Comparison of the Effect of Silver Nanoparticles Biosynthesized with Lavandula angustifolia Extract and Lavender Essential Oil Against Multidrug-Resistant and Biofilm-Forming Staphylococcus Species.

Background: Multidrug-resistant and biofilm-forming staphylococci pose a threat to the sustainability of public health, livestock health and the ecosystem. Pathogenic potential with a worsening prognosis of therapy is mainly due to methicillin-resistant Staphylococcus aureus (MRSA) or multidrug-resistant Non-aureus staphylococci and mammaliicocci (NASM). Alternative approaches based on the use of biosynthesized nanoparticles or substances of natural origin appear to be promising solutions to the problem of ineffective suppression of infections caused by pathogenic microorganisms. Methods: The aim of this study was to monitor and compare the biological effects of silver nanoparticles prepared by green synthesis using Lavandula angustifolia and lavender essential oil. In particular, the antibacterial, antibiofilm, and biofilm-eradicating effects against biofilm-forming and multidrug-resistant reference strains and field isolates of staphylococci were monitored. Results: AgNPs inhibited the growth and formation of biofilms of S. aureus strains at a concentration of 0.05 μg/μL, but clinical NASM at 0.025 μg/μL. Sensitivity to Lavender essential oil (LEO) was the same against all tested staphylococcal strains, with an antibacterial MIC of 0.901 μg/μL. The essential oil also had an effect on biofilm formation against all tested strains, but its effect was recorded at a tenfold lower concentration (antibiofilm MIC = 0.0901 μg/μL). No eradication activity was recorded for either tested substance. Their activity against the formed biofilms was not recorded. Conclusions: The results demonstrate promising antibacterial and antibiofilm activities of biosynthesized AgNPs and lavender essential oil under in vitro conditions. These findings support further investigation of these materials as potential alternative antimicrobial approaches, particularly in combination with conventional antimicrobial agents.