Green synthesized silver nanoparticles using Sempervivum tectorum extract have an antibacterial effect against Staphylococcus pseudintermedius isolated from a dog's otitis externa

Abstract

Despite developing a broad spectrum of antibiotics, pathogenic bacteria remain the primary health concern. The emergence of drug-resistant strains increased therapeutic failure and mortality. The researchers are currently focusing on developing nanotechnology-based medicines to combat resistance. Our study focuses on the antimicrobial characteristics of plant-mediated silver nanoparticles (Ag NPs). The AgNPs were green synthesized (using thermal treatment) to reduce silver nitrate solution (AgNO₃) using Sempervivum tectorum L. plant ethanolic aqueous extract. They were found to be broad-spectrum antimicrobial agents against two Staphylococcus pseudintermedius strains. We investigated AgNPs' antibacterial activity with time-kill curves, MIC, MBC, and well diffusion. The tests also showed a high activity of the particles against Staphylococcus pseudintermedius, with the minimum inhibitory concentrations ranging between 18.6–90.13 µg/ml. The prepared AgNPs were then characterized using scanning UV-visible spectroscopy, X-ray diffraction, and transmission electronic microscopy (TEM) to study their morphology and crystallinity. Two distinctive absorption peaks of AgNP samples were observed at 474 nm and 487 nm for leaf extract samples, with a spherical shape with face-centered cubic (FCC) crystalline structure and diameter range between 10–60 nm, respectively. The impact was significantly greater when the NPs were less than 30 nm in size. The study revealed that an ethanolic aqueous extract of Sempervivum tectorum L. may effectively reduce and stabilize silver nanoparticles (AgNPs) of various sizes, depending on the solvent concentration. The AgNPs have shown efficacy in both suppressing and eradicating microorganisms. The activity of AgNPs may be facilitated by a dual approach involving several processes of nanoparticles, such as the formation of reactive oxygen species and the presence of phytocompounds such as phenolics and proanthocyanidins bound to the nanoparticle surface. Nanotechnology-based therapies play a crucial role in treating microbial illnesses in veterinary medicine. Significant areas of research on nanoparticles (NPs) could include studying the synergistic interactions between Ag NPs and antibiotics, doing toxicity profiling, examining stability, and investigating bioavailability.