of elemental analysis, infrared (IR) spectroscopy, powder X-ray diffraction and thermogravimetric analyses. X-ray crystallography revealed that the complex was monoclinic, space group C2/c. The Cd(II) ion in the complex was six coordinated, adopting an octahedron geometry. The neighboring Cd(II) ions linked linear ligand 4,4'-bpy molecules to form an infinite 1D chain. The 1D chain was further interlinked by O-H···O and C-H···O hydrogen bonds, resulting in a 3-D supramolecular framework. Meanwhile, the photoluminescence spectrum of the Cd(II) complex at room temperature exhibited an emission maximum at 475 nm. Using the time-dependent density functional theory (TD-DFT) method, the electronic absorption spectra of the Cd(II) complex was predicted. A good agreement was achieved between the predicted spectra and the experimental data. Bioactivity studies showed that the complex exhibited significant inhibition halos against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus).

Biological and genomic characterization of a polyvalent phage PSH-1 against multidrug-resistant Salmonella Enteritidis.

BACKGROUND: Bacteriophage has been renewed attention as a new antibacterial agent due to the limitations of antibiotic treatment. Bacteriophages are generally thought to be highly host specific and even strain specific, but a small number of polyvalent bacteriophages have been found to infect bacteria of different genera. RESULTS: In this study, a virulent lytic bacteriophage (named Salmonella phage PSH-1) of Salmonella Enteritidis was isolated from the sewage samples of a large-scale pig farm, PSH-1 demonstrated lytic activity against four multidrug-resistant Salmonella Enteritidis isolates and Escherichia coli, and then its biological characteristics, genome and bacteriostatic ability were investigated. The results showed that the initial titer of PSH-1 was 1.15 × 1010 PFU/mL and the optimal multiplicity of infection (MOI) was 0.01, PSH-1 has stable activity in the range of pH 3.0-11.0. One-step growth curve showed that its latent period was 20 min, burst time was 80 min, and the burst was 495 particles. The whole-genome sequencing results revealed phage PSH-1 had a linear dsDNA with 48,466 bp length. The G/C content was 45.33%. Non-coding RNA genes and virulence factors were not found. Eighty- five open reading frames (ORFs) were identified after online annotation. By tests, the use of phage could succeed in controlling the artificial Salmonella contamination in milk at a range of temperatures. CONCLUSIONS: This study reports a novel Salmonella Enteritidis phage PSH-1, which has a robust lytic ability, no virulence factors, and good stability. The characterization and genomic analysis of PSH-1 will develop our understanding of phage biology and diversity and provide a potential arsenal for controlling of salmonellosis.

Evaluation of antibacterial activity on nanoline-array surfaces with different spacing.

Extensive research has been conducted on anti-biofouling or antibacterial surfaces, with nanostructured surfaces that mimic cicada and dragonfly wings emerging as promising candidates for mechano-bactericidal applications. These biomimetic nanostructured surfaces are capable of exerting a bactericidal effect by directly damaging the membranes of bacteria attached to nanostructures. Although research on bactericidal effect using various nanostructures have been conducted, no specific studies have yet reported on the antibacterial efficiency of the surface having nanoline array, especially regarding the spacing between nanolines. This study details the fabrication of nanoline array via ultraviolet (UV) molding with polyurethane acrylate (PUA), noted for its UV sensitivity and rapid curing, enabling the fabrication of precise and scalable nanoscale structures. Investigation into the nanoline array's antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reveals that nanoline spacing critically influences bacterial adherence and viability, with specific spacings enhancing antibacterial properties. Scanning electron microscopy (SEM) and confocal microscopy analyses show that surface topography significantly affects bacterial behavior, with specific spacings leading to varied bacterial responses, including membrane damage and altered attachment patterns. The study highlights the potential of nanoline array in fabricating surfaces with tailored antibacterial properties, emphasizing the importance of nanoscale design in influencing bacterial interaction and viability. We also confirm the relative mechanical rigidity of the nanoline array, which exhibits antibacterial effects, through both experimental observations and numerical analysis. This indicates our proposed nanoline-array surface could have potential future applications in mechanical anti-bacterial functions that require such structural robustness.

Surface carcass treatment with olive mill wastewater polyphenolic extract against Salmonella Enteritidis and Listeria monocytogenes: in vitro and in situ assessment.

In recent years, there has been an increased interest in substances that could inhibit or reduce microbial growth in food products. Olive oil industry by-products, due to bioactive compounds with potential antimicrobial properties such as polyphenols, could be used in carcass treatment to enhance hygienic and quality traits. The assessment of the antimicrobial efficacy of bioactive molecules against pathogens should be determined with in vitro and in situ models since it is not possible to evaluate it directly on carcasses at the slaughterhouse. This study aimed to evaluate the effect of an olive mill wastewater polyphenolic extract against Salmonella Enteritidis and Listeria monocytogenes, simulating carcass surfaces using bovine dermis samples that were experimentally contaminated with the selected pathogens. The minimum inhibitory concentration and minimum bactericidal concentration were first determined for S. Enteritidis and L. monocytogenes. In situ, bactericidal activity assessment was performed using 20 cm2 derma samples contaminated with 5 Log CFU/20 cm2 of S. Enteritidis and L. monocytogenes in separate trials. Treatment with the polyphenolic extract was not effective for either microorganism. In order to establish the bacteriostatic activity of the polyphenolic extract, suspensions of about 2 Log CFU/20 cm2 of S. Enteritidis and L. monocytogenes were used. Polyphenolic extract treatment was not effective against Salmonella, while for Listeria it allowed microbial growth to delay (around 1 Log CFU/cm2 difference at 3, 7, and 14 days between treated and control groups). Further investigations are needed to evaluate the application of polyphenolic compounds on carcass surfaces and their effects on sensory traits.

Barnacle-inspired and polyphenol-assisted modification of bacterial cellulose-based wound dressings for promoting infectious wound healing.

Bacterial cellulose (BC) is an ideal candidate for wound dressings due to its natural origin, exceptional water-holding capacity, pliability, biocompatibility, and high absorption capability. However, the lack of essential antimicrobial activity limits its biomedical applications. This study reported BC-based wound dressings containing silk fibroin protein (SF), offering the potential for biomimetic properties, and (-)-epigallocatechin-3-gallate (EGCG) for polyphenol-assisted surface modification to promote infectious wound healing. Glycerol was used as the carbon source to promote the formation of an adhesive layer by facilitating the ß-sheet folding of SF, and different concentrations of EGCG were employed to interact with SF through strong hydrogen bonding facilitated by the polyphenolic groups. The functionalized membrane exhibited outstanding water-holding capacity, swelling ratio, and degradation properties, along with enhanced hydrophilicity, adhesiveness, and a remarkable free radical scavenging ability. Both in vitro and in vivo experiments confirmed its potent bacteriostatic activity. The composite membrane displayed excellent biocompatibility, including cellular and hemocompatibility. Importantly, it effectively promoted wound healing in murine back infections. These findings suggest the significant feasibility of the innovative modification approach, and that functionalized membranes have great potential as wound-dressing materials for infection management in future clinical applications.

[Xiaozheng Granules combined with Jingqiankang Bacteriostatic Gelatin for chronic prostatitis with damp-heat and blood stasis: A clinical observation based on infrared thermography].

OBJECTIVE: To evaluate the clinical efficacy of Xiaozheng Granules (XZG) combined with Jingqiankang Bacteriostatic Gelatin (JBG) on chronic prostatitis of the damp-heat and blood-stasis type based on infrared thermography (IRT). METHODS: This study included 120 cases of chronic prostatitis with damp-heat and blood stasis treated in the First Affiliated Hospital of Henan University of Chinese Medicine with oral XZG (the control group, n = 60) or oral XZG combined with anal administration of JBG (the trial group, n = 60), both for 4 weeks. We obtained the NIH-CPSI and traditional Chinese medicine (TCM) syndrome scores of the patients, measured the temperatures in the belt-vessel, lower focal and inguinal regions by IRT before and after treatment, recorded the adverse reactions during the treatment, and compared them between the two groups of patients. RESULTS: Compared with the baseline, the NIH-CPSI and TCM syndrome scores were significantly decreased in the two groups of patients after treatment (P < 0.05), even more significantly in the trial than in the control group (P < 0.05), and after 1 hour of treatment, the temperatures in the Xiajiao (ï¼»34.09 ± 0.34ï¼½ vs ï¼»33.60 ± 0.40ï¼½ ℃, P < 0.05) and the groin region (ï¼»34.49 ± 0.28ï¼½ vs ï¼»33.78 ± 0.30ï¼½ ℃, P < 0.05) were remarkably reduced in the trial group, but showed no significant change in the control group (Xiajiao region: ï¼»34.02 ± 0.29ï¼½ vs ï¼»34.05 ± 0.26ï¼½ ℃, P > 0.05; groin region: ï¼»34.54 ± 0.25ï¼½ vs ï¼»34.51±0.22ï¼½ ℃, P > 0.05). After 4 weeks of treatment, the temperatures in the Xiajiao and groin regions were even lower in the trial (ï¼»33.13 ± 0.41ï¼½ ℃ and ï¼»33.21 ± 0.29ï¼½ ℃) and the control group (ï¼»33.42±0.25ï¼½ ℃ and ï¼»33.86±0.29ï¼½ ℃) than the baseline and those after 1 hour of treatment (P < 0.05), and still more significantly in the former than in the latter group (P < 0.05). The total effectiveness rate was markedly higher in the trial group than in the control (88.14% vs 77.19%, P < 0.05), and no obvious adverse reactions were observed in neither group. CONCLUSION: XZG combined with JBG is a safe and effective treatment of chronic prostatitis with damp-heat and blood-stasis, which can significantly reduce the NIH-CPSI and TCM syndrome scores and IRT temperatures in the lower focal and inguinal regions of the patients.

Pantothenate kinase: A promising therapeutic target against pathogenic Clostridium species.

Current treatment of clostridial infections includes broad-spectrum antibiotics and antitoxins, yet antitoxins are ineffective against all Clostridiumspecies. Moreover, rising antimicrobial resistance (AMR) threatens treatment effectiveness and public health. This study therefore aimed to discover a common drug target for four pathogenic clostridial species, Clostridium botulinum, C. difficile, C. tetani, and C. perfringens through an in-silico core genomic approach. Using four reference genomes of C. botulinum, C. difficile, C. tetani, and C. perfringens, we identified 1484 core genomic proteins (371/genome) and screened them for potential drug targets. Through a subtractive approach, four core proteins were finally identified as drug targets, represented by type III pantothenate kinase (CoaX) and, selected for further analyses. Interestingly, the CoaX is involved in the phosphorylation of pantothenate (vitamin B5), which is a critical precursor for coenzyme A (CoA) biosynthesis. Investigation of druggability analysis on the identified drug target reinforces CoaX as a promising novel drug target for the selected Clostridium species. During the molecular screening of 1201 compounds, a known agonist drug compound (Vibegron) showed strong inhibitory activity against targeted clostridial CoaX. Additionally, we identified tazobactam, a beta-lactamase inhibitor, as effective against the newly proposed target, CoaX. Therefore, identifying CoaX as a single drug target effective against all four clostridial pathogens presents a valuable opportunity to develop a cost-effective treatment for multispecies clostridial infections.

The many dimensions of combination therapy: How to combine antibiotics to limit resistance evolution.

In combination therapy, bacteria are challenged with two or more antibiotics simultaneously. Ideally, separate mutations are required to adapt to each of them, which is a priori expected to hinder the evolution of full resistance. Yet, the success of this strategy ultimately depends on how well the combination controls the growth of bacteria with and without resistance mutations. To design a combination treatment, we need to choose drugs and their doses and decide how many drugs get mixed. Which combinations are good? To answer this question, we set up a stochastic pharmacodynamic model and determine the probability to successfully eradicate a bacterial population. We consider bacteriostatic and two types of bactericidal drugs-those that kill independent of replication and those that kill during replication. To establish results for a null model, we consider non-interacting drugs and implement the two most common models for drug independence-Loewe additivity and Bliss independence. Our results show that combination therapy is almost always better in limiting the evolution of resistance than administering just one drug, even though we keep the total drug dose constant for a 'fair' comparison. Yet, exceptions exist for drugs with steep dose-response curves. Combining a bacteriostatic and a bactericidal drug which can kill non-replicating cells is particularly beneficial. Our results suggest that a 50:50 drug ratio-even if not always optimal-is usually a good and safe choice. Applying three or four drugs is beneficial for treatment of strains with large mutation rates but adding more drugs otherwise only provides a marginal benefit or even a disadvantage. By systematically addressing key elements of treatment design, our study provides a basis for future models which take further factors into account. It also highlights conceptual challenges with translating the traditional concepts of drug independence to the single-cell level.

Modification of polyvinylidene fluoride membrane with ciprofloxacin to improve the bacteriostatic performance.

The common polyvinylidene fluoride (PVDF) membrane itself is susceptible to membrane fouling, especially biofouling, which is a serious threat. In this study, PVDF membrane was modified with ciprofloxacin (CIP) through co-blending to investigate the filtration properties, bacterial inhibition and fouling resistance. Modified membranes were prepared by adding 0.3 g (MC0.3), 0.6 g (MC0.6), 0.9 g (MC0.9) and 1.2 g (MC1.2) CIP per 100 g casting solution. Among these modified membranes, MC0.6 showed the best filtration performances, with the pure water flux stabilized at about 416.67 L/(m2·h) and bovine serum albumin (BSA) rejection of 92.0% at a trans-membrane pressure of 0.1 MPa. The pore size was reduced, the average roughness was reduced to 29.4 nm, the contact angle was lowered to 68.9°, and the hydrophilicity was greatly improved. The width of the inhibition circle produced by MC0.6 was 0.35-0.45 mm, and the modified membrane showed good inhibition of non-specific bacteria and algal removal during urban river water filtration. The rejection of BSA was increased by 16.32% compared to the base membrane and the adsorption rate for BSA was reduced by 68.45%. In addition, the removal of conventional pollutants in urban river water by the modified membranes for was also improved. Compared with that of the base membrane, the removal of TN, NH3-N, TP and COD by MC0.6 was increased by 10.58%, 12.45%, 15.44% and 13.53%. The results showed that CIP co-blending modified PVDF membrane could effectively improve membrane performances and has good value for water treatment.

Synthesis and antibacterial effects of silver nanoparticles (AgNPs) against multi-drug resistant bacteria.

BACKGROUND: The emergence of the global problem of multi-drug resistant bacteria (MDR) is closely related to the improper use of antibiotics, which gives birth to an urgent need for antimicrobial innovation in the medical and health field. Silver nanoparticles (AgNPs) show significant antibacterial potential because of their unique physical and chemical properties. By accurately regulating the morphology, size and surface properties of AgNPs, the antibacterial properties of AgNPs can be effectively enhanced and become a next generation antibacterial material with great development potential. OBJECTIVE: The detection of the inhibitory effect of AgNPs on MDR provides more possibilities for the research and development of new antimicrobial agents. METHODS: Promote the formation of AgNPs by redox reaction; determine the minimum inhibitory concentration (MIC) of AgNPs to bacteria by broth microdilution method; evaluate the killing efficacy of AgNPs against multi-drug-resistant bacteria by plate counting; evaluate the inhibitory effect of AgNPs on biofilm construction by crystal violet staining; study the drug resistance of bacteria by gradually increasing the concentration of AgNPs; and detect the toxicity of AgNPs to cells by CCK-8 method. RESULTS: AgNPs has a significant bactericidal effect on a variety of drug-resistant bacteria. After exposure to AgNPs solution for 12 hours, the number of E. coli decreased sharply, and S. aureus was basically eliminated after 16 hours. In particular, AgNPs showed stronger inhibition against Gram-negative bacteria. In addition, AgNPs can effectively hinder the formation of bacterial biofilm, and its inhibitory effect increases with the increase of AgNPs solution concentration. When AgNPs is used for a long time, the development of bacterial resistance to it is slow. From the point of view of safety, AgNPs has no harmful effects on organisms and has biosafety. CONCLUSION: AgNPs can inhibit MDR, and the bacteriostatic ability of Gram-negative bacteria is higher than that of Gram-positive bacteria. It can also inhibit the formation of bacterial biofilm, avoid drug resistance and reduce cytotoxicity.

Physiological Microenvironment Dependent Self-Cross-Linking of Multifunctional Nanohybrid for Prolonged Antibacterial Therapy via Synergistic Chemodynamic-Photothermal-Biological Processes.

Herein, a multifunctional nanohybrid (PL@HPFTM nanoparticles) was fabricated to perform the integration of chemodynamic therapy, photothermal therapy, and biological therapy over the long term at a designed location for continuous antibacterial applications. The PL@HPFTM nanoparticles consisted of a polydopamine/hemoglobin/Fe2+ nanocomplex with comodification of tetrazole/alkene groups on the surface as well as coloading of antimicrobial peptides and luminol in the core. During therapy, the PL@HPFTM nanoparticles would selectively cross-link to surrounding bacteria via tetrazole/alkene cycloaddition under chemiluminescence produced by the reaction between luminol and overexpressed H2O2 at the infected area. The resulting PL@HPFTM network not only significantly damaged bacteria by Fe2+-catalyzed ROS production, effective photothermal conversion, and sustained release of antimicrobial peptides but dramatically enhanced the retention time of these therapeutic agents for prolonged antibacterial therapy. Both in vitro and in vivo results have shown that our PL@HPFTM nanoparticles have much higher bactericidal efficiency and remarkably longer periods of validity than free antibacterial nanoparticles.

A non-antibiotic antimicrobial drug, a biological bacteriostatic agent, is useful for treating aerobic vaginitis, bacterial vaginosis, and vulvovaginal candidiasis.

Background: Vaginitis is a common infection in women, with approximately 75% of women experiencing at least one episode during their lifetime. Although antimicrobial agents are widely used to treat vaginitis, recurrent vaginitis occurs in some patients. Resistance to these agents is the major cause of recurrent vaginitis. Therefore, there is an urgent need to develop novel drugs. Methods: We investigated the efficacy of a new biological bacteriostatic agent (BBA), composed of lysozyme, phytoalexin, chitosan oligosaccharide, sinensetin, 18ß/20α-glycyrrhizin, and betaine, against vaginitis using in vitro and in vivo studies. First, we evaluated the antibacterial effects of BBA against 13 microbial strains commonly present in aerobic vaginitis, bacterial vaginosis, vulvovaginal candidiasis, and healthy vaginas. Second, we assessed the safety of various doses of BBA administered orally for 4 weeks in female mice. Third, we examined the in vivo anti-proliferative and anti-inflammatory effects of BBA in Candida albicans-, Candida glabrata-, and Gardnerella-induced vaginitis models. Finally, we evaluated the anti-vaginitis effect of a BBA gel prepared with 0.5% (w/v) ammonium acryloyldimethyltaurate/Vp copolymer. Results: BBA effectively suppressed the growth of the main causative pathogens of vaginitis in vitro. BBA, either undiluted or diluted two-fold, inhibited all microorganisms cultured for 8 h. No obvious organ damage was detected when BBA was administered to mice. Both BBA alone and 70% BBA in a gel formulation effectively inhibited the proliferation of C. albicans, C. glabrata, and Gardnerella in vaginal lavage samples and alleviated tissue inflammation in mice with vaginitis. The 70% BBA gel performed better than BBA alone at treating vaginitis in mice infected with Gardnerella vaginalis. Conclusion: BBA alone and a 70% BBA gel inhibited the growth of pathogens and effectively alleviated inflammation caused by C. albicans, C. glabrata, and G. vaginalis.

Carbohydrate-Binding Properties and Antimicrobial and Anticancer Potential of a New Lectin from the Phloem Sap of Cucurbita pepo.

A Cucurbita phloem exudate lectin (CPL) from summer squash (Cucurbita pepo) fruits was isolated and its sugar-binding properties and biological activities were studied. The lectin was purified by affinity chromatography and the hemagglutination assay method was used to determine its pH, heat stability, metal-dependency and sugar specificity. Antimicrobial and anticancer activities were also studied by disc diffusion assays and in vivo and in vitro methods. The molecular weight of CPL was 30 ± 1 KDa and it was stable at different pH (5.0 to 9.0) and temperatures (30 to 60 °C). CPL recovered its hemagglutination activity in the presence of Ca2+. 4-nitrophenyl-α-D-glucopyranoside, lactose, rhamnose and N-acetyl-D-glucosamine strongly inhibited the activity. With an LC50 value of 265 µg/mL, CPL was moderately toxic and exhibited bacteriostatic, bactericidal and antibiofilm activities against different pathogenic bacteria. It also exhibited marked antifungal activity against Aspergillus niger and agglutinated A. flavus spores. In vivo antiproliferative activity against Ehrlich ascites carcinoma (EAC) cells in Swiss albino mice was observed when CPL exerted 36.44% and 66.66% growth inhibition at doses of 3.0 mg/kg/day and 6.0 mg/kg/day, respectively. A 12-day treatment by CPL could reverse their RBC and WBC counts as well as restore the hemoglobin percentage to normal levels. The MTT assay of CPL performed against human breast (MCF-7) and lung (A-549) cancer cell lines showed 29.53% and 18.30% of inhibitory activity at concentrations of 128 and 256 µg/mL, respectively.

Magnetic separation, sunlight-driven photocatalytic activity, and antibacterial studies of Sm-doped Co0.33Mg0.33Ni0.33Fe2O4 nanoparticles.

Magnetic nanoparticles have emerged as a promising tool for wastewater treatment due to their unique properties. In this regard, Co0.33Mg0.33Ni0.33SmxFe2-xO4 (0.00 ≤ x ≤ 0.08) nanoparticles were prepared to examine their magnetic separation efficiency (MSE), photocatalytic, antibacterial, and antibiofilm performances. Pure nanoparticles, having the highest saturation magnetization (Ms = 31.87 emu/g), exhibit the highest MSE, where 95.6% of nanoparticles were separated after 20 min of applying a magnetic field of 150 mT. The catalytic performance of the prepared samples is examined by the photodegradation of rhodamine B (RhB) dye exposed to direct sunlight radiation. Improved photocatalytic activity is exhibited by Co0.33Mg0.33Ni0.33Sm0.04Fe1.96O4 nanoparticles, labeled as Sm0.04, where the rate of the degradation reaction is enhanced by 4.1 times compared to pure nanoparticles. Rising the pH and reaction temperature improves the rate of the photodegradation reaction of RhB. The incorporation of 15 wt% reduced graphene oxide (rGO) with Sm0.04 enhanced the rate of the reaction by 1.7 and 2.4 times compared with pure Sm0.04 sample and rGO, respectively. The antibacterial and antibiofilm activities against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus, and Enterococcus faecium are assessed by the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) broth microdilution, the agar well diffusion, the time-kill assays, the biofilm formation, and destruction assays. The bacteria used in these assessments are isolated from wastewater. The nanoparticles exhibit a bacteriostatic activity, with a better effect against the Gram-positive isolates. Co0.33Mg0.33Ni0.33SmxFe2O4 (x = 0.00) nanoparticles have the best effect. The effect is exerted after 2-3 h of incubation. Gram-positive biofilms are more sensitive to nanoparticles.

Charge Effect of Mercaptobenzimidazole-Modified Ultrasmall Gold-Nanoparticles against Drug-Resistant Bacteria.

The threat of bacterial infections, especially drug-resistant strains, to human health necessitates the development of high-efficient, broad-spectrum and nonantibiotic nanodisinfectant. However, the effect of interfacial charge on the antibacterial properties of nanodisinfectant remains a mystery, which greatly limits the development of highly antibacterial active nanodisinfectant. Herein, we developed three types of ultrasmall (d < 3 nm) gold-nanoparticles (AuNPs) modified with 5-carboxylic(C)/methoxy(M)amino(A)/-2-mercaptobenzimidazole (C/M/A MB) to investigate their interfacial charge on antibacterial performance. Our results showed that both the electropositive AMB-AuNPs and electronegative CMB-AuNPs exhibited no antibacterial activity against both Gram-positive (G+) and Gram-negative (G-) bacteria. However, the electroneutral MMB-AuNPs exhibited unique antibacterial performance against both G+ and G- bacteria, even against methicillin-resistant Staphylococcus aureus (MRSA). Mechanistic investigation revealed a multipathway synergistic bacteriostatic mechanism involving MMB-AuNPs inducing damage to bacterial cell membranes, disruption of membrane potential and downregulation of ATP levels, ultimately leading to bacterial demise. Furthermore, two additional electroneutral AuNPs modified with 5-methyl-2-mercaptobenzimidazole (mMB-AuNPs) and 5-ethoxy-2-mercaptobenzimidazole (EMB-AuNPs) also demonstrated commendable antibacterial efficacy against E. coli, S. aureus, and MRSA; however, their performance was comparatively inferior to that of MMB-AuNPs. This work provides valuable insights for the development of high-performance antibacterial nanomaterials.

Isolation and Biological Characteristics of a Novel Phage and Its Application to Control Vibrio Parahaemolyticus in Shellfish Meat.

Vibrio parahaemolyticus is a common foodborne pathogenic bacterium. With the overuse of antibiotics, an increasing proportion of drug-resistant strains are emerging, which puts enormous pressure on public health. In this study, a V. parahaemolyticus-specific phage, VP41s3, was isolated. The head length, width, and tail length of the phage were 77.7 nm, 72.2 nm, and 17.5 nm, respectively. It remained active in the temperature range of 30-50°C and pH range of 4-11. The lytic curve of phage VP41s3 showed that the host bacteria did not grow until 11 h under phage treatment at MOI of 1000, indicating that the phage had good bacteriostatic ability. When it was added to shellfish contaminated with V. parahaemolyticus (15°C, 48 h), the number of bacteria in the experimental group was 2.11 log10 CFU/mL lower than that in the control group at 24 h. Furthermore, genomic characterization and phylogenetic analysis indicated that phage VP41s3 was a new member of the Podoviridae family. The genome contained 50 open reading frames (ORFs), in which the ORF19 (thymidine kinase) was an enzyme involved in the pyrimidine salvage pathway, which might lead to the accelerated DNA synthesis efficiency after phage entered into host cells. This study not only contributed to the improvement of phage database and the development of beneficial phage resources but also revealed the potential application of phage VP41s3 in food hygiene and safety.

Daptomycin Liposomes Exhibit Enhanced Activity against Staphylococci Biofilms Compared to Free Drug.

The purpose of the present study was to investigate the anti-staphylococcal activity of liposomal daptomycin against four biofilm-producing S. aureus and S. epidermidis clinical strains, three of which are methicillin-resistant. Neutral and negatively charged daptomycin-loaded liposomes were prepared using three methods, namely, thin-film hydration (TFH), a dehydration-rehydration vesicle (DRV) method, and microfluidic mixing (MM); moreover, they were characterized for drug encapsulation (EE%), size distribution, zeta-potential, vesicle stability, drug release, and drug integrity. Interestingly, whilst drug loading in THF and DRV nanosized (by extrusion) vesicles was around 30-35, very low loading (~4%) was possible in MM vesicles, requiring further explanatory investigations. Liposomal encapsulation protected daptomycin from degradation and preserved its bioactivity. Biofilm mass (crystal violet, CV), biofilm viability (MTT), and growth curve (GC) assays evaluated the antimicrobial activity of neutral and negatively charged daptomycin-liposomes towards planktonic bacteria and biofilms. Neutral liposomes exhibited dramatically enhanced inhibition of bacterial growth (compared to the free drug) for all species studied, while negatively charged liposomes were totally inactive. Biofilm prevention and treatment studies revealed high antibiofilm activity of liposomal daptomycin. Neutral liposomes were more active for prevention and negative charge ones for treating established biofilms. Planktonic bacteria as well as the matured biofilms of low daptomycin-susceptible, methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE) strains were almost completely eradicated by liposomal-daptomycin, indicating the need for their further exploration as antimicrobial therapeutics.

Antibacterial Activity of Plants in Cirsium: A Comprehensive Review.

As ethnic medicine, the whole grass of plants in Cirsium was used as antimicrobial. This review focuses on the antimicrobial activity of plants in Cirsium, including antimicrobial components, against different types of microbes and bacteriostatic mechanism. The results showed that the main antimicrobial activity components in Cirsium plants were flavonoids, triterpenoids and phenolic acids, and the antimicrobial ability varied according to the species and the content of chemicals. Among them, phenolic acids showed a strong antibacterial ability against Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterococcus faecium. The antibacterial mechanisms include: (1) damaging the cell membrane, cell walls, mitochondria and nucleus of bacteria; (2) inhibiting the synthesis of proteins and nucleic acids; (3) suppressing the synthesis of enzymes for tricarboxylic acid cycle pathways and glycolysis, and then killing the bacteria via inhibition of energy production. Totally, most research results on antimicrobial activity of Cirsium plants are reported based on in vitro assays. The evidence from clinical data and comprehensive evaluation are needed.