The Antimicrobial Activity of Silver Nanoparticles Biosynthesized Using Against Multidrug-Resistant Bacteria Isolated from an Intensive Care Unit.

This study aimed to evaluate the in vitro efficacy of silver nanoparticles (AgNPs) synthesized by bioreduction using lemongrass () essential oil against multidrug-resistant (MDR) bacteria isolated from an Intensive Care Unit (ICU). The essential oil was extracted and characterized by gas chromatography-mass spectrometry (GC-MS). Antioxidant activity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay, and total phenolic content. AgNPs (3 mM and 6 mM silver nitrate) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. Bacterial isolates were obtained from ICU surfaces and personal protective equipment (PPE). The essential oil presented citral A, citral B, and β-myrcene as major components (97.5% of identified compounds). AgNPs at 3 mM showed smaller size (87 nm), lower Polydispersity Index (0.14), and higher colloidal stability (-23 mV). The 6 mM formulation (147 nm; PDI 0.91; -10 mV) was more effective against a strain of spp. resistant to all antibiotics tested. FTIR analysis indicated the presence of O-H, C=O, and C-O groups involved in nanoparticle stabilization. The higher antimicrobial efficacy of the 6 mM formulation was attributed to the greater availability of active AgNPs. The green synthesis of AgNPs using essential oil proved effective against MDR bacteria and represents a sustainable and promising alternative for microbiological control in healthcare environments.