Chemical Composition, Antibacterial and Antibiofilm Activities of Nepeta curviflora Essential Oil Against Drug-Resistant Uropathogens

The global rise of multidrug-resistant (MDR) bacteria and biofilm-associated infections necessitates alternative therapeutic strategies. This study investigates the chemical composition, antibacterial, and antibiofilm activities of Nepeta curviflora essential oil (EO) against Gram-positive and Gram-negative clinical uropathogens, including Extended-Spectrum β-Lactamase (ESBL)-producing strains. The EO was obtained by hydro-distillation and analyzed using GC-MS, which identified 28 compounds representing 94.06% of the total oil—mainly oxygenated monoterpenes (37.26%) and sesquiterpenes (24.11%). Major components included 4aα,7α,7aβ-nepetalactone (15.09%) and 4aα,7α,7aα-nepetalactone (10.04%). The EO showed low to moderate antibacterial activity (Minimum Inhibitory Concentration (MIC) = 12.5–50 µL/mL) and significantly inhibited biofilm formation at sub-MIC levels (Minimum Biofilm inhibitory concentration (MBIC₅₀) = 1.5–6.25 µL/mL), especially in ESBL Escherichia coli and Pseudomonas aeruginosa. The ability to inhibit biofilms at sub-inhibitory concentrations suggests potential interference with quorum sensing. In conclusion, Nepeta curviflora EO exhibits promising antibacterial and antibiofilm activities, particularly against resistant Gram-negative uropathogens. The novelty of this study lies in its comprehensive evaluation of both planktonic and biofilm-inhibitory effects on clinically significant and drug-resistant urinary isolates, supporting the EO's potential as a natural therapeutic agent for managing MDR and biofilm-associated infections.