The Combating Impact of Biogenic Silver Nano Particles and Antibiotics on Combating Multidrug-Resistant Pseudomonas

Abstract

This study aimed to assess the synergistic effect of silver nanoparticles (AgNPs) in combination with different antibiotics against multidrug-resistant Pseudomonas aeruginosa (MDR P. aeruginosa) infections. A total of 120 surgical or burn wound samples were collected from a tertiary care hospital. The samples were cultured on cetrimide agar plates and then heated to 370 degrees Celsius. The isolates were identified based on colony shape, Gram's staining, and various biochemical tests. The antibiotic susceptibility profile was determined using the Kirby-Bauer disc diffusion technique according to CLSI 2022 recommendations. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were also determined. The antibacterial activity of AgNPs was evaluated using the agar well diffusion technique and the microdilution method. The synergistic effect of antibiotics and AgNPs was assessed using the Checkerboard method. Out of the 120 samples, 46 (38.8%) were confirmed as positive for P. aeruginosa, and among them, 33 were identified as MDR P. aeruginosa. Seven representative isolates were selected for further analysis. The antibacterial activity of AgNPs showed a maximum zone of inhibition of 12mm at 4mg/ml and a minimum of 2.5mm at 1mg/ml using the agar well diffusion method. The MIC and MBC of AgNPs indicated that all isolates were inhibited at a concentration of 250mg/ml. The Checkerboard results revealed that colistin and gentamicin exhibited complete synergism with AgNPs, while ciprofloxacin showed partial synergism with AgNPs.