Minimum Bactericidal Concentration Research Articles

Biosynthesis; Characterization; and Antibacterial, Antioxidant, and Docking Potentials of Doped Silver Nanoparticles Synthesized from Pine Needle Leaf Extract

The current study focused on the synthesis of doped silver nanoparticles (doped AgNPs) with yttrium (Y), gadolinium (Gd), and chromium (Cr) from pine needle leaf extract (PNLE). X-ray diffraction (XRD) was performed to assess the phase formation, detecting 61.83% from Ag and 38.17% for secondary phases of AgCl, AgO, Y, Cr-, and Gd phases. The size and shape of the NPs were determined by transmission electron microscopy (TEM), showing a spherical shape with an average particle size of 26.43 nm. X-ray photoelectron spectroscopy (XPS) detected the oxidation state of the presented elements. The scanning electron microscope (SEM) and the energy-dispersive X-ray analysis (EDX) determined the morphology and elemental composition of the NPs, respectively. Fourier transform infrared spectroscopy (FTIR) determined the different functional groups indicating the presence of Ag, Y, Gd, Cr, and other groups. Photoluminescence (PL) spectroscopy showed the optical properties of the NPs. A vibrating sample magnetometer (VSM) revealed the ferromagnetic behavior of the doped AgNPs. The antibacterial activity of the doped AgNPs was tested against six uro-pathogenic bacteria (Staphylococcus aureus, Staphylococcus haemolyticus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa) using the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) microdilution assays, agar well diffusion assay, time–kill test, and antibiofilm screening assays, revealing significant activity, with MICs ranging between 0.0625 and 0.5 mg/mL and antibiofilm activity between 40 and 85%. The antioxidant activity was determined by the 1,1, diphenyl 1-2 picrylhydrazyl (DPPH) radical scavenging assay with a potential of 61.3%. The docking studies showed that the doped AgNPs had the potential to predict the inhibition of crucial enzymes such as penicillin-binding proteins, LasR-binding proteins, carbapenemase, DNA gyrase, and dihydropteroate synthase. The results suggest that the doped AgNPs can be applied in different medical domains.

Exploring the Antibacterial Properties and Chemical Profiles of Essential Oils from Syzygium aromaticum and Nigella sativa Against MDR Bacteria

For centuries, plants have been studied for their healing properties. Recently, the rise of antibiotic resistance in bacteria has prompted scientists to explore herbal remedies. Syzygium aromaticum, from the Myrtaceae family, has been utilized as a histological clearing agent. In contrast, Nigella sativa (black cumin), a member of the Ranunculaceae family, has long been utilized in traditional medicine dating back to ancient times. The current study investigates the chemical composition and antibacterial activity of essential oils from Syzygium aromaticum (clove) and Nigella sativa (black cumin) against multidrug-resistant (MDR) bacteria. Using the agar well diffusion method, Syzygium aromaticum exhibited significant antibacterial activity, particularly against Salmonella typhi (30.66 mm inhibition zone), while Nigella sativa was effective only against Staphylococcus aureus (19 mm). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for Syzygium aromaticum ranged from 3.53 to 7.06 mg/mL, indicating stronger antibacterial properties than Nigella sativa (MIC: 12.7 mg/mL, MBC: 22.5 mg/mL). GC-MS analysis revealed that Syzygium aromaticum contained bioactive compounds like Diglycolic acid (76.59%) and Eugenol (2.06%), while Nigella sativa was dominated by Heptasiloxane (80.83%) and Thymoquinone (2.66%). These findings suggest that Syzygium aromaticum essential oil could serve as a potent natural antimicrobial agent against MDR pathogens.

ANTIOXIDANT, INHIBITION OF ADVANCED GLYCATION END-PRODUCT FORMATION AND ANTIMICROBIAL ACTIVITIES OF OCIMUM GRATISSIMUM (SCENT LEAF) METHANOLIC LEAF EXTRACT AGAINST Escherichia coli AND Bacillus SPP

The study investigates the antioxidant, inhibition of advanced glycation end-product formation and antimicrobial activities of methanolic leaf extract of Ocimum gratissimum. GC-MS, qualitative, antioxidant scavenging and antiglycation activities of the extract of Ocimum gratissimum were determined using standard procedures. The antimicrobial activity was evaluated by agar well diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using standard methods. The GC-MS analysis of Ocimum gratissimum leaf revealed the presence of 49 compounds with P –cymene been the most abundant. The phytochemical screening of the extract shows the presence of alkaloids, tannins, phenolic, flavonoids, saponins etc. The in-vitro antioxidant assay of the extract was found to have ?-carotene, lycopene, total phenolic compounds, total flavonoid compounds, reducing power and DPPH scavenging activities. The extract showed significant inhibitory effects on the formation of compounds containing two carbonyl groups and Advanced Glycated End products formation with IC50 of 75.85 ±4.87 µg/mL. Agar well diffusion assay was characterized by inhibition zones of 21.0 ± 0.30, 19.66 ± 0.20, 33.78± 0.30 and 33.25 ± 0.40 mm for Escherichia coli and Bacillus spp respectively at 250 mg/ml for Ocimum gratissimum and 25 mg/ml for tetracycline solution. The MIC values for E.coli and Bacillus spp were 33.33, 66.67, 0.78 and 0.78 for both extract and tetracycline while their MBC values were 66.67, 133.00, 1.56 and 1.56 respectively. MBC/ MIC values showed that Ocimum gratissimum extract and tetracycline had bactericidal effects. These results indicated that Ocimum gratissimum possesses antioxidant, prevents glycation and has antimicrobial activities.

The antimicrobial and antibiofilm effects of gentamicin, imipenem, and fucoidan combinations against dual-species biofilms of Staphylococcus aureus and Acinetobacter baumannii isolated from diabetic foot ulcers.

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia due to impaired insulin production or utilization, leading to severe health complications. Diabetic foot ulcers (DFUs) represent a major complication, often exacerbated by polymicrobial infections involving Staphylococcus aureus and Acinetobacter baumannii. These pathogens, notorious for their resistance to antibiotics, complicate treatment efforts, especially due to biofilm formation, which enhances bacterial survival and resistance. This study explores the synergistic effects of combining gentamicin, imipenem, and fucoidan, a sulfated polysaccharide with antimicrobial properties, against both planktonic and biofilm forms of S. aureus and A. baumannii. Isolates of S. aureus and A. baumannii were collected from DFUs and genetically confirmed. Methicillin resistance in S. aureus was identified through disk diffusion and PCR. Biofilm formation, including dual-species biofilms, was analyzed using the microtiter plate method. The antimicrobial efficacy of gentamicin, imipenem, and fucoidan was assessed by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC). Synergistic interactions were evaluated using the fractional inhibitory concentration index (FICi) and fractional bactericidal concentration index (FBCi). The expression of biofilm-associated genes (icaA in S. aureus and bap in A. baumannii) was analyzed, and the cytotoxicity of fucoidan was assessed. The study revealed that 77.4% of S. aureus and all A. baumannii isolates showed multidrug resistance. Among 837 tested conditions for dual-species biofilm formation, 72 resulted in strong biofilm formation and 67 in moderate biofilm formation. The geometric mean MIC values for gentamicin were 12.2µg/mL for S. aureus, 22.62µg/mL for A. baumannii, and 5.87µg/mL for their co-culture; for imipenem, they were 19.84, 9.18, and 3.70µg/mL, respectively, and for fucoidan, 48.50, 31.20, and 19.65µg/mL, respectively. The MBC values for gentamicin were 119.42, 128, and 11.75µg/mL; for imipenem, they were 48.50, 14.92, and 8µg/mL; and for fucoidan, they were 88.37, 62.62, and 42.48µg/mL. The MBIC values were 55.71, 119.42, and 18.66µg/mL for gentamicin; 68.59, 48.50, and 25.39µg/mL for imipenem; and 153.89, 101.49, and 53.53µg/mL for fucoidan. The MBEC values were 315.17, 362.03, and 59.25µg/mL for gentamicin; 207.93, 157.58, and 74.65µg/mL for imipenem; and 353.55, 189.46, and 99.19µg/mL for fucoidan. When cultured in planktonic form, the geometric mean FICi and FBCi values indicated additive effects, while co-culture showed FICi values of ≤ 0.5, suggesting a synergistic interaction. Treatment with gentamicin and fucoidan led to significant downregulation of the icaA and bap genes in both single-species and dual-species biofilms of S. aureus and A. baumannii. The reductions in gene expression were more pronounced in dual-species biofilms compared to single-species biofilms. Additionally, treatment with imipenem and fucoidan also resulted in significant downregulation of these genes in both biofilm types. Cytotoxicity assessments indicated that higher concentrations of fucoidan were toxic, yet no harmful effects were noted at the optimal synergistic concentrations used with antibiotics. In our investigation, we found that combining gentamicin, imipenem, and fucoidan had a synergistic effect on dual-species biofilms of S. aureus and A. baumannii, suggesting potential benefits for treating such infections effectively. This underscores the importance of understanding microbial interactions, antibiotic susceptibility, and biofilm formation in DFUs.

Doxifluridine effectively kills antibiotic-resistant Staphylococcus aureus in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality globally, often exacerbated by infections such as methicillin-resistant Staphylococcus aureus (MRSA). The rise in antibiotic-resistant strains complicates treatment and underscores the need for novel therapeutic drugs. In this paper, we further investigated the antimicrobial potential of a fluoropyrimidine anticancer drug doxifluridine against multidrug-resistant S. aureus. Determination of minimum inhibitory concentration (MIC) or minimum bactericidal concentration (MBC), monitoring of growth curve, time-kill assays, biofilm bactericidal assays, and chequerboard studies were conducted to evaluate the antibacterial efficacy of doxifluridine. Safety was assessed via hemolysis and cytotoxicity assays, and an in vivo Galleria mellonella larvae model was employed to test protective effects. Doxifluridine demonstrated significant antibacterial activity against clinical multidrug resistance (MDR) S. aureus isolates, with MIC and MBC values ranging from 0.5 to 2 µg/mL and 1 to 4 µg/mL, respectively. The results revealed doxifluridine's potent bactericidal effects within 8 hours. Moreover, doxifluridine-treated bacteria showed a substantial reduction in biofilm mass and viability. Furthermore, chequerboard assays indicated synergistic interactions between doxifluridine and other antibiotics, reducing MIC values by two- to eightfold. More importantly, safety evaluations confirmed that doxifluridine did not exhibit hemolytic toxicity or cytotoxicity. Finally, doxifluridine significantly increased the survival rate of MRSA-infected G. mellonella larvae in vivo. In brief, doxifluridine exhibited promising in vitro and in vivo antibacterial activity against MRSA, suggesting its potential as a repurposed drug for treating resistant bacterial infections in COPD patients.IMPORTANCEThe study provides robust evidence for the antibacterial efficacy of doxifluridine against Methicillin-resistant Staphylococcus aureus in chronic obstructive pulmonary disease (COPD) patients. Its rapid action, ability to disrupt biofilms, and synergistic effects with other antibiotics, combined with a favorable safety profile, highlight its potential as a repurposed therapeutic agent. Future clinical trials will be essential to confirm these findings and pave the way for its integration into clinical practice. This work not only provides candidate for tackling the management of bacterial infections in COPD but also exemplifies the potential of drug repurposing in combating antibiotic-resistant infections.

Physicochemical and Antimicrobial Properties of Lactic Acid-Based Natural Deep Eutectic Solvents as a Function of Water Content

The interest in natural deep eutectic solvents (NADESs) in green technology as an alternative to organic solvents has grown over the past decades. In this work, for the first time, the effect of dilution with water on the physicochemical and antimicrobial properties of lactic acid-based NADES with choline chloride (NADES1), sorbitol (NADES2), and glucose (NADES3) was systematically studied. According to FTIR data, after the dilution of NADESs with water, the strong hydrogen bonds weakened, however, were not destroyed after dilution of up to 40% water. The dilution of NADES with water resulted in a linear decrease in density and refractive index and in a linear increase in pH. The equations for the prediction of NADES density, pH, and refractive index as a function of water content were calculated. The viscosity decreased by half after adding approximately 10% water. The initial viscosity of NADES2 and NADES3 was significantly different. However, after adding 20% of the water, the viscosity was almost the same. The most pronounced decrease in surface tension (by 46.7%) was found for NADES1. The water activity was decreased in the following order: NADES3 > NADES1 > NADES2. The dilution of NADES with water caused a gradual increase in water activity. NADES1 showed the lowest minimal inhibitory concentrations (MIC) (7.8, 3.9, and 0.98 mg/mL) and minimum bactericidal concentrations (MBC) (15.6, 7.8, and 1.95 mg/mL) for Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, respectively. The antimicrobial activity was decreased by 2–8 times after the addition of 40% water. The water activity for all tested NADES together with low pH could explain the antimicrobial effect. The revealed regularity can be useful for the prediction of NADES properties and for the selection of green solvents on a laboratory and industrial scale.

The in vitro Study of the Synergistic Antibacterial Effect of Hydroalcoholic Mentha Extract with Alum on the Growth of Streptococcus mutans

: Antimicrobial resistance poses a significant global health challenge, necessitating the search for novel therapeutic approaches. Streptococcus mutans, a key etiological agent in dental caries, requires innovative strategies due to its biofilm-forming ability and resistance to conventional antibiotics. Natural plant-derived compounds have garnered attention as potential antimicrobial agents with a low risk of resistance development. In this study, we investigated the synergistic antibacterial effect of a hydroalcoholic Mentha extract combined with alum against Streptococcus mutans (PTCC 16836). The well diffusion assay demonstrated that alum exhibited a larger inhibition zone diameter (12.04 ± 2.02 mm) compared to the hydroalcoholic Mentha extract (10.33 ± 1.53 mm). However, the minimum inhibitory concentration (MIC) values for the hydroalcoholic Mentha extract (8.20 ± 5.57 mg/mL) and alum (0.35 ± 0.20 mg/mL) were comparable. The minimum bactericidal concentration (MBC) for the hydroalcoholic Mentha extract was 10 mg/mL, while the MBC for alum was 0.625 ± 0.006 mg/mL. The combination of these substances demonstrated a synergistic effect, indicating enhanced antibacterial activity against Streptococcus mutans. The study's findings suggest potential applications in dentistry, offering a natural and effective adjunctive treatment for dental caries management. The underlying mechanisms of this synergistic effect warrant further exploration. To translate these promising findings into clinical applications, further in vivo investigations and rigorously designed clinical trials are necessary to establish the safety and efficacy of this combination therapy. The natural origin of these substances may provide an environmentally sustainable and cost-effective approach in the fight against antimicrobial resistance.

Ginger Essential Oil Exerts Antibacterial Activity Against Shewanella putrefaciens by Disrupting Cell Structure and Resisting Biofilm

ABSTRACTThis study aimed to elucidate the antibacterial mechanism and antibiofilm activity of ginger essential oil (GEO) against Shewanella putrefaciens. On the basis of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), alkaline phosphatase (AKPase), succinate dehydrogenase (SDH), and glucose‐6‐phosphate dehydrogenase (G6PDH) activities were analyzed to evaluate the damage degree of S. putrefaciens on cell wall and membrane, and the microstructure was observed by scanning electron microscope (SEM) to evaluate the action effect against S. putrefaciens. The results showed that the MIC and MBC of GEO against S. putrefaciens were 27.8125 mg/mL and 55.625 mg/mL, respectively. The surface structures and cell membrane of S. putrefaciens were rigorously damaged by 1 MIC and 2 MIC GEO, leading to the leakage of cellular nucleic acids, protein, and β‐galactosidases from the bacterial cells. GEO could not only decrease the biomass of biofilm but also remove mature biofilm. In addition, GEO could reduce the production of exopolysaccharides and extracellular proteins, and could lessen the metabolic activity of biofilm cells. These results demonstrated that GEO exhibited efficient antibacterial characteristics against S. putrefaciens, which could act as a natural antibacterial and antibiofilm agent on the preservation of aquatic products.

Microbiological Characteristics of Beef Sausage Enriched With Roselle (Hibiscus sabdariffa L.) Sepal Extract

ABSTRACTAdding plant extracts to sausage and other meat products is very important to improve their quality, safety, and durability. The aim of this study was to evaluate the microbiological properties of beef sausage enriched with roselle (Hibiscus sabdariffa L.) sepal extract. The total content of phenolic and flavonoid compounds in hydroalcoholic extract of Roselle sepals was measured by Folin‐Ciocalteu test and aluminum chloride colorimetric method, and antioxidant activity was measured by DPPH method. Pectin was used to encapsulate the extract. The characteristics of capsules, including particle size, zeta potential, and capsule efficiency were measured. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of extracts were performed by tube dilution method. Microbial tests were performed on sausage treatment samples. Analysis of the obtained data was done using SPSS and Excel software. The study revealed that the total phenolic and flavonoid compounds in the extract were 174.6 mg of gallic acid per gram and 16.8368 mg of quercetin, respectively. The extract displayed the highest antioxidant activity at elevated concentrations. Particle size ranged from 16.833 to 640.534 μm. The zeta potential and capsule efficiency were found to be satisfactory. Compared to the encapsulated extract, the free roselle extract better inhibited Staphylococcus aureus (s. aureus), Salmonella typhimurium (S. typhimurium), and Escherichia coli (E.coli). During storage until day 20, these bacteria did not grow in the free or encapsulated extract groups. However, S. aureus appeared in the free extract group from day 25 and the encapsulated extract group from day 20. Roselle extract has antimicrobial properties that can improve the quality and safety of beef sausage during storage.

Surface-functionalized UIO-66-NH2 for dual-drug delivery of vancomycin and amikacin against vancomycin-resistant Staphylococcus aureus

BackgroundConventional antibacterial compounds can inhibit the growth of microorganisms, but their adverse effects and the development of drug limit their widespread use. The current study aimed to synthesize PEG-coated UIO-66-NH2 nanoparticles loaded with vancomycin and amikacin (VAN/AMK-UIO-66-NH2@PEG) and evaluate their antibacterial and anti-biofilm activities against vancomycin-resistant Staphylococcus aureus (VRSA) clinical isolates.MethodsThe VAN/AMK-UIO-66-NH2@PEG were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) to determine their size, polydispersity index (PDI), encapsulation efficiency (EE%), zeta-potential, drug release profile, and physical stability. Antibacterial activity was evaluated using minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill assays. Biofilm formation by VRSA was assessed using the crystal violet (CV) and minimum biofilm eradication concentration (MBEC) assays. The effect of sub-MIC concentrations of the formulations on the expression of biofilm-related genes (icaA, icaD) and resistance-related genes (mecA, vanA) was investigated using quantitative real-time polymerase chain reaction (RT-qPCR).ResultsAs demonstrated by MIC, MBC and time-kill assay, the VAN/AMK-UIO-66-NH2@PEG nanoparticles exhibited enhanced antibacterial activity against VRSA isolates compared to free drugs and prepared formulations. Furthermore, CV and MBEC tests indicated that the VAN/AMK-UIO-66@NH2/PEG can reduce biofilm formation dramatically compared to VAN/AMK and VAN/AMK-UIO-66@NH2, due to its great drug release properties. This study also found that the expression level of the mecA, vanA, icaA, and icaD genes in VAN/AMK-UIO-66@NH2/PEG treated VRSA isolates was substantially decreased compared to other groups.ConclusionsThese findings highlighted the efficiency of VAN/AMK-UIO-66@NH2/PEG in combating antimicrobial resistance and biofilm formation in VRSA isolates. Future studies, particularly in vivo models, are necessary to evaluate the safety, efficacy, and clinical applicability of these nanoparticles for the treatment of bacterial infections.

Anti-biofilm and anti-glucosyltransferase effects of nano liposomal plant extracts against Streptococcus mutans

The role of Streptococcus mutans in the initiation of caries is related to its acidogenicity, aciduricity, and polysaccharides extracellular layer production by glucosyltransferases in dental biofilms. Therefore, inhibition of glucosyltransferase activity impairs the virulence of cariogenic biofilms, which can be used to prevent dental caries. We evaluated the anti-bacterial, anti-biofilm, and anti-glucosyltransferases effects of nanoliposomal herbal aqueous extracts of Liquorice (Glycyrrhiza glabra; G. glabra), Ginger (Zingiber officinale; Z. officinale), Pomegranate (Punica granatum; P. granatum), and Rose (Rosa damascene; R. damascene) via minimum bactericidal concentration and minimum inhibitory concentration against Streptococcus mutans strain ATCC 35,668. An anti-biofilm assay was performed using a minimum biofilm inhibitory concentration test. Among herbs, only P. granatum showed an antibacterial effect. Therefore, a nanoliposomal formulation of P. granatum was developed and characterized. Its effect on S.mutans glucosyltransferases was assessed by measuring glucan amount. The nanoliposomal formulation of P.granatum showed a significantly higher anti-biofilm effect than P. granatum aqueous extract. Their similar potential in blocking glucosyltransferases showed that the nanoliposomal formulation of P.granatum blocked other pathways rather than blocking glucosyltransferases for its anti-biofilm effect. Collectively, the nanoliposomal formulation of P.granatum, due to its anti- Streptococcus mutans characteristics, would be a production which open a new horizon for the oral pharmaceutical industry.

Antibacterial Activity and Mechanism of Rose Essential Oil against Aeromonas veronii isolated from Northern snakehead (Channa argus).

To investigate and identify the antibacterial action and mechanism of rose essential oil (REO) against Aeromonas veronii isolated from northern snakehead for the first time by the phenotypic and metabolic analysis. The two-fold broth microdilution and spread-plate method identified that the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of REO against A. veronii were 1.25 μL mL-1 and REO impaired the growth in a concentration-dependent manner, indicating that REO possessed a significant bacteriostatic activity. Electron microscopy and live-dead cell staining found that REO caused a severe disruption of cellular morphology and increased the membrane permeability. Additionally, REO treatment induced the leakage of intracellular biomolecules such as proteins and nucleic acids from the bacteria. Metabolomics analysis showed that compared with the control, the REO treatment group exhibited a total of 190 differential metabolites (118 down-regulated and 72 up-regulated), which involved in the main metabolic pathways such as biotin metabolism, arginine biosynthesis, glutathione metabolism, lysine degradation, and histidine metabolism and the TCA cycle. These results verified that REO disturbed the metabolic processes of A. veronii to achieve the bacteriostatic effect. The REO exhibited the effective antibacterial activity against A. veronii via breaking the cellular structure, increasing the membrane permeation and disrupting the metabolic processes.

The antimicrobial properties of exogenous copper in human synovial fluid against Staphylococcus aureus.

The mechanism by which synovial fluid (SF) kills bacteria has not yet been elucidated, and a better understanding is needed. We sought to analyze the antimicrobial properties of exogenous copper in human SF against Staphylococcus aureus. We performed in vitro growth and viability assays to determine the capability of S. aureus to survive in SF with the addition of 10 µM of copper. We determined the minimum bactericidal concentration of copper (MBC-Cu) and evaluated its sensitivity to killing, comparing wild type (WT) and CopAZB-deficient USA300 strains. UAMS-1 demonstrated a greater sensitivity to SF compared to USA300 WT at 12 hours (p = 0.001) and 24 hours (p = 0.027). UAMS-1 died in statistically significant quantities at 24 hours (p = 0.017), and USA300 WT survived at 24 hours. UAMS-1 was more susceptible to the addition of copper at four (p = 0.001), 12 (p = 0.005), and 24 hours (p = 0.006). We confirmed a high sensitivity to killing with the addition of exogenous copper on both strains at four (p = 0.011), 12 (p = 0.011), and 24 hours (p = 0.011). WT and CopAZB-deficient USA300 strains significantly died in SF, demonstrating a MBC-Cu of 50 µM against USA300 WT (p = 0.011). SF has antimicrobial properties against S. aureus, and UAMS-1 was more sensitive than USA300 WT. Adding 10 µM of copper was highly toxic, confirming its bactericidal effect. We found CopAZB proteins to be involved in copper effluxion by demonstrating the high sensitivity of mutant strains to lower copper concentrations. Thus, we propose CopAZB proteins as potential targets and use exogenous copper as a treatment alternative against S. aureus.

Natural Bactericidal Effects of Psoralea glandulosa Essential Oil for the Control of Bacterial Canker and Speck in Tomato

Bacterial canker and bacterial speck are diseases affecting tomato caused by Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato, respectively. These diseases are considered a serious threat with a strong impact on tomato production and marketing worldwide, especially because of their reduced sensitivity to traditional controls. This work reports the chemical composition of the essential oil (EO) of Psoralea glandulosa and investigates its in vitro antimicrobial activity, along with its main compound, against three strains of Clavibacter michiganensis subsp. michiganensis (CmVC533, CmVLC78, and CmVQ59) and one strain of Pseudomonas syringae pv. tomato (Pst). The results indicate that both the EO and bakuchiol have significant antibacterial capacity, especially the EO, which reaches a minimum inhibitory concentration (MIC) between 4–16 µg/mL and 128 µg/mL, and a minimum bactericidal concentration (MBC) between 8–16 µg/mL and 128 µg/mL for the strains of C. michiganensis subsp. michiganensis and P. syringae pv. tomato, respectively. The EO and bakuchiol also had an inhibitory effect when applied directly onto plates seeded with C. michiganensis subsp. michiganensis. Overall, the results from this study should be verified in the near future by in vivo studies.

Efficient one-pot green synthesis of carboxymethyl cellulose/folic acid embedded ultrafine CeO2 nanocomposite and its superior multi-drug resistant antibacterial activity and anticancer activity.

Due to the prevalence of drug-resistant bacteria and the ongoing shortage of novel antibiotics as well as the challenge of treating breast cancer, the therapeutic and clinical sectors are consistently seeking effective nanomedicines. The incorporation of metal oxide nanoparticles with biological macromolecules and an organic compound emerges as a promising strategy to enhance breast cancer treatment and antibacterial activity against drug-resistant bacteria in various biomedical applications. This study aims to synthesize a unique nanocomposite consisting of CeO2 embedded with folic acid and carboxymethyl cellulose (CFC NC) via a green precipitation method using Moringa oleifera. Various spectroscopic and microscopic analyses are utilized to decipher the physicochemical characteristics of CFC NC and active phytocompounds of Moringa oleifera. Antibacterial study against MRSA (Methicillin-resistant Staphylococcus aureus) demonstrated a higher activity (95.6%) for CFC NC compared to its counterparts. The impact is attributed to reactive oxygen species (ROS), which induces a strong photo-oxidative stress, leading to the destruction of bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CFC NC are determined as 600µg/mL and 1000µg/mL, respectively. The anticancer activity against breast cancer cell resulted in the IC50 concentration of 10.8μg/mL and 8.2μg/mL for CeO2 and CFC NC respectively.The biocompatibility test was conducted against fibroblast cells and found 85% of the cells viable, with less toxicity. Therefore, the newly synthesized CFC NC has potential applications in healthcare and industry, enhancing human health conditions.

Ultrastructural polymicrobial Staphylococcus aureus-Pseudomonas aeruginosa interactions and antimicrobial resistance in ex vivo cornea model.

Aim: To investigate antagonistic interactions among pathogens, in ex vivo donor corneas infected with monomicrobial or polymicrobial combinations of antibiotic susceptible and resistant clinical isolates of Staphylococcus aureus (MSSA, MRSA) and Pseudomonas aeruginosa (S-PA, MDR-PA).Materials & methods: Scanning electron microscopy and antimicrobial susceptibility testing (AST, broth microdilution for minimum inhibitory and bactericidal concentrations [MIC/MBC]) pre-and post-polymicrobial interactions, in infected donor corneas.Results: MSSA lost viability with S-PA/MDR-PA, while MRSA formed larger cells, biofilm and lower MIC (teicoplanin) with S-PA, but lost viability with MDR-PA. S-PA had lower MIC (ceftazidime, meropenem, chloramphenicol) with MSSA, and lower MBC (cefoperazone, ciprofloxacin) and fewer cells with MRSA. MDR-PA had abundant cells and no change in AST with MSSA or MRSA.Conclusion: Significant antagonistic interactions occur in ocular polymicrobial infections, affecting antibiotic susceptible isolates more than resistant ones.

A New Approach to Evaluate the Bactericidal Activity of Different Antiseptic Ophthalmic Preparations Used as Surgical Prophylaxis

Background: A survey conducted by the European Observatory on Cataract Surgery showed high heterogeneity in the use of antiseptics both preoperatively and in the operating room, highlighting the absence of a global consensus regarding ocular infection prophylaxis in cataract surgery. Methods: The antibacterial activity of seven antiseptic ophthalmic formulations (AOFs) registered as medical devices and the two most common disinfectants were evaluated in vitro against five bacterial species. The viability of bacterial strains after exposure to the antiseptic was evaluated with different techniques: the in vitro Minimum Inhibitory Concentration and the subsequent Minimum Bactericidal Concentration, performed on liquid and solid culture medium. Furthermore, a real-time assessment of bacterial viability was conducted using double staining for live/dead bacterial cells by fluorimetric assay. This evaluation was performed on both the time-killing curve and the tear dilution effect test. Results: We observed a high variability across the different AOFs in terms of inhibitory/bactericidal concentration and timing on Gram-positive and Gram-negative bacterial classes. The results indicated that among the tested AOFs, Visuprime, Iodim, and Oftasteril were the most rapid and effective for ocular surface disinfection against the tested bacterial species. Conclusions: The obtained results can support the clinician’s choice of the most suitable AOF for the prevention and treatment of ophthalmic infections associated with surgery.

Antimicrobial, Synergistic, and Antibiofilm Activity of Sildenafil Against Pseudomonas aeruginosa: Preliminary Studies

The present study tested sildenafil citrate as an example of pharmacological repositioning against the opportunistic pathogen Pseudomonas aeruginosa, known for its potent biofilm formation. We evaluated its antimicrobial, synergistic, and antibiofilm effects using broth microdilution, checkerboard assays, and atomic force microscopy techniques. Sildenafil citrate showed antimicrobial activity, effectively inhibiting bacterial growth at minimum inhibitory concentrations ranging from 3.12 to 6.25 mg/mL and minimum bactericidal concentrations between 3.12 and 25 mg/mL. When combined with reference antimicrobial agents—cefepime, imipenem, cilastatin, and polymyxin—sildenafil citrate had a synergistic effect. It also effectively inhibited and eradicated biofilms, reducing total biomass by 87.1% for inhibition and 83.8% for eradication. Atomic force microscopy confirmed the efficacy of sildenafil citrate in destroying and inhibiting biofilms, decreasing the overall amplitude of the biofilm. Consequently, sildenafil citrate appears to be a promising candidate for combination with commercial antimicrobial drugs to prevent and treat P. aeruginosa infections.

Antibacterial Potential of Ethanol Extract from White Pidada (Sonneratia alba) Leaves Against Gastrointestinal Pathogens

The antibacterial properties of the ethanol extract of White Pidada leaves (Sonneratia alba), a mangrove plant rich in bioactive compounds such as phenols, flavonoids, steroids, saponins, triterpenoids, tannins, and alkaloids, were evaluated in this study. The research focused on determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) against gastrointestinal infection-causing bacteria, including Salmonella typhii, Shigella dysenteriae, Escherichia coli, and Vibrio cholerae. The MIC results showed effective inhibition at concentrations as low as 0.025% for Shigella dysenteriae, 0.05% for Salmonella typhii and Vibrio cholerae, and 0.5% for Escherichia coli. The MBC analysis indicated bactericidal activity at higher concentrations, with significant effects observed at 1% for Salmonella typhii, 0.05% for Shigella dysenteriae and Vibrio cholerae, and 0.1% for Escherichia coli. Agar diffusion tests confirmed that increasing extract concentrations correlated positively with the inhibition zone diameter, highlighting the potential of White Pidada leaves as a natural antibacterial agent.

Bio-MOFs Based on Natural Phenolic, Hematoxylin Leverages Biomedical Applications: Enzyme Inhibition, Antioxidant, and Antibacterial Properties.

Here, using natural hematoxylin (HT) as linker, metal-organic frameworks (MOFs) from Cu(II), Fe(II), and Fe(III) ions was prepared. The SEM images and DLS analyses revealed HT-based MOFs are <micrometer sizes with the highest surface area value of 49.2 m2/g for HT-Fe(III) MOFs. Interestingly, HT-based MOFs exhibit fluorescent properties at λem=330 nm with fluorescence intensities of 11485, 2120, and 6790 (a.u) for HT-Cu(II), Fe(II), and Fe(III) MOFs, respectively. Moreover, HT-based MOFs inhibited α-glucosidase enyzme in a concentration-dependent manner e. g., 33.1 %, 69.8 %, and 59.7 % of Cenzyme=500 mg/mL was inhibited by HT-Cu(II)-MOF, HT-Fe(II)-MOF, and HT-Fe(III)-MOFs, respectively. The minimum bactericidal concentration (MBC) values of HT-Cu(II) MOFs for Escherichia coli (gram -), Staphylococcus aureus (gram +), and Candida albicans are determined as 5, 5, and 10 mg/mL, respectively. Also, the antioxidant activities of 250 ppm HT-based MOF based on total phenol content (TPC) tests revealed 279, 208, 124, and 152 mg.gallic acid equivalent/mL (mg GA equivalency/mL) for HT, HT-Cu(II) MOF, HT-Fe(II) MOF, and HT-Fe(III), respectively affirming that antioxidant properties were retained. Moreover, HT-Fe(II) and HT-Fe(III) MOFs (62.5 μg/mL) against human null-1 lung cell line revealed cell viabilities of 98.7±12.2 % and 88.9±11.7 %, respectively as concentration-dependent biocompatibility of MOFs.