Efficacy of green synthesis of Silver nanoparticles from Tulsi (Ocimum sanctum) leaf aqueous extract and its antibacterial effect on clinical multidrug-resistant Staphylococcus aureus in West Bengal

Rapid augmentation in the prevalence of multidrug-resistant (MDR) Staphylococcus aureus is a worldwide threat. Advising newer antibiotics may fail to reduce the chances of the emergence of newer drug-resistant Staphylococcus aureus. Very little shreds of evidence can be found to treat clinical MDR Staphylococcus aureus with biogenic silver nanoparticles (AgNPs) in West Bengal. To prepare AgNPs biogenically using aqueous tulsi leaf extract (TLE) and also to assess its antibacterial effect upon clinical MDR Staphylococcus aureus, biogenic synthesis of the AgNPs using aqueous TLE was done, characterized those with UV-Vis Spectrophotometer, dynamic light scattering, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and evaluated the antibacterial activity against the clinical MDR Staphylococcus aureus. ANOVA followed by LSD post hoc test was used to test the differences between the OD (optical density) of different experimental sets. The biosynthesized AgNPs were spherical, monodispersed, and of smaller size (9-23 nm) with the involvement of eugenol, quercetin, and oleanolic acid present in the tulsi leaf. A significant change in OD was observed in AgNPs (prepared using TLE) treated broth compared to only tulsi leaf extract treated culture. There was a significant similarity between the efficacies of AgNPs and clindamycin (P 0.05). Our findings propose that AgNPs synthesized using TLE were fast and efficient to ameliorate the bacterial growth, which may be used as a potent antibacterial agent for the treatment of clinical MDR Staphylococcus aureus infection in near future.