title: Antimicrobial activity of essential oils and five terpenoid compounds against Campylobacter jejuni in pure and mixed culture experiments.
abstract: The aim of this study was to examine the antimicrobial potential of three essential oils (EOs: tea tree oil, lemon myrtle oil and Leptospermum oil), five terpenoid compounds (α-bisabolol, α-terpinene, cineole, nerolidol and terpinen-4-ol) and polyphenol against two strains of Campylobacter jejuni (ACM 3393 and the poultry isolate C338), Campylobacter coli and other Gram negative and Gram positive bacteria. Different formulations of neem oil (Azadirachta indica) with these compounds were also tested for synergistic interaction against all organisms. Antimicrobial activity was determined by the use of disc diffusion and broth dilution assays. All EOs tested were found to have strong antimicrobial activity against Campylobacter spp. with inhibitory concentrations in the range 0.001-1% (v/v). Among the single compounds, terpinen-4-ol showed the highest activity against Campylobacter spp. and other reference strains. Based on the antimicrobial activity and potential commerciality of these agents, lemon myrtle oil, α-tops (α-terpineol+cineole+terpinen-4-ol) and terpinen-4-ol were also evaluated using an in vitro fermentation technique to test antimicrobial activity towards C. jejuni in the microbiota from the chicken-caecum. EO compounds (terpinen-4-ol and α-tops) were antimicrobial towards C. jejuni at high doses (0.05%) without altering the fermentation profile. EOs and terpenoid compounds can have strong anti-Campylobacter activity without adversely affecting the fermentation potential of the chicken-caeca microbiota. EOs and their active compounds may have the potential to control C. jejuni colonisation and abundance in poultry.
authors.affiliation: CSIRO Animal, Food and Health Sciences, Queensland Biosciences Precinct, 306 Carmody Road, St Lucia, QLD 4067, Australia; School of Agriculture and Food Sciences, The University of Queensland, Gatton, QLD 4343, Australia.
authors.forename: Cemil
authors.initials: C
authors.lastname: Kurekci
authors.forename: Jagadish
authors.initials: J
authors.lastname: Padmanabha
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Bishop-Hurley
authors.forename: Errol
authors.initials: E
authors.lastname: Hassan
authors.forename: Rafat A M
authors.initials: RA
authors.lastname: Al Jassim
authors.forename: Christopher S
authors.initials: CS
authors.lastname: McSweeney
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D016123:Campylobacter jejuni / Q000187:drug effects*; D002645:Chickens / Q000382:microbiology; D005285:Fermentation; D006094:Gram-Positive Bacteria / Q000187:drug effects; D008460:Meat / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D009822:Oils, Volatile / Q000494:pharmacology*; D013729:Terpenes / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D009822:Oils, Volatile; D013729:Terpenes
keywords: Antimicrobial activity; Campylobacter jejuni; Essential oils