Evaluation of the Biological Activity of Manganese oxide-Nanoparticles as antibacterial Staphylococcus aureus

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Sarab morad, Laith A. Yaaqoob


Pathogenic strains frequently spread infections by producing virulence factors like potent protein toxins and the expression of a cell-surface protein that binds and inactivates antibodies. Staphylococcus aureus is one of the leading pathogens for deaths linked to antimicrobial resistance and the emergence of antibiotic-resistant strains. There is currently no licenced S. aureus vaccine, despite extensive research and development. Therefore, the aim of this study includes biosynthesize of Manganese oxide-nanoparticles (MnO-NPs) using Lepidium sativum aqueous plant leaves extract, and use of the biosynthesized nanoparticles as antibacterial and antibiofilm against multi-drug resistant S. aureus. 150 samples of both sexes, ranging in age from 1 to 60 years, were randomly selected from 65 male and 85 female patients who had infected burns and wounds at various hospitals. After the final diagnosis of the clinical samples, 20 isolates of Staphylococcus aureus were obtained, then full identification of S. aureus using conventional biochemical tests. The antibiotic susceptibility test for fourteen antibiotics was performed by the standard well diffusion method, The results of the current investigation revealed that all S. aureus isolates varied in their resistance to the 14 antibiotics utilized in this study. Therefore, ten multi-drug resistant isolates of S. aureus were selected and examined their ability to form biofilm using the micro-titter plate method; the results revealed that eight isolates were strong in biofilm formation and two isolates were moderate. Maceration method was used to prepare Lepidium sativum aqueous plant leaves extract. Furthermore, MnO-NPs were prepared from the Lepidium sativum aqueous plant leaves extract and diagnose using ultraviolet (UV) spectroscopy, Field emission Scanning electron microscopy (FE-SEM), atomic fluorescence microscopy (AFM), X-ray scattering (XRD) and Fourier transformation infrared spectroscopy (FTIR). In addition, several experiments were conducted on the nanoparticles, including evaluation of antibacterial activity, biofilm formation and determination of the minimum inhibitory concentration.

       The diagnostic results showed that the nanoparticles are spherical in shape, single or combined, and crystalline for MnO-NPs and an average size of 27.69 nm. As the results showed that the MnO-NPs in concentration of 64 mg/ml was more effective than the MnO-NPs in concentration of 32 mg/ml, which gave the highest inhibition zone value of 19.67 mm. Furthermore, The result of the minimum inhibitory concentration (MIC) values of MnO-NPs on S. aureus isolates  were 1, 2 and 4 mg\ml in various isolates. The results of the anti-biofilm activity on S. aureus isolates showed the MnO-NPs inhibit 100% biofilm formation in concentration 1 mg/ml.

        From the results obtained in this study, several conclusions were concluded as the following, Staphylococcus aureus isolates showed high resistance to All antibiotics used in the study. It can also synthesize of MnO-NPs by extracted from Lepidium sativum aqueous plant leaves, and the synthesized MnO-NPs have significant antibacterial S. aureus agent, it also inhibits of the formation biofilms in S. aureus depending on the concentration used.

       More studies should be conducted about the antibacterial activities of MnO-NPs on the other microorganisms associated with different human infections, and conduct more studies of MnO-NPs on immunological and cancer cell lines due to their effectiveness as an antioxidant.

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