Evaluation of the single and combined antibacterial efficiency of essential oils for controlling Campylobacter coli, Campylobacter jejuni, Escherichia coli, Staphylococcus aureus, and mixed cultures

Single and combined antibacterial activities of cumin, cardamom, and dill weed essential oils against Campylobacter jejuni, Campylobacter coli, Escherichia coli, Staphylococcus aureus, and mixed cultures were determined by using the broth microdilution method for determining minimum inhibition concentrations. Among the bacteria tested, C. coli and C. jejuni were generally more susceptible to essential oils, with lower minimum inhibition concentrations. The minimum inhibition concentration values were obtained against Gram-negative and Gram-positive bacteria tested within the range of 0.012–15.00 and 3.75–15.00 μL/mL, respectively. Fractional inhibitory concentrations (FICs) were also calculated to evaluate the antimicrobial activities of essential oil combinations. Although the combined effects of essential oils changed depending on the strain and the type of essential oils used, generally the use of combinations increased the efficacy of the essential oils. Interestingly, according to the FIC index, the most synergetic effect was against C. coli and C. jejuni. This study has demonstrated the potential use of cardamom, cumin, and dill weed essential oils, and their combinations, against important pathogenic bacteria and their mixed cultures.