Amikacin-loaded selenium nanoparticles improved antibacterial and antibiofilm activity of amikacin against bovine mastitis-causing .

BACKGROUND

Antibiotic resistance in various microorganisms has become one of the most serious health problems worldwide. The use of nanoparticles in combination with conventional antibiotics is one of the recent efforts to overcome these challenges. This study aims to synthesize and evaluate the possibility of using amikacin-loaded selenium nanoparticles as antibacterial agent against multidrug-resistant , that causes bovine mastitis.

METHODS

Selenium nanoparticles (SeNPs) were synthesized through chemical reduction of sodium selenite using L-cysteine. Loading of amikacin on selenium nanoparticles was done by mixing both in solution and confirmed by UV-Vis spectroscopy, XRD, SEM, and DLS. Antibacterial properties of obtained nanoparticles against were determined using agar disc diffusion, broth micro dilution methods and also time-kill assay. Anti-biofilm properties of amikacin-loaded selenium nanoparticles was determined using microplate method and through determining the expression level of biofilm associated genes including A and D in isolates treated with sub-MIC concentration of these nanoparticles by real-time PCR.

RESULTS

Synthetized SeNPs and amikacin-loaded selenium nanoparticles (SeNPs@AMK) exhibited spherical appearances and 80.4 % of Se° had a diameter of 120 nm. SeNPs and SeNPs@AMK exhibited antibacterial effects against isolates at the range of 32-128 μg/mL and 1-32 μg/mL respectively. Dependent on concentration and the exposure time, bacterial killing was promoted by the SeNPs@AMK treatment. The use of SeNPs@AMK decreased the biofilm formation of the isolates by more than 50 % and also lead to down-regulation of and biofilm associated gene compared to the control.

CONCLUSIONS

The results of this study suggest the antimicrobial properties of SeNPs and the reduction in the effective concentration of nanoparticle-loaded amikacin. Therefore, loading of antibiotics on the surface of nanoparticles may be used as a strategy to deal with the growing problem of drug resistance.