Inhibition of Biofilm Formation by Terpenes from Oregano () Essential Oil.

is a nosocomial pathogen known for its ability to form biofilms, leading to persistent infections and antibiotic resistance. The limited effective antibiotics have encouraged the development of innovative strategies such as using essential oils and their constituents. This study evaluated the efficacy of oregano () essential oil (OEO) and its terpene compounds, carvacrol and thymol, in inhibiting biofilms. These treatments showed a minimum inhibitory concentration of 0.6, 0.3, and 2.5 mg/mL and a minimum bactericidal concentration of 1.2, 0.6, and 5 mg/mL, respectively. Sub-inhibitory doses of each treatment and the OEO significantly reduced biofilm biomass and the covered area of biofilms as measured by fluorescence microscopy. Carvacrol at 0.15 mg/mL exhibited the most potent efficacy, achieving a remarkable 95% reduction. Sub-inhibitory concentrations of carvacrol significantly reduced the biofilm formation of in stainless steel surfaces by up to 1.15 log CFU/cm compared to untreated bacteria. The OEO and thymol exhibited reductions of 0.6 log CFU/cm and 0.4 log CFU/cm, respectively, without affecting cell viability. Moreover, the terpenes inhibited twitching motility, a crucial step in biofilm establishment, with carvacrol exhibiting the highest inhibition, followed by OEO and thymol. The study provides valuable insights into the potential of terpenes as effective agents against biofilms, offering promising avenues for developing novel strategies to prevent persistent infections and overcome antibiotic resistance.