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.