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The World Health Organization has identified Acinetobacter baumannii as the most threatening multidrug-resistant pathogen, necessitating the development of new antimicrobial agents. In this study, the antibacterial, anti-adhesion, and antibiofilm activities of Eryngium ilicifolium against carbapenem resistant A. baumannii were investigated, alongside its impact on surface physicochemical properties. Among the extracts tested, only the Soxhlet diethyl ether extract exhibited effectiveness, with inhibition diameters ranging from 20.7 to 23.3 mm, and minimum inhibitory and bactericidal concentrations between 0.156 and 0.625 mg/ml. The anti-adhesion assay of this extract yielded promising results, showing inhibition percentages between 0.92% and 29.24%. However, the extract was active against only one strain of biofilm. Moreover, treatment with E. ilicifolium did not alter the hydrophobic nature of the surface. Nevertheless, the E. ilicifolium extract demonstrated significant efficacy against A. baumannii in planktonic form and could potentially serve as an effective preventive strategy against biofilm formation. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the antibacterial and antibiofilm activities of Lavandula mairei and Thymus leptobotrys essential oils against Extended spectrum β-lactamase producing Enterobacteriaceae, responsible of nosocomial infections. PCR and sequencing methods detected three different resistance genes (blaSHV-42, blaSHV-12 et blaCTXM-15) in the studied strains. Gas chromatography-mass spectrometry analysis highlighted the predominance of carvacrol in both Lavandula mairei and Thymus leptobotrys essential oils. Their antibacterial activity was conducted by disk diffusion and microdilution methods. Great sensitivity of the multidrug resistant strains was noted for the two essential oils with inhibition zones' diameters ranging from 13.3±2.3 to 32.3±1.4 mm (Thymus leptobotrys) and from 22 to 34.66±0.57 mm (Lavandula mairei), and low minimal and bactericidal concentrations varying from 1.56 to 6.25 mg/mL (CMI) and from 1.56 to 12.5 mg/mL (CMB) for both essential oils. Four strains out of six, considered as the strongest biofilm producers by congo red agar and crystal violet methods, were chosen to evaluate biofilm inhibition and eradication effects of Lavandula mairei and Thymus leptobotrys essential oils. In most cases, these latter inhibited considerably the biofilm formation of the targeted strains with proportions greater than 80%. The eradication effect was lower, with rates not higher than 50%. Thus, these essential oils could be used as an effective alternative approach to prevent biofilm formation of multidrug resistant Enterobacteriaceae. To our knowledge, no previous works have reported the antibiofilm activity of Lavandula mairei and Thymus leptobotrys essential oils against these multidrug resistant bacteria. [ABSTRACT FROM AUTHOR]