Open AccessAntibacterial effects and resistance induction of silver and gold nanoparticles against Staphylococcus aureus ‐induced mastitis and the potential toxicity in rats
Author(s) -
Elbehiry Ayman,
AlDubaib Musaad,
Marzouk Eman,
Moussa Ihab
Publication year - 2019
Publication title -
microbiologyopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.881
H-Index - 36
ISSN - 2045-8827
DOI - 10.1002/mbo3.698
Subject(s) - staphylococcus aureus , antimicrobial , microbiology and biotechnology , antibiotics , minimum inhibitory concentration , mastitis , antibiotic resistance , broth microdilution , chemistry , bacteria , silver nanoparticle , biology , nanoparticle , materials science , nanotechnology , genetics
Staphylococcus aureus ( S. aureus ) is one of the prevalent mastitis‐inducing pathogens worldwide. The resistance of S. aureus to antibiotics is a common issue for dairy farms. Recently, nanoparticles ( NP s) have been used for treating antibiotic‐resistant bacteria. We therefore aimed to investigate the antimicrobial effect of silver and gold NP s (Ag NP s and Au NP s, respectively) and the resistance developed by S. aureus as well as the toxic effects of both NP s in rats. We used 198 S. aureus strains to determine the antibacterial effects of Ag NP s and Au NP s. The microdilution method was used to establish the minimum inhibitory concentrations ( MIC s) of both NP s. To induce resistance, 20 S. aureus strains were passaged 10 times in broth medium with sublethal doses of NP s and an additional 10 times without NP s to examine the stability of resistance. Histopathology was performed after oral administration to the rats with the study doses of 0.25, 0.5, 1, and 2 mg/kg of NP s for 30 days. The MIC s of 10‐nm Ag NP s, 20‐nm Ag NP s, 10‐nm Au NP s, and 20‐nm Au NP s against S. aureus were 14.70 ± 1.19 μg/ml, 9.15 ± 0.13 μg/ml, 24.06 ± 2.36 μg/ml, and 18.52 ± 1.26 μg/ml, respectively. Most strains developed strong resistance when treated with 20‐nm or 10‐nm Ag NP s, whereas only two strains were resistant to 10‐nm Au NP s and three strains to 20‐nm Au NP s. No cross‐resistance between NP s and various antibiotics was identified in any of the adapted S. aureus strains. Organ histopathology revealed that 0.25, 0.5, and 1 mg/kg doses of Ag NP s and Au NP s were not toxic to rat tissue. In contrast, a higher dose (2 mg/kg) of NP s impaired all organs tested. This study demonstrates the antibacterial effects of NP s. S. aureus strains develop resistance less frequently against Au NP s than Ag NP s, and neither Au NP s nor Ag NP s was toxic to rats at low doses.