The bioactivity of herbal essential oils and ethanol extracts against Escherichia coli of animal origin
Elevated levels of antimicrobial resistance for bacteria prevalent in food-producing animals represent a major concern for both human and veterinary medicine  and as an alternative for the control and treatment of the bacteria associated pathologies, herbal products are studied [2, 3]. The research investigated activities of different commercial essential oils and/or ethanol extracts of Thymus vulgaris L. (aerial parts), Salvia officinalis L. (leaves), Lavandula officinalis Mill. (flowers), Mentha piperita L. (leaves), Rosmarinus officinalis L. (aerial parts), Ocimum basilicum L. (leaves), Mellisa officinalis L. (leaves), Origanum vulgare L. (aerial parts), Calendula officinalis L. (flowers), Arnica montana L. (flowers), Echinacea purpurea L. (aerial parts), Hypericum perforatum L. (flowers), Hippophae rhamnoides L. (fruits and buds), Coriandrum sativum L. (fruits), Foeniculum vulgare Mill. (fruits), Pelargonium graveolens L. Her (leaves and flowers) against multidrug-resistant E. coli clinical isolates (O101:K28:F5, O8:K25, O9:K35 -bovine mastitis, n=7 and calf diarrhoea, n=3; O141:H4, O138:H1, O139:K82 -swine oedema disease, n=10; O1:K1, O2:K1, O78:K80:F1 -avian colibacillosis, n=20). The antimicrobial potency was established by disc diffusion test. Minimal inhibitory (MIC) and bactericidal (MBC) concentrations were determined based on a broth microdilution method. Some essential oils with inhibitory effects on E. coli growth enhanced the activity of ampicillin against the tested strains (Etest method). The sensitivity of E. coli to essential oils (20–31mm diameter inhibition zones and MIC and MBC values ranging from 0,125% to 2% (v/v)) suggested that some of the screened herbal products should be considered for further in vitro and in vivo assays regarding the therapeutic use in animals.
References: 1. Hammerum, A.M., Heuer, O.E (2009) Clin Infect Dis 48(7):916–21.
2. Delamare, A. et al. (2007) Food Chemistry 100:603–608.
3. Moreira, MR. et al. (2005) LWT 38:565–570.