Synergistic effect of A novel antimicrobial peptide and silver nanoparticles against drug-resistant P. aeruginosa

Drug-resistant Pseudomonas aeruginosa poses a significant clinical challenge due to its intrinsic antibiotic resistance and the formation of metabolically dormant persister cells. Here, we evaluated the antibacterial and anti-persister activities of a novel 20-amino-acid cationic antimicrobial peptide (RRFFKKAAHVGKHVGKAARR) alone and in combination with silver nanoparticles (AgNPs) against P. aeruginosa PAO1. Minimum inhibitory concentrations (MICs) were determined by broth microdilution (128 µg/mL for the peptide; 8 µg/mL for AgNPs), and checkerboard assays revealed a strong synergistic interaction (fractional inhibitory concentration index (FICI) = 0.25). Treatment of colistin-induced persister populations with the peptide-AgNP combination reduced viable cells by 94.3 ± 2.1% (p < 0.01), markedly outperforming either agent alone. MTT assays in Caco-2 cells demonstrated > 85% viability at concentrations up to the MIC, indicating low host cytotoxicity. Mechanistic insights suggest that membrane disruption by the peptide, coupled with reactive oxygen species (ROS) generation and intracellular interference by AgNPs, underlies the enhanced eradication of both active and dormant bacterial cells. These findings support further in vivo investigation of AMP-AgNP co-therapy as a promising strategy to overcome antibiotic tolerance in P. aeruginosa.