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The problems of drug resistance in bacteria have become one of the daily challenges of the clinical treatment of patients, which inevitably forces us to use agents other than common antibiotics. Among these, we can take help from different properties and applications of nanoparticles (NPs). In this work, we evaluate the antibacterial activity of biosynthesized selenium nanoparticles (SeNPs) against standard strains of multidrug‐resistant Pseudomonas aeruginosa and Acinetobacter baumannii. The production of biosynthesized SeNPs was proved by ultraviolet‐visible, Fourier transform infrared, X‐ray diffractometer, Field Emission Scanning Electron Microscopy, Dynamic light scattering, and Zeta potential methods. The cytotoxicity effect of SeNPs was investigated by MTT assay. Disk diffusion agar (DDA) and minimum inhibitory concentration (MIC) tests were performed on the mentioned bacteria using different classes of standard antibiotics and SeNPs separately. The impact of SeNPs combined with the desired antibiotics for better treatment of these infections was evaluated by checkerboard assay to determine the synergism effect. After the confirmation results based on the biosynthesis of SeNPs, both standard bacterial strains were susceptible to SeNPs and had a zone of inhibition using the DDA test. Also, the results of MICs showed that biosynthesized SeNPs in lower concentrations than antibiotics cause no growth of bacteria. On the other hand, according to the checkerboard assay, SeNPs had a synergistic effect with conventional antibiotics. The antibacterial sensitivity tests demonstrated the inhibition of bacterial growth in the presence of lower concentrations of SeNPs than common antibiotics. This property can be exerted in future applications to solve the drug resistance obstacle of microorganisms in bacterial diseases. [ABSTRACT FROM AUTHOR]

The biosynthesis of nanoparticles stands as an uncomplicated, biocompatible, inexpensive, and secure approach for replacing the available chemical and physical methods. In this paper, Selenium nanoparticles (Se-NPs) and silver nanoparticles (Ag-NPs) were biosynthesized using Nepeta and Berberine plant extracts, respectively. UV–Vis, FT-IR, and FESEM/EDAX techniques were applied for confirming the synthesis of nanoparticles. In addition, the method of Minimum Inhibitory Concentration (MIC) was utilized to perform a sensitivity test on fungal species' leachates through the usage of Duplicate. The application biosynthesized Se-NPs and Ag-NPs at concentrations of 1 µg/mL and below caused no growth of fungal agents. However, antifungal drugs at concentrations higher than 1 µg/mL and even up to 64 µg/mL inhibited the growth of these drug-resistant fungi. A comparison of the results showed that even these nanoparticles in some cases have a better effect than the group of antifungal drugs. Therefore, the usage of biosynthesized nanoparticles is considered to be more convenient and economical due to the increasing drug resistance of opportunistic and pathogenic microorganisms towards the exerted target drugs. [ABSTRACT FROM AUTHOR]