Anti-biofilm activity of essential oils from Salvia abrotanoides leaves and flowers against extensively drug-resistant and multidrug-resistant Acinetobacter baumannii

Acinetobacter baumannii is a formidable nosocomial pathogen whose biofilm production is a key contributor to its multidrug resistance. This study reveals the significant antibacterial and antibiofilm potential of Salvia abrotanoides essential oils (EOs) against MDR and XDR A. baumannii. GC-MS analysis identified 19 novel compounds within the leaf (L-EO) and flower (F-EO) extracts. F-EO exhibited greater potency, inhibiting bacterial growth and biofilm formation at 1.75 mg/mL and 0.9 mg/mL, respectively. At sub-inhibitory concentrations, both EOs caused substantial downregulation (>84%) of the critical biofilm genes bap and csuD, which was visually confirmed by SEM. Cytotoxicity assays on A549 cells showed IC50 values of 1.6 mg/mL (L-EO) and 2.3 mg/mL (F-EO). These findings position S. abrotanoides EOs as a promising therapeutic strategy to combat resilient, biofilm-mediated infections.