Multi drug control of ESKAPE pathogens by using silver nanoparticles produced by Pseudomonas putida

Despite increasing concerns about antimicrobial resistance among ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.), limited studies in Iraq have examined the antimicrobial effects of silver nanoparticles (AgNPs). This study evaluated biogenically synthesized silver nanoparticles using a cell-free extract of Pseudomonas putida combined with antibiotics against 83 ESKAPE pathogen isolates and efflux pump activity. The biogenic AgNPs were characterized by Ultraviolet-Visible (UV) spectroscopy, X-Ray Diffractometry (XRD), Fourier Transform Infrared (FT‑IR) spectroscopy, Transmission Electron Microscopy (TEM), and Field Emission Scanning Electron Microscopy (FESEM). Combining AgNPs with amoxicillin, nitrofurantoin, levofloxacin, and erythromycin enhanced antibacterial activity against all tested pathogens. Significant enhancement was observed with erythromycin against E. faecium (13.5 mm increase) and amoxicillin against P. aeruginosa (16.6 mm increase), and the differences were statistically significant (p < 0.001). Efflux pump activity was found in 50/83 (60.2%) isolates, and all 50 (100%) showed enhanced EtBr fluorescence after AgNPs treatment, indicating reduced efflux. This study suggests that AgNPs are efficient antimicrobials and adjuvants against multidrug-resistant (MDR) pathogens. Further investigations are required to determine clinical efficacy and safety.