ABSTRACT
Background: Multi-drug resistant (MDR) bacteria are seriously endangering the antibiotics. Different alternative strategies are needed to reinforce antibiotics, of, these; nanostructured materials may play a fruitful role. This study aimed to investigate the antibacterial and antibiofilm activity of silver nanoparticles (AgNPs) against MDR bacteria. Methods: In a cross-sectional study, a total of 33 methicillin resistant Staphylococcus aureus (MRSA) and 52 MDR Pseudomonas aeruginosa (P. aeruginosa) isolates were recovered from intensive care units' (ICUs) admitted patients over a period of 9 months, from December 2017 to August 2018. The antibacterial activity of AgNPs on the clinical isolates of MRSA and MDR P. aeruginosa was assessed by minimum inhibitory concentrations (MICs) using broth microdilution method. The minimum bactericidal concentrations (MBCs) were determined as the lowest concentrations required to kill 99.9% of the initial inoculum. Tissue culture plate method was used to evaluate the antibiofilm activity. Results: The MIC and MBC values ranged from 1 to 16 µg/ml and 2 to 64 µg/ml, respectively. Silver nanoparticles exerted a significant antibiofilm activity against MRSA and MDR P.aeruginosa at all tested concentrations, recording a maximum inhibition value of (82%) and (91%), respectively. Conclusions: AgNPs exhibited a considerable antibacterial and antibiofilm, effect; it could represent a promising weapon in the fight against biofilm forming MDR organisms