No induction of antimicrobial resistance in Staphylococcus aureus and Listeria monocytogenes during continuous exposure to eugenol and citral.
The aim of this study was to evaluate the adaptation response of Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and Listeria monocytogenes to the essential oil (EO), eugenol, and citral. The minimum inhibitory concentration of eugenol and citral was determined by agar dilution and microdilution. Adaptation to eugenol and citral was done by sequential exposure of the pathogens to increasing concentrations of the essential oils. The M2-A9 standard was used to determine the antibiotic susceptibility. The effect of eugenol and citral on the adherence ability was evaluated by the crystal violet assay. The impact of adaptation to eugenol on virulence was estimated using the Galleria mellonella model. No development of resistance to the components and antibiotics was observed in the adapted cells of S. aureus, MRSA, and L. monocytogenes. Eugenol and citral at subinhibitory concentration reduced the bacterial adherence. Adaptation to subinhibitory concentration of eugenol affected the virulence potential of S. aureus, MRSA, and L. monocytogenes. Eugenol and citral do not pose a risk of resistance development in a continuous mode of use. These EO components showed a high efficacy as antistaphylococcal and antilisterial biofilm agents. Adaptation at subinhibitory concentration of eugenol protected the larvae against listerial and staphylococcal infection.
IBB-Centro de Biomedicina Molecular e Estrutural, Faculdade de Ciências e Tecnologia, Universidade do Algarve, Faro, Portugal; Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal.
Joana
J
Apolónio
Maria L
ML
Faleiro
Maria G
MG
Miguel
Luís
L
Neto
D000080462:Acyclic Monoterpenes; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D024881:Drug Resistance, Bacterial / Q000187:drug effects; D005054:Eugenol / Q000494:pharmacology*; D006801:Humans; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000502:physiology; D008088:Listeriosis / Q000382:microbiology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000502:physiology; D008826:Microbial Sensitivity Tests; D039821:Monoterpenes / Q000494:pharmacology*; D010938:Plant Oils / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology
D000080462:Acyclic Monoterpenes; D000900:Anti-Bacterial Agents; D039821:Monoterpenes; D010938:Plant Oils; D005054:Eugenol; C007076:citral
adaptation; essential oil; resistance; virulence