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There is an increase of pathogenic multidrug-resistant bacteria globally due to the misuse of antibiotics. Recently, more scientists used metal nanoparticles to counteract antibacterial resistance. In this study, orange peel waste (OPW) was used for selenium nanoparticles’ (Se-NPs) biosynthesis through the green and ecofriendly method, and their applications as antibacterial and antibiofilm agents. Green biosynthesized Se-NPs were characterized using FTIR, XRD, SEM, EDAX, and TEM. Characterization results revealed that biosynthesized Se-NPs were highly crystalline, spherical, and polydisperse, and had sizes in the range of 16–95 nm. The biosynthesized Se-NPs were evaluated as antibacterial and antibiofilm activities against multidrug-resistant bacteria. Results illustrated that Se-NPs exhibited potential antibacterial activity against Gram-positive bacteria (S. aureus ATCC 29213 and biofilm-producing clinical isolates of S. aureus) and Gram-negative bacteria (Pseudomonas aeruginosa PAO1, MDR, biofilm, and quorum-sensing and producing clinical isolates of MDR P. aeruginosa, MDR E. coli, and K. pneumonia). Moreover, results illustrated that S. aureus ATCC 29213 was the most sensitive bacteria to Se-NPs at 1000 µg/mL, where the inhibition zone was 35 mm and MIC was 25 µg/mL. Furthermore, Se-NPs at 0.25 and 0.5 MIC decreased the biofilm significantly. The largest inhibition of biofilm was noticed in MDR K. pneumonia, which was 62% and 92% at 0.25 and 0.5 MIC, respectively. In conclusion, Se-NPs were successfully biosynthesized using OPW through the green method and had promising antibacterial and antibiofilm activity against multidrug-resistant bacteria, which can be used later in fighting resistant bacteria.

This study investigates the creation and analysis of chitosan-zinc oxide (CS-ZnO) nanocomposites, exploring their effectiveness in inhibiting bacteria. Two synthesis approaches, physical and chemical, were utilized. The CS-ZnO nanocomposites demonstrated strong antibacterial properties, especially against Staphylococcus aureus , a Gram-positive bacterium. Chemically synthesized nanocomposites (CZ10 and CZ100) exhibited larger inhibition zones (16.4 mm and 18.7 mm) compared to physically prepared CS-Z5 and CS-Z20 (12.2 mm and 13.8 mm) against Staphylococcus aureus . Moreover, CZ nanocomposites displayed enhanced thermal stability, with decomposition temperatures of 281°C and 290°C, surpassing CS-Z5 and CS-Z20 (260°C and 258°C). The residual mass percentages at 800°C were significantly higher for CZ10 and CZ100 (58% and 61%) than for CS-Z5 and CS-Z20 (36% and 34%). UV–Visible spectroscopy revealed reduced band gaps in the CS-ZnO nanocomposites, indicating improved light absorption. Transmission electron microscopy (TEM) confirmed uniform dispersion of ZnO nanoparticles within the chitosan matrix. In conclusion, this research underscores the impressive antimicrobial potential of CS-ZnO nanocomposites, especially against Gram-positive bacteria, and highlights their enhanced thermal stability. These findings hold promise for diverse applications in industries such as medicine, pharmaceuticals, and materials science, contributing to the development of sustainable materials with robust antimicrobial properties.

The continuous increase in antibiotic resistance necessitates a global need to search for new sustainable antimicrobial agents, such as plant-delivered antimicrobial components. This study investigates the antimicrobial and antibiofilm properties of two tannins isolated from the flowers of Jatropha integerrima against multidrug-resistant Klebsiella pneumoniae . The two active tannins were isolated from the methanol-soluble portion of 70% aqueous methanol flower extract, by consecutive column chromatography. Their antimicrobial activity against the resistant K. pneumoniae isolate (BKP-122) was assessed through agar well diffusion and minimum inhibitory concentration (MIC) assays. Their antibiofilm activity was evaluated by using the microtiter plate method and real-time PCR to reveal their effect on the biofilm-associated genes. Their structures were identified as 2 hydrolysable ellagitannins, namely 1- O -galloyl-3,6-( R )-hexahydroxydiphenoyl- D -B 1,4 -glucopyranose (Jatrophenin-1) and 1- O -galloyl-3,6-( R )-valoneoyl- D -B 1,4 -glucopyranose (Jatrophenin-2), together with vicenin-2, acacetin 7- O - β - D -glucopyranoside, ( E )- p -coumaric acid, and sucrose, based on the chromatographic characters, 1 H-, and 13 C NMR analyses. They were found to have potent antimicrobial activity and antibiofilm activity against the resistant K. pneumoniae isolate (BKP-122). Real-time PCR analysis indicated that treatment with tannins resulted in the downregulation of critical biofilm-related genes, including luxS , mrkA , pgaA , wzm , and wbbM . Additionally, the two compounds showed high docking binding scores against Topoisomerase IV, KPLpxH, and β -lactamase enzymes, and stable complexes, as evidenced by binding energy values ranging from -8.2 to -10 kcal/mol. These findings underscore the effectiveness of J. integerrima tannins as a viable therapeutic strategy to combat antibiotic resistance and biofilm-related infections, highlighting their role in modulating bacterial gene expression and biofilm development.

The detection of N-hexanoyl-l-homoserine lactone (C 6 -HSL), a crucial signal in Gram-negative bacterial communication, is essential for addressing microbiologically influenced corrosion (MIC) induced by sulfate-reducing bacteria (SRB) in oil and gas industries. Metal oxides (MOx) intercalated into conducting polymers (CPs) offer a promising sensing approach due to their effective detection of biological molecules such as C 6 -HSL. In this study, we synthesized and characterized two MOx/polyaniline-dodecyl benzene sulfonic acid (PANI-DBSA) nanocomposites, namely ZnO/PANI-DBSA and Fe 2 O 3 /PANI-DBSA. These nanocomposites were applied with 1% by-weight carbon paste over a carbon working electrode (WE) for qualitative and quantitative detection of C 6 -HSL through electrochemical analysis. The electrochemical impedance spectroscopy (EIS) confirmed the composites’ capability to monitor C 6 -HSL produced by SRB-biofilm, with detection limits of 624 ppm for ZnO/PANI-DBSA and 441 ppm for Fe 2 O 3 /PANI-DBSA. Furthermore, calorimetric measurements validated the presence of SRB-biofilm, supporting the EIS analysis. The utilization of these MOx/CP nanocomposites offers a practical approach for detecting C6-HSL and monitoring SRB-biofilm formation, aiding in MIC management in oil and gas wells. The ZnO/PANI-DBSA-based sensor exhibited higher sensitivity towards C 6 -HSL compared to Fe 2 O 3 /PANI-DBSA, indicating its potential for enhanced detection capabilities in this context. Stability tests revealed ZnO/PANI-DBSA's superior stability over Fe 2 O 3 /PANI-DBSA, with both sensors retaining approximately 85–90% of their initial current after 1 month, demonstrating remarkable reproducibility and durability.

Growing data suggest that Aspergillus niger, an endophytic fungus, is a rich source of natural compounds with a wide range of biological properties. This study aimed to examine the antimicrobial and antibiofilm capabilities of the Phragmites australis-derived endophyte against a set of pathogenic bacteria and fungi. The endophytic fungus Aspergillus sp. AP5 was isolated from the leaves of P. australis. The chemical profile of the fungal crude extract was identified by spectroscopic analysis using LC-HRESIMS. The fungal-derived extract was evaluated for its antimicrobial activity towards a set of pathogenic bacterial and fungal strains including Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella sp., Candida albicans, and Aspergillus niger. Moreover, antibiofilm activity toward four resistant biofilm-forming bacteria was also evaluated. Additionally, a neural-networking pharmacophore-based visual screening predicted the most probable bioactive compounds in the obtained extract. The AP5-EtOAc extract was found to have potent antibacterial activities against S. aureus, E. coli, and Klebsiella sp., while it exhibited low antibacterial activity toward P. Vulgaris and P. aeruginosa and displayed anticandidal activity. The AP5-EtOAc extract had significant antibiofilm activity in S. aureus, followed by P. aeruginosa. The active metabolites’ antifungal and/or antibacterial activities may be due to targeting the fungal CYP 51 and/or the bacterial Gyr-B.

Background Klebsiella pneumoniae is a significant healthcare-associated pathogen. We investigated the antimicrobial interaction pattern between zinc sulfate and antibiotics against K. pneumoniae biofilm on the phenotypic and genotypic levels. Methods Determining the minimum biofilm inhibitory concentrations and the transcriptomic profile of K. pneumoniae biofilm formation genes post-treatment were carried out to evaluate the effect on the phenotypic and genotypic levels, respectively. Results Zinc enhanced the antibiofilm potentials of cephalosporins, aminoglycosides, and ertapenem, whereas it antagonizes the effectiveness of fluoroquinolones and meropenem on the phenotypic level. On the molecular level, zinc enhanced the anti-biofilm efficacies of cephalosporins (cefotaxime, ceftriaxone, ceftazidime, cefpirome, and cefepime) via down-regulating the expression of biofilm-related genes by 18-, 38-, 5-, 77- and 2-folds, respectively. Zinc in combination with aminoglycosides (kanamycin, gentamicin, and amikacin) reduced the expression of biofilm-related genes by 40-, 2602- and 20-folds, respectively, and by 2-folds in combination with ertapenem. However, a reduction in the down-regulatory potentials of fluoroquinolones was recorded following combination with zinc by 2-, 2-, 15- and 14-folds, respectively, and an up-regulation in the expression levels of the tested genes by 2-folds in the case of zinc/meropenem combination. Conclusions Results revealed variable interaction patterns between different antibiotics in combination with zinc. Current findings also shed light on the antibiofilm potentials of zinc/antibiotics combinations especially when combining zinc with fluoroquinolones or meropenem to avoid their antagonistic effects.

Background Carbapenem-resistant Pseudomonas aeruginosa (CRPA) represents an escalating healthcare hazard with high mortality worldwide, especially in presence of biofilm. The current study aimed to evaluate the anti-biofilm potentials of ceftazidime, colistin, gentamicin, and meropenem alone and in combinations against biofilm-forming CRPA. Methods Biofilm killing and checkerboard assay were performed to detect the effectiveness of combined antibiotics against biofilms and planktonic cells, respectively. The bacterial bioburden retrieved from the established biofilms following treatment with combined antibiotics was utilized to construct a three-dimensional response surface plot. A sigmoidal maximum effect model was applied to determine the pharmacodynamic parameters (maximal effect, median effective concentration, and Hill factor) of each antibiotic to create a mathematical three-dimensional response surface plot. Results Data revealed statistically significant (p < 0.05) superior anti-biofilm potential in the case of colistin followed by a lower effect in the case of gentamicin and meropenem, while ceftazidime exhibited the least anti-biofilm activity. The fractional inhibitory concentration index (FICI ≤ 0.5) indicated synergism following treatment with the combined antibiotics. An elevated anti-biofilm activity was recorded in the case of gentamicin/meropenem compared to ceftazidime/colistin. Synergistic anti-biofilm potentials were also detected via the simulated pharmacodynamic modeling, with higher anti-biofilm activity in the case of the in vitro observation compared to the simulated anti-biofilm profile. Conclusions The present study highlighted the synergistic potentials of the tested antibiotic combinations against P. aeruginosa biofilms and the importance of the mathematical pharmacodynamic modeling in investigating the efficacy of antibiotics in combination as an effective strategy for successful antibiotic therapy to tackle the extensively growing resistance to the currently available antibiotics.

Nanotechnology is emerging as a new technology with encouraging innovations. Global antibiotic use has grown enormously, with antibiotic resistance increasing by about 80 percent. In view of this alarming situation, intensive research has been carried out into biogenic nanoparticles and their antibacterial, antifungal, and antitumor activities. Many methods are available to enhance stability and dispersion via peroration of conjugate with a polymer, such as chitosan, and other bioactive natural products. Two marine fungi were isolated and identified as Aspergillus sp. and Alternaria sp. via sequencing of the 16S rRNA gene. In this work, these strains were used to form the conjugation of biogenic silver nanoparticles (AgNPs) from Aspergillus sp. Silv2 extract and gold nanoparticles (AuNPs) from Alternaria sp. Gol2 extracts with chitosan to prepare chitosan–AgNPs and chitosan–AuNP conjugates. A variety of imaging and analytical methods, such as UV–vis, X-ray powder diffraction (XRD), FTIR spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were utilized to characterize biogenic nanoparticles and conjugates. The biosynthesized Ag and Au nanoparticles along with the prepared conjugates were evaluated for their antimicrobial effects on Gram-negative and Gram-positive bacterial isolates, including Escherichia coli and Staphylococcus aureus. Both chitosan–AgNP and AuNP showed powerful antimicrobial activities compared to the control. On the other hand, chitosan–AgNP conjugation had better antibacterial ctivity than chitosan–AuNPs, which exhibited moderate activity against S. aureus and very low activity against E. coli. Furthermore, the antibiofilm potentials of the prepared conjugates were tested against four biofilm-forming bacteria, including P. aeruginosa, B. subtilis, E. coli, and S. aureus. The obtained results indicate that the chitosan–AgNP showed a promising anti-biofilm activities on all strains, especially S. aureus, while chitosan–AuNP conjugates showed moderate anti-biofilm against B. subtilis and weak activities against the other three strains. These results showed the superiority of chitosan–AgNP as a promising antibacterial as well as biofilm formation inhibitors.

Background: Quorum sensing (QS) controls the virulence of P. aeruginosa. This study aims to determine the anti-QS activity of aspirin alone and in combination with chitosan to reach maximum inhibition. We tested ten virulent Pseudomonas aeruginosa (P. aeruginosa) isolates and screened for N-acyl homoserine lactone (AHL) production using Agrobacterium tumefaciens as a biosensor. P. aeruginosa isolates were treated with sub-minimum inhibitory concentrations (MICs) of aspirin and chitosan–aspirin. We used broth microdilution and checkerboard titration methods to determine the MICs and the synergistic effect of these two compounds, respectively. Real-time polymerase chain reaction (PCR) was used to estimate the anti-QS activity of the aspirin–chitosan combination on the expression of lasI and rhlI genes. Results: Aspirin decreased the motility and production of AHLs, pyocyanin, and biofilm. Chitosan potentiated the inhibitory effect of aspirin. The chitosan–aspirin combination inhibited lasI and rhlI gene expression in PAO1 (ATCC 15692) by 7.12- and 0.92-fold, respectively. In clinical isolates, the expression of lasI and rhlI was decreased by 1.76 × 102- and 1.63 × 104-fold, respectively. Molecular docking analysis revealed that aspirin could fit into the active sites of the QS synthases lasI and rhlI with a high binding affinity, causing conformational changes that resulted in their inhibition. Conclusions: The chitosan–aspirin combination provides new insights into treating virulent and resistant P. aeruginosa.

In vitro fertilization (IVF) has revolutionized human reproduction. Originally designed to assist couples who are unable to conceive, the clinical applications of IVF have significantly broadened to encompass many medical and genetic disorders, as well as fertility maintenance. The poor ovarian response is a very challenging issue in the field of infertility, \"double triggering\" combines a single bolus of gonadotropic releasing hormone (GnRH)-agonist with a standard dosage of human chorionic gonadotropin (HCG) at the time of triggering has been proposed that it improves the outcomes in poor responders. To study this effect, 73 POR patients received 10,000 units of HCG plus 0.2 mg of GnRH-agonist for ovulation triggering (study group) after induction of ovulation using antagonist protocol, while other 73 POR patients received standard dosage of HCG trigger (10,000 units of HCG) (control group) after the same IOO settings. Our results showed that the study group had a higher number of retrieved Metaphase II oocytes, fertilized oocytes, and number of embryos obtained, than the control group. This difference was statistically significant (P-value < 0.05). Other outcomes like chemical and clinical pregnancy rates were also higher in the study group than in the control group, but this difference was not statistically significant (P-value 0.322 and 0.355, respectively). These findings demonstrated that the use of a double trigger with GnRH agonist and HCG, compared to HCG alone, leads to improved outcomes in poor responder IVF patients. Subsequently, the double-trigger protocol may be a beneficial approach for optimizing outcomes in IVF patients with POR.