Antimicrobial susceptibility and time-kill analysis of single and combined essential oil blends against clinical and non-clinical isolates of bacteria and fungi

Adukwu, E.C; Edwards-Jones, V

Abstract

The continued emergence of antibiotic resistant bacteria and infection outbreaks in healthcare and community settings has created a need for development of new antibiotics and exploration of alternative therapeutics. Essential oils (EOs) have been identified as a potential alternative for use as antimicrobial agents. EOs are complex mixtures containing various chemical compounds with reports showing antimicrobial, antiviral, anti-inflammatory, and antifungal properties. In this study, EOs of geranium, manuka, lavender and lemongrass in single and combined blends were investigated for antimicrobial activity against a range of Gram positive bacteria, Gram negative bacteria and fungi. Methods: The agar incorporation and broth dilution assays were used in determining the MIC and MBC of the EOs. The time-kill assay was performed to compare the microbicidal activity of the single essential oils and a blend of two essential oils during several time intervals. The compositions of the single and combined EOs blends were characterized by GC-MS. The major components in the EOs were: citral (Lemongrass EO), citronellol and Citronellyl formate (Geranium EO), 3, 5-pyridinedicarbonitrile and 1s-cis-calamene (Manuka EO), Linalool and Linalyl acetate (Lavender EO). Results:The tested EOs demonstrated antimicrobial activity against the gram positive bacteria including the MRSA,Listeria monocytogenes and Enterococcus sp, as well as Candida sp. at concentrations between 4% (v/v) for manuka, geranium and lavender EOs. However, all the Gram negative bacteria were inhibited by Lemongrass EO at MIC concentrations 0.06 and 0.5%. Blending of Lemongrass EO with the other three EOs at a 1:1 ratio, caused a total inhibition of both gram positive and gram negative bacteria with MICs ranging between

• Presentation Conference Type: Poster
• Conference Name: 114th General Meeting of the American Society for Microbiology Conference
• Start Date: May 17, 2014
• End Date: May 20, 2014
• Acceptance Date: Feb 15, 2014
• Peer Reviewed: Not Peer Reviewed
• Public URL: https://uwe-repository.worktribe.com/output/821114
• Additional Information: Title of Conference or Conference Proceedings : 114th General Meeting of the American Society for Microbiology Conference