Biogenic Synthesis of Selenium and Copper Oxide Nanoparticles and Inhibitory Effect against Multi-Drug Resistant Biofilm-Forming Bacterial Pathogens.

Antimicrobial resistance (AMR), caused by microbial infections, has become a major contributor to morbid rates of mortality worldwide and a serious threat to public health. The exponential increase in resistant pathogen strains including Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) poses significant hurdles in the health sector due to their greater resistance to traditional treatments and medicines. Efforts to tackle infectious diseases caused by resistant microbes have prompted the development of novel antibacterial agents. Herein, we present selenium and copper oxide monometallic nanoparticles (Se-MMNPs and CuO-MMNPs), characterized using various techniques and evaluated for their antibacterial potential via disc diffusion, determination of minimum inhibitory concentration (MIC), antibiofilm, and killing kinetic action. Dynamic light scattering (DLS), scanning electron microscopy (SEM/EDX), and X-ray diffraction (XRD) techniques confirmed the size-distribution, spherical-shape, stability, elemental composition, and structural aspects of the synthesized nanoparticles. The MIC values of Se-MMNPs and CuO-MMNPs against S. aureus and E. coli were determined to be 125 µg/mL and 100 µg/mL, respectively. Time-kill kinetics studies revealed that CuO-MMNPs efficiently mitigate the growth of S. aureus and E. coli within 3 and 3.5 h while Se-MMNPs took 4 and 5 h, respectively. Moreover, CuO-MMNPs demonstrated better inhibition compared to Se-MMNPs. Overall, the proposed materials exhibited promising antibacterial activity against S. aureus and E. coli pathogens.

Fungus-mediated synthesis of Se-BiO-CuO multimetallic nanoparticles as a potential alternative antimicrobial against ESBL-producing Escherichia coli of veterinary origin.

Bacterial infections emerge as a significant contributor to mortality and morbidity worldwide. Emerging extended-spectrum ß-lactamase (ESBL) Escherichia coli strains provide a greater risk of bacteremia and mortality, are increasingly resistant to antibiotics, and are a major producer of ESBLs. E. coli bacteremia-linked mastitis is one of the most common bacterial diseases in animals, which can affect the quality of the milk and damage organ functions. There is an elevated menace of treatment failure and recurrence of E. coli bacteremia necessitating the adoption of rigorous alternative treatment approaches. In this study, Se-Boil-CuO multimetallic nanoparticles (MMNPs) were synthesized as an alternate treatment from Talaromyces haitouensis extract, and their efficiency in treating ESBL E. coli was confirmed using standard antimicrobial assays. Scanning electron microscopy, UV-visible spectroscopy, and dynamic light scattering were used to validate and characterize the mycosynthesized Se-BiO-CuO MMNPs. UV-visible spectra of Se-BiO-CuO MMNPs showed absorption peak bands at 570, 376, and 290 nm, respectively. The average diameters of the amorphous-shaped Se-BiO-CuO MMNPs synthesized by T. haitouensis extract were approximately 66-80 nm, respectively. Se-BiO-CuO MMNPs (100 µg/mL) showed a maximal inhibition zone of 18.33 ± 0.57 mm against E. coli. Se-BiO-CuO MMNPs also exhibited a deleterious impact on E. coli killing kinetics, biofilm formation, swimming motility, efflux of cellular components, and membrane integrity. The hemolysis assay also confirms the biocompatibility of Se-BiO-CuO MMNPs at the minimum inhibitory concentration (MIC) range. Our findings suggest that Se-BiO-CuO MMNPs may serve as a potential substitute for ESBL E. coli bacteremia.