Green-synthesized magnetic core-shell NiFe2O4@Ag nanoparticles enhance antibiotic efficacy against nosocomial pathogens

Nosocomial infections pose a significant threat to patient health and healthcare systems globally. This study explores the synergistic potential of green-synthesized NiFe2O4@Ag core-shell nanoparticles in enhancing the efficacy of conventional antibiotics against multidrug-resistant nosocomial pathogens. The NiFe2O4@Ag nanoparticles were synthesized using a green method and characterized by X-ray diffraction (XRD), revealing particle sizes of 36.4 nm for NiFe2O4 and 51.54 nm for NiFe2O4@Ag. The antibacterial activity of these nanoparticles was evaluated alone and in combination with antibiotics—ciprofloxacin, tetracycline, and chloramphenicol—against five antibiotic-resistant bacterial strains associated with nosocomial infections, including Gram-negative Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae, as well as Gram-positive Staphylococcus aureus. NiFe2O4@Ag nanoparticles exhibited potent antimicrobial activity, with minimum inhibitory concentration (MIC) values of 256–512 mg/L). Notably, the combination of NiFe2O4@Ag nanoparticles with chloramphenicol and ciprofloxacin resulted in fractional inhibitory concentration index (FICI) values ranging from 0.25 to 0.75, indicating significant synergistic or additive effects, against most of tested gram-negative pathogens. While combination of NiFe2O4@Ag with ciprofloxacin exhibited the strongest enhancement, no synergistic effects were observed using NiFe2O4@Ag nanoparticles and tetracycline combinations for most tested pathogens (except for E. coli). The core-shell structure of NiFe2O4@Ag nanoparticles effectively integrates the magnetic properties of NiFe2O4 with the antimicrobial activity of silver, enabling potential magnetic separation and reducing environmental impact. Additionally, the nanoparticles exhibited low cytotoxicity in HFF-2 cells, suggesting good biocompatibility. These findings highlight the potential of NiFe2O4@Ag nanoparticles as a promising therapeutic strategy to combat multidrug-resistant nosocomial pathogens.