Assessment of the Antibacterial Potential of Biosynthesized Silver Nanoparticles Combined with Vancomycin Against Methicillin-Resistant Staphylococcus aureus–Induced Infection in Rats

Methicillin-resistant Staphylococcus aureus (MRSA) is considered one of the most serious multidrug-resistant bacteria worldwide. MRSA resistance to methicillin antibiotics made vancomycin, the acceptable treatment option. Silver nanoparticles (Ag-NPs) are among the well-known antibacterial substances showing multimode antibacterial action. Therefore, Ag-NPs are appropriate applicants for use in combination with vancomycin in order to augment its antibacterial action. This study aimed to biosynthesize silver nanoparticles and to evaluate its antibacterial activity against MRSA alone and when combined with vancomycin both in vitro and in vivo. Agaricus bisporus is used to reduce the silver nitrate salts in solution to yield silver nanoparticles which was characterized by UV-visible spectrophotometric analysis that shows maximum absorption at 420 nm as a preliminary confirmation for nanoparticles synthesis, Energy-Dispersive Analysis of X-ray (EDX) which confirms the crystalline nature of silver nanoparticles and transmission electron microscopy (TEM) image shows the particles in spherical form with mean size 27.45 nm. The synthesized silver nanoparticles were tested for antibacterial activity against MRSA, and the synergetic effects of the combination of silver nanoparticles and vancomycin were evaluated. The results showed a strong synergistic antibacterial effect between Ag-NPs and vancomycin in vitro with fractional inhibitory concentration 0.37 and in vivo against MRSA strain. The result revealed that mycosynthesized silver nanoparticles (NPs) enhance the in vitro and in vivo antibacterial activity of vancomycin against MRSA. These results suggested that sliver nanoparticles have an effective antibacterial activity against MRSA count, histopathology, and liver enzymes as well as protective immune response specially when combined with vancomycin in the lungs of infected rats with MRSA.