Study of the In Vitro Antibacterial Activity of Blue Light Activated Curcumin and Curcumin-Silver Nanoparticles on Methicillin Resistant Staphylococcus aureus and Multidrug Resistant Pseudomonas aeruginosa

Background: S. aureus and P. aeruginosa are critical nosocomial pathogens that cause various wound infections. They have become a global concern due to their high resistance to many antibiotics. Thus, PDT and nanoparticles represent promising alternative antimicrobial strategies. Objectives: This study aims to evaluate the antimicrobial effect of PDT in combination with Curcumin, AgNPs and CurAgNPs against MDR p. aeruginosa and MRSA. Methodology: Specimens were collected from wound infections at Tanta University Hospital. P. aeruginosa and S. aureus isolates were identified using conventional methods. The antibiogram of the isolates was investigated. The MICs of each tested material were determined using the broth microdilution method in sterile 96-well microtiter plates. Results: For MRSA and MDR P. aeruginosa, MIC values were significantly lower for AgNPs and CurAgNPs compared to Curcumin (p1 < 0.001, p2 < 0.001), indicating enhanced antibacterial efficacy. The MICs of CurAgNPs were significantly lower than AgNPs (p value = 0.009 for P. aeruginosa and p value = 0.021 for MRSA), supporting synergism upon combination. AgNPs and CurAgNPs exhibited significantly lower MICs against MDR P. aeruginosa than MRSA (p value < 0.001), indicating greater efficacy of these formulations against Gram-negative isolates under PDT conditions. Conclusions: AgNPs demonstrated significantly higher antimicrobial activity than Curcumin. CurAgNPs achieved the most potent antibacterial effect, demonstrating a strong synergistic interaction. AgNPs and CurAgNPs were significantly more effective against MDR P. aeruginosa than MRSA. These combinations represent promising alternatives for treating infections caused by these multidrug-resistant pathogens.