Ursolic Acid Loaded Chitosan Coated Silver Nanoparticles Exhibits Robust Antibacterial Activity Against Drug Resistant Nosocomial Pathogens: Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli, and Klebsiella peumoniae

The increasing emergence and dissemination of nosocomial bacterial pathogens warrant the discovery of new antibiotics. Therefore, the present study was carried out to synthesize ursolic acid (U) loaded chitosan-capped silver nanoparticles (U-C@AgNPs) to evaluate its antimicrobial and anti-inflammatory potential. The synthesized U-C@AgNPs were characterized with UV-Spectra, DLS, FTIR, and SEM. It showed a minimum inhibitory concentration between 6.25 and 12.5 μg/ml and a minimum bactericidal concentration between 6.25 and 25 μg/ml against drug-resistant nosocomial pathogens, P. aeruginosa, E. faecalis, E. coli, and K. peumoniae. Moreover, the antibiofilm activity of the synthesized U-C@AgNPs was also assessed against P. aeruginosa and K. pneumoniae. In the pre-treatment method, concentration-dependent significant inhibition of the biofilm development was reported against P. aeruginosa (73.53%) and K. pneumoniae (81.86%) at 30 μg/ml and in the post-treatment method; the highest inhibition was observed at 100 μg/mL against P. aeruginosa biofilm (86.37%) and K. pneumoniae biofilm (85.97%) as compared to individual bacterial control. Further, the fluorescence staining test for live/dead bacterial viability confirmed that 100 µg/ml effectively inhibits the biofilm formed by P. aeruginosa and K. pneumoniae. Moreover, no cytotoxicity of U-C@AgNPs was observed in the THP-1 cell line. C@AgNPs also exhibited anti-inflammatory activity by inhibiting the expression of proinflammatory cytokines (TNF-α, IL-6, IL-1β, and IFN-γ) in lipopolysaccharide-treated THP-1 differentiated macrophages. This study concludes that U-C@AgNPs exhibit solid antimicrobial, antibiofilm, and anti-inflammatory activity and may be developed as a promising antimicrobial agent for treating nosocomial pathogens.